Dutch agriculture faces challenges due to cutbacks on derogation limiting manure and fertilizer application and a focus on nutrient-contaminated areas. To maintain crop quality, farmers are seeking methods to achieve the same or higher yields with less nutrient input. We are testing various tools to gain insight into the nutrient availability in the soil and leaf juice. Together they provide information on how successful the current nutrient management is and if further nutrient application is necessary.  Using this information the farmer can make improvements in their nutrient management system. 

Satellite images offers tools for improving nitrogen use efficiency and reduce environmental impact. By using satellite-derived vegetation indices, farmers can monitor crop vigor and detect nitrogen deficiencies, especially during key growth stages like V6-V8 and pre-tasseling. Combined with weather forecasts and soil data, satellite insights help farmers fine-tune timing and dosage. 
Instead of applying a uniform nitrogen dose across an entire field, satellite biomass maps can help identify zones with lower growth or chlorophyll content. These areas may require additional nitrogen, while well-performing zones may need less. This variable rate application (VRA) approach reduces input costs and minimizes leaching risks. For example, a farmer using satellite imagery notices a drop in NDVI in the northern part of a maize field during the vegetative stage. Ground truthing confirms nitrogen stress. The farmer then adjusts the fertilization plan, applying an extra 30 kg/ha of nitrogen only in the affected zone. This targeted action improves yield in that area without over-fertilizing the rest of the field.
 

Drones equipped with multispectral or RGB sensors enable high-resolution monitoring of potato crops, identifying spatial variability in nutrient status through vegetation indices like NDVI. These indices help detect early signs of nutrient deficiencies, particularly nitrogen, phosphorus, and potassium. By integrating drone data into GIS-based prescription maps, farmers can apply variable-rate fertilization with greater accuracy. This targeted correction reduces input costs, optimizes nutrient uptake, and improves yield uniformity. The expected outcomes include enhanced nutrient use efficiency, lower risk of over-fertilization, and environmental benefits. For implementation, drone flights should be scheduled during key growth stages (canopy closure) and combined with calibrated field sampling to validate remote sensing data. Adoption is especially beneficial on medium to large farms with access to VRA equipment. This precision approach supports data-driven decision-making and improves the agronomic and economic performance of potato production.

Potato tuber analysis is an important tool for optimising fertilisation, ensuring balanced nutrient supply, and improving yield quality. By assessing nutrient concentrations in tubers, farmers can adjust fertilisation strategies to correct deficiencies and avoid excesses, enhancing nutrient use efficiency and sustainability. However, tuber analysis should be combined with soil and leaf analysis for a complete understanding of nutrient dynamics. While soil analysis determines nutrient availability and leaf analysis reflects real-time plant uptake, tuber analysis evaluates the final nutrient accumulation in the harvested crop. Differences between soil, leaf, and tuber nutrient levels can indicate uptake inefficiencies or nutrient translocation issues. This integrated approach supports site-specific fertilisation, improving crop health, reducing environmental impact, and lowering production costs. 

Accurate measurements of yield are important for: reviewing the success of nutrient management strategies, understanding a sites expected yield and also when calculating harvested nutrient offtakes. Utilising weighbridges and/or combine yield mapping is more accurate than relying on the bulk sale of produce from storage sheds. 

Key principles for using weighbridges to weigh trailer loads of harvested grain include: 1) measure an accurate harvested area. 2) accurately weigh trailers before and after harvest. 3) measuring the moisture content (MC) of harvested grain. Yield (t/ha @ standard MC) = Net weight of harvested grain (tonnes)/area harvested (Hectares)*(100-measured grain MC)/standard grain MC).

Key principles for using yield mapping to estimate yield include: 1) Calibrate the yield monitor according to the manufacturer’s instructions. Ideally test the yield monitor against harvested grain weights over a weighbridge as above. 2) If measuring harvested area with the combine yield monitor, avoid non-full headers and try to keep to a constant speed. 3) Ensure that the yield is corrected to the right moisture content for the crop.

Soil Nitrogen Supply (SNS) is a measure of the nitrogen (N) available to the crop  from the soil. The N fertilisation rate for a crop can be calculated as the difference between the total N requirement for the crop and the SNS. SNS includes a) the soil mineral N, b) the potential N that may continue to be mineralised, c) the amount of N already capatured by the growing crop (Figure 1).

Estimates of crop N uptake should occur at the time when soil mineral and potentially mineralisable N are estimated. Methods include the following:

1) Estimating crop N uptake using plant biomass.  This can be performed by either estimating the number of shoots/m2 or the Green Area Index (GAI). 
2) Measuring crop N uptake using commercial lab analysis. A quadrat can be used to collect a known area of plant material to convert  the N concentration to kg N/ha.

3) Remote sensing based estimations of crop N uptake using satelite data or drone data. Several online platforms or apps provide biomass imagery, and someprovide  an estimation of crop N content.

In each case it is important that estimates of crop N uptake are added to estimates of SMN and further potential mineralisable N to calculate SNS.

A variable rate fertilization plan allows you to accurately determine how much fertilizer is needed in specific areas of the field, taking into account the results of soil tests. This helps to avoid over-fertilization or under-fertilization. When fertilizing with variable rates, the optimal amount of mineral fertilizers helps plants receive the necessary amount of nutrients, and therefore the quality and quantity of the harvest. 
On the farm of the Kėdainiai Plant Nutrition Club (CNC), after testing the soil and starting to use plant fertilization with a variable PK rate, potash fertilizers were saved.
Previously, farmers would purchase potash fertilizers by calculating the potassium (K2O) requirement based on the planned crop yield. Soil testing revealed that there were significant amounts of mobile potassium in the soil. Variable rate fertilization allowed for the uniform distribution of bulk fertilizers, both in terms of the respective amounts of PK in the soil in different fields and in individual areas of the fields, resulting in more uniform plant development and lower cultivation costs, saving on potash fertilizers.

Since 2023, the Netherlands has designated “nutrient-polluted areas” based on surface water data showing excess nitrogen or phosphorus. In these areas, nitrogen application standards are reduced by 20%. For certain crops, this brings fertilization below agronomic minimums, leading to nutrient shortages and reduced yields. To cope, farmers apply less slurry and more solid manure combined with mineral fertilizer. Solid manure benefits soil health, but its nitrogen release is irregular and less predictable. This unpredictability causes temporary nitrogen deficits during key growth phases. As a result, precise and timely application of mineral fertilizer is crucial to compensate for these dips and maintain crop performance. This shift requires better monitoring of soil nutrient dynamics and more adaptive, data-driven fertilization strategies throughout the season. Balancing regulatory compliance with crop needs has become increasingly complex in nutrient-polluted zones, requiring both innovation and flexibility from farmers.

In acidic soils, liming helps neutralize soil acidity by increasing the pH value, and also increases the amount of nutrients available to plants in the soil and reduces the concentrations of phytotoxic elements such as aluminum (Al3+) and iron (Fe3+). Liming has a positive effect on both the structure and physical properties of the soil, so plant roots can more easily absorb nutrients. Variable-rate liming of fields is particularly effective.

An agricultural company from Western Lithuania, a client of LAAS, who performed variable-rate liming, saw a positive effect already during liming. The biggest advantage of variable-rate liming, according to the client, is that applying a uniform lime rate results in expensive liming, since the soil pH in the company's fields varies greatly (4.5-6.5 pH), so there is no point in adding lime where it is not needed. This saves on lime and is cheaper in terms of money. After liming the fields with precise lime rates, growing plants became more uniform due to improved nutrient availability in individual areas of the fields, which also had a direct positive impact on the yield.

Knowing the nutrient content of your soil helps determine the right type and amount of fertiliser for each field. Key parameters include pH, humus, mobile phosphorus (P₂O₅), potassium (K₂O), sulfur, magnesium, calcium, and soil texture. LAAS monitored fertilisation on five farms over three years and compared actual practices with soil test-based recommendations. Results showed that farms not using soil tests under-applied potassium by 45 kg/ha and over-applied nitrogen by 52 kg/ha annually. This led to missed yield potential and unnecessary costs. Soil testing helps optimise fertiliser use—either by reducing inputs or increasing yields where nutrients are lacking. It’s especially useful for farms without precision tools but aiming for more accurate, uniform fertilisation planning.

Whilst many farms create a nutrient management plan, checking its appropriateness and adjusting the plan is also necessary to avoid sub-or-super optimal nutrient applications, causing unnecessary costs, pollution and compromised production levels. Checking (i.e. observations or sensing of crop structure and colour) is most important as rapid growth begins, and nutrient uptake becomes greatest. Checking allows a manager to determine whether their plan is working for each crop.  Observations may include plant or shoot density, ground cover, height, and leaf colour.  Additionally, crop analyses can diagnose in-season nutrient deficiencies. Hand-held, tractor-mounted or satellite-bourn sensors may use spectral reflectance indices to build a picture of the crop, gauge its nutrient requirements and inform adjustments to initial plans. Amendments may be required to rates or timings of nutrient applications to accomodate recent effects of weather and soil conditions on growth, nutrient uptake and crop potential.   Adjustments to the plan such as a reduced nitrogen rate must ultimately be checked through the final step of Crop Nutrition Management: Reviewing.

Planning is fundamental to successful crop nutrition management.  It defines the quantities and timings of organic material and inorganic fertiliser applications to maximize crop yields whilst minimising environmental impacts. A nutrient management plan tends to be created before fertilisers are purchased, and is ideally finalised before crops are sown .   Growers should work on a field-by-field basis to ensure applications will meet each crop's nutrient demands. Planning tends to make use of national or regional recommendation systems, and must account for relevant legislation. Software packages are often available for farmers and advisors, to create nutrient management plans. Crop choices and markets, fertiliser availabilities and prices, and soil analyses tend to form the framework of a nutrient management plan, but additional information may contribute to plan accuracy, such as manure analyses and nutritional performance of recent crops. Crop nutrition management must extend beyond the planning phase, as weather and other unexpected events usually alter crop behaviour from that initially expected.

A review is essential to final assessment of a nutrition manager's success and forms the basis for future improvement. Crop yields are essential to each review, but these have multiple effects other than nutrition.  Hence lab analyses of harvested materials are also crucial.  Measurements of nutrient removals in harvested materials enable calculation of soil nutrient balances, and efficiencies of nutrient applications. Nutrient concentrations of harvested produce then also show whether crops captured insufficient, adequate, or excess nutrients. Standard nutrient concentrations are generally over-estimates, so measuring nutrient concentrations of harvested produce provides more accurate values, and on average leads to reduced fertiliser use in the following season. By identifying nutrient shortfalls and surpluses, the review step can support farms in optimising nutrient applications and build confidence in future crop nutrition planning.  Thus reviewing is key to effecting progress towards maximum profitability and minimum environmental impacts of crop nutrition.

