Flowering field pea in farmers field   Components of the pre-crop effect The pre-crop effect includes two elements: the nitrogen effect and the break crop effect. The nitrogen effect is the provision of nitrogen to the following crop through the nitrogen carried over in the residue from the previous crop. The size of the nitrogen-related effect depends on residue quantity and quality from the legume crop. The break crop effect is due to the reduction in the risk of diseases, pests and weeds in cropping sequences otherwise dominated by another plant family, usually grasses (cereals). These biotic risks are reduced as their life cycles are “broken”. Legumes also improve soil structure and enhance soil microbial processes, which in turn may increase the availability of some nutrients, e.g., phosphorus. Deep rooting in some legumes species such as lupin reduces soil compaction and increases waterholding capacity of soil for the following crop. Phosphorous availability for subsequent crops can also be improved because some legumes are able to mobilise reserves of phosphorus in the soil that are less available to other crops.   Farm-level implications Growth and yield of cereals following legumes is often increased and incidences of pests, diseases and weeds are reduced. In situations where soil mineral nitrogen supply is enhanced by legumes, nitrogen fertilisation can be reduced. This is directly translated into increased revenues and reduced costs for fertilisers and pesticides. In addition, improved quality such as higher protein content can increase the market value of the following cereal crop. Better soil structure caused by tap roots supports higher yields and allows reduced tillage. For instance, no ploughing is needed before the seed bed preparation for the crop following grain legumes such as lupin or soybean. This reduces machinery costs. Quantification and valuation of the effects on crop inputs and outputs are difficult since they are dependent on a range of interacting agronomic and economic variables. Variations in yield effects can be high and current producer prices, costs for fuel, fertilisers and pesticides also largely impact the value of the effect. Additionally, increased revenues and cost reductions are not always realised simultaneously. However, estimations of pre-crop values of grain legumes to subsequent cereals compared to cereal pre-crops allow us to sort the farm-economic relevance of the effects roughly and price scenarios enable us to assess the potential value of the effects in different market situations (Figure 1).     The most important effect is the yield increase in the subsequent crop compared with the yield in a sequence without the legume. This translates into increased revenues. Depending on the current market prices, revenues from the first subsequent crop can be several hundred Euros higher as a result of the break crop effect of the legume. Positive effects were found even in second cereals after the break crop. Cost reductions from reduced tillage, reduced nitrogen fertilisation and pesticide savings are also relevant. The effect of the fertiliser savings increases as prices for fertilisers increase, as we are currently seeing in markets. Potential effects through increased quality of following crops can be very variable and below economic relevance. In the context of the individual farm, a simplified calculation of the pre-crop value of grain legumes can support the estimation of potential effects at the farm level - as it was done on the demonstration farms of the network for cultivation and utilisation of field peas and faba beans in Germany (Table 1). The assessment of the pre-crop value is key to getting a more realistic picture of a grain legume’s economic value. Therefore, adequate profitability measures such as expanded gross margins that credit the pre-crop value on subsequent crops to the legume’s gross margin itself or even an economic assessment of whole cropping systems are necessary.     A range of experiments, reviews, and surveys of farmers provide estimates of the size of the pre-crop effect of grain legumes. Cereal crops often yield 0.5–1.6 t per ha more after grain legumes than after cereals in Europe (Preissel et al., 2015). However, several aspects need to be taken into account when estimating the effects for a specific farming context. The estimated values differ depending on the reference pre-crop chosen for comparison. Largest effects can be found when legumes are compared to cereal crops as pre-crops. In contrast, other broad-leaved crops can have a pre-crop effect on cereals that is similar to that of legumes. The management of the following crop also influences the magnitude of the pre-crop effect from the preceding crop. Management practices such as tillage, residue treatment, and the application of nitrogen fertiliser impact on the magnitude of the pre-crop effect. The importance of nitrogen carried over from the previous crop is reduced as the nitrogen fertiliser application increases. The yield effect declines from +2.2 t per ha without fertilisation to +1.5 t per ha when 100–200 kg of N fertiliser is applied to the following cereal (Preissel et al., 2015). Therefore, the nitrogen-related effect of the legume is highest in systems with low N fertilisation such as in organic farming. Site and climatic conditions such as soil characteristics, water availability and temperature also greatly influence the pre-crop effect. Differences in mineralisation of organic nitrogen in the pre-crop residues is one reason why there are considerable differences in the nitrogen saving potentials on different sites. The pre-crop effects are likely to be relatively larger on sites with a low yield potential than on sites with a higher yield potential. Besides, the pre-crop effect varies depending on the particular legume species. Legume species such as faba bean have a high-biomass and deep root system. These leave more crop residues with available nitrogen than low-biomass legumes such as lentil. Lastly, the effects of grain legumes as pre-crops depends on the rotations in which they are introduced and are highest in cereal-dominated rotations. The disease and weed-related break crop effects are particularly large in these systems.   Key practice points Grain legumes reduce input costs and increase the yield of subsequent crops because of a combination of nitrogen and break crop effects. High fertiliser prices increase the relevance of the pre-crop effect. Cereal-dominated cropping systems respond most to the pre-crop effect of introducing legumes. The increase in yield of the subsequent cereal crop ranges often from 0.5–1.6 t per ha. The yield increase from the pre-crop effect declines (from 2.2–1.5 t per ha) with increasing N fertilisation (from 0–200 kg). Estimation of the economic value of the pre-crop value is useful in assessing the effect on an individual farm. Models such as ROTOR can help in evaluating the pre-crop effect in rotations (see further information).   High-biomass legume crop – faba bean   Further information Software tool ROTOR - download: www.zalf.de/de/forschung_lehre/software_downloads/Documents/oekolandbau/rotor/ROTOR.zip

Pea plant   Outcome Useful knowledge on cultivating faba bean and pea under Nordic conditions.   Uses of the crops The most common grain legumes grown in the Nordic countries are pea (Pisum sativum L.) and faba bean (Vicia faba L.). Both provide a good break crop in the cerealdominant monocultures common in many Nordic countries. There is a growing demand for both species, especially as part of the effort to increase domestic sourcing of raw materials for feed, and increasingly for the plant-protein food industry. Pig and poultry production can make use of both crops as feed instead of imported soybean. In cropping systems, they fix atmospheric nitrogen and their residues provide residual nitrogen for the next crop. They are further valued for other attributes such as their ability to break soilborne disease cycles and improve soil structure.   Choice of cultivar There are relatively few well-adapted cultivars of these species available to Nordic farmers on account of the short growing season in the region. The key novelty in faba bean breeding is the reduction in vicine-convicine content (favism factors). These two natural chemicals restrict the use of faba bean for some people and in animal feeds. New cultivars have only 5% of the normal vicine-convicine content and are safe for all consumers. For pea, resistance to lodging (standing ability) has long been the main problem for farmers. Most modern cultivars are semi-leafless, meaning that the true leaves have been replaced by tendrils and the stipules are greatly expanded, restoring the photosynthetic area. These cultivars stand up well because the tendrils form a strong network between plants.   Site characteristics The opportunities for growing faba bean and pea in this region decline with increasing latitude. However, farmers grow faba bean and pea as far north as latitude 63°N. Common parameters for achieving good yield levels include soil type, pH level, water management and drought susceptibility (Table 1). The margins of pH tolerance are tested by farmers, often at the expense of yield. In soils with high organic content, vegetative growth is favoured so there is a greater risk of lodging and late maturity, but experienced farmers can achieve high yields in this situation.     Waterlogging and drought Waterlogged soils lack oxygen, so roots suffocate. While faba bean is considered more resistant to waterlogging than other grain legumes, the wet conditions favour the growth and spread of diseases. In drought conditions, plants close their gas-exchange pores, preventing both the loss of water and the uptake of carbon dioxide for photosynthesis. When water is not taken up from the soil, nutrients are also not absorbed. Drought can occur at any time in the growing season and appropriate management depends on its timing. Terminal drought, near the end of grain filling, is typical of Mediterranean climates and uncommon in northern Europe. Transient drought in the middle of the growing season can be managed with irrigation, if the infrastructure is available, and plant breeders seek ways of avoiding it through improved root systems. Drought during seedling establishment in May is common in northern Europe and exceptionally hard to manage, since the roots have had little opportunity to find water in the soil. Pea is less sensitive than faba bean to drought, as shown in both 2018 and 2021, when prolonged mid-summer drought reduced mean faba bean yields far more than those of pea.   