Tractor-mounted sensor technologies using the NDVI (normalized difference vegetation index) indicator, such as Yara and Green Seeker, and drone technologies (Unmanned Aerial Vehicles, UAV) can be successfully used in nutrient management. The nutrient supply of plants and the heterogeneity of the plots can be seen indirectly from the data of the field maps made on the basis of the recorded raw data. The satellite communication of the tractor technologies use the 20m x 20m or 10m x 10m grid resolution, while the drone technology uses centimeter- precise information. Since the drones are equipped with positioning device, multi-spectral and thermal cameras, they can be used even in cloudy or unstable weather conditions, can adapt to the local conditions, and provide real-time information at a relatively low cost. They can be successfully applied to heterogeneous crops such as grapes and orchards. The results of the tests carried out within the Nutri2Cycle project showed that drone technology offers more perspectives than the tractor mounted sensor technology because a) their use can be easily learned by farmers b) there are several types of software available for raw data processing, b) the information can be made compatible with the automatic control of tractors, c) the processed data can be used also for spraying, and by determining the evapo-transpiration index in yield estimation, in irrigation and in evaluating the crops carbon sequestration potential, but also in the variable rate of sowing. Lately, farmers are constantly switching from the tractor sensor technology to the drone technology.

As part of the Nutri2Cycle project, the Chamber of Agriculture was asked for demonstrating the situation of nutrient cycling in a farm combining livestock, crops and agroforestry. So we followed from 2019 to 2022 an agroforestry plot at the Manicot farm which combines geese’ husbandry and cropping in Charente-Maritime. A 8 ha plot, planted since 2010 with linear intra-plot coppice for the production of energy biomass with, has been monitored on four different areas established according to the spreading of effluents and the agroforestry situation. The evaluation of the annual stocks of effluents led to a result of 145 m3 of slurry and 25 tons of manure.The contents of NPK elements on raw matter are lower than 0.5% per element: these effluents cannot claim the commercial qualification of fertilizer but they have a fertilizing value at farm.The four areas were followed mainly using remote sensing associated with analyzes of soil organic matter and tests of nitrogen mineralization kinetics. Observations were cross-referenced with fertilization balance calculations and crop development simulations using the STICS tool designed by INRAe.

A two-year demonstration was carried out in an organic farm combining field crops and a vineyard. The aim was to decide whether the oil-cake obtained from extracting rapeseed, hemp, sunflower and camelina oil should be used as livestock feed for a neighbouring farm, as was usually done, or as a fertiliser or soil-enhancer with biostimulating effect for the vineyard. During the first year, the fertilising efficiency of the oil-cake was compared to a commercial organic compost and a mix of both. During the second year, the oil-cake was compared to a control plot. The obtained results were mixed. One explanation is that the plots chosen for the demonstration were already showing differences in the soil profile, probably due to differences in sun exposure. Furthermore, legumes had been planted in every second interrow of the vineyard in every plot, which may have biased greatly the N content of some samples. Finally, the varying climatic conditions between the two years of demonstrations may have affected the results. The main recommendation would be to consider the oil-cake as an as effective fertiliser as the commercial compost. More experimentations should be done over more years to confirm these findings.

Variable Rate Application (VRA) of pig manure in top dressing fertilization may have a positive effect on the yield of potato. Therefore standard top dressing of chemical fertilizer and evenly spread of 50m3 basic fertilization (April) plus 14m3 top dressing (July) of manure was compared to application in 3 VRA zones: low (25+7m3) medium (50+14m3) and high (75+21m3). Two strategies were tested: more manure on rich soil (high buffering capacity, ‘all for the best’) and more manure on poor soil (‘robin hood’).Soil buffering capacity was assessed by measuring Electrical Conductivity (EC). EC is an indicator for the organic matter content, water-holding capacity and nutrient content. Based on this, 3 field zones were determined: poor (EC 1,6-3,7), medium (EC 1,9-4,0) and rich (EC 2,6-4,8). Per zone, soil was analysed on nutrients (NPK) content.The growth of the crop was assessed by drone thermal and spectral images, from which different indexes (NDVI, NDRE, VARI, WDVI) were calculated and represented in spatial maps. In addition, manual probe harvests were done on different moments; during the final harvest a yield map was produced. With data of treatment zones, differences in yield were calculated and economic consequences were discussed.

Practice Center for Precision Agriculture, Reusel, South Netherlands, tested application of BioBased Fertilizer (BBF) on potato for project Nutri2Cycle in 2022.Basic fertilization was applied with a standard slurry injector. The test focussed on top dressing with pigmanure; where two issues were addressed: (i) Standard slurry is too heterogenous to do a reliable top dressing. Therefore the Liquid Fraction Dosing (LFD) of pig slurry was used, with a more constant NPK content. Even the thin fraction of pig slurry is difficult to pomp through an application system, it might cause constipation, therefore it was treated with plasma. (ii) Application was done with a trailing hose fertilization device, just before complete canopy coverage. It was expected that this system limits exhaust of fermentation gases, especially ammonia, and reduces the risk of burn marks on leaves.

Application of manure to agricultural soils can improve soil quality and productivity by maintaining its nutrient status and organic matter (OM) content. Resulting nitrogen (N) emissions in the form of ammonia (NH3) and the greenhouse gas nitrous oxide (N2O) may however lead to substantial environmental pressure. Manure plasma activation has been considered an innovative technique that lowers nitrogen losses during and after soil application. The scientific documentation on its effects is still limited.In 2022 Wageningen Environmental Research (WEnR) conducted a study within Nutri2Cycle project to quantify gaseous losses of NH3 and N2O from plasma activated manure (PAM) and non-treated raw manure (RM) applied to soil.

The trial site, which was located on a working arable farm, was established in 2019 and ran for the duration of the Nutri2Cycle project. The crop rotation consisted of maize silage (2019), spring wheat (2020), oilseed rape (2021), winter wheat (2022) & spring beans (2023). The trial site consisted of seven fertiliser treatment plots, which were zero fertiliser (control), chemical fertiliser (CF) only, and, a further five bio-based fertiliser (BBF) treatments, namely, treatments including cattle slurry, pig slurry solids, poultry manure, and two types of dairy processing sludge (DPS), to supply part of the crops nutrient requirements based on soil test data and targeted yield. These five BBF were analysed to assess both their nutrient value & nutrient availability. As the BBF did not provide all the crops N, P, K and S requirements, these treatments were supplemented or ‘’balanced’’ with CF in order to ensure all plots received the same amount of nutrients for optimal yield. Using available data from 2019 to 2022, several benefits of incorporating BBF into an arable NMP are apparent. Using BBF to recycle nutrients can provide a considerable amount of a crops P requirements, and, in doing so, can reduce the associated fertiliser costs and P imports. In addition, soil data from the trial has shown that BBF can also be used to effectively build soil P and K fertility. In addition, CF only plots and balanced BBF plots returned comparable yields, which indicates that incorporating BBF fertilisers into arable systems could be a financially viable option for crop farmers and a way to reduce the reliance on CF

Microalgae are small photosynthetic organisms, which means they can produce their own organic carbon from CO2. These organisms are much more efficient in capturing CO2 from the atmosphere than conventional crops, and therefore have a higher potential for mitigation of greenhouse gas emissions.Besides CO2, microalgae require N, P, K and other macro and micronutrients, which can be provided in the form of liquid fraction of digestate, creating value from it. However, the liquid fraction of digestate has high ammonia concentration and high turbidity, which can hinder microalgae growth.To address these challenges, the Nutri2Cycle project evaluated the growth of microalgae on digestate on a pilot scale 500 L photobioreactor installed in a greenhouse in Belgium. Filtration, dilution and fed-batch strategies were tested to improve the quality of the digestate for microalgae cultivation.

