Problem: Continuous monocropping of silage maize is associated with non-intended impacts on production levels and the environment, such as decreasing soil quality, pressure on biodiversity and ground water quality and increasing GHG emissions (Riemens et al., 2017; Schils et al.,2019).



Solution: To counteract these impacts, cover crops are grown in the winter, as a break crop between two maize crops. Using ultra-early maize varieties ensures that these winter crops have more time to grow and increases their positive effects for example to soil quality.



Practical recommendations

• After the harvest of silage maize, cover crops can be sown without

main additional tillage, if the field is free of deep harvest traces.

Cover crops can also be undersown.

• Winter-hardy cover crops can include winter rye and ryegrass. Red

clover, winter pea and other legumes can be added in a mixture to fix

extra nitrogen.

• After winter, cover crops can either be mown for livestock feed or

used as green manure.

• Before sowing maize the following season, (strip) tillage can be useful to prepare a good seedbed for the maize. A proper seedbed

preparation for the following winter crop is also crucial.

• Ultra-early (short season) maize varieties ensure that cover crops have a longer growing time, which will help to maximise benefits of the

cover crops on soil quality and weed control. Sowing time can be

delayed with these varieties, which might also be benificial for weed

control.



More information: https://zenodo.org/record/4061599

Problem: There is a general lack of engagement from grain farmers to crop diversification, namely due to limited markets and outlets for harvested products. On the flip side, within the dairy sector, there is reliance on imported soybean and it is currently hard to substitute this cheap source of protein with locally produced protein crops.



Solution: One solution is to increase crop diversification in arable systems, while increasing locally produced protein in livestock systems, by facilitating and promoting win-win exchanges between grain and livestock farmers. Livestock farmers can use protein crops produced by local grain farmers, thus offering a local outlet for enhancing crop diversification in arable systems.



Outcomes:

11 exchanges between grain and livestock farmers showed improvements in the sustainability (in its economic, social and environmental dimensions) of both farm systems. Moreover, in most cases (8 out of 11), these exchanges helped to enhance crop diversification within an arable system.



More information and practical recommendations: https://zenodo.org/record/4032601

Problem:

Farming landscapes dominated by monocultures are vulnerable to pests and diseases, in part because of a general loss of biodiversity in the field.



Solution:

Strip intercropping creates spatial diversity within the field, which helps support biodiversity and related ecosystem services (such as biocontrol of pests and diseases).



Recomendations:

• Determine strip width based on available machines, and make strips as narrow as the machine can handle (narrower strips have stronger effect on disease suppression)

• Crop rotation determines which crops can be combined on a field, at least a one-year gap is required between neighbouring strips of the same crop to minimise risk of disease development

• Crop combination compatibility should be evaluated on aspects such as management type and intensity, growing period, ground cover and expected edge interactions i. Combine winter and spring crops, as they provide year-round refuge for beneficial insects on the field ii. Combine pest-sensitive crops with winter crops so beneficial insects have resources to over-winter and can be present in the field early in the season iii. Put ley crops next to intensive crops and use ley crops as a traffic lane to reduce soil compaction iv. Choose neighbour crops with complementary traits to avoid competition at strip edges

• Treat strips as a new management unit, like small fields.



More information: zenodo.org/record/3956363

Problem:

Forage production of silage maize becomes increasingly challenging due to soil quality degreadation, increasing pressure of diseases and pests, legal limitations in N and P fertilisation rate, higher chances of drought and excessive water due to climate change.



Soution:

In temperate climates silage sorghum deeper roots allow for a better drought tolerance and soil carbon increase. Silage sorghum tolerates less fertiliser and is less susceptible to pests and diseases than maize.



Practical recomendations:

Production of silage sorghum is similar to silage maize except for:

- Ploughing prior seeding elevates the soil temperature and suppresses weeds. Consider making a false seedbed prior to seeding.

-Row distance can be 50 or 75 cm with densities of 20-25 plants/m2 (S. bicolor) or 30-35 plants/m2 (S. bicolor x sudanese) and sowing depth is around 3-4 cm. Sorghum is tillering.

- Sorgum growth is slow at the begining. Be on top of weed managment, apply preferably mechanical weeding.

-Be careful with herbicides as sorghum is sensitive E.g., Callisto herbicide can cause a lot of damage and retard growth of sorghum up to 2 weeks. Should mechanical weed control fail, herbicide application is good to assure yield. Ask your seed supplier which herbicide is best used for sorghum.

-For silage, dry matter contents lower than 32 % are recommended. Optimal harvest timing is between milk and dough ripening around 30 % dry matter: risps have grain and are reddish.



More information: zenodo.org/record/3965537

Problem: All agricultural soils harbour a microbiome, consisiting of a high diversity of bacteria, archaea fungi and protists. Together they provide ecosystem services which are crucial for sustinable agriculture and a healthy environment. Agricultural soils management may not deliberately impact soil microbial diversity function, however it may possibly trigger adverse effects e.g. higher production of greenhouse gases, increased levels of soil borne plant pathogens or inefficient use of fertilisers.