The Crop Nutritional Monitoring (CNM®) by AGQ Labs, provides continuous information to assess plant response to fertilisation plans and monitor physiological control. Its methodology integrates continuous in situ analysis with advanced sensor technology to track plant response to fertilisation. By comparing irrigation water with fertigation solutions, the tool monitors the dynamic movement of ions around the root profile and evaluates the chemical composition of different plant organs throughout the growth cycle. This systematic approach enables precise detection of nutrient absorption and assimilation patterns, ensuring tailored fertilisation strategies for each phase of crop development. The comprehensive data-driven methodology minimises excess fertilisation and environmental impact while enhancing crop yield and quality. 

Herculano's Green Precision project focuses on developing cost-effective, intelligent slurry tankers to enhance fertilization efficiency across environmental, agronomic, and economic dimensions, aligning with Agriculture 4.0 principles. These advanced tankers are equipped with Near Infrared (NIR) sensors that accurately analyse slurry nutrient content, including nitrogen (N), phosphorus (P), and potassium (K), enabling precise nutrient application tailored to specific crop and soil requirements. Additional sensors measure conductivity and temperature, further refining application accuracy. A flow meter informs the system to adjust slurry distribution optimally. Data from these sensors are processed by an onboard processor, which communicates with the operator through an ISOBUS connection or a dedicated console for tractors lacking ISOBUS technology. The system's GPS and GSM connectivity facilitate precise slurry placement and equipment tracking. This precision approach ensures optimal nutrient application, promoting sustainable farming practices and improved crop yields.

The agrochemical properties of sandy loam Cambisol were primarily influenced by the application of NPK mineral fertilizer, while biochar application had no major impact. However, water availability for plants increased by 5.4% when reduced tillage (RT) was combined with 15 t ha⁻¹ of biochar, and by 5.0% with no-till (NT) application without biochar.

According to a 3-year average data on CO2 emissions, the application of 15 t ha⁻¹ of biochar resulted in emissions of 1.7 μmol m⁻² s⁻¹ under RT and 2.0 μmol m⁻² s⁻¹ under NT management. This indicates that biochar had a positive effect on autotrophic and heterotrophic processes in the soil.

Emissions of CH4 and N2O were not affected by the studied biochar rates. Additionally, different biochar rates did not increase the maximum allowable concentrations of potentially toxic elements such as Fe, Mn, and Zn in the soil.

It is recommended to apply 15 t ha⁻¹ of high ash content biochar on the soil surface under RT and NT soil management for sandy loam Cambisol.

Wheat grain quality directly affects flour performance and final product value. Nitrogen (N) fertilisation strategies—timing, method, and formulation—play a key role in shaping both yield and quality. Applying a previously estimated total dose in split doses at tillering and stem elongation stages, especially as soil-applied urea, improved grain protein, gluten content, and flour strength (alveograph W). Foliar N with micronutrients had less impact on quality. In contrast, N applied with compound fertilisers containing macro- and micronutrients tended to reduce grain protein and Zeleny index. While mineral N increased grain yield, differences in dry matter, kernel size, and hardness were more influenced by application method than total N dose. For farmers aiming to improve both yield and baking quality, targeted soil N applications at key growth stages offer the best balance between productivity and grain quality.

Adding nitrogen fertiliser initially increases yield, but as the crop nears optimal N levels, yield gains plateau. Beyond this, extra N costs may not be recovered by additional grain value—this defines the Break-Even Ratio (BER).

Growers should use current fertiliser and grain prices to estimate the N rate where fertiliser cost equals extra grain value. BER assumes a highly accurate base recommendation, so in normal years with stable prices (BER ~6-9), detailed BER analysis may only be a rough guide, especially when fertiliser prices are high compared to grain prices.

Example: Calcium ammonium nitrate costs €450/t (~€1.66/kg N). Grain price is €150/t (€0.15/kg). At the yield plateau’s low end, 1 kg N produces 30 kg grain (€4.50), covering fertiliser cost (€1.66). At higher N rates, 1 kg N produces only 11 kg grain (€1.65), barely covering cost, so extra N is uneconomical.

Different fertilisers —organic and mineral—can significantly affect potato quality and yield. Organic options like fresh or composted farmyard manure and aerated slurry tend to improve dry matter content and reduce nitrogenous compounds such as nitrates and free amino acids, compared to high rates of mineral fertilisers. While mineral fertilisers often increase fresh yield, it may negatively impact certain quality traits. Slurry shows intermediate effects. Dry matter and starch yields are generally similar across treatments, but quality indicators such as extract darkening and electrical conductivity vary with fertiliser type and rate. Organic fertilisation offers environmental benefits and stable quality, while mineral fertilisers may boost yield but require careful management to avoid excess nitrogen accumulation. For farmers, balancing fertiliser choice with crop quality goals is key.

The method of nitrogen (N) application and the choice of maize hybrid significantly influence nitrogen use efficiency (NUE). Applying N in rows or combining row placement with top dressing improves N uptake and fertiliser recovery compared to traditional broadcast methods. These practices help reduce losses and increase the return on fertiliser investment. Hybrid selection also matters: stay-green types tend to maintain N uptake longer into the season, which can enhance overall efficiency. However, they may show lower internal N use efficiency, meaning not all absorbed N is effectively converted into yield. For optimal results, farmers should align fertiliser placement strategies with hybrid characteristics and field conditions to maximise both productivity and sustainability.

Soil mapping provides detailed information on soil variability across a field, helping optimize crop nutrition, improve yields, and ensure long-term soil health. To achieve accurate soil mapping, it is essential to measure the basic properties of the soil using the appropriate sensors. Electrical conductivity (EC) is a fundamental property of materials that characterizes their ability to conduct or resist electricity. In agriculture, soil EC is the most widely used parameter for management zone delineation because it shows high temporal stability, as it is related to several soil physical and chemical properties. EC data can be translated into valuable agronomic insights with relatively high accuracy. increasing in soils with higher salt concentration. At the same time, salt concentration depends on water content and, therefore, on soil moisture. Once an EC sensor has scanned the entire field, georeferenced data is collected in the form of points to create a map that demonstrates the spatial variability of the measured parameter. Measured soil properties can provide insights into crop vigor, which can be used to adjust fertilization inputs.

In a context where sustainability is becoming increasingly essential, cover crops (CC) are emerging as a recommended and often necessary practice. Grown between main crop (MC) cycles, they can significantly reduce or even eliminate the need for chemical fertilisers when properly managed. Leguminous species, such as Melilotus, are particularly effective in nitrogen (N) fixation, with recorded contributions of up to 238 kg/ha of N in potato systems (Griffin & Hesterman, 1991).

Beyond nutrient management, CCs reduce soil erosion, increase organic matter, suppress weeds, and enhance biodiversity—often without increasing pest or disease pressure, and in some cases, even reducing it. However, their success depends on appropriate species selection and timing. Poor variety choices can increase pest risks, and misaligned sowing dates may interfere with MC cycles.

Ultimately, cover crops are not just a technique but a multifunctional strategy that regenerates soil, reduces input costs, supports biodiversity, and contributes to a more resilient and sustainable agricultural system.

The potato crop is one of the most high-cost productions which has high risks of soil, water and nitrate pollution from fertilizers applied. Βy using Crop Sensing Technologies (CSTs), innovative technologies are adapted to cropping systems, focusing on smart farming services in potato crops. Specifically, system data are collected from sensors installed in the field recording atmospheric, soil and plant parameters (e.g., temperature, humidity, precipitation, atmospheric pressure, wind speed, soil moisture, leaf temperature). All the aforementioned data are collected to a central cloud computing repository, processed, combined and converted into fact-based advice for the optimisation of procedures for irrigation, pest management and fertilization. The advice is then communicated to the farmers through web-based applications. Farmers lag behind in terms of the adoption of smart technologies that optimise the use of external inputs and the implementation of regulated deficit strategies, while few attempts have been made by researchers and document benefits to the farmers considering environmental, social and economic factors.

Management of fertilizer application is essential for wheat production and environmental safety. The objective of the practice is to reduce fertilizer losses and optimize efficiency of fertigated wheat crops. The use of drone imaging for fertilization is a procedure which is used to locate where the field needs more or less fertilizer application to optimize the use of the fertilizer and avoid leaching and run-off. The procedure starts by taking images of the field from a drone which can be analysed in a computer by using GIS programs, such as ArcGIS, where  vegetation index maps indicate essential information can be created, aiming to detect which plants have higher or lower needs of fertilization. Subsequently, for the information received, a spraying drone can apply the correct doses of fertilizer in every spot in the field. The technical part of the procedure can also be implemented by a company with experience in this sector. Finally, the benefits of this practice are the mitigation of the leaching and run-off of the fertilizer which results in providing environmental protection and saving fertilizer costs, as well as an increase in the yield of the wheat.

CropManager is a practical digital tool developed by SEGES Innovation to help farmers make better decisions in the field—saving time, reducing input costs, and improving crop performance. With an easy-to-use interface, it gives a full overview of your fields, tasks, and cropping history, all in one place.

The platform brings together key data like pH and phosphorus levels, helping you compare fields and plan fertilisation more precisely. You can create variable rate maps and send them directly to your machinery, ensuring inputs go where they’re needed most. Satellite images with biomass indices help track crop growth, while forecasting tools support decisions on lodging risk, yield potential, and more. You can also mark problem areas like pests or weeds using hotspot mapping.

CropManager helps you grow smarter—not harder—by turning your field data into clear, actionable insights. It’s free to access with an AgroID and works seamlessly with other SEGES tools like MarkOnline and FarmTracking. Available in Danish, English, and German.

Decision Support Systems (DSS) integrate data from soil tests, crop models, weather forecasts, and farm management records to assist in fertilization planning. These tools provide actionable recommendations tailored to specific field conditions and crop requirements. They also facilitate compliance with regulations and support documentation for certification schemes. Developed before the season’s first nitrogen application, the "Fertilization Planning Document" ensures fertilization planned meeting crop needs and complying with environmental regulations. The guidelines by the COMIFER Prev’N Label help structure this plan by considering factors like soil fertility and crop requirements, enabling us to set a realistic, science-based nitrogen target. This approach is integrated into the HVE label, or Haute Valeur Environnementale, is a French certification that promotes agricultural practices with a high level of environmental performance. It was created by the French Ministry of Agriculture and is awarded to farms that demonstrate reduced environmental impact and sustainable resource management.