Waterlogged faba bean   Crop establishment Inoculation Both legumes form a nitrogen-fixing symbiosis with soil bacteria classified as Rhizobium leguminosarum symbiovar viciae. Different strains of this bacterium can make 5% differencein the amo unt of nitrogen fixed. It is widespread throughout Europe but the population may not be large enough if the field has no history of cultivation of pea, faba bean or its other hosts. Hence, inoculation with a commercial rhizobium preparation is widely recommended in this circumstance. Intercropping legumes with non-legumes usually increases the nitrogen fixation of the legume as the companion takes up the available mineral nitrogen from the soil. To avoid desiccation, the drying out of the bacteria on the seed, the inoculum is applied shortly before planting – no more than a couple of days; see the video “Inoculating grain legumes” under further information. Sowing takes place in early spring, as soon as the soil is sufficiently warm (about 5°C) and dry enough to take the weight of the seeder, which in Finland is usually at the beginning of May. Faba bean has one of the longest growing seasons of Nordic crops, so on most farms it should be the first to be sown. The shorter growing period of peas (approximately 90 days) allows for more flexibility when it comes to the seeding time. Table 2 shows the main sowing requirements of both crops. Deep sowing helps to ensure access to water for the germinating seed, which reduces the effects of early-season drought, and reduces the risk of predation by crows and pigeons. The water requirement is high due to the relatively large seed size. The target populations are lower for faba bean than for pea. Faba bean cultivars adapted to the Nordic region tend to have small seeds, 300–400 g/thousand, but in climates with longer growing seasons, the most productive beans are in the 500–800 g/thousand range and broad beans for food use can be up to 3000 g/thousand. Peas are generally somewhat smaller than the smaller sizes of faba beans.     Soil compaction and removal of stones Soil compaction is an issue for both faba bean and pea as it reduces their overall plant growth and yield. Good aeration, deep tillage and deep sowing ensure good emergence and root development. Autumn or spring tillage makes it easier to drill the soil during spring. Other farmers manage well with zero tillage and direct drilling, and yields are widely better in zero-tillage systems. Rolling after sowing presses down stones that can interfere with harvesting and rolling helps to prevent contamination with soil when harvesting. Weed management Few herbicides are available for use on any grain legume and the crops are sensitive to the residues of herbicides widely used against broad-leaved weeds in previous crops. In practice, this means selecting a field with minimal herbicide residues from preceding crops e.g. cereals. Seedlings of weeds are best controlled before the crop is 5–7 cm in height. Fertilizers The organic matter content of the soil and its available nutrients determine the amount of fertilizer needed. Fertilizer products that are low in nitrogen are most suitable for faba bean and pea, so the farm can take full advantage of their nitrogen-fixing ability. Although scientific experiments have widely failed to show any benefit of starter nitrogen, many farmers see one, so they apply starter nitrogen fertilizer at 20–40 kg/ha. Phosphorus and potassium fertilization of faba bean and pea is similar to that for cereal cultivation. Potassium, phosphorus and magnesium improve resilience against disease, such as chocolate spot (Botrytis) of faba bean. Micronutrients may also be needed in some soils. For example, molybdenum is essential for nitrogen fixation.   Management during the growing season Disease control There are several diseases affecting faba bean and pea in the region (Table 3). Farmers have many tools with which to prevent the arrival of crop diseases and pests. To prevent disease outbreaks, the recommended minimum interval is 3 years of non-legume crops between successive legumes on the same field. Fungi such as Sclerotinia and Phytophthora can persist 3–5 years in the soil, whereas Aphanomyces root rot of pea survives for up to 10 years. Fungicide treatment of seeds improves the emergence percentage and protects the crop against some early disease symptoms. The use of such fungicides in some countries requires permits and is not widely practiced in the Nordic region. It is important to inspect the crops regularly for diseases and pests in July, during flowering, so any necessary treatment can be applied in a timely manner, according to the principles of integrated management.     Downy mildew requires cool growing conditions. It was widespread on faba bean in the cool summer of 2017 in the Nordic and Baltic countries, but is otherwise rare in this region. Rust of both legumes is a disease of warm, humid conditions and arrives late in the growing season in this region when it causes no detectable damage. Chocolate spot disease is almost universally seen as a few spots on faba bean leaves and is not a serious problem until the weather conditions are right, typically 20–22°C with nearly 100% humidity and damp leaf surfaces. In this situation, generally predictable from the weather forecast, the whole plant stand can be killed in 48 hours, so rapid fungicide treatment is vital.   Chocolate spot at dangerous levels   Pest control In Finland, both faba bean and pea are prone to attacks from aphids, leaf weevils, pollen beetles and pea moth caterpillars as well as birds. Pea moth (Cydia nigricans) caterpillars eat the developing seeds in the pods of many legume species, but given a choice, they will take pea in preference to faba bean, lupin or lentil. Pea moths are detected using pheromone traps that are normally placed at least a week before flowering starts and examined every second or third day. More than ten moths after two consecutive checks indicates that pest control threshold has been reached. Chemical treatment normally commence around 8–12 days after their peak emergence. Adults of the leaf weevil, Sitona lineatus, cut crescents from the edges of leaves and stipules. It is their larvae that do the damage by consuming the developing root nodules. Pyrethrum is the usual insecticide to control this pest and the intervention needs to be early, as once the eggs are laid on the soil, the damage to the roots cannot be stopped. Both crops have aphids, the pea aphid being Acyrthosiphon pisum and the black bean aphid being Aphis fabae. Weather conditions greatly affect the spread of aphids: heavy rain washes off much of the population and a period of intensely dry weather desiccates them. The pest control threshold is reached when 10% of the plants are infested and the weather forecast indicates that conditions are good for the pest rather than for the plant. Genetic forms of resistance to aphids have not been identified in pea or faba bean, so breeding for resistance is unlikely in the near future. Both aphid species over-winter in hedgerows and woodlands. They spread from random landing points near the edges of the field, so a large field is likely to show less damage than a small one. There is some evidence that early-sown crops are more likely to be found by aphids, but this has to be balanced against the other benefits of early sowing in this region. Seed weevils (Bruchus pisorum on pea and B. rufimanus on faba bean) ruin the seeds for food use and reduce their value for feed. Pea weevils have been present in the Nordic region for decades but the bean weevil is a recent arrival. Control is difficult because the eggs are laid within the flower and after hatching, the larva immediately penetrates the seed, so it is protected from most protection chemicals. Early detection with pheromone traps is vital, to be followed by appropriate treatment as advised by the local agricultural consultant.   Aphids on faba bean   Lodging Lodging makes the crops very hard to harvest. The strong stem of faba bean makes it more resistant to lodging than pea (Table 4). Rain during seed filling increases the risk of lodging. To prevent pea crops from lodging, companion crops with strong straw, such as oat, barley and wheat, are often used. The target is one cereal stem per pea stem, so the cereal sowing rate is 15–30 kg/ha, because at higher densities the cereal out-competes the legume.     Harvesting and desiccation As the plants approach harvest readiness, first the pods and later the stems turn straw-coloured (pea) or black (faba bean). Lower pods mature before upper ones and when they start to open, it is a sign that harvesting needs to be done soon. Normally, all leaves have fallen by this time. In this region, faba bean is harvested at a moisture content of 18–20% and pea at 20–25%. In warmer climates, the harvest moisture content is 14–15%. Lower moisture content increases the risk of pod shattering and high moisture content allows seeds to get crushed in the harvester. Although the seed coats are thick, legume seeds are more easily bruised during harvesting than cereal grains, so the combine harvester needs to be set up accordingly. The driving speed and drum speed are low, the fan speed high, the flails and screens open. Green pods are returned to the field by adjusting the top screen as they can cause blockages in the combine and other problems later in the dryer. The straw chopper has a lot of work to do in a faba bean crop, especially when the vegetation is dense, so it may need adjustment to make longer chaff. Since some seeds are moister than others and may start heating and rotting, drying is started quickly but proceeds slowly, often in two stages, as the thickness of the seeds prevents the centre of the seed from drying as quickly as its perimeter. The drying temperature is usually 50–60°C. The target moisture content for faba bean is 14.5% (not below 14%) and for pea 15%. Catch crops After the harvest, the crop residues are rich in nitrogen. Most farmers leave them in place to nourish the succeeding crop. This comes at the risk of loss by leaching or nitrate or emission of nitrous oxide, a powerful greenhouse gas, so current recommendations include sowing a catch crop, cover crop or winter cereal that will start taking up nitrogen promptly. Faba bean fixes about 80% of its nitrogen needs and pea about 70%. The EU project “Legume Futures” estimated that faba bean added about 24 kg of fixed nitrogen per tonne of harvested beans and that pea added about 6 kg. This helps to reduce the need for nitrogen fertilization of the next crop. Pre-crop effect The pre-crop effect of legumes consists of more than just nitrogen. The activity of the nitrogenfixing bacteria supports other beneficial soil microorganisms. The nitrogen-rich residues help maintain the populations of larger soil fauna such as earthworms. A grass-free legume crop allows some soil-borne pathogens of maincrop cereals to die, so the following cereal grows better.   Harvest-ready faba bean   Key practice points The decision to grow peas or faba beans can be based on some guiding questions (nonexhaustive): Is sowing time an issue? The optimal time for sowing faba bean is very early in the growing season. This poses challenges if the weather does not permit early sowing. Pea can be sown a few days later. Are you worried about waterlogging? Faba bean is more tolerant. Are you worried about risk of drought? Pea shows more tolerance. Do you want a grain legume that is less prone to lodging? In that case, faba bean stands better than pea. Are you searching to diversify your crop rotation? Both crops provide nitrogen for the next crop and disease control.   Further information Stoddard, F. L., 2017. Grain Legumes: an overview. In: Murphy-Bokern, D., Stoddard, F. L. & Watson, C. A. (Eds.). Legumes in Cropping Systems. CABI, Wallingford, pp. 70–87. Schauman, C., Leinonen, P., Mäki, S., Stoddard, F. L., Lindström, K., 2021. Inoculating grain legumes. University of Helsinki. Legumes Translated video.