Phosphorus is industrially upcycled from the renewable food grade animal bone meal unexploited biomass that is converted into macroporous and economically high nutrient density “ABC” Animal Bone Char BioPhosphate. Unique zero emission/energy independent innovative 3R pyrolysis process applied that has been specifically developed to upcycle animal bone meal by-products to make ABC. In the second processing step the blank ABC is biotech formulated into multi-nutrient compound BIO-NPK-C biofertilizer commercial products with multifunctional character and combined with other bio-origin nutrient sources. This is a high added value transformation of unexploited biomass into new and lawful biofertilizer products at less cost, perceived to be of greater quality and environmental/climate value with second life/new function that finished product becomes more practical and valuable than what it previously was. The 3R is aiming to replace in significant industrial scale the imported, energy intensive, chemically processed and non-renewable mineral compound fertilizers, which supply chain/security is disrupted for long term by the new 2023 energy and geopolitical situation. ABC targets agri food crop producer users with demands for environmental friendly and efficient BIO-NPK-C compound formulated bio-based fertilisers to be market competitive, resilient and adaptive to wide range of different climatic/soil applications at less cost. Lawfulness demonstrated, EU REACH certified, MS Authority permitted for commercial applications while EU 2019/1009 EC fertilizer conformity pre-audited to meet different product functional category requirements to create multiple financial and non-financial benefits for the users.

Livestock manure is typically applied to cropland when it is generated in an amount that fits the farm’s land nutrient needs. But when it is produced in excess, livestock manure will need to be exported and/or treatment due to its high and concentration of nutrients, such as nitrogen. Ammonia recovery from livestock manure can produce fertilisers as marketable products and allows for nitrogen loop closure. This particular lighthouse demo investigation develops low temperature vacuum evaporation for the recovery of ammonia from pig slurry, to obtain a salt solution that can be used as a fertiliser. A vacuum evaporation plant (Ammoneva®) has been placed and operated in a farm of UPB Genetic World, S.L. (Viver i Serrateix, Barcelona, Spain). The field pilot plant consists of a solid-liquid separator, a 6.4 m3 vacuum evaporator, a liquid ring vacuum pump, and an acid trap. After a solid liquid separation, and prior entering the evaporator, the pH value of liquid fraction (LF) of pig slurry is modified to a range of 9-11. Each evaporation cycle lasts for 4 hours, and is performed at a temperature of 40-45 °C and 800 mbar of vacuum. Ammonia evaporated from the LF is conducted to the acid trap, where it is absorbed as an ammonium solution, and a LF with low ammonia content is obtained. 

Portuguese Farmers need some evidence that mineral fertilizer can “safely” be replaced by organic fertilizers, namely by manure-based fertilizers. Some issues regarding the management and application of such materials need to be clarified/evidenced to farmers namely: 1) The impact on soil health; 2) The impact on weed development; 3) The mineral fertilizer replacement potential; and (iv) The ability of these materials to increase soil organic matter (SOM) content. The potential use of poultry manure compost and pig slurry to replace mineral fertilizers as basal fertilization in maize crop was tested in a commercial Farm located at Azinhaga (Quinta da Cholda – Portugal) in three contrasting sites: site 1) a sandy soil with low organic matter content, submitted to regular application of compost and conventional agriculture practices; site 2) a loamy soil with medium soil organic matter content, no application of organic materials and conventional agriculture practices; and site 3) sandy loam soil under no-tillage practice over the last 15 years. At each site, basal nitrogen fertilization using mineral fertilizers was replaced by pig slurry or poultry compost application. Greenhouse gases emissions were measured during maize growth and the crop yield, nutrient recovery and soil health were assessed at the end of the experiment.The maize yields obtained in the three sites in plots fertilized with pig slurry or poultry manure were all similar or higher than those obtained with mineral fertilization. However, the use of compost led to an increase of nitrous oxide, one of the stronger GHG.

A life cycle assessment (LCA) study compared the acidification of pig slurry with sulfuric acid in the outdoor storage with no treatment in intensive pig production in Denmark in terms of their environmental performance. Slurry acidification reduces environmental emissions and impacts directly related to the farm, such as emissions of greenhouse gases (mainly methane, CH4), acidification, eutrophication and fine particulate matter (derived from ammonia, NH3), but may also contribute to enhanced nutrient recycling overall. However, it can also have harmful effects due to the consumption of additional energy and sulphuric acid manufacturing derived from off-farm resources and increased nitrate leaching due to changed chemical properties of the slurry. To justify slurry acidification as a cleaner production technology on all levels, energy and material sources should be examined and carefully selected. Acidification costs between 1 – 2 € per ton of slurry, which can partially be substi¬tuted by reduced mineral N fertiliser needs as the slurry fertiliser equivalent value increases by about 30-40%. Since farmers are expected to adjust their mineral Nitrogen (N) fertiliser application to the con¬centration and expected efficiency of N in the slurry, no great differences in yield are expected. 

A life cycle assessment (LCA) study compared the acidification of pig slurry with sulfuric acid in the outdoor storage with no treatment in intensive pig production in the Netherlands in terms of their environmental performance. Slurry acidification reduces environmental emissions and impacts directly related to the farm, such as emissions of greenhouse gases (mainly methane, CH4), acidification, eutrophication and fine particulate matter (derived from ammonia, NH3), but may also contribute to enhanced nutrient recycling overall. However, it can also have harmful effects due to the consumption of additional energy and sulphuric acid manufacturing derived from off-farm resources and increased nitrate leaching due to changed chemical properties of the slurry. To justify slurry acidification as a cleaner production technology on all levels, energy and material sources should be examined and carefully selected. Acidification costs between 1 – 2 EUR / t slurry, which can partially be compen¬sated by reduced mineral N fertiliser needs as the fertiliser equivalent value increases by about 30-40%. Since farmers are expected to adjust mineral N fertiliser application to the concentration and ecpected efficiency of N in the slurry, no great differences in yield are to be expected.