Maize cultivation in Portugal is closely linked to irrigation, taking advantage of the soil and climate potential offered by its geographical location, but also because this location makes irrigation an essential contribution to the crop's vegetative development (ANPROMIS, 2023). 
In 2023, the maize production area accounted for 91,785 ha of Portugal's agricultural area, of which 85.2 per cent is irrigated and 14.8 per cent is non-irrigated. The main maize producing region in Portugal is the Centre of the country, specifically the district of Santarém, accounting for 20.4% of the national production area (IFAP, 2023). 
In evolutionary terms, the wheat production area in 2023 decreased by 67.2% compared to 2013, representing a decrease of 44829 ha in the production area over ten years. In fact, national maize production has been on a downward trend in recent years, leading to a gradual increase in imports of this product. Portugal is not self-sufficient in maize production, with only 35% of the wheat consumed coming from domestic sources (IFAP, 2023; Costa ,2023).

Properly designating sampling zones is key to reliable soil analysis
In the traditional approach, soil sampling zones, with an area of no more than 4 ha, take the shape of a regular grid. In reality, however, it often happens that sectors designated in this way do not reflect the actual diversity of the soil mosaic. Only the proper determination of sampling locations allows for its reliable characterization. The innovative approach assumes the division of the field into zones based on its actual diversity visible in satellite data showing the vegetation index or data obtained as a result of electromagnetic soil scanning. Both methods, although different in many aspects, allow for precise capture of soil variability. The information obtained with their help allows for the separation of internally consistent soil sampling zones and can also be used, among others, to designate field management zones.
 

Chemical fertilizers boost yields by ~50% but reduce plant–microbe interactions, harming soil health. Plant growth-promoting microorganisms (PGPMs) offer a sustainable alternative by enhancing nutrient uptake and growth. In a greenhouse study using a randomized block design (10 treatments, six replicates, two fertilization levels), maize inoculated with rhizospheric strains showed improved nutrition. H. seropedicae and G. diazotrophicus increased nitrogen, while B. pumilus and B. amyloliquefaciens improved phosphorus uptake. Fertilized plants had higher shoot dry matter, but microbial inoculation reduced dependence on fertilizers. Strains tested included G. diazotrophicus, H. seropedicae, A. brasilense, B. amyloliquefaciens, B. subtilis, and B. pumilus (16S rRNA ID: MT604067). Statistical analyses (Duncan, Shapiro–Wilk) confirmed significant treatment effects, highlighting PGPM potential for sustainable maize production.

The effect of Long-Term Fertilization on Soil Agrochemical Properties has been studied in a strila started in 1971 In both 1971 and 2021, the application of mineral NPK fertilizers increased the yields of winter wheat, spring barley, sugar beet, and other crops by 21.5-47.0 GJ ha⁻¹. The average annual nitrate leaching without N fertilization was 68 kg ha⁻¹, while an N216 rate increased N loss to 299 kg ha⁻¹. When N216 was applied without K and P fertilization, N loss increased to 510 kg ha⁻¹.

After 50 years, a P50 fertilization rate did not change the concentration of soil mobile P2O5, while a P95 rate increased P2O5 content by 324 kg ha⁻¹, and a P180 rate increased it by up to 529 kg ha⁻¹.

On loamy soil, even at the highest fertilizer rates, soil phosphate (PO4) leached down to a depth of 40 cm, amounting to 4.2-4.9 kg ha⁻¹, while potassium ion (K⁺) loss was up to 6.8-8.0 kg ha⁻¹. At optimum fertilization rates, the leaching was only one-third of these amounts.

For soils with moderate concentrations of mobile P and K, the optimum rate of fertilizers in crop rotation is N 108, P 64, K 96.

Crop rotations with legumes are more productive. 
The study was carried out in two four-field rotations: A) rotation I: beans → winter wheat → spring barley → winter oilseed rape; B) rotation II: beans → winter wheat → spring barley → spring barley / mustard → maize. Two different soil tillage technologies were applied: conventional tillage (CT) and reduced tillage (RT). 
Under CT, the lowest soil compaction (0.7–1.5 MPa) in the 0–20 cm topsoil layer was recorded after maize. However, maize yielded best under RT, with a harvest of 7.6 t/ha. In contrast, winter wheat had a 0.41 t/ha higher yield under CT compared to RT.
The most cost-effective rotation in terms of yield is the four-field rotation with intercrops, i.e. beans → winter wheat → spring barley / intercrop mustard → maize. Intercropping reduces soil density and compaction, increases porosity and improves soil structure. In the long term, alternating conventional and reduced tillage is recommended, especially under drought-prone meteorological conditions.

A good (8 t/ha and more) winter wheat grain yield should be achieved by establishing a crop with at least 450 mature ears per m2 and 18 000 thousand grains per m2. The choice of variety and sowing timing are the most important tools for managing the development of winter wheat, and adequate plant nutrition is a prerequisite for a high yield. Varieties should be selected from among the well-tested varieties with high winter hardiness, low susceptibility to disease and high productivity in the country's climate. Winter wheat overwinters and produces better when well supplied with phosphorus and potassium, so all or a large part of the phosphorus and potassium application rate for the planned harvest should be applied before or at the time of sowing of the winter wheat. For winter wheat grown after good nitrogen-fixing pre-crops (bean crops), it is not necessary to apply nitrogen fertiliser in autumn. For cereals sown after other pre-crops, nitrogen rate of up to 20 kg/ha could be applied at sowing together with phosphorus and potassium in the form of complex fertilisers. In fields with low nitrogen content, autumn fertilisation with nitrogen rate (30 kg/ha) may be beneficial.

The main agrotechnical measures in potato growing technology is optimal fertilisation. Potatoes consume about 5 kg of nitrogen, 2 kg of phosphorus and 8 kg of potassium per tonne of yield. The effectiveness of mineral fertilisers for potatoes depends on the phosphorus and potassium and the mineral nitrogen content of the soil. The correct choice of fertiliser not only determines the size of the potato crop but also the quality of the tubers. Increasing the nitrogen rate promotes tuber growth but usually results in a lower quality of the tubers by increasing the nitrate content. Proper choice of pre-seed and crop rotation can help to prevent the spread of soil-borne diseases, overwintering pests and some weeds, while also reducing the need for plant protection products. Potatoes should be planted in the same field after 3-4 years. In cultivated, well-fertilised soils, the potato yield is not significantly affected by the pre-crops. Winter cereals, oilseed rape, bean crops, root crops, maize and fallow land are good pre-crops for potato. Perennial grasses are not a good starter crop as they often have a high incidence of potato leafhoppers which can affect potato yields.

Grain nutrient analysis can be a helpful tool for optimising fertilisation in cereals like wheat and maize, as it helps assess nutrient uptake. However, complementing grain analysis with soil analysis is vital for a complete nutrient management strategy. Soil tests provide information about nutrient availability, pH, and organic matter, which affect how plants absorb nutrients. Without soil data, grain analysis alone may not reveal nutrient imbalances or deficiencies that stem from the soil. Comparing grain nutrient content with soil nutrient levels can highlight discrepancies in nutrient supply, such as nutrients in the soil that are not available to plants. This combined approach allows for more accurate fertiliser recommendations, improving nutrient use efficiency. Understanding both grain nutrient levels and soil conditions ensures fertilisation strategies are tailored to the specific needs of the crop.

Issue.
One of the main factors in influencing both fertiliser spreading, uniformity and accuracy is the physical characteristics of the product being spread. 

Solution.
Testing your fertiliser products prior to spreading with a fertiliser test kit is the easiest way of determining these physical features. 

1; A fertiliser sieve box from 2 – 5mm will show the operator what size particles and the distribution they are dealing with. Aim for fertiliser to be in the 2 – 4mm size range i.e. the 2 middle sections of the sieve box.

2; Fertiliser density is the mass of fertiliser to the volume ratio of granules. Density will have the biggest impact on spreading widths. Denser particles such as CAN 27% will be easier to spread over wider widths than less dense products such as Urea. 

3; Granule hardness is the force that can be applied to a single fertiliser granule before it breaks. This can be measured using a crush tester with a scale of 1 to 10 (1 being the weakest and 10 being the strongest). Granule hardness will dictate the disc speed and the bout width. 

Problem.
Having a properly functioning and calibrated fertiliser spreader ensures optimum return on investment and minimises environmental impact. The co-efficient of variation or CV (how evenly fertiliser is spread across a field) should ideally be under 10%. 

Solution.
When calibrating a spreader, you will want to check a few vital things.
the fertiliser spreader is level both front to back and side to side on the tractors 3-point linkage and that the stabiliser bars are tight.

That the fertiliser veins move freely, and the bearings are in proper working order to ensure there is no play or uneven movement on their axis of rotation and that the agitator located inside the spreader is working correctly.

Next measure the flow rate by removing one of the discs and running the machine for 30 seconds while collecting the fertiliser it dispenses in a bucket. Weigh this bucket and compare the weight with the fertiliser spreader manufacture guidelines. 

Measure the height of the fertiliser spreader either above ground or above the crop to ensure that we are meeting the manufactures working height guidelines.

Uneven fertiliser distribution can reduce yield and crop quality. Tray testing ensures even spreading across the spreader’s full bout width, improving nutrient efficiency and return on investment. To perform a tray test, place trays at 0.25 m intervals across the bout width (e.g., 48 trays for 24 m). Use trays with baffles to prevent granule bounce and align them in a straight line in a long, uninterrupted field section. Drive the tractor at a steady speed over the trays and continue spreading beyond them. Weigh each tray’s contents individually and enter the values into Excel or a calculator. Calculate the mean and standard deviation (SD), then compute the coefficient of variation (CV = SD/Mean × 100). A lower CV indicates more uniform spreading, which helps ensure consistent nutrient delivery, better crop performance, and more sustainable fertiliser use. 

Various paid platforms (Geoface, Agrosync, OneSoil, Yara Atfarm) create variable rate nitrogen fertilization maps based on satellite images. Users can log in to their accounts via the platforms' websites. Fields can be loaded automatically from the crop declaration or manually marked on the map. The system analyzes satellite images and vegetation indices (e.g., (NDVI, NDRE) to determine the condition of plants in different field zones and the yield forecast. Based on the condition of the plants, the system automatically creates a variable rate fertilization map, in which a different N fertilizer rate is assigned to each field zone. The maps can be exported to fertilizer spreaders or sprayers that support variable rate technology. 

Geoface announces that out of 8,200 farmers who have tried the program, 2,800 use this platform regularly. Several members of the Raseiniai Farmers Nutrition Group of the Nutricheck project use this program, which helps to plan and adjust plant fertilization during the vegetation period.

Variable-rate fertilization based on yield maps is a precision agriculture approach that improves nutrient management and crop performance. Platforms like the John Deere Operations Center automatically collect yield data from combines, enabling detailed post-harvest analysis of agronomic practices. Yield maps help identify low-yield zones that may signal nutrient deficiencies and allow fertilizer rates to be adjusted according to actual yield potential. These maps can be cross-referenced with satellite imagery (e.g., NDVI), soil test results, and crop type data to refine fertilization strategies. They also support evaluation of how in-season fertilization decisions affect yield across different field zones and varieties. This data-driven method enables farmers to develop targeted, cost-effective fertilization plans for the next season, reduce input waste, and enhance overall productivity and sustainability.