Pea and barley mixture   Protein from alternative forages Increasing on-farm plant protein production addresses emerging consumer expectations. Producing more high-protein forage reduces reliance on imported protein sources. This reduces the carbon footprint of the feed and reduces the impact of fluctuations in the price of imported feeds, e.g., soya from South America. Demonstration plots of alternative forages were grown and harvested in a cool wet temperate climate in Scotland to support discussion with farmers and industry stakeholders. Plots were sown in early May and harvested in early August. Red clover, a red clover/grass mixture, lupin and a lupin/barley mixture, forage pea, a forage pea/barley mixture and crimson clover were grown in plots (3 m x 10 m) and compared with a perennial ryegrass/white clover mixture. Initial measurements of dry matter (DM) showed that the pea/barley mixture produced 8 t/ha, the lupin/barley mixture provided 7.3 t/ha, compared to the ryegrass/white clover at 3.8 t/ha. The red clover mixture had the highest crude protein content (17.7%) compared to the grass/white clover (16.9%) and pea (16.1%). Metabolisable energy (ME) level was highest for the pea and the grass white clover (10.5 MJ/kg DM) while the red clover (10.3 g/kg DM), crimson clover (10.2 MJ/kg DM) and lupin (10.2 MJ/kg DM) were very similar.     Silage quality Sub-samples of the fresh cut material were compressed into 3 litre plastic air-tight containers and ensiled for 5 weeks. These were then analysed for feed quality. The silage analysis showed the pea, pea/barley and the lupin/barley mixtures gave the greater DM contents (g/kg). The crude protein content of the lupin (19.2%) and red clover mixture (19.6%) were most similar to the ryegrass/white clover (20.8%). The protein content of the crimson and red clover, at 18%, were close to the lupin (19.2%) and red clover mixture (19.6%). The ME content of the lupin provided just over 10 MJ of ME/kg DM compared to the grass and white clover that provided 11 MJ of ME/kg DM. The barley in pea/barley and the lupin/barley mixtures increased the metabolisable energy of the silages.   Blue lupin   Key practice points Alternative forage crops can be grown successfully in a cool wet temperate climate. Forage yield, protein content and metabolisable energy levels can be maintained with most of the alternative crops. The grass/clover and clover swards are harvested several times through the growing season. The legumes fix nitrogen that is available to subsequent crops. This has been estimated to be 150 to 250 kg N/ha for red clover compared to 80 to 100 kg N/ha for white clover.

Yellow lupin   Outcome The main outcome is the identification of a suitable grain legume species for a given farming situation or field. Selecting the right kind of legume crop can affect the yield potential. Length and warmth of growing season The first thing to consider is whether the cultivated legume can reach maturity in the growing season at the site. The shorter the growing season, the less choice. Of the cool-season legumes, pea is grown the furthest north, followed by narrow-leafed lupin and faba bean. Looking further south, yellow lupin, lentil, chickpea and white lupin are added to the list. All of these species will tolerate cold soils at sowing and mild frosts during early growth. They are less tolerant of high temperatures, above 27°C, than the warm-season legumes. Soybean and common bean are the best-known warm-season grain legumes. Some soybean cultivars will tolerate a degree or two of frost. Generally, these species stop active growth when temperatures fall below 10°C. Hence, the northern limit for reliable production of soybean is currently around the southern edge of the Baltic Sea.   Peas   Soil texture and pH levels The next thing to consider relates to the growing site’s soil texture and pH. Unlike the small grain cereals such as wheat, barley, oat and rye, the cool-season legumes, especially faba bean and lupins, are selective about what soil type they grow on best. For example, if the soil is sandy it is likely to have a low pH (acid) and lupins are the best choice for it. The three species (blue or narrow-leafed, yellow and white lupin) can be grown on soils with pH as low as 4.5. Pea, chickpea and lentil are at their best on fields with intermediate soil texture and a pH between 5.5 and 7. Faba bean is the most suitable legume for heavier clay soils with a neutral to alkaline pH of 6 to 7.5 or even 8. Soybean is less sensitive to soil type and the optimal pH level is between 6.3 and 6.5.   Faba bean grown in clay soil   Lentil and lupins prefer free-draining soils and at the end of the season, need to dry out in order to mature. Narrow-leafed lupin is exceptionally deep-rooting with a tap root that can grow as fast as 2.5 cm per day, so it can reach deep water and nutrients. Its roots have been traced to 2.5 m depth in sandy soils in Western Australia. Soil compaction and waterlogging are severe problems for grain legumes. If your soil is susceptible to waterlogging, it is worth considering amendment or drainage. Faba bean survives waterlogging better than most of the other legumes, but it does not thrive in such conditions. Mid-season drought disrupts the growth of all the legumes. They stop flowering prematurely, which greatly reduces yield potential. Plentiful organic matter in the soil helps in both aeration and water retention. Later drought impedes seed filling, but terminal drought can be useful when it stops the indeterminate growth of the plant and promotes its senescence and maturity.     Length of day Most cool-season grain legumes are considered to be day length neutral. In other words, their flowering does not depend on the day length being longer or shorter than a certain value. In contrast, flowering of soybean is suppressed by long days and there is genetic variation in response to day length. In practice, only day-neutral cultivars can be grown reliably north of about 45°N. The day-neutral cultivars result in extraordinary flexibility in soybean. Some farmers have succeeded in growing soybean at 61°N in Finland. Growing legumes is often called “challenging” or “demanding”, but it would be better to consider them as “giving” or “rewarding”. They need a little more attention than spring-sown cereals, especially when growing them the first few time(s), so one can expect to make a few mistakes along the way. Their diseases, pests and stress symptoms look a little different from those of the cereals or oilseeds. By giving them attention and learning their needs, they will repay with high yields and quality. Ignore them and they fail. Where possible, it is wise to sow a catch, cover or winter crop after the grain legume in order to capture its residual fixed nitrogen.   Waterlogged faba bean in southern Finland. Although stunted, the plants are surviving and flowering.   Key practice points Identifying the right legume crop for your field is dependent on its pH levels and soil texture along with the length of the growing season. Good soil conditions are as important for grain legumes as for other crops. Drainage is especially important for lupins and lentil while adequate moisture is particularly important for faba bean.