A life cycle assessment (LCA) study compared the acidification of pig slurry with sulfuric acid in the outdoor storage with no treatment in intensive pig production in Denmark in terms of their environmental performance. Slurry acidification reduces environmental emissions and impacts directly related to the farm, such as emissions of greenhouse gases (mainly methane, CH4), acidification, eutrophication and fine particulate matter (derived from ammonia, NH3), but may also contribute to enhanced nutrient recycling overall. However, it can also have harmful effects due to the consumption of additional energy and sulphuric acid manufacturing derived from off-farm resources and increased nitrate leaching due to changed chemical properties of the slurry. To justify slurry acidification as a cleaner production technology on all levels, energy and material sources should be examined and carefully selected. Acidification costs between 7 – 15 DKK / 1 – 2 € per ton of slurry, which can partially be substituted by reduced mineral N fertiliser needs as the slurry fertiliser equivalent value increases by about 30-40%. Since Danish farmers are required to adjust their mineral Nitrogen (N) fertiliser application to the concentration of N in the slurry and a minimum required efficiency, no great differences in yield are to be expected.

Life cycle assessment (LCA) was applied to evaluate duckweed ponds and constructed wetlands as polishing steps in pig manure liquid fraction treatment. Using nitrification-denitrification (NDN) of the liquid fraction as the starting point, the LCA compared direct land application of the NDN effluent with different combinations of duckweed ponds, constructed wetlands and discharge into natural waterbodies.Duckweed ponds and constructed wetlands are viewed as a viable tertiary treatment option and potential remedy for nutrient imbalances in areas of intense livestock farming, such as in Belgium. As the effluent stays in the duckweed pond, settling and microbial degradation reduce the remaining phosphorous (P) and nitrogen (N) concentrations. Combined with duckweed and/or wetland plants that take up nutrients in their plant body, this approach can reduce over-fertilisation of soils and prevent excessive N and P losses to aquatic environments. In addition, duckweed could serve as an alternative livestock feed and replace imports of protein destined for animal consumption.

A life cycle assessment study evaluated the environmental impacts of insect production based on agro-residues with soybean meal and fishmeal as protein sources.Given their nutritional value and ability to convert agro-residues into fertilisers, the larvae of Black Soldier Fly may foster nutrient recycling and feedstuff production within the EU on less land than current practices. However, BSF originate from the tropics and their rearing in Europe requires substantial heating and diets composed solely of residues rarely meet their dietary requirements and additional feed is needed.Both heating and non-residue feed are environmental hotspots of insect production and cause great impacts on fossil resource and water use, and climate change. Overall, insect protein had greater impacts than protein from soybean meal or fishmeal unless location and/or heating source are changed.Since non-residue feed inputs are needed, insect production based on endive roots and Brussels sprout stems performed worse than their natural degradation on agricultural fields. For manure, BSF production showed advantages due to avoidance of industrial composting and field application, but a clear superiority could not be demonstrated.Using renewable source instead of natural gas for heating decreased impacts but for non-manure diets such switch was insufficient. Transferring BSF production to warmer regions where no heating is needed could be a more promising option.

This study assessed a selected range of innovative agricultural technologies (12 in total) aimed at closing loops of Nitrogen (N), Phosphorus (P) and Carbon (C) with regards to their overall environmental and social performance.All environmental life cycle assessments (eLCAs) were compliant with the EU Product Environmental Footprint methodology. Data inventories were based on data from technology providers, field scale modelling, literature and/or the ecoinvent database. Given the different purposes of the technologies (e.g. slurry ammonia volatilisation reduction vs. waste stream P recovery), they cannot sensibly be compared on how much they improve C, N and P recovery and recycling. Therefore, each technology was compared against a baseline without the technology, to quantify the environmental benefits and drawbacks in relative terms.Further, Dashboard Indicators (DBI) of environmental impacts, assessed qualitatively by experts, were compared against the quantitative LCA results, to see if these simple DBI could provide useful technology guidance, saving more comprehensive LCA studies. This comparison of DBI vs. LCA can provide useful learnings for where and how to improve guidelines for DBI assessment.Finally, the social LCA study selected and tested a range of indicators of potential social hotspots and opportunities related to the implementation of these novel technologies.

Intensive livestock activity in Lombardy (northern Italy) and in other regions in Europe (like Denmark; Catalonia, Spain; Flanders, Belgium; Netherlands) is causing several environmental issues. The nitrates directive limits the amount of manure that can be used in fields (depending on if the area is considered vulnerable or not). The possibility to export some fractions of the effluent can increase the number of livestock heads without jeopardising the environment.The solution has the aim to reduce pig slurry volumes to allow a better management of nutrients, both for export from livestock areas and on site (top dressing with ready effect nitrogen). The products are: a solid fraction (19% ww), a concentrate (a RENURE like material, 33% ww) and clean water (48% of mass). The plant separates the effluent in a solid fraction (19%), which will be composted and a liquid fraction. The latter is further separate thanks to reverse osmosis (super tight filtrations) in clean water (48%) and a concentrate (33%) that can be exported from the farm as RENURE (it could be considered a chemical fertiliser instead of livestock effluent). The liquid concentrate has high concentration of ready-to-use nutrients for plants. Field experiment on corn demonstrate that fertilisation with concentrate is as good as a chemical fertilisation (urea), as yield were the same.

The solution encompasses a plant performing anaerobic digestion of sewage sludge and a “stripping system” extracting ammonia to increase the plant's digestion efficiency and produce ammonium sulphate, which can be used as valuable fertilizer or sold for industrial uses. Digestate and ammonium sulphate are used to fertilise crop, zeroing the use of synthetic fertilisers and providing valuable organic matter to the soil. Minimum tillage and precision distribution of digestate is implemented.To investigate the effect of the combined use of digestate, precision agriculture and no-tillage, field trials were set up close to the abovementioned facility. Two crops, rice and wheat, were considered and a randomised field test was performed. The investigated theses were: i)fertilisation with digestate+ AS distribution ii) fertilization with urea iii) no fertilisation(control) During the agricultural season, ammonia emissions nitrous oxide, methane, and carbon dioxide emissions were measured Odour emissions during fertilization are evaluated, and changes in main soil characteristics are also analysed. All agronomical data related to fertilization, field management, and irrigation operations were collected, together with yield data.