Many farmers follow the recommended fertilizer rates and achieve satisfactory results, so they tend to stick to traditional methods because they seem reliable to them. This is especially true for smaller farms, whose owners believe that the cost of soil testing is not necessary. Recommended fertilizer rates are often based on long-term research and can be accurate enough for many farmers. 

However, without knowing the true condition of the soil, it is possible to over-fertilize or under-fertilize, which can have a negative impact on both yield and cultivation costs. 

The Nutricheck project in the Kėdainiai Farmers' Nutrition Club (CNC) fertilization of winter wheat, assessing the amounts of applied fertilizers and nutrients (NPK) accumulated in plants, showed that when fertilizing at the recommended rates, plant nutrient uptake was lower than when fertilizing based on soil tests. When fertilizing at the recommended rates, N uptake in winter wheat was 80 EUR/ha, phosphorus – 58 EUR/ha, and potassium – 131 EUR/ha lower than when fertilizing winter wheat, taking into account the nutrients in the soil.

In the Netherlands the fertilisation within the cultivation of potatoes on average consists of a combination of manure with synthetic fertilisers. This is due to on the one hand legislative limitation of use of nitrogen amount out of manure. And also the use of synthetic fertilizer provides a better controllable fertilization of the crop throughout the season, compared to mineralization of manure which is partly dependent on environmental factors. However, the production of chemical fertilizer is considered to have a large environmental impact. In addition, there is a large availability of manure in the Netherlands. A solution for these contradictive facts might lay in the development of so called RENURE, Recovered Nitrogen from Manure. Within this method, manure is processed and split up into organic fraction and an inorganic fraction. The inorganics fracture consists of ammonium nitrate or ammonium sulfate, which can be used in fertilisation of potatoes. This provides the controllability of a synthetic fertilizer, optimizing the use of nutrients while on the other hand having less impact on environment and helps closing the nutrient cycle within agriculture.

Graduated phosphorus (P) application within a field gives a better P utilisation. Thus, areas with high soil P-values* (Pt) can be fertilised with less P. To achieve a good resolution, a soil sample density of 100 meters is recommended. Graduated application is most beneficial when Pt variation is high – often in undulating areas or where fields with differing cultivation histories are merged. A model for P-redistribution within the field is available in CropManager; a software programme for precision farming to send allocation maps di-rectly to farm machinery. The model is based on Pt, soil texture, predicted yield, and a norm for yield and P application. The model enables a more correct coverage of P-requirements in the field and thus a more uni-form crop. Further, the mapped Pt can be compared with maps of P-loss risk in landmand.dk, which high-lights areas in the field to take action to reduce soil-P loss risk. Thus, P fertiliser may be saved where it is not needed, while higher yields can be realised in areas with low Pt, which is good for farm economics and the environment.
*The P-value is a Danish measurement. One unit Pt corelates to 25 kg P per ha in the topsoil (20 cm).

Catch crops are a sustainable practice that improves nutrient management and soil structure. Sown after the main crop, they absorb residual nitrogen in autumn. Over winter, this nitrogen is mineralized and becomes available to spring crops. Some species also accumulate phosphorus and potassium. Deep-rooted species like radish improve soil porosity and nutrient mobility. Sowing time is critical: early sowing boosts biomass and nitrogen uptake but may expose young plants to drought stress. In 2022, LAAS on-farm trials showed that sowing between harvest and early August led to higher soil nitrogen levels in spring than later sowing. However, sowing too early can reduce emergence due to summer dryness. The first half of August appears optimal—balancing biomass growth and water availability. Proper timing ensures effective nutrient capture and supports soil structure improvement.

Through the Yield Enhancement Network (YEN), grain nutrient concentrations, yields and associated nutriional data have been collated for wheat and provide insights into nutrient deficiencies and their frequencies. Critical values, below which yields may be limited, have been reported for eight nutrients - Nitrogen (N) - Phosphorus (P) - Potassium (K) - Magnesium (Mg) - Sulphur (S) - Manganese (Mn) - Zinc (Zn) - Copper (Cu). Fig.1 highlights that 86% of the wheat crops analysed from 2016-2021 show deficiencies in one or more of these nutrients (Fig. 1). P is the most commonly deficient nutrient (>60% fields affected) and S is second (30% fields); only 14% of fields show no deficiencies.  These results can be used by farmers to identify possible yield limiting nutrient deficiencies and help to highlight where improvements could be sought. Changes to nutrient inputs to correct deficiencies are best tested on-farm, to understand if the solution was successful.  As datasets continue to grow, the certainty in critical values for the detection of deficiencies is expected to improve, and this should be supplemented with testing on-farm to understand yield limitations. 

Plants need nutrients primarily to support photosynthesis, and secondarily to support regeneragtion. Crop-captured nutrients are seldom lost during growth (except some potassium; K).  Most nutrients move in large quantities from leaves to grains as the crop matures, especially P and N (Fig. 1), so harvested materials can provide a reliable nutritional post-mortem on each crop. 

Nutrients for which grain analysis is useful are N, P, K, S, Mg, Mn, Zn & Cu. These show most redistribution, and critical concentrations are known for all of these grain nutrients.  Grain nutrient concentrations multiplied by grain yield also accurately quantify nutrient removals from land, hence the need to replenish the soil. 

Grain analysis is new, so benchmarking helps users to assess their crop’s nutrient status. Benchmarking diagrams (Fig.2) require results to be shared in big datasets, enabling comparisons with many similar crops from the same season, hence identifying nutritional successes and deficiencies.  YEN Nutrition is an example of a Grain Nutrient Benchmarking service. 

In years with high precipitation early in the growing season, there may be a need for supplementary fertilisa-tion in maize. Nitrogen (N) is leached as nitrite, which is retained poorly in the soil – particularly in coarse sandy soils, where water easily percolates. The need for supplementary fertilisation further depends on when the previous fertiliser was applied. The earlier a slurry is applied, the more the leaching and the higher the need for supplementary fertilisation. It is thus not recommended to apply slurry on coarse sandy maize fields before 1 April. Nitrification from ammonium to nitrate in animal manure may be slowed by nitrification inhibitors, which reduces N leaching and thus the need for supplementary fertilisers. Plant analysis showing an N-content below 3.3 % of the plant dry matter, indicates that N might be a yield limiting factor and reveals a need for supplementary fertilisation, which should be applied as soon as possible. A yield effect is possible until the end of July but recedes with time. To prevent ammonia volatilisation, supplementary fertilisation with slurry may be injected, trail hose applied after weeding and/or acidified.

Essential crop nutrients (Table 1) are needed primarily to enable leaf photosynthesis, respiration and transpiration, so are initially concentrated in leaves. The leaves doing most photosynthesis are at the top of the canopy; hence the topmost and youngest leaves contain most nutrients. After leaves are formed, they continue to photosynthesise for several weeks, accumulating photosynthates (Fig.1). This dilutes some leaf nutrients such as N, P & K, whilst others remain stable, or even accumulate like Mg, Ca & B. 

Leaf analysis is commonly used to assess crop nutrient status. To minimize uncertainties of dilution or accumulation through development, leaves are best sampled from a standardized leaf position and age (like the youngest fully expanded leaf) and at a standardized growth stage (like GS31). Leaves are best analysed using the Dumas method for N and Inductively Coupled Plasma (ICP) spectroscopy for other nutrients; results are usually expressed as concentrations in dry matter (DM) and are then best compared with standard concentrations published for the same species, growth stage and region, or benchmarked against crops from a network of similar farms. 

Nitrogen (N) plays a crucial role in crop production but causes substantial economomic and environemtnal costs. Farmers must understand whether they are optimising their N fertilisation. Grain yield hardly changes as N supplies become superoptimal, but grain protein (or N%) continues to respond (Fig.1), so is the best indicator of whether a crop’s N supply was optimal.  Farmers can use grain protein retrospectively to understand whether their crop took up enough N. 

Growers should target a protein level of approximately 11% (or 1.9% N in grain DM) for feed wheat (Fig.1), or variety specific protein levels may be published for the region.  Grain protein levels below target suggest that N availability or uptake was insufficient. Conversely, high protein content suggests over-application of N fertiliser. A protein response of 1% relates to a change in total N applied of 50 kg/ha, and indicates the change to N application necessary to achieve optimal N use. Farmers should analyse samples from barometer fields over several years, to draw robust conclusions. However, even results from grain stores can indicate the success of N management on the farm.

Most of a crop's phosphorus (P) uptake (>80%) is redistributed to its grain (or tubers) by harvest.  So analysis of grain (or tubers) assesses a crop's final P status.  Recent research on grain crops in NW Europe has confirmed results of old research which showed that grain P concentrations <0.32% indicate that yield could have been greater with an enhanced soil P supply, achieved by building soil P content (Fig.1).  

Comparison of soil P analysis with grain P analysis (Fig.2) shows that soil analysis does not reliably predict final crop P status. Many crops grown on soils deemed to have adequate soil P (>16 mg/l) had grain P levels which showed yields could have been increased by building soil P supplies.  Hence grain analysis is an essential tool to support management of crop P nutrition, additional to soil P analysis.  We estimate that the average loss in profit on crops with grain P <0.32% was ~£2,360/field!  Efficiency of P capture from soil is expected to relate to low soil pH (Fig.2), availability of topsoil moisture, and intensity of topsoil rooting, and mycorrhizal associations with topsoil roots.

In Poland, the content of available forms of elements is usually determined by the following methods:- phosphorus and potassium by the Egner-Riehm method (extraction with calcium lactate solution),- magnesium by the Schachtschabel method (extraction with calcium chloride solution),- microelements (zinc, copper, manganese, iron, molybdenum, boron) by the Rinkis method (extraction with hydrochloric acid solution).
This means that in order to assess the soil content of the given elements, 3 separate analyses must be carried out, using different extractants and maintaining different extraction conditions.
An alternative is therefore the possibility of using one analytical method - the Mehlich-III method - to assess the abundance of different macro- and micro-elements in the soil. Compared to standard methods, the Mehlich-III method
20% lower reagent costs,
40% lower labour costs
83% less water consumption,
95% less energy consumption.
It also allows for more accurate determination of phosphorus fertiliser requirements.