Figure 1. Dehulled and split faba beans   Goal of dehulling Is there a customer requirement for dehulling? Is there a strong market for dehulled seeds for food products and processing? If the answer is yes to any of the questions, then dehulling is something to consider. The main processing goal is to remove the seedcoat or ‘hull’ of the grain legume seed. The dehulled seeds usually split into two, each half being a whole cotyledon or seed-leaf, and the product is often called “splits”.  The splits are an attractive yellow, green or red, depending on the cultivar and its pigments. The hulls are 90% lignocellulose, i.e., insoluble dietary fibre, but the cotyledons have plenty of dietary fibre so the loss is not important in the food chain. The other important component of the hulls is tannins that have both positive and negative effects on the product. Tannins are useful antioxidants in the human diet and they add a distinctive flavour, but they are coloured, so they are not desirable in many wet processes, such as protein isolation or making tofu, where additional colours and flavours should be minimized. They cross-link with raw proteins and precipitate them, which is also enabled in a wet process. In a dry milling process such as flour production or dry fractionation, the hull particles form dark flecks in the light-coloured mass of flour. Dehulled beans have a higher protein content than whole beans because of the low protein content of the hull. The hull slows water intake into the intact seed, so a dehulled seed cooks more quickly. The hull keeps the seed in shape during cooking, whereas a dehulled split easily becomes a puree: both are desirable depending on circumstances. Dehulling usually takes a small portion of the cotyledons with the hulls. The value of the fraction is, however, low and its particles are often dust-sized so its use is restricted.     The dehulling technique Traditional dehulling methods involve thorough drying of the seeds. This is followed by rubbing or pounding with a simple mortar and pestle. In larger commercial units, abrasion is applied, using emery-coated rollers made from silicon carbide. Millstones are typically made of two burrstones with farrows or grooves. The gap between the stones is adjusted to remove the hull with minimal damage to the cotyledons. Uniformity of seed size is clearly important. The brittleness of the seeds needs to be taken into consideration as seed breakage is an issue regardless of the machinery used. Newly harvested beans are harder to process if their moisture content is high. Drying to a moisture content under 14%, often around 12%, is usually needed before dehulling. Large seeds are often more economic to dehull than small ones because their lower surface to volume ratio means that losses are lower. This is considered good for the process as the machine adjustments can be kept the same. Shrivelled seeds do not dehull well because the wrinkles prevent removal of many parts of the hull. Other factors that make the cotyledons soft or fragile, such as altered starch composition, will make dehulling difficult. Ease of dehulling is an objective in several grain legume breeding programmes around the world, particularly for lentil, pea and chickpea. When the hull is firmly attached to the cotyledons, dehulling can be a time-consuming process. Dehulling creates by-products such as seed coats, small particles and broken bits of legumes. These can be sold to livestock farmers or feed compounding companies. More recently, a small demand for faba bean seed coats has developed in the pet food industry.   Figure 2. Cleaned and size sorted faba beans fed into silo.   The Arolan Tila processing plant in Finland The Arola farm in southern Finland specializes in gluten-free and organic crop production. In addition, the farm operates a dehulling line for food-grade legumes. This automated processing line, with sorting and dehulling stages, can process large quantities and achieve consistently high quality. The technology removes impurities, stones and metal debris before dehulling and splitting of the beans. First, the seeds are cleaned of debris, sieved to include seed sizes of 6 mm – 10 mm, and poured into 750 kg container bags. Seeds that are too small or too large are not suitable for processing, mainly due to equipment limitations, and can be sent for livestock feed. The cleaned beans of the correct size are then put through the processing stages described in table 2.     Four machines are used to process the beans into clean splits. The colour sorter removes green, half-green or darkened cotyledons, which could be useful in the event of a poor quality harvest. Nevertheless, a colour sorter adds significantly to the capital cost. It is also possible to have fewer machines - one machine could do the job sufficiently but this increases the chances for impurities in the batch. The removal of dust or flour is an important part of improving the visual quality of the end product. The processing capacity of this unit is roughly 5,000-6,000 kg a day. Cleaning the machinery between cultivars or species normally takes 3-4 hours. There is a wide range of machines on the market with varying dehulling capacities, with some having outputs as high as 6,000-10,000 kg per hour.   Figure 3. Magnet to remove metal debris.   Storing the dehulled product The dehulled beans are stored in bulk containers (big bags). Processing is done on order, so storage time is minimized. This reduces the exposure to air which starts a process of oxidation that reduces the shelf life of the splits. Logistics The beans are normally placed in flexible intermediate bulk containers – big bags (approved for food purposes) of approximately 750 kg or 1000 litres of material and transported on euro-pallets. Bagging systems can be flexible and are closely linked to customer requirements, as some consignments prefer sealed paper bags, e.g., canteens.   Figure 4. Elevator and dust build up. Overall the entire process produces a lot of fine dust.   Main practice points Dehulled beans are used in the food and feed industry. Drying before dehulling improves results. Sorting and dehulling with specialized machinery saves time and ensures a good quality end-product. Processing on order reduces storage time and reduces risks of spoilage from oxidation.   Further information Wood, J. A., and Malcolmson, L. J., 2011. Pulse milling technologies, in: B. K. Tiwari, A. Gowen, and B. McKenna, (Eds.), Pulse Foods: Processing, Quality and Nutraceutical Applications. Elsevier, New York, pp. 193-221.

Dry faba bean   Protein solubility is not a reliable indicator of rumen degradability Proteins in less commonly used grain legumes, such as in pea and lupin, are highly soluble and so the in sacco (nylon bag) technique over-estimates protein degradability because protein washes out of bags irrespective of whether it is degraded. Soluble protein from lupin seeds can escape rumen degradation. Recent work with rapeseed proteins showed that soluble proteins can be adsorbed to microbial cells or taken up directly into microbial cells. Both pathways result in more under-graded protein passing from the rumen than would be predicted from protein solubility.   Solubility methods produce widely divergent values for grain legumes It has long been known that factors such as extraction time, pH, ionic strength, and temperature affect protein solubilisation and this seems to be particularly evident for grain legumes. De Jonge et al. (2009) showed that there were large effects of pH on N solubility (Figure 1), with much lower solubility at lower pH levels (5.0–5.6) that are quite common in high producing ruminants.     Given these effects, it is not surprising that there are no consistent relationships between measurements of N solubility and estimates of N degradation based on in sacco or in vitro measurements. Results from Kandylis and Nikokyris (1997; Figure 2), de Jonge et al. (2009; Figure 3) and our own results of analysis of N solubility using pH 6.8 buffer, water, or a 16-hour in vitro incubation with buffered rumen fluid (Figure 4) all confirm that N solubility methods are not an appropriate method for evaluating the nutritional value of pea, faba bean or lupin – nor for comparison with soybean meal (for which laboratory methods are more secure).         Key practice points The nylon bag technique under-estimates undegradable dietary protein (UDP) supply from grain legumes. Estimates of protein (N) degradability should not be based on in sacco (nylon bag) techniques for such highly soluble feeds. Significant proportions of soluble protein can pass from the rumen undegraded. This means that promising grain legumes, such as pea, bean and lupin, may have been under-valued relative to other protein sources, including soybean meal. Solvent characteristics, particularly pH, have a very large effect on protein (N) solubility estimates for grain legumes. Low pH (acid condition) leads to lower values for degradable protein. This latter effect will also occur in the rumen so that protein degradability values for grain legumes will be much less when included in diets leading to lower rumen pH (5.6 and below). This is potentially a very useful phenomenon because requirements for undegraded dietary protein are often highest in high performing ruminants that are offered higher levels of high concentrate diets, resulting in lower rumen pH. Thus, the under-estimation of protein value of grain legumes may be most pronounced when feeding the most productive ruminants.    

Flowering pea   Outcome Numerous scientific studies show that livestock can be successfully fed with protein-rich cool-season grain legumes such as faba bean, pea and others. On the basis of the ‘Löhr substitution method’, it is possible to compare different feedstuffs with standard feeds based on soybean considering energy and protein content. This indicates the point at which an alternative feedstuff costs as much as the feedstuffs currently used, with approximately the same feed value. This article helps in calculating the approximate equilibrium price of grain legumes in comparison with other protein and energy sources. With the help of this equilibrium price, a decision can be made as to which feedstuffs are economically preferable for the same feed value (energy and protein).   Required information Some constituents of the feeds to be compared must be known to calculate the substitution value of faba bean and grain pea using the Löhr substitution method. The parameters shown in Table 1 are used.     Ideally, data for these parameters are available from analyses of the feed ingredients themselves. Published standard values for many ingredients are available but these are often not sufficiently accurate in specific situations to give an accurate assessment of value. The additional costs of using European-grown grain legumes associated with transport and initial processing must be considered so that the faba bean or pea is compared properly with soybean meal.   Calculation aids There are some freely available Excel-based applications that can be downloaded from the internet. These can be used to calculate the value of a new feed ingredient based on how it substitutes for an existing standard feed ingredient. The Excel application \"Comparative value of feed - substitution values of feed\" from the Landesanstalt für Landwirtschaft, Ernährung und Ländlichen Raum Schwäbisch Gmünd (LEL) covers a range of animal species and types. It is available for download here: https://lel.landwirtschaft-bw.de/pb/,Lde/Startseite/Unsere+themes/animal-keeping A wide variety of feed ingredients can be selected and compared. For a selected feed component, e.g., faba bean, the programme indicates the substitution price in comparison to two comparable components, usually a protein and an energy supplier such as soybean meal and wheat. It also calculates how much of the previously used feed can be replaced by the alternative feed.   Calculation examples Table 2 provides data for the ingredients of the feeds compared later.     Table 3 provides data on the value of faba bean for fattening cattle as determined by the cost of soybean meal (45% CP) and the cost of wheat.     Table 4 provides the equivalent data for pig fattening.     The substitution value is the value of the alternative as determined by the value of the standard materials it replaces. If the calculated substitution value of the alternative feed is higher than its current market price, including transport and processing (e.g., to meal), its use reduces costs compared to the use of the established standard feed component. An example based on the scenario from Table 3 illustrates this: Standard feed component prices: wheat (€150/t) and soybean meal (€400/t) The substitution value of faba bean is €268/t (Table 3). Alternative feed component: Faba bean €240/t (purchase price €220/t + €20/t transport and processing) Introducing the faba bean into the feed reduces feed costs under this scenario. At €240/t, faba bean is a cost-effective alternative to wheat and soybean meal because the value as a substitute for wheat and soybean meal at €268/t is higher than the actual purchase price of 240 € (including transport and processing).   Limitations of the method The presented method takes into account the two feeding parameters energy and protein content of feedstuffs. Many other parameters such as crude fibre content, digestibility, rumen resistance, etc., also play an important role in optimal ration design. In addition, many other feedstuffs which influence and complement each other are usually included. Therefore, it makes sense in specific cases to prepare a detailed ration calculation with the alternative feedstuff after calculating the substitution value in order to evaluate it fully and to be able to make a well-informed decision.   Faba bean   Key practice points A substitution value must be calculated using comparison with the feedstuffs previously used to assess the economic effect of using faba bean and grain pea as alternative feedstuffs. The energy and protein contents of the feedstuffs, the purchase prices, and any transport and processing costs must be known. The actual calculation can be carried out using freely available software tools. If the purchase price of alternative feedstuffs including transport and preparation is lower than the calculated substitution value, their use becomes economically viable. This use should be further checked with a detailed ration calculation.