Pig farmers struggle to dispose all manure on farm. (Processed) manure involves laborious and expensive transport. The fast growing plant duckweed might be a solution because it requires a lot of nitrogen (N) and phosphorus (P) to sustain its growth.The principle is simple: (de-)nitrified effluent is added to a pond of water, and the plant takes up all N and P it requires. By doing so, the effluent can be discharged without a negative impact on the natural ecosystem and at the same time, a protein rich plant is produced which is a source of essential minerals, which could be used in animal feed.Maximizing the addition of the (de-)nitrified effluent from pig manure within the legal limits, can still cause troubles. N is taken up, but the effluent contains more potassium (K) than required for the plant growth. As a result, K slowly builds up, until it becomes toxic for duckweed. In the project we determined a method to estimate the speed of the accumulation. We found that the depth of the pond dilutes the nutrient build up and acts as a buffer. A pond depth of 1 m allows the K levels to be below any toxicity levels after one growing season. Each winter, the pond can be discharged and refreshed with rain water. Sadly, the K cycle is generally overlooked in legislation and research. We learned to increase the amount of the unprocessed liquid fraction of pig manure in our pond

Large surpluses of on-farm N and P are processed or exported out of Flanders while tons of synthetic N-fertilisers are purchased and used for crop production. The use of recycling-derived fertilisers (RDFs) from manure can counter this situation. Currently, RDFs derived from animal manure still need to comply with the legal application constraints of animal manure and are thus not often used. That is why five RDFs (ammonium nitrate and ammonium sulphate (from stripping-scrubbing), digestate from co-digestion of pig manure, liquid fraction of digestate and pig urine) were compared with mineral fertiliser CAN, pig manure and a blank treatment in a 3-year field trial focusing on short term N-effects of the RDFs. During the first (crop: maize) and second (crop: spinach) year, the weather conditions were extremely dry and hot. Therefore water availability became the principal factor determining crop growth. In these extreme conditions, no significant differences in fresh and dry yield were observed for the different objects. Residual nitrate of all RDFs was comparable to mineral fertilizers.During the third year (crop: early potatoes), the weather conditions were wet and rather cold. Intensive precipitation led to nitrate leaching so crop yield was lower than expected in all objects. In these circumstances, delayed N mineralization from pig slurry may have coincided better with the N uptake from the early potatoes, leading to a somewhat better (not significant) yield. N - mineralization from digestate however appeared to happen too late for the potatoes (N demand is high in the early phases of the growing season in early potatoes). This may also explain the (not significant) higher residual nitrate in the soil after digestate at harvest.

Farm scale anaerobic digestion (AD) is a technology by which farmers can create renewable energy by valorising agricultural residues. The AD process takes place in a large reactor in the absence of oxygen, where organic material (e.g. manure or crop residues) is being converted into biogas. The biogas (mainly methane) is subsequently burned in a combined heat and power (CHP) unit and results in a renewable energy source in the form of heat and electricity. The fermented biomass is called digestate and can be used on the farm as organic fertilizer.The majority of the 50+ farm scale anaerobic digesters in Flanders are active on dairy farms and run on mono digestion of cattle slurry. Other agricultural sectors (pig farming or vegetable farming) however also show potential for the application of farm scale AD. The most important conditions to be an economically feasible case on farms appear to be a sufficiently high demand for electricity on the farm, the availability of sufficient agricultural residual flows and limited additional cost (e.g. for potential extra pretreatment steps or logistic aspects).Pig farming in particular seems to be highly interesting to apply farm scale AD. To validate the feasibility of performing mono digestion of pig manure in a stable way, Inagro performed a pilot scale test in their farm scale digester (31 kW) during three months. The input feed consisted of the solid fraction coming from an adapted stable system and pig slurry (to decrease the dry matter content in order to prevent operational problems).

The intensification of agriculture has greatly enhanced crop productivity, much needed with the present population growth, but its potential environmental impact also increased. Precision Agriculture has potential to tackle this challenge and the present work is framed within that context, as it intends to study the spatial variability of soils in order to precisely apply organic fertilizers. For this, three distinct zones were defined in a 6.77 ha vineyard based on high and low values of 1) apparent soil electrical conductivity (ECap), measured using an indirect sensor (Geonics EM38®), and 2) normalized difference vegetation index (NDVI), obtained from satellite images. Soil samples from each zones were then collected and chemically analysed. Most of the selected soil chemical properties, such as nutrients concentration, varied significantly among zones, showing a potential for differential application of fertilizers. Regarding soil mineralogy, significant differences were also observed between zones, as zones defined with high ECap showed higher percentage of clay and lower percentage of sand, with the opposite also true. Another reassuring but expectable outcome was the fact that zones with high NDVI presented the highest concentration of soil nitrogen and phosphorus. Both indicators are non-destructive, cost less and require less labour and, as seen, has showed efficiency in the delineation of distinct zones and in providing information about soil properties. With this information, the farmer knows which areas lack or have an excess of a specific nutrient and manage soil and crop fertilization in accordance, thus applying only the necessary amount or providing higher amounts in the poorer areas, resulting in a more evenly production.

Poultry manure, due to the high content of organic substances, are an attractive raw material for biogas production, however, mono-digestion in their case may be difficult due to the low C/N ratio. Therefore, it seems reasonable to optimize the substrate, obtained by creating a homogeneous mixture of manure with other organic waste and their co-digestion. For this reason, in our study we tested the possibility of anaerobic co-digestion of poultry manure with sewage sludge. The proposed solution, seems to be very interesting option, because it leads to an enhanced production of biogas (>40%), as well as volatile solids removal (>20%). In this context, the implementation of this solution in WWTPs provides an unique opportunity for these facilities to improve their energy self-sufficiency as well as profitability which are possible by enhancing energy recovery from sludge as well as full utilisation of the existing infrastructure (oversized digesters) and hence creates a new place for the treatment of the poultry manure. Moreover, considering the solution at the investment planning stage may significantly impact the disposal capacity per volume unit of the digester, thereby affecting investment costs. However, the implementation of this solution in the wastewater treatment plant is still a big challenge and needs further studies including the identification of optimal digesting conditions, information about substrate pumping, infrastructure for WWTP (e.g. efficiency co-generation devices, energy consumption in activated sludge system, inhibition thresholds and processing properties). Other challenging task for future research is: 1) the identification of the microbial community structure which can vary in response to the changing environmental conditions such as: OLR, HRT; 2) optimization of feedstock composition.

Due to chemical composition and properties poultry manure is considered a valuable substrate to obtain fertilizing products such as composts and biochars. Compost from poultry manure compared to poultry manure when applied to fields does not contribute to excessive gaseous emissions including ammonia or carbon dioxide. It is microbiologically safe, and thus does not pose any threat to the environment. Biochars produced through pyrolysis of poultry manure can be used in composting as a supplementary material in composting mixtures to limit nitrogen loss during composting. Poultry derived biochar can be also used as an additive to mature composts or as a soil enhancer directly introduced to soils. The main goal of this research is to convert poultry manure into composts such as nitrogen losses can be limited during the process and to evaluate the obtained composts, composts mixed with poultry manure derived biochar and poultry manure derived biochar itself for fertilization of soils with low organic matter. So far, the results show that the obtained compost from poultry manure fulfils the requirements for fertilizers. It is microbiologically safe (free from pathogens), contains 73% of organic matter, 41.7% of carbon, 1.8% of nitrogen, 8.1% of phosphorous, C/N of 22 and pH of 9.2. Currently, the pot experiments with selected growing media amended with poultry manure composts, biochars and their mixtures are in progress. They are aimed to evaluate the effect of poultry manure derived fertilizing products on soil properties and growth of selected plants.