Maize roots can host free-living nitrogen-fixing bacteria (diazotrophs), but their agronomic potential remains underutilized. A study with two maize inbred lines (FV2, FV252) inoculated with Herbaspirillum seropedicae (SmR1, SmR54) and Azospirillum brasilense (FP2, FP10) showed differential colonization. FV2 displayed significantly higher N₂-fixation than FV252, confirmed by acetylene reduction assay (effective within 7–14 days). Inoculation with nitrogenase-active strains altered root and leaf metabolites, as revealed by metabolomic profiling. Endophytic H. seropedicae cells were quantified by a specific protocol, while confocal microscopy (SmR1-RAM10 strain) confirmed colonization. Data were clustered and analyzed using t-tests in MeV software (v4.9). Findings highlight strain- and genotype-dependent N₂-fixation efficiency and metabolic changes, offering insights into optimizing maize–diazotroph associations for sustainable nitrogen input.

In the Netherlands, home-grown roughage, including silage maize, is essential for dairy farms. An important aspect of growing maize is the optimal use of nitrogen. With derogation restrictions in place, every kilogram of nitrogen (N) that farmers can apply counts. Nitrogen that no longer increases maize yields is better used on grassland. But where is the tipping point? Knowledge of the soil, previous crops and field management history helps farmers fine-tune nitrogen application. But it takes more than a few quick calculations on a notepad.
NDICEA is a calculation tool that links expected yields to soil fertility, weather conditions and field management history to predict nitrogen dynamics and balance. How much nitrogen is there? When will it be released? Is it enough? Last season, our Crop Nutrition Clubs tested NDICEA and provided feedback to the tool's developers to improve the input options. Features such as manual input for grassland cuts and an adapted maize growth curve will improve the accuracy of the tool for nitrogen fertilisation in maize.

Mineral nitrogen (N), or N-min, refers to the amount of nitrate and ammonium nitrogen found in the root zone, i.e., the plant-available N in the soil at the time of sampling. N-min analyses are conducted on soil samples taken to a maximum depth of 100 cm, depending on the soil type. The samples are ideally collected as close to the fertilizer application time as possible. These samples are used to determine the economically optimal application of N, which is based on the total N needs of the crops; the amount of plant-available N present in the soil before fertilizer application (the N-min); as well as the quantity of plant-available N released during the growing season from applied organic matter, such as manure. The N-min analysis does have some limitations associated with soil type and crop type and is also most reliable in uniform fields. Nevertheless, in fields meeting these criteria, the analysis can provide valuable insights into the quantity of N already present in the soil. This information can guide the farmers decision on how much N should be applied to reach the economically optimal fertilization level, thereby avoiding the purchase and application of excess N.

Splitting nitrogen (N) fertilizer application is key to increasing potato tuber yield and nitrogen fertilizer uptake efficiency (NUpE), particularly in coarse-textured soils. The study objective was to determine optimum N fertilizer rates and application timing to maximize yield and plant growth under four irrigation methods: seepage, subirrigation with drain tile, subsurface drip irrigation (SDI) for water table level management, and sprinkler. A factorial design of three N rates applied at planting (Npl) (0, 56, and 112 kg ha−1), followed by two N rates (56 and 112 kg ha−1) applied at plant emergence (Neme), and tuber initiation (Nti) . There was no interaction between irrigation method and N treatment on tuber yield; thus, an N fertilizer strategy of timing and rate of application for potato cultivated under these irrigation methods was determined. Seepage had the highest incidence of tuber disorders and the lowest tuber specific gravity, indicating that alternative irrigation methods, when managed to maintain ideal soil moisture in the rootzone, can potentially outperform the seepage method regarding water conservation, tuber yield and quality.

Nitrogen use efficiency during fertilization based on N sensors.

The use of nitrogen (N) sensors for fertilization has many advantages over conventional fertilization. Nitrogen sensors allow to accurately determine the nitrogen demand of plants in real time. With nitrogen sensors, wheat yield can increase from 3% to 6%, and fertilizer costs can decrease from 2% to 13%. Nitrogen sensors help optimize resource utilization, allowing farmers to make data-driven decisions. 

In the Nutricheck project at the Kėdainiai Farmers Nutrition Club, when evaluating nitrogen fertilization in winter wheat, fertilization with an  N sensor   (in interaction with other precision technologies used on the farm) allowed for more efficient use of nitrogen in winter wheat, compared to N fertilization according to the recommended rates for the planned yield. When adjusting N fertilization with an N sensor, a total of 155 kg/ha N was applied to winter wheat, plants accumulated 275 kg/ha of nitrogen, and the resulting wheat yield was 8.8 t/ha. On the farm where winter wheat was fertilized according to the recommended N rates for the planned yield, 215 kg/ha N was applied, plants accumulated 233 kg/ha N. The resulting yield was 7.1 t/ha. Nitrogen use efficiency in winter wheat using an N sensor was 110 EUR/ha, compared to N fertilization according to the recommended N rates.

Dutch agriculture faces challenges due to cutbacks on derogation limiting manure application and a focus on nutrient-contaminated areas. To maintain crop quality, farmers are seeking methods to achieve higher yields with less manure. Significant gains can be made, particularly in maize cultivation. In a demo in the north of the Netherlands, various fertilization techniques were tested.

The demo provided valuable insights for livestock farmers. The fertilization techniques were examined for their effects on nitrogen utilization, plant development, and yield. The strip injector was the best in the comparison, due to its ability to place slurry close to the plant roots, allowing optimal uptake.

Nitrogen efficiency was also evaluated, with the strip injector again coming out on top because of minimal residual nitrogen in the soil. The importance of soil and crop knowledge, as well as the use of appropriate fertilization techniques at the right time and place, is highlighted as essential for maintaining soil and water quality. Measurements such as plant uptake analysis are key to efficient fertilization and minimizing losses.

For Dutch arable farmers, macronutrient fertilization is rather restricted by legislation than availability of manure. Farmers need to be strategic in utilizing the legislative limit for organic manure. Recently, the legislative limit on N-application from manure has sometimes been lower than the agronomic advice. Despite this, the N-balance (application minus offtake) is still positive in most cases, indicating that N-use efficiency is the limiting factor, not the amount of N applied.
Various tools have the potential to support more precise nutrient planning, such as Tipstar, a growth model that uses soil, crop, fertilization, and weather parameters for topdressing and irrigation of potatoes. Another tool is NDICEA, a model that couples expected yield with soil, weather, and management history, helping to predict an overall N-balance. Some farmers already use N mineralization analyses and yield analyses to support nutrient decision-making, but the use of interactive tools to predict yield gaps or overapplication of N is not yet common.
In the coming season, farmers, together with advisors, will try to better understand the utility of these tools.

As the season nears, concerns arise about nitrogen shortages in soil following a high-rainfall fall, which has caused nitrogen leaching. Soil conditions post-crop vary widely, influenced by factors such as prior crops (sugar beets, maize, etc.) and cultivation practices. Recent N mineral sampling underscores diminished N levels, primarily as nitrate, due to denitrification from waterlogged soils. Cover crops, if present, offer varying nitrogen contributions: larger ones potentially supply 30 kg/N per ha, while smaller ones might yield 10 kg/N per ha. Additionally, the choice of potato variety plays a pivotal role, with newer varieties with greater nitrogen efficiency compared to older ones. In our CNC, we will examine some of these varieties, like Avamond and Adelinde, and benchmark them against BMC or Festien.

The selection of fertilizer type and quantity is also critical; commonly, a blend of pig manure, cattle manure, and digestate in a 6N:2P:6K ratio is utilized. This blend will be used by our CNC members for fertilizing their potatoes. The composition of the manure mixture is crucial for achieving a balanced nutrient supply throughout the growing season.

NMP online is a software package where growers can input data such as soil sample results, crop type, expected yield and the quantity timing and type of fertiliser they have planned to use. The package will then give them a nutrient management plan on a field by field basis which complies with environmental regulations subject to maximum rates of fertiliser allowed. 
Outcome;
The Teagasc NMP Online tool has been designed for agri-professionals to assess the current nutrient balance of Irish farms and devise a fertiliser management programme that will optimise soil fertility and ensure compliance with the limits set under the Nitrates Regulations. The programme uses the latest in online mapping technology to produce a farmer friendly nutrient management plan along with colour coded maps.

The best time to sow maize is when soil temperatures reach 10 degrees Celsius. This is usually somewhere in April or May. It is important to wait until the soil conditions are warm and dry  and no night frost is forecast.  Young plants are sensitive to cold temperatures and a lack of phosphorus uptake. Therefore a readily available form of P can be given at the moment of sowing. When planting on former grassland, the farmer should take into account the subsequent delivery of nitrogen after ploughing the grass. 

Selenium (Se) is an essential micronutrient for human health, and enriching wheat grain with Se can improve its nutritional value. To explore practical applications, field trials tested different Se fertilisation methods and timings, aiming to increase grain Se content without compromising yield or bread-making quality.

Results showed that Se fertilisation did not affect grain yield but significantly increased Se concentration in the grain. The most effective strategy combined seed treatment, soil application, and foliar sprays at the tillering and stem elongation stages—maximising Se uptake.

In terms of bread-quality traits, Se had a positive effect on protein content and falling number, both key indicators for baking. All treated grain met bread-quality standards.

Selenium fertilisation can therefore be considered a safe and effective way to enhance both the nutritional and technological quality of spring wheat grain. However, the timing and method of application are critical to achieving optimal results.

On fertile soils, a significant yield increase was observed only with S30 fertilization and only at nitrogen levels of N105 and N225. Applying fertilizer at an N
ratio of 3.5:1 resulted in a significant increase in total amino acid content, while a lower S rate (7.5:1) showed only a trend towards increased amino acid content.

When sulphur was applied in the form of ammonium sulphate, it significantly increased grain yield in two specific cases: during the regeneration of winter wheat vegetation and at the end of the crop tillering stage. Sulphur fertilizer also increased the number of grains per ear. Additionally, the protein content of the grain increased significantly only after the application of ammonium sulphate.

Before applying sulphur, it is advisable to test the concentration of S-min in the soil. If the soil sulphur content is high, additional crop fertilization will not have a positive effect.

In Portugal, potato varieties such as Red Scarlett, Agria, and Bellarosa are widely cultivated, each with distinct fertilisation requirements. Variety choice plays a crucial role in nutrient efficiency and sustainability. Red Scarlett needs more than 250 kg/ha of nitrogen (N), 100 kg/ha of phosphorus (P), and 300 kg/ha of potassium (K) due to its vigorous growth and high tuber yield. Agria, more commonly used in industry, requires less intensive fertilisation, with 230 kg/ha of N, 100 kg/ha of P and 300 kg/ha of K, which are essential for achieving high-quality dry matter content. 

Bellarosa is earlier maturing and more resistant, responding well to fertilisation with 220 kg/ha of N, 100 kg/ha of P and 275 kg/ha of K, to ensure ideal tuber size and texture. Investing in varieties like Bellarosa can reduce input costs and environmental impact. Additionally, farmers in some regions have reduced nitrogen use by up to 20% through soil and water analysis combined with fertigation, maintaining yields and improving quality. Optimising fertilisation requires both variety selection and precise, site-specific management.