Winter pea grown in Pleven, northern Bulgaria.   Outcome The experience and knowledge accumulated is applicable across the south-east Europe region. Pea for forage or grain establishes a nitrogen-fixing symbiosis with the pea nodule bacteria Rhizobium leguminosarum biovar viciae, which is naturally widespread in the European soils. This symbiosis is important for maintaining soil fertility. The inclusion of winter pea in crop rotation as a precursor of other crops reduces the nitrogen fertiliser use. The early harvest of winter pea provides the possibilities for additional economic use of the agricultural land. The intensive growth and development of green mass occurs in April and May when rainfall is sufficient to ensure an intensive growth without irrigation. Forage crops reach mowing maturity at the end of May. As an over-wintering crop, winter pea protects soil from wind and water erosion.   Pea in Bulgaria Pea has been grown in Bulgaria for centuries. It became a widespread crop in the 19th century, when its cultivation expanded in northern Bulgaria as a forage crop, and in southern Bulgaria as a vegetable crop. The cultivation of pea for both dry grain and forage became popular in the 20th century. For many years, the efforts of breeders and farmers were concentrated on forage pea grown in mixtures with cereals. Gradually, the area occupied by pea increased and reached 54,000 ha in 1967. It decreased to 10,000 ha in the period 1975 to 1980. Significant growth of the areas occupied by peas was observed during the period 1983 and 1988 when it was recognised as a perspective forage crop and the areas reached 150,000 ha. The reform in agriculture, which started in 1989, disrupted cultivar maintenance and seed production and caused a decline in production to only 10,000 ha in 1993. Interest of private farmers has increased since 2000 and the area of forage, grain and vegetable pea has recovered to over 50,000 ha. Vegetable pea accounts for about 14% of the area.   Winter pea cultivars There are three Bulgarian cultivars of winter fodder peas which are preferred by farmers: Mir, Pleven 10 and Vesela. Mir yields 33 to 55 t/ha of forage or 2.5–3.0 t/ha of grain. It is characterised with rapid growth and development in early spring. It is a great precursor for tobacco and forage maize. It performs well on all types of soil but does not tolerate acidic saline or poorly drained soils. Pleven 10 is a forage cultivar that grows 140 to 200 cm tall. It is particularly frost tolerant. It is ready for mowing in late May - beginning of June. Yields of forage are 33–35 t/ha. Grain yields amount to 2.0-2.5 t/ha. Vesela is grown for forage and dry grain for feed. It matures as a forage crop in early May. Yields of forage are 33–35 t/ha. Grain yields account for 2.5 to 3.5 t/ha.   Seeds from winter pea.   Key practice points Preceding crop The basic requirement for the preceding crop is to leave the soil clear of weeds and ready for soil tillage. Suitable preceding crops are cereals (wheat barley, triticale, rye and oat). Sunflower is less suitable and maize is unsuitable. Pea does not tolerate sowing after itself and other legume crops. It is recommended to produce pea not more frequently than once in five years. Soil tillage Shallow cultivation (5–10 cm) after the harvest of the preceding crop conserves soil moisture while stimulating the germination of weeds and volunteer cereals. This is usually followed by ploughing and conventional cultivation. Reduced tillage is an option especially with dry soils and where continued drought is expected, for example in southern Bulgaria. This commonly comprises disk harrowing at 10–15 cm deep. Sowing date and rate Pea should be sown by mid-October in northern Bulgaria and by early November in southern Bulgaria. Winter cultivars are sown with 120–150 germinating seeds per m-2 or 160–180 kg/ha. The peas are sown in a row (row spacing 12–15 cm) at a depth of 6–8 cm depending on the seed size and soil type. Rolling is required. Fertilisation Productive pea crops require a good supply of phosphorus and potassium. Applications of moderate amounts of phosphorous (60–80 kg/ha P2O5) and potassium (40–50 kg/ha K2O) are commonly used. It should be applied with basic tillage in autumn. Phosphorus fertilisation contributes to a better development of the root system and increases disease resistance. A small amount of nitrogen (20–30 kg/ha) incorporated during soil tillage before sowing can be useful as a starter in poor soils when the symbiosis with rhizobia is slow to establish. Plant protection measures The most economically important pests in pea seed production are the pea weevils Bruchus pisorum L. and Tychius quinquepunctatus L. They are widespread throughout the country and can cause damage of the crop up to 100%. Timely treatment of crops with insecticides is important for successful control of these pests. The initial treatment should be done at the beginning of flowering. Economically important diseases are Ascochyta pisi and Erysiphe pisi. Immediate ploughing of crop residues after harvest to avoid spore dispersal from diseased plants is recommended against diseases. Harvest The optimal stage for harvesting for forage is at the end of flowering/early pod setting to get the best combination of forage yield and quality. When the harvest time is delayed, dry matter yield can increase while the forage quality declines. Harvesting for grain is difficult because these forage-type varieties lodge, ripen unevenly, and the pods and seeds are easily damaged by moisture. Traditionally, the grain is dried in the sun after harvest. The seeds are cleaned and stored.   More information As part of the European project „Legumes Translated“ ID 817634, www.legumestranslated.eu, aiming to promote the cultivation and use of leguminous crops in Europe – the units of Bulgarian Legumes Network /BGLN/ Fodder Institute crops -Pleven, Agricultural Academy /AA/, Dobruzhanski Agricultural Institute /AA/-General Toshevo, Institute Plant Genetic Resources, Sadovo offer basic seeds of Bulgarian varieties of fodder pea, various materials related to its cultivation.