Extensive agriculture results in increasing amounts of phosphorous compounds in soils mostly due to the use of mineral fertilizers. In consequence, this biogen is transferred to water, and in turn can cause eutrophication of water reservoirs. Phosphorus fertilizers contain some heavy metals which can lead to soil contamination due to improper fertilization. What is more, excessive acidification of soils can contribute to mobility of heavy metals already present in soils. One of the potential solutions to mitigate and/or prevent from these threats is introducing to soils substances with suitable sorption properties such as biochars. The overall goal of this research was to evaluate the sorption properties of biochars produced from poultry manure. The obtained results demonstrated that sorption of phosphorus was above 95% of the applied dose. At the same time biochar produced from poultry manure at 425 °C showed not only high sorption capacity but also demonstrated desorption of phosphorus at around 21%. This biochar property could be of importance when it comes to agricultural soils where excessive phosphorus fertilization could be a threat. Such sorbent could also function as phosphorus storage. The research confirmed high efficiency (above 99%) of biochars to remove heavy metals ions, even at high concentrations in solutions (1000 mg L-1). Alkaline character of these biochars is also important. The application of obtained biochars to soils could prevent from excessive acidification of soils. In conclusion, the obtained poultry manure derived biochars can be valuable additives to soil, and thus prevent from improper fertilizing practices by immobilizing excessive amounts of phosphorus and at the same time limiting the mobility of selected contaminants such as heavy metals.

The main aim of the deep-technology and product development driven BioPhosphate research (2002-2022) is to replace mineral fertilisers, most importantly the Cadmium and Uranium contaminated mineral and soft rock phosphate fertilizers, closing the CNP loops/reducing GHG emissions at less cost. High material core temperature, innovative zero emission pyrolysis (3R) applied to recover 35% P2O5 concentrated Phosphorus from pressure sterilized food grade cattle bone byproducts, which is than controlled release BIO-NPK-C compound biofertilizer formulated as of organic farmer user demands. The average dose is 300-500 kg/ha. The outcome of BioPhosphate research so far is TRL8, where the technology has been experimented in deployment conditions (i.e. real world) and proven its functioning in its final form with compliance with industrial/enviro standards of the addressed markets (EU, UK, USA, AU, JP). The BioPhosphate BIO-NPK-C compound biofertilizer products MS Authority permitted in 2020, fully meet the new 2022 EC Fertiliser criteria in several product functional categories and prepared for REACH certification (ongoing). As a result so far the BioPhosphate research so far already removed most technical/market risks, while majority of the underlying scientific/engineering problems being solved. The last research action is in progress, e.g. TRL9 first full industrial replication model deployed at 20,800 t/y capacity that is the ultimate evidence that research is successfully completed. TheBIO-NPK-C compound BioPhosphate biofertilizer is safer, better and less costly versus any market competitive productin the agri sector.

In combination with precision farming, in under-root fertilization of maize seeds (or similar row crops), mineral fertilizers can be replaced by liquid organic fertilizers, such as liquid manure or biogas residue. This is the first precise application technology for liquid organic fertilizers for early under-root fertilization of maize, and potentially other row crops. In order to replace mineral fertilizer banded below seeds, a precise placement of manure close to the seeds (in the seeding lines and in a precise soil depth) is necessary. The new technology consists of a precise application technique of liquid organic fertilizer in terms of positioning, making use of GPS information, and in terms of dosage. Application of under-root fertilization can be carried out before or after sowing, even simultaneously. The preliminary conclusions are: (a) liquid manure for under-root fertilizer application instead of application of mineral P (and N) fertilizers has advantages with regard to the on-farm nutrient management; (b) in soils rich in P due to prior intensive manure application, under-root fertilization with liquid manure would reduce the P demand in form of mineral fertilizers; (c) in poor soils, this technique can increase particularly the P use efficiency; (d) N and P surplus thus can be reduced by reducing mineral fertilizer application around seeding; (e) results also show that under-root application of liquid manure can be combined with the strip-till technique; this combination makes it possible to make advantage of mulch sowing, which protects soils against erosion; (f) results showed that under-root application of liquid manure did not negatively affect yields and quality of silage maize.

Processing manure can contribute to closing carbon (C) and nutrient loops, but this will only succeed when the products resulting from manure processing (also called bio-based fertiliser) are being accepted by arable farmers as a replacement for mineral fertilisers. This not only depends on the performance of these bio-based fertilisers compared to mineral fertiliser, but also on the costs and benefits. In this study, the effect of refining bio-based fertilisers was tested on potato yield. The less refined, and therefore cheaper, product (thin fraction of the digestate) as well as the refined product (ammoniumsulphate) showed a high nitrogen fertiliser replacement value (81% and 73% respectively). This means that both products are suited as a replacement for mineral N fertiliser. In the field, the different products showed limited differences in plant growth and yield which confirms the safe use of these products for potato growing. The fields that received only bio-based fertiliser showed similar results, but bio-based fertilisers will not be used as a replacement for animal manure in practice in the Netherlands due to the higher costs. Although this study concludes that both products are suitable as a replacement for mineral N fertiliser, only the refined product will potentially be used because it has the status of anorganic fertiliser.

Understanding consumer behaviour, perception and acceptance of eco-friendly and sustainable food products is one of the key objectives for the Nutri2Cycle project with the aim of bridging the current environmental informational gap between producers and consumers. As a first step towards achieving this goal, techniques of meta-analysis were applied to studies on the relationship between sustainable agricultural products and consumers' willingness to pay (WTP). The data obtained from over 100 papers screened in the analysis showed that the percentage difference in the WTP estimated ranged from 2% to 92%. The overall WTP valuation was calculated as 33%, that is, consumers are willing to pay about a 33% more for sustainable attributes in food products. This WTP depended significantly on variations of the consumers' region (the highest WTP was located in Asia, 65%) as well as the food categories (cereal & bread provided the highest WTP, 60%). Moreover, the results showed the presence of different sustainable claims was not a significant factor and it did not influence the WTP significantly which means that consumers have knowledge about what sustainable food product is but should become more familiar with them to learn to distinguish between the different sustainable claims and their meanings. There are currently a wide range of Ecolabels in the market, with significant differences in scope, indicators, verification processes or claims affecting the overall effectivity of Ecolabels. The farmers can indeed benefit from striving towards a label - as consumers are willing to pay more – however, the labelling landscape is too scattered. Therefore, unification of the Ecolabelling schemes is required and the European ecolabelling landscape need a continuous updating that allows an easy decision-making process for consumers and stakeholders involved.