Microbiological indicators are key to assessing soil organic quality and fertility. Microbial biomass reflects the abundance of living organisms (bacteria, fungi, protozoa) and represents the living fraction of soil organic carbon. It responds quickly to changes in practices and is proportional to total carbon, offering insight into microbial activity. A high value indicates strong microbial presence, promoting organic matter mineralisation and soil structure. ABM (Anaerobic Mineralisation of Nitrogen) measures nitrogen release under controlled conditions (40 °C, 7 days), offering a quick estimate of mineralisable nitrogen. It complements the 28-day aerobic test and is easier to implement. High ABM values suggest strong nitrogen supply potential, but also risk of nitrogen losses through volatilisation. Together, these indicators help interpret soil biological health and guide fertilisation strategies. Good soil fertility requires balancing biological, chemical, and physical parameters.

On arable farms Phosphorous is essential for high yielding crops. It is essential for fruit and seed production through its role in the cell membrane and in genetic structures. However recently concerns have grown regarding decline of global P supplies, increasing P fertiliser prices which threaten future food production and the loss of P to the wider environment. 

The application method and timing of P fertiliser in arable applications has also shown to affect the P fertiliser use efficiency increasing uptake and reducing P losses through leachate.                                           

Since P is not very mobile in the soil under low soil test P levels plants must increase their root density. On the majority of Irish farms most P fertiliser is broadcast onto the soil surface and then incorporated at sowing. This seems to be work for soils with relatively high STP levels (index 3 and 4). However, in low STP situations the soil can lock up much of this P fertiliser in a relatively short time. Research has shown that placing the P fertiliser with the seed at sowing in spring barley is the most efficient way to reach target yields.

In industrialized agri-food systems, nitrogen overfertilization in potato cultivation remains common, often used as insurance against uncertain soil fertility and low crop N use efficiency (NUE). While nitrogen strongly influences yield and quality, excess leads to poor NUE (50–60% for potato), increasing environmental risks due to its shallow root system. Applying the 4R principles—right rate, source, timing, and placement—is key. One of the technologies and management practices for optimal nitrogen management at farm level, following the 4R principle, is splitting N applications across growth stages to match crop needs, especially during rapid growth (up to 5 kg N/ha/day). Monitoring plant and soil responses enables adaptive management, enhancing yield while minimizing environmental impact. Digital support systems (DSS) using Crop Nitrogen Status (CNS) indicators help fine-tune N applications based on cultivar, soil N, climate, and crop stage. CNS tools must be robust and user-friendly to address field variability and improve fertilization efficiency.

Unlike wheat, barley’s yield potential is largely set early in the growing season, depending on the number of tillers produced and their survival. To align fertiliser use with crop nutrient demand—the “right rate” of the 4R nutrient stewardship principles—growers and advisors should perform plant counts before growth stage 30 (late tillering, early to mid-March). This early yield estimate enables more precise calculation of nitrogen requirements and avoids over- or under-fertilisation.

After this initial count, the first nitrogen application—typically 25–30% of the total planned rate—should be applied. A second plant count after GS31 (late March to early April) reveals tiller survival, allowing adjustments to nitrogen rates based on updated yield estimates.

Early plant counts not only inform fertiliser strategies to promote tiller development and maximise yield but also help assess crop establishment success. This data supports decisions such as reseeding in winter crops if needed and guides future seed rate planning and sowing conditions for improved crop performance and nutrient efficiency.

The CNCs workshop in Portugal provided key findings on agricultural fertilisation practices. Discussions focused on essential data for decision-making, available tools and technologies, and barriers to adoption. Farmers emphasised the importance of soil analysis and fertilisation history, though challenges persist in quantifying organic nutrient content. Traditional methods like fertilisation tables and soil tests were widely used, whereas newer technologies, such as sensors and decision-support software, faced adoption difficulties due to cost and complexity. Participants highlighted the need for independent research, technology demonstrations, and financial incentives to promote efficient fertilisation. Universities, consultants, and policymakers were identified as key players in facilitating change. Overall, the workshop reinforced the necessity of informed policies and collaborative efforts to improve sustainable fertilisation strategies in Portuguese agriculture.

Rising populations, dietary shifts, and shrinking arable land demand improved maize yield, stability, and quality. Climate extremes such as heat and drought reduce spikelet fertility, raise transpiration, and hinder grain filling, cutting yields. Without irrigation and fertilization, maize growth is increasingly limited. Precision agriculture (PrA) tools like SPAD, RTK, and UAVs enable monitoring of plant health, nitrogen, and soil moisture. The SPAD-502 sensor estimates chlorophyll and nitrogen non-destructively, aiding yield prediction, while UAV multispectral imaging assesses traits like phenophase, LAI, and carotenoids. PrA tools (SPAD, UAV-NDVI) effectively tracked maize response to nitrogen and irrigation under drought. Highest yields were achieved with spring basal fertilization (A120) and top-dressing at V6–V12, especially with irrigation. SPAD and NDVI strongly correlated with yield at R1 and R3, making them reliable predictors under stress. Measurements used a Minolta SPAD-502 device and UAV-NDVI with a DJI Phantom 4 Pro V2 equipped with Sentera Double 4K sensors. Data were analyzed with Duncan’s multiple range test (DMRT).

Potato cultivation requires specific management in agricultural inputs in order to achieve proper growth development and yield. Excess use of Nitrogen inputs can lead to excessive vegetative growth that causes delay in tuber formation, and increases sensitivity to diseases such as Phytophthora rot, while low phosphorus input can lead to poor root and tuber development, reducing yield. In order to address these issues, vegetation indices can be created by acquiring data from proximal and remote sensing sensors. Drones mounted with multispectral camera can provide images from different zones of the spectrum (green, red, red-edge, near infrared) which can be merged to generate vegetation indices, like NDVI and proximal sensors (Trimble Greenseeker) which can directly provide NDVI values directly at a specific area of the potato crop. Furthermore, thermal cameras can be used to identify water stress of the potato crop to optimize irrigation. By receiving information about the health of the potato crop from vegetation indices, management of potato nutrition can be optimized to accomplish proper growth development and yield.

Under-fertilisation with potassium (K) in potatoes can lead to significant yield loss, while over-fertilisation can reduce the starch content. Further, the cost of using fertiliser unnecessarily reduces the economic payoff. Thus, it is relevant to apply the correct amount of K fertiliser based on the soil K status, which can vary with-in the field. A model for redistribution in the field is available in CropManager; a software programme for precision farming, from which allocation maps can be sent directly to farm machinery. The model is based on soil K status, soil type, predicted yield, date of soil sample, correction for type of fertiliser and finally, pre-vious L-application in the season is subtracted, so only the remaining K-need is displayed. The model ena-bles a more even coverage of K-requirements within the field and thus a more uniform crop. According to the model, more clayey soils have a lower K-requirement than more sandy soils. Soil samples taken close to the time of fertilisation will give a more correct graduation model and preferably 1 sample per ha.

A higher pH on clayey soils increases the plant availability of phosphorus and create a better soil structure, which improves germination, water infiltration, soil moisture and ease of tillage. Liming increases soil pH and both soil clay and humus content influence the optimal soil pH and thus the need for liming. The software MarkAnalyse Online (MAO) is able to create liming plans, where soil laboratory results can be loaded auto-matically, but clay and humus percentages are often missing. New digital soil maps in Denmark can model these soil parameters and calculate lime placement in the field in the CropManager software. This is a digital tool for precision farming, where field data from the farm is loaded and the resulting lime placement plans are sent to the farm machinery directly. This way, fields can get a more homogeneous soil pH distribution, and lime is not wasted where it is not needed. Nutrients such as nitrogen and phosphorus can also be used more sparsely, as less nutrients are lost through leaching and erosion and the phosphorus becomes more plant available when the soil structure is better. This is good for farm economics and the environment.

Supporting farmers in selecting the most suitable nitrogen source is essential for balancing crop productivity with environmental sustainability. Trials comparing different fertiliser types showed that granulated cattle manure and green waste compost led to smaller maize yield increases and should be used alongside mineral fertilisers rather than alone. In these specific trials, combining a reduced rate of ammonium nitrate (80 kg N/ha) with organic fertilisers-maintained yields comparable to full mineral fertilisation (170 kg N/ha). This suggests that, when growing maize for grain, farmers can rely on granulated poultry manure as a primary nitrogen source before sowing, while other organic fertilisers may be better suited as complements to mineral inputs. However, full-rate ammonium nitrate and poultry manure fertilisation (170 kg N/ha) left elevated levels of mineral nitrogen in the soil post-harvest, raising concerns about nitrate leaching.

The Irish Climate Action Plan (2021) aims to reduce greenhouse gas emissions from agriculture by 22–30% by 2030, including a 20% reduction in chemical nitrogen use. A field trial with a randomised plot design tested various bio-based fertilisers, from P-rich dairy sludges to N-rich poultry and pig manures, used alone or with synthetic fertilisers to meet crop N-P-K needs. Control plots received no fertiliser, others received synthetic-only inputs. Bio-based fertilisers increased soil organic matter (from 4% to over 5%) and improved P and K stocks. Yields were comparable to synthetic-only treatments. A 2019 maize trial estimated €130/ha savings when using bio-based fertilisers. These results show their potential to reduce input costs and emissions while sustaining yields. They also highlight the need for decision-support tools to guide farmers in choosing, combining, and applying fertilisers based on crop needs, nutrient balance, and environmental outcomes.

It is important to accurately meet a crop’s nitrogen (N) requirement, as under-fertilisation costs yield, and over-fertilisation wastes fertiliser and can cause environmental problems from N leaching. In Denmark, crop N requirements are set by legislation as norms based on field trials with an increased N application. The norms are general and cannot consider conditions on individual fields. In the digital tool for precision agricul-ture CropManager, the N-Tool-Precise model can customise the N requirement in winter wheat using satel-lite data combined with cultivation data from electronic fertiliser planning programmes. Thus, N uptake can be determined from satellite measurements of the vegetation index NDRE based on crop light reflectance. The model enables adjustment of N application during the growing season. To this end, a split dose fertiliser application is necessary. The sum of N applied at the start of crop growth and in mid-April must be about 50 kg N per ha below the expected N need as stated in the norms. It is estimated that by using the N-Tool-Precise model, additional yields of 3 hkg per ha may be achieved and N leaching can be reduced by 3 kg N per ha.