Solution: Microbiomes strongly respond to environmental changes and management practices such as tillage and fertilisation. This responsiveness can be used for stirring their activities. Farming systems should be managed to promote diverse microbiomes, thereby stablising microbial ecosystem services.



Practical recommendations:

- Diverse cropping systems: Crops provide energy and carbon to the soil microbiome via roots and residues. Crop diversity, thereby inhibiting enrichment of microbial pathogens.

-Include legimes, bacteria inside of root nodules fix atmospheric nitrogen therby increasing N richeness without fertiliser.

-Preserve soil structure, microorganisms collaborate best inside of ontact soil affregrates. Destroying reduces the efficiency of their services and releases valuable carbon.

- Do not fertilise with N without adding organic C, microbial activities are temperature sensistive.

-Minimise spatial areas of pesticide inputs, pesticides can have off target effects on soil microbiomes which can be reduced by targeted applicaton techniques avoiding unintended dispersal.



More information: https://zenodo.org/record/3839781

Problem: Lupin crops (white lupin, narrow-leafed lupin) fix nitrogen, produce protein-rich seeds and can diversify crop rotations. However, the low competitive ability of lupin towards weeds and its high yield variability is a barrier to increase its cultivation with no or reduced herbicide use.



Solution: A cereal (winter or spring) or camelina (spring) crop can be grown with lupin at a low density. The intercrop can compensate the low utilisation of soil nitrogen and light interception by lupin helping to reduce weed burden for lupin during the early stages of growth.



Outcome: Intercrops often contain around half the weed biomass of lupin sole crops. The crop grown together with lupin provides a complementary grain production that can compensate for low productivity of lupin in some years. The grains of the two species are easy to separate after threshing. An additional benefit is that the protein concentration of the intercropped cereal is often increased compared to a sole-cropped cereal.



Practical reccomendations:

1. Use the full sowing density of lupin and add 20 to 30% of the sole crop density of a cereal or brassica; do not fertilise with N.

2. If a high soil N availability is expected, the companion crop can be too competitive for the lupin so reduce the companion crop sowing density or choose a species/variety with a low competitive ability to lupin.

3. Criteria for the choice of species to intercrop with lupin is the compatibility with lupin regarding sowing and harvest dates, strong early competitive ability for N and light, moderate shading of the lupin in later growth stages, ability to grow in low N input situations and tolerate competition by lupin.



More information: https://zenodo.org/record/3741487

Problem: Grain peas are a valuable feed crop containing around 20% crude protein. Cultivated as a pure crop, grain peas are prone to lodging, which often leads to late weed infestation, soil contaminationted grains and yeild loss.



Solution: The cultivation of half-leafless grain peas and barley prevents lodging anfd quality/ yeild loss. After several years of trials in Switzerland the intercropping of grain peas and barley become a standard to cultivate grain peas.



Benefits: The barley provides support to the peas, preventing lodging and, thus reduces yield loss. It increases the soil cover and thus suppresses weeds. Growing two crops at the same time also mitigates the risk of yield loss in one of the crops. With intercropping there is a higher land utilisation per hectare thena with pure stand.



Practical reccomendations:

•Finding the suitable varieties to combine (same maturity) can be accomplished by a simple strip trial. We use half-leaved peas varieties.

•The seedbed should not be too fine-grained after cultivation or reduced tillage (advantage: better channel flow from deeper soil layers during drought periods). A further possibility is mulch-till, whilst on heavy soils a plough might be needed. Possible application of green manure or compost.

•For sowing machines with only a single tank, homogeneously mix the seeds at a seed rate of 80% of pure pea stand density and 40% of pure barley stand density before filling the seeder. During sowing, repeatedly check the homogeneity of the mixture, and for sowing machines with two or more tanks, apply the seeds of the mixture species sepa-rately. The mixing ratio might be adapted over time according to local growing conditions.



More information: https://zenodo.org/record/3794916

Problem: On arable farms without livestock, nitrogen insufficiency can occur when cultivating nutrient-demanding crops like maize. This can lead to yield losses and weed infestation.

Solution: In temperate climates use a green manure of winter field peas before growing crops that have a high nitrogen demand in the rotation.

Benefits: Ploughing in winter field peas in spring can provide more than 100 kg of nitrogen to the following crop and increase yield. The improved development of the crop also leads to improved weed control. Possible disadvantages are growing costs and restrictions when cultivating peas as a main crop in the rotation.

Practical recommendations

Position of green manure in the crop rotation

• After late crops like potatoes, sunflowers and field vegetables. After grain crops, green manure is possi-ble after repeated stubble treatment against root weeds.

• Possible following crops are maize, potatoes or field vegetables (e.g., spinach) that require a lot of ni-trogen. Grain legumes are not suitable as a following crop.

• The minimum time period before repeating pea cultivation on the same field is 6 years. During this peri-od, pea must not be cultivated as a main crop.