Intensive livestock activity in Lombardy (northern Italy) and in other regions in Europe (like Denmark; Catalonia, Spain; Flanders, Belgium; Netherlands) is causing several environmental issues. The nitrates directive limits the amount of manure that can be used in fields (depending on if the area is considered vulnerable or not). The possibility to export some fractions of the effluent can increase the number of livestock heads without jeopardising the environment. The plant separates the effluent in a solid fraction, which will be composted and a liquid fraction. The latter is further separate thanks to reverse osmosis (super tight filtrations) in clean water and a concentrate that can be exported from the farm as RENURE (it could be considered a chemical fertiliser instead of livestock effluent). Results are not complete yet because tests are still in progress, but we can already share some comments:
I. “Clean” water, more than half of the input volume, fit all the parameters to be disposed in superficial water bodies (rivers or lakes) or used for irrigation, 
II. about one-sixth of the input volume is recovered as solid fraction that can be composted
III. The liquid concentrate has high concentration of ready-to-use nutrients for plants.
Moreover, a real scale field experiment is set (on corn) to demonstrate that fertilisation with concentrate is AT LEAST as good as a chemical fertilisation (urea).

Due to the increase of the population and the improvement of life quality for large groups of people worldwide, the food need and the production of wastes is increasing consequently. Higher food production will require a higher quantity of fertilizers, while waste disposal (mainly sewage sludge) can be expensive, energy consuming and environmentally hazardous. The system encompasses a plant performing anaerobic digestion on sewage sludge. Anaerobic digestion is a biological process, conducted without air that stabilizes the substrate, makes the nutrients more available for plants, and increases the product's health safety while producing biogas. The digestate can partly substitute chemical fertilizers in a very efficient way. Moreover, this plant has a “stripping system” that can extract ammonia to increase the plant's digestion efficiency and produce ammonium sulphate, which can be used as valuable fertilizer or sold for industrial uses. Results are not complete yet, because tests are still in progress, but we can already share some comments:
I. In a full-scale field experiment, rice yields were similar using chemical fertilizers vs digestate + ammonium sulphate, showing the excellent quality of this solution for fertilization (experiment now running for two years out of three).
II. Analyses on rice grain showed similar composition for chemical fertilizers and for digestate + ammonium sulphate fertilization.
III. Using digestate + ammonium sulphate, we expect an increase of soil quality, intended as organic matter quantity and stability.
IV. Nitrate leaching in digestate + ammonium sulphate fertilization resulted very low, similar with chemical treatment and the untreated. The Digestate + Ammonium sulphate combination is a suitable fertilizer, safe, and with performance substantially equal to traditional chemical fertilizers. Nevertheless, such equivalent performance cannot be reached if other practices are not assured in its production and use (i.e. digestate highly stabilized and injected in soil). Besides, the parallel electric energy production (through biogas combustion) and the safe sewage sludge disposal make this technology very efficient. Finally, based on the provisional data, it has a positive effect on soil in the long run, increasing the amount and stability of organic matter, while the concentrations of pollutants (both organic and inorganic) are similar to that of a traditional fertilized field.

Large surpluses of on-farm nitrogen (N) and phosphorus (P) are processed or exported out of Flanders while tonnes of synthetic N-fertilisers are purchased and used for crop production. The use of recycling-derived fertilisers (RDFs) from manure can counter this situation. Currently, RDFs derived from animal manure still need to comply with the legal application constraints of animal manure and are thus not often used. That is why five RDFs (ammonium nitrate, ammonium sulphate, digestate from co-digestion of pig manure, liquid fraction of digestate and pig urine) are compared with mineral fertiliser CAN, pig manure and a blank treatment in a 3-year field trial focusing on short term N-effects of the RDFs. The main goal of the trial is to establish a clear relationship between the amount of N applied by RDF and dry matter production for each applied RDF. During the second year of the field trial (crop: spinach), weather conditions had a significant impact: the trial period was extremely dry, with only 12 l/m² of rain received between sowing and harvest. Therefore water shortage was an important factor influencing the growth of spinach. Hence, local differences in soil fertility appeared causing N availability as no longer the only decisive factor for crop growth and causing extra variability in the field trial, parallelly with a sandstorm that damaged many young plants. Therefore, no differences in fresh and dry yield were observed between RDFs, except ammonium nitrate which had significantly lower yield. This is probably also due to soil treatment because the applied N via ammonium nitrate had to be directly in contact with the root zone in harmful dry conditions. Residual nitrate was lower than legal limits for all RDFs except pig urine at 70% N dose.

Management of poultry and chicken manure is a challenge not only in Poland but globally. Due to the concentration of large poultry farms, it is more important to use such a management methods that will reduce the negative impact on the environment, and at the same time will be consistent with the principles of circular economy and economically justified. It is also important to take into account the carbon footprint and legislation in force in a given country, as well as the European Green Deal strategy. Currently, poultry and chicken manure are most often used as an organic fertilizer in agriculture. However, due to the environmental nuisance and periodicity of application, new technologies are considered as a source of energy and fertilizers. The most advanced methods of energy recovery include methane fermentation, but in Poland manure or chicken manure is used only in a few agricultural biogas plants, only in the process of co-fermentation with other substrates. This is due to high investment costs and the optimization process that requires specialist knowledge. More widespread is drying and granulating of chicken / poultry manure itself or prior mixing with various other substrates (dolomite, opoka-rock, coal), which are placed on the market after being certified as eco-fertilizers. The most important criterion for selecting a technology for farmers is the cost of the investment and the benefits that would be obtained from the selected technology. Additional important factors in the final choice are incentives and technical support, environmental regulations and level of education. The size of the farm is also important as there must be consistency between the quantity of the waste stream and the processing technology. On the other hand, external investors take into account the net profit as the most important criterion, and for the local government an important aspect is the acceptance or not of the local community. Poultry farm owners who plan to handle and manage poultry manure onsite can use the help from specilized consulting companies or scientific consultants who can help with the selection of a poultry manure processing technology and the development of a case-specific solution.