It is essential for maize cultivation to be monitored in order to assess the efficiency of the fertilization and irrigation plan. Nutrient deficiencies induced by improper fertilization can lead to stunted growth, poor grain and root development, and leaf edge necrosis. Nitrogen over-fertilization may cause leaf tip burn and excessive vegetative growth with poor grain filling, while maize crop water stress at critical stages can significantly impact yield and quality. Satellite imagery may be used to monitor maize crops, offering high resolution data for crop monitoring while storing data from previous years of cultivation for comparison. Applications such as SNAP (a free application by ESA) provides continuous satellite data which can be processed using Geographic Information Systems (GIS). These tools enable the creation of vegetation index maps and thermal maps, allowing for the precise identification of fertilization and irrigation issues within specific areas of the maize field. Farmers can thus make real-time decisions that optimize fertilization and reduce input waste according to the needs of the cultivation.

The nutrient content of slurries can vary widely, making their use in crop nutrient management plans often inaccurate. On-farm adoption of quick assessment tools, such as the slurry hydrometer, allows for immediate estimation of nutrient concentrations based on slurry dry matter. This hydrometer is easy to use: after collecting freshly mixed, fully agitated slurry in a suitable container, the hydrometer is submerged and allowed to settle to determine the dry matter percentage at the slurry surface. This measurement is crucial for accurately calculating nutrient application rates and improving precision in nutrient management strategies. In cases where the slurry is too thick for the hydrometer to sink, dilution with water is recommended, and the dry matter value is adjusted accordingly. Careful handling and cleaning of the hydrometer, typically made of fragile glass, ensures its durability and reliability for repeated use on farms. This tool represents a significant advancement in optimizing the utilization of slurries alongside conventional fertilizers, contributing to more efficient and sustainable agricultural practices.

Smart Agrometer is a smart plant diagnostic handheld device developed by Lithuanian company UAB “Žemdirbių konsultacijos”, designed to determine the nutritional status of plants and help farmers make more accurate fertilization decisions during plant vegetation. It uses a spectrometer (light reflection analysis) and cloud technology to provide real-time insights into plant nutrient deficiencies. The device determines not only the deficiency of major nutrients, but also micronutrients in plants.

Unlike laboratory tests, Smart Agrometer provides data immediately, allowing for quick decisions on plant fertilization. Developed algorithms determine which major and micronutrients plants lack. After performing plant measurements in the field with Smart Agrometer, it is possible to diagnose the deficiency of an element that limits crop growth. The results are immediately visible on the user portal.

Foliar fertilisation is increasingly used in Polish agriculture to address specific micronutrient deficiencies, particularly when soil availability or root uptake is limited. However, its application should be guided by validated foliar analysis to accurately diagnose the type of deficiency and select the most appropriate foliar fertiliser.

It is important to note that the majority of nutrient uptake occurs through the root system. Foliar absorption accounts for only a small proportion of total nutrient intake and should be reserved for exceptional cases of deficiency that arise during the growing season. Foliar fertilisation should not replace a well-planned, multi-year fertilisation strategy based on soil and crop requirements.

These products are also being investigated for their potential role in crop biofortification, aiming to enhance the nutritional quality of agricultural produce. While foliar application allows for targeted nutrient delivery at critical growth stages, its effectiveness depends on agronomic context and should be integrated into a broader nutrient management plan.

Phosphorus (P) starter fertiliser is a common and widely used solution to improve maize emergence and early vigour. Field trials evaluated how the depth of P placement affects maize growth and nutrient uptake. Results showed that early development was more influenced by temperature than rainfall. However, dry matter yield of ears and whole plants responded clearly to phosphorus application. The most effective placement depths were 5 cm and 10 cm, which consistently improved nutrient uptake across different years. The SPAD (Soil Plant Analysis Development) index, which measures leaf greenness, proved to be a sensitive and practical tool for detecting maize response to NP fertiliser placement. These findings support the use of shallow, targeted phosphorus placement to enhance early growth and nutrient efficiency without increasing fertiliser inputs. This approach helps farmers optimise fertiliser use and improve maize productivity under variable field conditions.

SmartSlurry, a free app developed by SEGES Innovation, makes it easy to digitize slurry analyses, calculate precise fertilization values, and enables farmers to register and view analyses, and thereby monitor nutrient levels in their slurry tanks, including nitrogen, phosphorus, potassium, dry matter, and pH. Slurry analyses can be registered manually by entering the values into the app or automatically by scanning the QR code on the slurry analysis order. However, the automatic registration only works if the farmer is also using the registration app FarmTracking. The data registered in SmartSlurry are automatically synchronized with the fertilizer planning tool MarkOnline. Additionally, users can track activities related to the slurry tanks, such as agitation, transport, establishment of crust, or if the tank is empty. The app also includes an inspection function, allowing farmers to take notes and add pictures from tank inspections, and keep track of when the next inspection is due. This provides farmers with an easy-to-use tool to monitor slurry analyses, nutrient contents, and tank inspections for each respective slurry tank on the farm, all in one place.

Accurate interpretation of these results is essential for identifying nutrient deficiencies or toxicities early, allowing for timely and effective corrective actions. Interpreting soil analysis requires both technical expertise and contextual understanding, tailored to environmental conditions, agronomic practices, and specific crop systems. The first step is to correctly associate the results of soil analysis with a soil type. This classification enables the use of interpretation thresholds specific to that soil category. Several parameters —such as soil texture, total calcium carbonate content, and CEC (Metson method)—provide valuable clues for this identification. The soil data can be used to customize farm management and fertilization strategies to match field-specific conditions. This approach enhances nutrient use efficiency and minimizes environmental impact Practical resources are available to support this process, such as the Guide for Soil Analysis Interpretation published by Arvalis in 2020. More advanced interpretation methods incorporate spatial variability and historical data to refine recommendations further. 

Granulometric fractionation of organic matter (OM) provides insights into its quality and effects on soil biological fertility. OM is divided into coarse (>50 μm) and fine (<50 μm) fractions, where carbon and nitrogen are distributed. The fine fraction, representing 70–90% of total carbon in temperate soils, corresponds to humidified OM and indicates long-term carbon storage. High carbon in this fraction suggests strong chemical stabilisation. It may also reflect OM mineralisation (CO₂ loss), but supports physical stabilisation and soil aggregation. High nitrogen in coarse fractions benefits crop nutrition. The fine fraction influences water retention and cation exchange capacity. Coarse fractions, or labile OM, consist of decomposing plant debris, a key energy source for soil organisms. Labile carbon, also called active or oxidised carbon, is the least stable and degrades quickly, but plays a vital role in soil biological activity.

Soil structure refers to the shape, size and development of soil structural units or ‘peds’. Soil structure is critical in determining the provision of nutrients, water and air in soil as this is dictated by soil structure. The benefits of good soil structure from an agronomic and an environmental perspective are plenty. 
• Root support, water and air for the growth of food and fibre
• Cycling of nutrients into plant usable forms
• Purification of water through the percolation process that relies on good soil structure
• Storage and cycling of carbon
• Represents the largest biological habitat on earth
• A reservoir of potential and currently usable genetic and pharmaceutical resources
The natural structure of the soil depends upon the texture and organic matter content of the soil. 

Solution
The soil hand-texture practice developed by Teagasc in Johnstown Castle Co. Wexford allows farmers and agronomists to quickly and relatively easily determine the texture of the soils they are working with to develop a tailored approach to managing these soils appropriately.

Soil structural stability is vital for resilience and erosion prevention, with the Slake Test Method offering a cost-effective solution. This method assesses soil aggregates' resistance to erosion through rapid wetting, involving steps like drying aggregates, immersing them in water, and grading their stability. Scores range from 0 to 6, with lower scores indicating reduced stability and higher scores (>5) indicating good resistance. It's applicable to both surface and sub-surface layers, though sandy soils may not achieve the maximum score. Factors like soil texture, organic matter, and compaction influence stability, cautioning against comparisons between different plots. Monitoring stability changes over time within the same plot is advised. Additional resources for conducting the test and assessing soil quality are provided, including a French video demonstration and a guide from the NRCS.

Soil structure helps to increase water and nutrient retention for sustainable cropping system.
The spade test is a cheap and reliable on-field method to assess the soil resistance  using a rod driven vertically into the ground and identify potential areas of compaction.
A steel tube with a conical tip is driven into the ground recording the soil resistance. The higher the resistance of the soil and the more difficult it is to push the rods in, the better the soil quality, the more stable it is or the higher the bearing capacity. Based on the results of the penetrometer test and taking into account the geological data available for the soil studied, it is possible to deduce the composition of the soil.
It is necessary to measure the soil moisture profile in order to interpret the curves, as this test is very sensitive to soil moisture.
This is an indirect measure of soil structure that can complement other indicators such as the spade test.
It can be used to identify a structural problem, to assess the depth of compaction, and to reason intervention according to the problem identified and the following crop. Other factors can influence resistance, in particular soil moisture.

The Spade Test, an ISARA Method, addresses the critical need to assess soil structure directly in the field for resilient soil and sustainable cropping. This method offers a cost-effective solution to observe the upper layer's structure (0-25 cm) and diagnose soil tillage issues, aiding decisions on whether to till the soil, especially in cases of heavy compaction. The test distinguishes clods into types Γ (gamma), Δ (delta), and Δb, providing insights into their internal structure, porosity, and biological activity. Additionally, it evaluates the mode of clod aggregation, indicating the state of soil macroporosity crucial for water infiltration and root penetration. With practical applications and detailed classifications, the Spade Test facilitates effective soil management and crop health assessment, contributing to sustainable agricultural practices.

Measuring soil mineral nitrogen stock (nitrogen residue) in post-winter period is crucial for adjusting and optimizing crop fertilization plans effectively. Nitrogen residue levels vary annually, influenced by previous crop nitrogen absorption efficiency, presence of intercrop cover, and winter leaching intensity.  Sampling should occur within the largest homogeneous area of the plot, with at least 14 core samples forming a representative sample, within a 20-meter diameter circle for accurate results. Ideally, samples should cover the full rooting depth of the considered crop, in 30 cm increments. Samples from each depth horizon should be mixed to create a composite sample. Samples should be collected post-winter, after winter rains and before humus mineralization resumes, to estimate nitrogen residue. Samples should be refrigerated (4°C) and delivered to the lab within 2-3 days or frozen (-18°C) for delayed delivery, identified and accompanied by a sampling sheet for analysis guidance.

Annual application of straw, with or without additives such as ammonium nitrate or biofertilizers, increased the number of water-stable aggregates in the soil and reduced the amount of micropores.

In a crop rotation sequence of wheat → barley → beans → wheat → triticale, adding straw with either ammonium nitrate or biofertilizers enhanced the sequestration of soil organic carbon (SOC) within the plough layer.

Removing straw from the field and applying only nitrogen fertilizer resulted in the greatest reduction of SOC, exacerbated in arsenic-contaminated soils. This decline was partially mitigated by balanced fertilization with mineral NPK fertilizers but not completely prevented.