Experience at the Vogt organic farm: peas for laying hen This farm in Lower Franconia in Germany converted to organic in 1987. Starting with 60 laying hens, the flock have been kept in a repurposed cowshed with an adjoining orchard meadow since 1991. The flock is now 500 hens. The entire home-grown pea crop is fed to the laying hens. Every eight weeks, a mobile milling and mixing plant comes to process and blend the components with a protein supplement called Concentrate Bio-L-Konz 40 from the Kaisermühle. This protein supplement consists mainly of soya cake, sunflower cake, corn gluten and minerals. By using the higher quality components such as husked spelt, naked oats and peas, the proportion of this highprotein supplement can be reduced from the recommended 40% to 30%. Laying hen. Photogaph: Werner Vogt-Kaute Depending on the age of the hens, some lime and salt must then be added. While wheat and naked oats can be crushed, spelt and peas must be milled finely. „Coarse fragments of pea hull or husks are sorted out by the laying hens,“explains Kornelia Vogt. The goal is a feed with 0.3% methionine and an energy content of around 10 MJ/kg. No oil is added to the feed so that the energy content remains low and the laying hens are encouraged to eat more. With this ration, the laying performance reaches just over 90% in the young hen (about 25 eggs/month), but then remains constant between 80 and 90% for several months. The laying hens remain on the farm for 16 to 18 months. The stability of the egg affects egg handling, storage and use. While the proportion of pea used here is relatively low, experience at Vogt shows that even this low inclusion boosts performance while replacing cereals. „Including pea reduces the cereal grain content and the associated non-starch polysaccharides which are anti-nutritional factors for poultry” the plant manager explains. Up to 20% peas are fed in the ration, which can also be tannin-containing, violet-flowered varieties „We have never observed a decrease in laying performance when using tannin-containing cultivars at these inclusion rates. But we limit the inclusion of faba bean with pea to 10%.“ Martin and Inge Ritter from Ostheim vor der Rhön in Lower Franconia converted their business to organic farming in 2000. At conversion, the farm business was based on a dairy herd and a livery service for local horse owners. The livery service was retained but the dairy herd was sold off. New enterprises were established and son Tim joined the company as a trained poultry farmer. Two turkey sheds were built. The turkey chicks are first reared by a specialised organic rearing company until they are about 40 days old. From then on, 2000 animals are kept in the open shed with free run of the adjoining woodland. Family Ritter also likes to bring male turkeys together with female, because the flock is calmer as a result. The breed used is chosen to meet market demand. Some of the turkeys are marketed from the farm, as are a few broilers and geese. Feeding turkeys is demanding The turkeys receive a complete feed in the first stages of life to give them the best start. Turkey chicks are the most demanding of all poultry species in terms of feeding. In the later growing and finishing phase, Martin Ritter uses his own feed mix produced by a mobile grinding and mixing plant. The home-grown ingredients are rolled to give a coarse-textured feed. At the beginning of the finishing period, the proportion of the home-grown component is 10%, at the end 50%. Peas are always included. „Tannin-containing pea is used without any problems,“ explains the plant manager. „Feed conversion efficiency declines towards the end of the fattening period when the animals eat endlessly. It is therefore important to reduce the cost of the ration. Weight at slaughter will not be affected by reducing the ration quality if the daily gains in the initial phase are adequate.“ Turkeys on open pasture. Photograph: Werner Vogt-Kaute Further information Bellof, G., Halle, I., Rodehutscord, M., 2016. Ackerbohnen, Futtererbsen und Blaue Süßlupinen in der Geflügelfütterung. UFOP-Praxisinformation. Jeroch, H., Lipiec, A., Abel, H., Zentek, J., Grela, E., Bellof, G., 2016. Körnerleguminosen als Futter- und Nahrungsmittel. DLG-Verlag, Frankfurt. Demonstrationsnetzwerk Erbse/Bohne, website: www.demoneterbo.agrarpraxisforschung.de Union zur Förderung von Öl- und Proteinpflanzen e.V., UFOP: www.ufop.de/medien/downloads/agrar-info/praxisinformationen/tierernaehrung/  

Grain from a crop mixture of short stemmed protein peas, barley and camelina.   Outome Intercrops usually have a higher yield than the average of the same crops grown separately. The information here can help farmers optimise the use of this type of intercropping. These intercrops are resilient and require no nitrogen fertiliser or herbicide applications. The cereal component prevents the pea component from lodging. Intercrops can make a contribution to low input systems in particular.   Steps to successful intercropping of pea and cereals Cultivar selection: Semi-leafless short-stemmed grain pea and barley are ideal intercropping partners. Experience shows that a seed mixture that combines 80% of the pure stand density for pea and 40% of the pure stand density for the cereal is a good general starting point. This ratio may be adapted to individual experiences with growth patterns of different cultivars. Semi-leafless spring and winter pea cultivars are suitable and possible matching combinations are shown in Table 1.     Long-stemmed pea cultivars are often also used for forage production. Rye or triticale is a suitable partner crop for these tall pea cultivars. The pea component of the seed mixture is lower than with shorter semi-leafless pea due to the strong vegetative growth. A combination of 20–40% of pure stand seed rate for tall pea and 70% of pure stand density for rye/triticale gives good results. No field work is required between sowing and harvest due to the strong growth of the crops. It is important that the pea and cereal cultivars mature around the same time. Finding the suitable cultivar combination (same maturity) and adapted seed mixing ratios can be accomplished by setting up simple strip trials.   Forage pea (Szarvasi) and rye   Crop rotation: Producing legumes more frequently than one year in five increases the risk of soil-borne diseases that cause ‘legume fatigue’. A legume-based intercrop must be treated as a pure-stand legume crop in the rotation. Seedbed preparation: Due to the rapid development of ground cover, these cereal/pea systems are especially suitable for sowing into mulch. Otherwise, pea establishes best in well-consolidated seedbeds. Soil compaction and crust formation on the soil surface reduces plant growth and prevents good development of root nodules that fix nitrogen. Ploughing or other deep loosening may be required for heavy soils. Spring sowing on very heavy soils may require autumn ploughing, otherwise ploughing in February is sufficient. Light cultivation that preserves soil crumb structure reduces the risk of soil crusting. Application of green manure or compost is also possible. Sowing: We use a simple gravity-fed seed drill as is traditionally used for cereals. The seed must be pre-mixed before filling the drill tank. The homogeneity of the mixture should be checked regularly during sowing. Combine drills (with two tanks) can be used to sow the pea and cereals separately. Typical cereal row spacing is suitable with a sowing depth of 3–4 cm. Seeding time: Peas/cereals can be sown in autumn or spring at sowing time of the pea. Autumn sowing reduces the impact of spring and summer drought, particularly if pea flowering time occurs before drought hits the crop. This is a drought avoidance strategy and the longer growing season from autumn sowing tends to stabilise yields. The ideal sowing date in autumn is one that produces well established but small plants by winter (3–4 leaf stage). Spring sowing takes place as early as possible at the beginning of March, so that the crop can use the moisture accumulated during the winter. Pea seedlings tolerate slight frost events around -4°C. Weed control is usually not needed, but a high weed pressure can be controlled by harrowing in early stages. Tall pea/rye mixtures are particularly competitive and a completely weed-free crop is often achieved. Fertilisation: No nitrogen fertilisation is needed. Nitrogen fixed by the pea has only a small effect on the cereal. However, the cereal has been reported to stimulate nodulation. Harvest: The peas are ready to harvest when a fingernail can no longer penetrate the grain at a moisture content of 12–15%. The pods are particularly brittle and susceptible to shatter when the air is dry. Harvesting in the morning and evening, when humidity rises, reduces pod shatter. The optimum combine setting is a compromise between minimising damage to the pea seeds while harvesting as much of the cereal grain as possible. This involves the following considerations for setting the combine harvester: Careful use of the reel to avoid pod shattering. Use the crop lifters with tips pointed downwards. Low drum speed. Open concave to avoid damaging the pea grain. Adjust grain sieves to the pea. Low fan speed compared with a pure pea harvest to avoid losing the cereals (they are smaller and lighter). Where relevant, retraction of the vario-table with the cutter bar kept close to the table auger.   Forage peas and rye at harvest, rye prevents complete lodging and facilitates harvest.   Separation of the grains: A key success factor for adopting intercropping systems is the separation of harvested grains. Grain of pea and cereals are relatively easy to separate. In Switzerland, separating up to 3 components at a time is offered as a service by grain handlers. Separating the harvest allows the components to be used and traded separately. This is important where the grain is not fed on the farm.   Crop performance Yield: The ratio of grain legumes to cereals in the harvested crop fluctuates for different reasons, depending on how stresses impact on the crop. The proportion of pea in the crop of autumn-sown grain pea mixtures in many trials (from 2009–2015) ranged between 30 and 80%. The crop yield (pea and barley) varied between 3 and 6 t/ha. The yields of mixtures of forage pea and rye ranged between 2.5 and 5.2 t/ ha and the share of peas in the harvest varied between 26 and 80% (Trials 2016 and 2017).   A semi-leafless protein pea and barley mixture.   Balancing the effects Advantages More resilient cropping systems and reduced risks of crop failure. If one component fails, the second partly compensates. More efficient use of ressources (nutrients, water, light, land). No need for nitrogen fertilisation. Weed suppression thanks to fast and dense ground cover. Defence against or distraction of potential pests. Attraction of beneficial insects. Easier harvest thanks to the greatly reduced lodging and weed infestation. Disadvantages Matching the cultivars is not easy. Simultaneous maturation within mixed crops is required. Cereal quality might be inferior due to nitrogen deficiency. Additional expenditure in post-harvest processing to separate the pea from the cereal.   Key practice points Mixing of seeds of intercropping partners before sowing, prevent de-mixing during sowing (occasional control of seedtank), sowing depth according to grain legume needs. Start with proposed seed mixing ratios and adapt to local conditions or varieties. Make sure separation of the harvested crop is possible.   Further information Alföldi T., 2015: „Anbau von Mischkulturen - Körnerleguminosen mit Getreide“, FiBL. www.youtube.com/watch?v=gAYNXCw2CiE FiBL Switzerland ongoing, Mischkulturen. www.bioaktuell.ch/pflanzenbau/ackerbau/mischkulturen.html Hauggaard-Nielsen, H., Jørnsgaard, B., Kinane, J. and Jensen, E. S., 2007. Grain legume–cereal intercropping: The practical application of diversity, competition and facilitation in arable and organic cropping systems, Renewable Agriculture and Food Systems: 23(1); 3–12.