Treatment and nutrient recovery of waste streams have an essential role in improving the sustainability of conventional agriculture. Lemna minor, small floating-flowering aquatic plants known as duckweed, has been shown to grow on wastewaters and subsequently produce a protein-rich feed ingredient suitable for pig production, offering a possible solution for addressing both the protein scarcity and local nutrient abundancy. In this study, the potential of Lemna minor to valorise agricultural wastewater into a protein-rich feed component to meet the growing demand for animal feed protein and reduce the excess of nutrients in certain European regions was investigated. Three pilot-scale systems were fed with a mixture of the liquid fraction and the biological effluent of a swine manure treatment system diluted with rainwater in order that the weekly N and P addition was equal to the N and P removal by the system. The study shows that a duckweed lagoon can be used as an extra polishing step after swine manure treatment, converting the manure into dischargeable water instead of spreading it on arable land. Based on the N and P removal, it is estimated that one hectare of duckweed can remove the residual N and P of the biological effluent produced by 2805 swines. However, the side streams contain also K, Cl, S, Ca, Mg, and Na. It was found that these are inadequately removed from the system and will accumulate over time. By extrapolation, it was found that after 9 years K will be the first element to reach toxic concentrations for duckweed. This means that an operator should replenish the growing medium before this time. Furthermore, it should be avoided that potential harmful elements like the heavy metals As, Cd, and Pb would accumulate over time in the growing medium and subsequently taken up by the plant reaching toxic concentrations for animal consumption. It was observed that As, Cd, and Pb content were below the limits of the feed Directive 2002/32/EC in the duckweed grown on the tested medium are the elements even decreased over time. This is evidence for policy makers to consider the use of agricultural side streams like the biological effluent of the pig manure treatment system as a nutrient source for duckweed cultivation which is intended for animal consumption, if other safety risks are also validated in a similar way. In contrast, the plant is even a source of Mn, Zn, and Fe which are beneficial elements for swine’s metabolisms.

The Nutri2Cycle project will assess the current Nitrogen (N), Phosphorus (P) and Carbon (C) flows looking into existing management techniques in different farms across Europe and analysing their related environmental problems. One of such technologies is the application of digestate in orchards. If taking into consideration that the vast majority of Croatian farmers don’t apply digestate in agricultural production, one could conclude that digestate application can be considered as an innovative solution. Application of digestate in large scale orchards may have been applied across EU already, but it is considered to be an innovative management solution in Croatia. Furthermore, when digestate is applied it is usually for the energy crop production and not in long-term plantations. The underlying working principle refers to the application of digestate in raspberry plantation in the beginning of the project. In the phase of soil preparation, a combination of Ca(OH)2 in concentration of 1,00 t/ha, thick fraction of digestate in concentration of 50,00 t/ha and cattle manure in concentration of 33,00 t/ha was used. Also, next to organic fertilizers, 30 grams/plant of mineral fertilizer (NPK 7-20-30) was also applied. When investigating existing research databases, there were no specific research found on application of digestate in raspberry plantation. Use of digestate contributes to the Nitrogen and Carbon cycles in agriculture. It can also increase soil biodiversity, while reducing erosion, leaching and water pollution Numerous research findings indicate that digestate from agricultural biogas plants cannot only be a good fertilizer but also an effective mean to close the carbon cycle in the soil for a more sustainable agriculture. To conclude, digestate in Croatia is often neglected in application. When deciding, farmers should take into account important benefits that digestate has for crops, such as presence of high amounts of easily accessible plant nutrients, improved physical structure of soil, reduced ammonia emissions, and the appearance of unpleasant odours.Considering all of this, farmers now have a new and significant role in society, as both, crop and energy producers and waste processors.

The production of a manure-based fertilizer will proportionate a more sustainable agriculture practice through the valorisation of animal manure in a circular economy. Hence by adding an organic material to the soil the carbon soil reserve should increase and thereby improve its fertility and productivity. The production of a manure-based fertilizer will allow a better control of the nutrients flow, since it will ensure a decrease in the nutrient losses associated with the raw manures, such as ammonia emissions or nitrate leaching. Also, one of the difficulties in applying manure is the nutrients’ concentration that are unbalanced for the crop’s necessities, so in that case, this production aims to produce a fertilizer based on the mixture of manures, treated or not, that will have a known ratio of N:P. In that line, two scenariosare possible, one at farm scale where the farm manure can be amended with a small amount of mineral fertilizer to achieve the desired N:P ratios, and a second scenario where, at a central plant, different manures will be blended between them also to reach the intended N:P ratios. In both scenarios, the intention is to use mineral fertilizers as a complement and not as the main nutrients sources. The manure-based fertilizer will allow to close the nutrient cycle since the solution proposed here intended to reduce the known environmental impacts of manure application to the soil and, by reducing nutrients losses, the agronomic results should be comparable to the mineral fertilizers. The results obtained in this project showed that it is possible, at farm scale, to improve the agronomic value of manure by using some simple treatment as separation or by using some additives. It is to believe that such improvement might contribute to a wider use of manure as susbtitute of mineral fertilizers.

The excessive use of mineral fertilizers seen in the last few decades has contributed to an increase in environmental impacts, such as water contamination, soil erosion and resource depletion. To maintain crop productivity high but its impacts low, it is vital to promote the recycling of nutrients and to increase resource use efficiency. The present work’s aim is the substitution of the conventional mineral fertilizers with manures and slurries, thus taking avail of livestock production wastes and hopefully maintain crop productivity but with less impacts. As such, it is important to study the effects of organic (manures and slurries) versus mineral fertilization. In our trials, cattle manure, poultry manure, cattle slurry, and acidified cattle slurry were applied to soil in an apple orchard, with the purpose of evaluating fruit production and quality, greenhouse gas (GHG) emissions and soil nutrient content. Regarding fruit production, there were no significant differences between the mineral and the organic treatments, indicating that the organic materials did not injure crop productivity as one would expect due to their characteristic slow mineralization rate, however, leaf analysis has shown that the organic treatments presented higher content of phosphorus, potassium, and boron, indicating that the plants were able to obtain nutrients from the manures and slurries. However, the organic treatments produced more GHG, although it is worthy to note that acidified cattle slurry has significantly reduced CH4 emissions when compared to raw cattle slurry, hence reducing the environmental impacts associated with slurry application. More results are expected, as the trials are still on-going, nonetheless the outcomes seem promising. Replacement of mineral fertilizer by manure in orchards fertilization is an excellent tool to improve the soil quality but also to decrease the carbon footprint of apple production. Furthermore, the use of manure might be beneficial for maintenance of soil cover.

A farm in Charente Maritime, France, combines field crops with a vineyard. Crop production is done through organic farming for the past 5 years, whereas the vineyard already for ten years. With this progressive change into organic farming, the farmers had to change their fertilization practices towards organic fertilizers. However, an important problem to face in organic farming is the lower efficiency in NP inputs, because of the more unpredictable behavior of organic fertilizers without appropriate monitoring. The farm cultivates about ten species including Rapeseed, Hemp, Sunflower and Camelina for oil. After treating the oilseed crops, the farm gets oil-cake as residue. Until now the oil-cakes are used as livestock feed for a neighboring farm, but the farmers would like to recover their residues. To decide whether the oil-cake could be used as fertilizer, or soil enhancer with biostimulating effects for the vineyard, they need to monitor the synchronization between NP release from residues and the grapevine uptake and optimize the balance between C storage and organic fertility in the soil of grapevine plots. A demonstration essay has been designed to follow up and assess the fertilizing efficiency of the farm residues alone or combined with a commercial organic fertilizer on the plot with vineyard, from 2019-2021. With the characterizations of the oil-cake and the plot soil, the grapevine development will be monitored with a manual sensor and remote sensing to assess the biomass and nitrogen status, and will be explained with the properties of the organic inputs. 
The results provided by this demonstration should provide key information to decide on the best way for recycling their residue and whether this is the right way to go.