Incorporating straw with or without additives (ammonium nitrate or biofertilizers) increased soil CO2 exchange and reduced N2O emissions, while potentially increasing the risk of CH4 emissions.

The use of biofertilizers mixed with macro- and micro-nutrients is recommended. Their effectiveness in straw mineralization is comparable to that of ammonium nitrate.

Nitrogen (N) is crucial for wheat yield and grain quality, both influenced by cultivar, soil, climate, and management. Environmental variation makes quality hard to predict across sites and years. This study assessed winter wheat grain quality under organic and mineral fertilization at two Czech sites. Mineral N fertilization consistently gave the highest yield and protein content, while organic fertilizers improved yield but often failed to meet food-grade standards. Temperature during grain filling strongly affected bulk density and interannual variability. A two-year field trial compared six treatments: Control, Sewage Sludge (SS), Farmyard Manure (FYM), Mineral N, NPK, and Mineral N + straw (N+ST). Grain nitrogen was measured by the Kjeldahl method (VAPODEST 50s), after homogenization with an SM 100 mill. Results were statistically analyzed over two years using ANOVA and Tukey’s test in STATISTICA 12.0.

The Olsen-P test is used in Denmark as a standard analysis to determine available phosphorus (P) in the soil, and guidelines for P application are also based on it. However, in recent years, it has been found that this test is not always reliable for assessing P requirements, as several studies have shown yield increases in cereals that received P despite high expected P levels in the soil. The P-CaCl₂ test has been assessed through trials as more accurate than the Olsen-P test in certain areas of Denmark with naturally high levels of oxalate-extractable aluminum in the soil. Additionally, the method is expected to be more reliable on soils with low pH values. P-CaCl₂ is a soil test in which soil is shaken with the chemical calcium chloride (CaCl₂), and the extracted P content is then measured. The same principle is used in the Olsen-P test with sodium bicarbonate, which also extracts the aluminium bound P. In both cases, the extracted amount is assumed to reflect the plant-available P in the soil. The method can be used as a supplementary test for soils where the Olsen-P test is not reliable, providing farmers with a more accurate assessment of the actual P requirement in the field.

The principles of crop fertilization plan development according to LAMMC involve several key steps. First, the crop fertilization plan is based on calculating the required amounts of nitrogen (N), phosphorus (P), and potassium (K) to achieve the target crop yields, taking into account soil capabilities. If organic fertilizers are to be applied, nutrient inputs must be adjusted in relation to the rates of mineral fertilizers. The amount of nutrients needed to produce the target yields is calculated according to nationally approved recommended rates and methods. Periodic soil analyses, typically conducted every 3 to 5 years, are used to control the amount of nutrients necessary for sufficient plant nutrition. These analyses include testing soil pH, P, K, and other relevant factors in a lab. The fertilization plan must be developed or revised annually for all fertilized fields on the farm larger than 30 hectares. Additionally, the fertilization plan must be drawn up each year before manure or slurry is applied to the fields, and officials may conduct on-site checks to ensure compliance.

The Teagasc crop report is an app provides farmers with key management advice in real-time throughout the growing season. The app provides structured crop specific advice on key management decisions related to planning crops, crop nutrition, and plant protection which are relevant to the time of the year, location and prevailing climatic conditions which may be affecting the crop. 
Outcome:
The Crop Report is published every 3 weeks and more frequently at key times when crops are developing throughout the year.  These updates highlight areas of concern relating to crop nutrition, pests and diseases and provides tips and advice to guide farmers to help prevent issues escalating in the fields.  The main and minor crops grown in Ireland have a detailed growing guide featuring the latest research findings which are translated into practical actions which are practical for farmers and agronomists.

Strategic fertilization tools include nutrient budgeting software guide long-term nutrient planning. Decision Support Systems (DSS) play a central role here, providing insights on nutrient losses from volatilization or leaching and helping us understand how these affects both yield and environmental sustainability. These tools use Key Performance Indicators, like nutrient use efficiency, yield, and environmental impact, to evaluate Economic profitability. By analyzing these results, we identify areas for improvement, making our nutrient plans more resilient and effective for future seasons. These tools help define fertilization goals based on yield targets, soil fertility trends, and economic constraints. They support decisions on product selection, application methods, and timing. Integration with farm management platforms allows for holistic planning across crop rotations and seasons. Strategic tools also enable benchmarking and performance tracking, fostering continuous improvement. By aligning fertilization with agronomic and environmental objectives, they contribute to resilient and efficient farming systems.

The use of recycled digestates from biogas production as fertiliser for agricultural crops is promising. To use digestates it is necessary to assess the quality of the digestates prior to each fertilisation. The chemical composition of the digestates varies considerably depending on the feedstock used and the efficiency of the biogas production process. All types of digestates are suitable for fertilising agricultural crops. The rate of fertiliser application should take into account the amount of nitrogen supplied by organic fertilisers should not exceed N170 kg/ha. As digestates processed in biogas production, especially separated digestates, add a significant amount of organic matter to the soil, it is recommended that they are applied prior to sowing or during the growing season of the crop. This application of digestates should not be a one-off application but should be repeated over several years to begin to show positive results.

Pig slurry is a valuable fertiliser in potato farming, improving soil structure, nutrient supply, and crop rotation efficiency. Potatoes are highly responsive to potassium and nitrogen, both of which are present in slurry. When properly applied and incorporated, slurry enhances soil friability, water retention, and microbial activity, while reducing the need for mineral fertilisers.

A farmer from the NCN project in Kėdainiai (CNC) transitioned from using only mineral fertilisers to applying pig slurry before sowing rapeseed and potatoes (30 t/ha). Potatoes also receive potassium chloride, DAP, and ammonium nitrate, while cereals and rapeseed are now fertilised only with nitrogen. This shift reduced fertilisation costs and improved soil structure, making potato harvesting easier and improving tuber quality.

Crop models simulate plant growth and nutrient uptake under varying environmental and management conditions. By integrating weather data, soil characteristics, and crop physiology, these models provide valuable insights into crop development and nutrient dynamics throughout the growing season. 

One of the key strengths of crop models, such as CHN, developed by Arvalis, is their ability to perform scenario analysis. Users can evaluate the impact of different fertilization strategies on yield, quality and resource use efficiency. 

Integrating crop models into Decision Support Systems (DSS) involves incorporating decision rules that reflect the farmer’s primary objectives—such as maximizing yield, improving protein content, complying with environmental regulations, or optimizing nutrient use efficiency. This integration allows for dynamic, site-specific recommendations that adapt to changing conditions and goals, particularly under conditions of climate variability and regulatory constraints.

Ultimately, they help predict optimal fertilization timing and dosage, supporting more precise and efficient nutrient management.

In 2024 our CNC has tested a growth model, called "Tipstar", for potatoes and especialy Starch potatoes. we evaluate 3 different varieties about growth and nutrient needs of the crop. Tipstar model focuses mainly on Nitrogen and water. With those variables and data generated out of open available sources the optimal yield is estimated. With the constraints given by the farmer about Nitrogen and water it returns a actual yield and gives insight in where the lost yield is found. The evaluation has demstrated that the model is relatively accurate in prediciting the yield (about 5-10 tonnes difference). but that there are some flaws in calculating N out of manure, wich it doesn't calculate but sees as fully mineral nitrogen wich seeps out also in the calculation of the rainfall for specific fields is some flaw, for now it is a broader measurement wich sometimes isn't true due to locally rain. our CNC will test it next year too to get better feeling and hopefully benefit of improvements in data use and model quality.

When slurry is processed in a biogas plant, organic nitrogen (N) is partially mineralised to ammonium (NH4+), which increases the nutrient value. NH4+-N in digested slurry can vary between 60-80 % depending on the digested biomass type. In Denmark, the fertiliser value for N in slurry is set by law to 75-80 %. The fertiliser value of digested biomass might be higher, especially if efforts are made to reduce ammonia (NH3) loss. However, biomasses with a high content of dry matter (DM), e.g. deep litter, straw and energy crops, lowers the nutrient value of the digestates as it reduces the share of ammonium N, and the higher DM con-tent prolongs the time before the slurry infiltrates the soil. This increases the risk of NH3 volatilisation – par-ticularly in combination with the rise in pH which is a side effect of the biogas process. At high DM contents, it is important to use slurry application technologies that reduce this risk e.g. slurry injection, trail hose appli-cation and acidification. Almost half of NH4+-N may be lost as NH3 if the DM% of the digestates is above 8 %. It can therefore be beneficial to ask the biogas plant to separate the digested slurry to reduce the DM content.

Variable rate of fertilizers is the most important function of the CropManager program, which allows you to optimize yields and crop quality according to selected scenarios. The benefits of this function are as follows: adjust the amount and type of fertilizers to the needs of plants, soil and climatic conditions, save costs by reducing the use of fertilizers and fuel, reduce the risk of over-fertilization or nutrient deficiency, which affects the health of plants and soil, it is much easier to identify fields ready for harvest, improve the natural environment by reducing greenhouse gas emissions and water pollution. Prepare a preliminary fertilization plan, which will then be sent directly to CropManager. This programme will select the most optimal fertilisation scenario, then simply export it to the machine.
 

In Greece, improper use of nitrogen fertilizers can result in water pollution. Nitrogen is an essential nutrient for wheat, ensuring both high yields (due to an increase in the number of ears per unit area), the number of grains per ear, and the specific weight of grains. An effective solution involves assessing available nitrogen levels in the soil to ensure precise fertilizer application for wheat crops. The Kjeldahl Method is pivotal in this determination by extracting and quantifying the "plant available" nitrogen in soil samples.

This method involves three phases: converting nitrogen into nitric acid through organic material digestion, distilling released ammonia onto an absorbing medium, and volumetrically analyzing the resulting ammonia. The measured nitrogen content allows for the creation of a soil map that can be integrated into smart tractor systems equipped with specialized software. This integration enables accurate fertilizer dosing for wheat crops based on the soil's nitrogen levels. This practice mitigates environmental impacts from excessive soil use and enhances resource efficiency, including optimized fertilizer and water use.

For a couple of years now its been common to use leaf sample analysis in the cultivation of starch and storage potatoes. commen use of this technique is when the plants touch each other the leaves can be picked and sent to the nutricontrol laboratory. once arrived there they get tested and results are sent to Delphy within that day. this results in a 3 day span between picking and results which gives fast chances to adjust your nutrient giving. these leaves are tested for 18 different variables such as potassium, nitrate, ammonia, phosphate, manganese and magnesia. these nutrients can be applied through canopy treatments and are therefore directable and measurable during the season. this gives the grower a quick and safe way of analysing and acting on actual deficiencies of these macro and micro nutrients. for the 3 major nutrients nitrogen, potassium and magnesia, Delphy has developed trajectories for the amount that needs to be available during the season, giving the grower direct insight into the status of his crop.