Spring pea for grain in the region of Pleven, North Bulgaria.   Outcome The information set out here helps the development of the pea crop in Bulgaria providing an example for the wider south-east Europe region. Pea is a crop with high plasticity which helps it to overcome adverse weather conditions. It uses soil resources very effectively. In addition, it is able to establish a nitrogen-fixing symbiosis with Rhizobium leguminosarum biovar Viciae bacteria to fix up to 150 kg N/ha and to add 45–70 kg N/ha to the soil for the benefit of the following crop. Thus, pea leaves a nitrogen soil reserve for the subsequent cereal crop. Pea is easy to insert into rotations with cereals (e.g., wheat) as pure stand or in mixture with a companion cereal (i.e., triticale, oat, barley). In addition, in a rotation with cereals, pea contributes to breaking the cycle of cereal diseases. It also ripens early giving the possibilities for a second crop later in the year.   Pea in Bulgaria Pea has been grown in Bulgaria for centuries. It became a widespread crop in the 19th century, when its cultivation expanded into northern Bulgaria as a fodder crop, and in southern Bulgaria as a vegetable crop. The cultivation of pea for both dry grain and forage became popular in the 20th century. For many years, the efforts of breeders and farmers were concentrated on forage pea grown in mixtures with cereals. Gradually, the area occupied by pea increased and reached 54,000 ha in 1967 and decreased to 10,000 ha in the period of 1975 to 1980. Significant growth of the areas occupied by pea was observed during the period between 1983 and 1988 when it was recognised as a perspective forage crop and the areas reached 150,000 ha. The reform in agriculture, which started in 1989, disrupted proper cultivar maintenance and seed production and caused another decline in production to only 10,000 ha in 1993. Interest of private farmers has increased since 2000 and the area of forage, grain and vegetable pea has recovered to over 50,000. Vegetable pea accounts for about 14% of the area.   Seeds from spring pea in the region of Pleven, North Bulgaria.   Spring pea cultivars The biological characteristics of pea enable it to be grown as a spring and winter crop (Table 1). “Pleven 4” and “Kerpo” are important Bulgarian forage cultivars for spring sowing. They were bred in the Institute of Forage Crops in Pleven in northern Bulgaria. Two grain cultivars (Mistel and Kristel) were bred in the Dobruzhanski Agricultural Institute, General Toshevo, North Bulgaria. Three grain cultivars (Teddy, Amitie and Picardy) come from the Institute of Plant Genetic Resources, Sadovo, southern Bulgaria. The intensive growth and development of spring pea cultivars occur during the period May-June, when rainfall is sufficient to ensure an intensive crop development without irrigation.   Kristal: plants are well-branched and leafy, height 67–87 cm, vegetation period 110–130 days. The 1,000-seed weight is 280 g and grain yield amounts to 4–5 t/ha. The cultivar is medium early. Mishel: height 50 cm, vegetation period 110–125 days. The weight of 1,000 seeds is 202 g, it is small-seeded with a grain yield of 3.5 t/ha. Pleven 4: plant height 100–120 cm. The pods are medium-sized usually with 4–6 seeds. The mass of 1000 seeds weighs 180–190 g. The cultivar is medium early with good resistance to powdery mildew and ascochitosis. It is grown for green mass and seeds. The vegetation of the cultivar is 90–100 days and yields 3.6–3.8 t/ha. Kerpo: leafy, medium in height at 60–80 cm. The leaf is compound with a maximum leaflet number of 6 that are medium in size. The 1000-seed weight is 240 to 250 g, i.e., it is small-seeded. Depending on the climatic factors, the cultivar begins flowering in late April – early May and ripens in the second half of June. The vegetation period varies from 80 to 90 days. The grain yield is 3.7–5.0 t/ha. Amitie: short growing period from 68 to 84 days. Seed yield is 3.2–4.5 t/ha, used for grain feeding. Picardy: grain yield amounts to 3.8–4.5 t/ha. Growing period is 68 to 80 days. The cultivar is suitable for dry grain for fodder and processing. Teddy: used in the canning and processing industries (dietary flours and additives), because of its good taste. The vegetation of the cultivar is 68 to 80 days and seed yield 3.8–4.5 t/ha.     Key practice points Preceding crop The basic requirement for the preceding crop is to leave the soil clear of weeds. Pea is not compatible with pea and so should not be grown more often than one in five years. Soil tillage Ploughing followed by conventional tillage is most commonly used and provides the essential compaction-free 30 cm layer. Reduced tillage should be used where severe summer drought is expected. Although adapted to a range of soils, the preferred ones of pea are those aerated, with good water holding capacity, moderate lime content and a pH between 6.5 and 7.5. Sowing date and rate The most suitable time for sowing spring pea is February to beginning of March (for some south-east regions it could be end of January to middle of February). Thus, the plants use the accumulated winter moisture and develop a strong root system that makes them more resistant to summer droughts. Delayed sowing reduces yields. The recommended seed rate – that can vary depending on soil characteristics and cultivar - is 100-120 germinating seeds per m-2 or 240–280 kg/ha for large seeds and 120–180 kg/ha for small seeds. The peas are sown in a row (row spacing 12–15 cm) at a depth of 6–8 cm depending on the seed size and soil type. Rolling is required. Fertilisation Pea productivity is closely dependent on phosphorus and potassium fertilisation. Moderate amounts of phosphorous (60–80 kg/ha P2 O5) and potassium (40–50 kg/ha K2O) are required. It should be applied with basic tillage in the autumn. Phosphorus fertilisation contributes to a better development of the root system and also increases disease resistance. A small amount of nitrogen (20–30 kg/ha) incorporated during soil tillage before sowing can be useful as a starter in poor soils when the symbiosis with rhizobia is not yet established. Plant protection measures Spring pea is a weak competitor of weeds. For this reason, rapid seedling emergence, adequate crop density, pre- and post-plant tillage, and herbicides help to reduce weed pressure. If appropriate, chemical control of both grass and broadleaf weeds is possible using a range of pre-and post-emergence herbicides. The most economically important pest of crop grown for grain is Bruchus pisi. The successful treatment of this pest is the timely application of insecticide to crops. Economically important diseases are Ascochyta pisi and Erysiphe pisi. Immediate ploughing of crop residues after harvest to avoid spore dispersal from diseased plants is recommended against diseases. Harvest The optimal stage for harvesting for green mass is at the end of flowering/early pod setting, to maximise forage yield and quality. When the harvest time is delayed, dry matter yield can increase, but simultaneously the forage quality declines. Most often the seeds are harvested by direct combining, which is applied when more than 70% of the beans are ripe, in dry weather, but not in the hottest hours of the day. Peas must be harvested as soon as possible. Otherwise, grain losses are significant. After threshing, the grain is dried in the sun, cleaned in high humidity and what will be stored for a long time is fumigated. Seeds should be stored in dry, ventilated rooms.   Spring pea for forage in the region of Pleven, North Bulgaria.   More information The members of Bulgarian Legumes Network (Fodder Institute Crops-Pleven, Agricultural Academy; Dobruzhanski Agricultural Institute Toshevo; Institute Plant Genetic Resources, Sadovo) offer basic seeds of Bulgarian cultivars of fodder pea, various materials related to its cultivation.  