An agricultural holding in Charente-Maritime, France produces arable crops (wheat, triticale, pea, corn, and rapeseed) to breed goose livestock. The farmers decided to plant trees on an arable plot to develop an agroforestry system combining energy biomass and feeding crops while simultaneously improving animal welfare.
Using its livestock effluents – slurry and manure – to fertilize the crops , this farm already engages into circular economy. However, the farmers wanted to optimize the efficiency of the effluents use, and decrease their synthetic fertilizer input.
The Chamber of agriculture proposed a demonstration action on the agroforestry plot to analyze the effluents behavior as fertilizers and to assess carbon storage and soil fertility in 2019-2021, using soil analysis, remote sensing and modeling tools. The feeding crops are commonly fertilized using synthetic Nitrogen fertilizer. In the first year (2019), this was partially substituted by livestock slurry : 15% of the crop requirement was provided by soil stock nitrogen, 20% from animal manure and 65% by synthetic fertilizers. Considering climatic conditions it is too early to make firm conclusions on comparison of nutrient efficiency from effluents against that of mineral fertilizer. In the following growing seasons, we aim to systematically increase the use of biobased fertilizer sources and reduce the dependency on mineral fertilizers.
As results of this demonstration, it is expected to draft possible scenarios to increase the substitution of synthetic fertilizers by farm effluents and assess the increases of soil fertility and carbon storage in this agroforestry system.
When the results are positive, the farmers will extend the agroforestry system to a wider area.

In Lombardy (Italy) an anaerobic digestion (AD) plant is situated that treats 70.000 t/y waste (mainly sewage sludge) producing digestate, used as fertilizer, and biogas. An innovative stripping system reduces ammonia inhibition in the reactor while also producing ammonium sulphate, a fertilizer. Both digestate and ammonium sulphate comply to the legal limits for fertilizers. 
To evaluate the effect of digestate fertilization a 2 ha field test was set up. Digestate, mineral fertilizer and non-fertilized control treatment were compared in triplicate for the cultivation of wheat, rice, and corn following the principles of minimum tillage and precision agriculture. Field trials started in 2018 and will continue for three years. 
We observed that corn yields are statistically higher in digestate treatments, while rice yields are not statistically different between treatments. Odour emissions from digestate distribution are similar to those from mineral fertilizer, if injection in soil is used, instead of spreading. Ammonia emissions are higher in digestate treatments and lower in chemical treatments. Digestate treatments show higher cumulative emissions of N2O and lower cumulative emissions of CH4, compared with mineral fertilization treatments. During crop season there’s a risk of nitrate leaching only after fertilizations, but nitrate concentrations at 100 cm depth are very low (< 20 mg kg-1), with no differences between digestate and mineral fertilization.

This practice aims to balance the nutrients in manure (especially C:N ratio) so that a fertilizer is produced that is better useable by plants and also reduces nutrient loss through leaching.
Manure is inoculated with microorganisms that have been selected to perform specific functions. The product is a liquid suspension of microorganisms based on phototropic and lactic acid bacteria and yeast in a natural environment of sugarcane molasses. These microorganisms act directly on the slurry first, and on the soil later, reducing nitrogen losses by enhancing the biodegradation of manure.
When these additives under investigation are added to the manure, they are anticipated to improve the hygienic conditions in facilities (barns, coops, pens…) reducing ammonia emissions (at least 65%) and also moving carbon sources and nutrients in manure to forms easily assimilated by the plants (from ammonium to nitrate in the case of nitrogen, residual proteins converted into amino acids and solubilisation of solids and phosphorus).
The microorganisms contained in this additive constitute is the ideal environment for plant growth, directly affecting the quality of the crops and the soil (the product progressively inhibits the attack of other bacteria and microorganisms that cause pathologies by having a colonizing effect on the soil).

Anaerobic digestion (AD) technology promotes the bioconversion of livestock waste, apart from other organic waste streams (such as those from the agrifood industry), into methane and carbon dioxide, allowing its energetic valorization. However, AD does not significantly reduce the concentration of nitrogen or phosphorus, and it is essential in all cases to carry out a nutrient balance before applying the digestate to farmland in order to minimize the environmental impact and, in many cases, it is essential to resort to techniques for reducing or recovering these nutrients.
The crystallization of nitrogen and phosphorus in the form of struvite (MgNH4PO4·6H2O), is one of the possible techniques used to eliminate and/or recover nutrients from the digestate, obtaining a product that can be applied as a base for high quality ecological fertilizers.
Several factors influence the struvite precipitation: the chemical composition of the residual effluent, the pH, the molar ratio of Mg:N-NH4:P-PO4 (Mg:N:P), the degree of supersaturation, the temperature and the presence of foreign ions (such as calcium).
In the investigated pilot struvite reactor, the reaction takes place at room temperature or similar (25-30 ºC), so there is no large energy consumption and there is no need to add water. 
As raw materials the following were used: pig slurry digestate, magnesium salt (usually MgCl2·6H2O) and NaOH.
The technology has been demonstrated at a sufficiently relevant scale (crystallization reactor with a capacity of 50 L), so that the results can be used for subsequent implementation on an industrial scale. Phosphorus removal yields of over 95% have been obtained.

Large surpluses of on-farm nitrogen (N) and phosphorus (P) are processed or exported out of Flanders in the form of animal manure, while tonnes of synthetic N-fertilisers are being used. The use of recycling-derived fertilisers (RDFs) from manure could counter this. Currently, RDFs derived from manure still need to comply with the legal application constraints of animal manure and are thus not often used.
That is why five RDFs: ammonium nitrate, ammonium sulphate, digestate from co-digestion of pig manure, liquid fraction of digestate and pig urine, are compared with mineral fertiliser CAN, pig manure and a blank treatment in a 3-year field trial focusing on short term N-effects of the RDFs. The main goal of the trial is to establish a clear relationship between the amount of N applied by RDF and dry matter production. Each RDF was applied in 4 doses.
Currently we are one year into the 3 year trial. Weather conditions during the summer months 2019 were extremely dry and hot. Therefore water availability became the principal factor determining crop growth. Lab analysis showed that N and P content could vary up to 50% in different samples in time of pig manure, digestate, liquid fraction from digestate or pig urine. In these extreme conditions the agricultural value of ammonium nitrate and ammonium sulphate appears to approach that of CAN. Furthermore, no significant differences with respect to residual nitrate in the soil profile at harvest are observed for treatments with high Nmin/Ntot ratio when good practices are adopted towards applied dosage based on initial available nitrogen in the soil, good knowledge of composition (considering higher variability of biobased fertilizers as compared to synthetic fertilizer), timing of application etc.