Cultivation of winter field peas

• In case of soil compaction, primary soil tillage should be carried out. Seedbed preparation with a rotary harrow or a tined rotor.

• Ideal seeding period: Beginning of October to middle of November. Sowing depth: 3-5 cm.

• Quantity of seeds: End of September/beginning of October: about 1.5 kg a-1 (100 seeds m-2), middle to end of October: 2 kg a-1, frost seeding in winter: max. 4 kg a-1

More information: https://zenodo.org/record/3234504

Problem: Among legume crops, forage peas and field beans show the most symptoms of legume fatigue. This is due to infestation with Mycosphaerella, Phoma, Fusarium, Aphanomyces and other soil-borne pathogens as a result of over-cultivation of peas or other legumes such as lupines, field beans, vetches, red clover or lucerne. A heavy infestation may lead to a total loss of the peas or beans.



Solution: With the help of a simple legume fatigue test, the soil can be examined for legume-fatigue symptoms prior to cultivation with field peas.



Benefis: The method offers reference points regarding the soil contamination with the above-mentioned pathogens, and thus indication for a possibly required cultivation break. Refraining from cultivating on contaminated soils helps avoid high yield loss due to legume fatigue.



Recommendations:

1. Extract 10 litres of humid soil from the field plot you wish to examine and sieve it down to a grain size of 10 mm.

2. Moisten dry samples and mix them up evenly.

3. Fill four aluminium trays with the humid soil and store the remaining soil.

4. Cover the trays filled with soil with tinfoil and place them in the baking oven. Sterilise the samples for at least 12 hrs at

70-100 °C in the oven.

5. Let the aluminium trays cool for 12 hrs after sterilisation.

6. Mark four flowerpots with "R" (for untreated reference) and another four with "H" (for heat-treated soil).

7. Fill the four H-flowerpots with the heat-treated soil and fill the four R-flowerpots with the untreated soil.

8. Place 5 field pea seeds in each pot and cover them with 0.5 cm of soil.

9. Place the pots in a tray with some water and keep them in a sheltered place with at least 18 °C and daylight.



More information: https://zenodo.org/record/3232910

Problem: Modern varieties of winter rapeseed require a lot of nitrogen in early spring. In cool, moist and dry soils, N mineralisation can be inhibited, which leads to an insufficient N supply and yield losses.



Solution: In areas with winter oilseed rape cultivation, fast-releasing fertiliser application in autumn and spring can perfectly complement the basic fertilisation (applied via crop rotation and manure before sowing) and prevent a lack of nitrogen in spring.



Benefits: Optimal fertilisation ensures that current rapeseed varieties reach their full yield potential.



Practical recommendations:

• In conventional cultivation, nitrogen uptake of winter oilseed rape amounts to 140 kg N per ha for a yield expectation of 35 dt per ha. In organic agriculture, about 100 kg N suffice for a yield expectation of 20-25 dt.

• The ideal time for cultivating oilseed rape is after grass-clover or legumes. After grains, apply about 30 tonnes of manure or manure compost per ha before cultivating rapeseed.

• In dry conditions in spring, an early single application of nitrogen is preferable to two smaller applications. In the case of slurry with a low N content, two applications are often required because a maximum of 40 m3 of slurry can be applied at once. Regularly analyse the N content of your slurry (regular content: 1 kg of N per m3 of slurry or tonne of manure, respectively; range: 0 to 3 kg available N per m3 for cow slurry diluted 1:1, 3 kg available N per m3 for pig slurry). The N contents of commercial fertiliser and liquid digestate are disclosed by the suppliers.

• On farms without livestock, one dose of organic commercial fertiliser is applied in early spring.



More information: https://zenodo.org/record/3234410

Problem:

Oilseed rape sown in summer only forms a dense canopy in the following spring. In autumn and winter, the stands can become infested with weeds, and in vulnerable areas, soil erosion can occur.



Solution:

Undersowing helps to increase soil cover. In areas of oilseed rape cultivation with a moderate climate north of the Alps, frost-sensitive legumes are best suited for undersowing. They fix some N and thus contribute to the large nitrogen requirement of oilseed rape plant through mineralization. After dieback they form a layer of mulch on the field.



Benefits:

• Suppression of seed weeds

• Reduction of soil erosion

• Reduction of nutrient leaching

• Nitrogen is fixed and utilised by the oilseed rape.

• Weed control is usually not required, which helps to reduce variable costs.

• Carbon is stored and released less from soil



Disadvantages:

• Significant competition with the oilseed rape crop is possible (depending on the undersown crop and the date of die-back).

• No mechanical weed control possible in autumn

• Additional costs for undersown crop seed



More information: https://zenodo.org/record/3234430

DiverIMPACTS will develop a range of technical and organisational innovations to help remove barriers all along the value chain from farmers to consumers, as well as create strategies and recommendations to strengthen crop diversification practices on the long-term.