Laying hens   Nutritional components Pea is used in livestock feed primarily because of its protein content. The dry matter is about 24% protein and also contains energy-rich ingredients such as starch, oil and sugar (Table 1). The nutrient contents vary depending on growing conditions and cultivar. The quality of the protein is determined by the amino acid profile which in turn is determined largely by the cultivar (variety). Pea is rich in lysine, but relatively poor in methionine and cysteine (Table 1). The limiting factor for the use of pea in poultry rations is the low methionine content. The digestibility of the amino acids is good. The mineral content is similar to that of cereals. Pea contains less phosphorus than soy and rapeseed extraction meal. The phosphorus is partly bound to phytin, which reduces uptake. The addition of phytase reduces this problem.     Anti-nutritional factors Pea may contain anti-nutritional components such as tannin, protease inhibitors, lectins and saponins. These can affect digestion and animal health. Harmful levels of tannins are only found in purple-flowering pea that has a dark seed hull (seed coat). The bitter taste reduces feed intake. Most commercial cultivars are white-flowering, have a light-coloured seed hull and therefore, contain little tannin. A reduced digestibility of crude protein and enzyme binding due to tannins only plays a role with high inclusion rates of purple-flowering pea. Other anti-nutritional ingredients such as protease inhibitors, lectins and saponins are only present in small amounts in pea, which do not have a negative effect at the amounts listed below.   Turkeys   Feed value The protein feed value depends largely on the amount of protein and the nutritional quality of the protein and the energy feed value resulting from the digestibility of the nutrients. Protein quality in poultry nutrition is characterised by the contents of the essential amino acids. These are lysine, methionine and cysteine, threonine and tryptophan. The digestibility of the amino acids is also important. This varies both between amino acids and between different grain legumes (Table 2).     Maximum inclusion rates of pea in poultry feed The quantities used depend on age and performance phase (Table 3). Depending on the other components in the feed, the use of peas can reduce the proportion of anti-nutritional substances in the total ration, e.g. non-starch polysaccharides (NSP) from oil cakes.     Further Information Bellof, G., Halle, I., Rodehutscord, M., 2016. Ackerbohnen, Futtererbsen und Blaue Süßlupinen in der Geflügelfütterung. UFOP-Praxisinformation. Jeroch, H., Lipiec, A., Abel, H., Zentek, J., Grela, E., Bellof, G., 2016. Körnerleguminosen als Futter- und Nahrungsmittel. DLG-Verlag, Frankfurt. Losand, B., Pries, M., Steingaß, H., and Bellof, G., 2020. Ackerbohnen, Körnerfuttererbsen, Süßlupinen und Sojabohnen in der Rinderfütterung. UFOP-Praxisinformation. www.ufop.de/medien/downloads/agrar-info/praxisinformationen/tierernaehrung Demonstrationsnetzwerk Erbse/Bohne, website: www.demoneterbo.agrarpraxisforschung.de Feedipedia. Animal feed resources information system, website: www.feedipedia.org

Flowering pea Outcome Soya can be successfully substituted with peas in dairy cows without affecting milk output or compositional quality. However, this is highly dependent on stage of lactation and yield. Pea can be used as the sole protein source for herds with moderate milk production (averaging 7,000 to 8,000 litres/cow/year). For higher yielding cows, pea can be used to partially substitute soya, but additional bypass protein sources will be required for optimum performance in many situations. The greater the substitution, the greater is the need for additional bypass  protein if output is to be maintained. Supplementation with the amino acid methionine may also be required as pea is low in methionine compared to soya, and this essential amino acid is one of the first to limit milk production. Being able to produce more home-grown protein in the form of pea can reduce the reliance on soya and feed costs.   Nutritional value of pea On an energy basis, pea can compete with soya, being of similar energy content of around 13.6 MJ/kg dry matter. However, the protein content is just below half that of soya. More needs to be fed to achieve a similar protein level in the diet. There are also differences in the degradability of the protein present, as well as in the amino acid composition (see Table 1 for comparison), which can impact on milk yield and composition. Lysine and methionine are the two most limiting amino acids for dairy cows. Dairy rations are not usually deficient in lysine but are often deficient in methionine. As the methionine content of pea is about a third of that in soya, use of pea may require supplementary methionine in order to maintain yield and milk protein percentage. About 86% of the protein in pea is rumen degradable, compared to only 55% in hipro soya. Ensuring the correct balance of rumen degradable protein (RDP) and un-degraded protein (DUP or bypass protein) is important for maintaining milk production in high yielding cows which have a higher requirement for bypass protein. One of the benefits of pea is its moderately high starch content. Around 20% of this is resistant to degradation in the rumen compared to 15% in barley and wheat. The starch in pea is degraded at a slower rate compared to cereal starch making pea more “rumen friendly”. This is one of the reasons that some studies show higher milk fat yields when pea is fed. This contribution of starch in pea is significant because the inclusion rate of pea is higher than for soya for a given protein level. The pea substitutes soya and cereals. Overall, this reduces the risk of acidosis.   Soya substitution effects There have been many studies investigating the use of pea as an alternative to soya in dairy cows, with a range of outcomes depending on the stage of lactation, milk yield and level of pea inclusion in the diet. Research from the University of South Dakota (Diaz, 2017) looked at replacing maize and soyabean meal with pea at 0, 12, 24 and 36% of the diet on a dry matter basis. As the inclusion of pea increased, dry matter intake, milk yield and milk solids decreased linearly. A pea inclusion of more than 24% in the concentrate negatively affects milk protein percentage and yield. Vander Pol et al. (2008) also looked at partially substituting maize and soyabean meal with pea, where about 45% of maize and 78% of soya in the control diet were replaced with 15% pea (in the diet dry matter). There was no effect on intake, milk yield, milk fat and protein content or yield in cows averaging 34 kg of 4% fat corrected milk per day. The effect of pea has also been looked at in late lactation cows (more than 200 days in milk), with pea replacing 0, 33, 67 and 100% of the soya portion of the concentrate at different intensities of concentrate use (0, 10, 20 and 30% of dietary dry matter). Barley inclusion was adjusted to ensure diets had a similar starch content. There were no significant differences between pea and soya on intake, milk yield (average yield 21.5 kg/day) and milk compositon, leading the researchers to conclude that protein quality is not important in late lactation cows where daily milk output is low (Khorasani et al., 2001). Teagasc (Agriculture and Food Development Authority, Ireland) recommends that the inclusion of pea should not exceed 20% of the overall dry matter intake. The results of the first two studies reported here would support that view.     Barriers to uptake While it makes sense to reduce soya imports and rely on more home-grown protein sources, there are several limitations: Soya can be sourced from certified environmentally sustainable sources (from areas not affected by deforestation). Soya has been the main “go-to” protein source of choice for dairy farmers. It is frequently the most cost-effective high-protein feed ingredient compared to rapeseed meal and distillers dark grains in terms of cost per unit protein. It is also higher in energy than some protein sources, being of superior nutritional value in its DUP content. Dairy farmers may not have access to land for home-grown pea production. Even for those with arable enterprises, producing pea must compete with other arable crops, including those grown for feeding the herd. For farmers who cannot grow pea, availability depends on local and regional production, processing and marketing. Pea yields vary due to weather, pests and diseases. However, growing the crop to provide home-produced protein reduces the cost of protein supplementation. Pea is a low input crop and so home-grown production reduces total farm input costs.   Crichton cows at feed fence Key practice points The response to substituting soya using pea depends on the level of milk production. Soya can successfully be replaced using pea without affecting milk output with later lactation cows or low- to medium-yielding cows which have a lower requirement for DUP. However, for higher yielding cows (over 8,000 litres/year) in early to mid-lactation, including more than 20% pea or more in the total dry matter intake is likely to depress milk yield and milk protein content due to less DUP in the diet and possibly less methionine. In this situation, an additional source of DUP will be required, with protected rapemeal being the most obvious choice. Cost and the potential effect on income of any impact on milk volume and composition changes must be taken into consideration. Although pea (whether home-grown or purchased) will be cheaper on a cost per tonne basis, the financial impact of the change will depend on the relative costs of soya and cereals. Other costs to factor in are the possible requirements to supply DUP from another source and the need for supplementary methionine.   Further information Corbett, R. R., Okine, E. K., Goonewardene, L. A., 1995. Effects of feeding peas to highproducing dairy cows. Can. J. Anim. Sci., 75,625–629.

Figure 1. Close-up photograph of a split nodule showing the characteristic pink colour. This is indicative of a successful establishment of the rhizobium and active biological nitrogen fixation.   Legumes are the most important hosts of biological nitrogen fixation in terrestrial ecosystems, especially agricultural ecosystems. Nitrogen fixed by legumes is an alternative to synthetically-fixed nitrogen in fertilisers. Because of BNF, introducing legumes into cropping systems reduces some of the damaging emissions from the agricultural nitrogen cycle, especially nitrous oxide (N2O) which is a potent greenhouse gas.   Outcome The direct effect of improved BNF is higher yielding crops, often associated with higher protein content. About 800,000 tons of dinitrogen (N2) from the air is fixed each year by BNF in cultivated grain and forage legumes in the European Union. The main grain legume crops (soybean, pea and faba bean) account for about one third of this. A high rate of BNF is the foundation of successful and sustainable production. The agronomic success of grain legume crops depends to a great extent on the amount of nitrogen fixed in the nodules of their root systems. This means paying attention to establishing and maintaining the symbiosis between the host plant and the bacteria of the genus Rhizobium and Bradyrhizobium. The total amount of nitrogen fixed usually ranges from 100 to 300 kg N/ha depending on factors such as legume species (and cultivar), length of growing season and environmental conditions. The symbiosis between soil bacteria and legumes promotes nitrogen uptake by the plants themselves and enriches the soil with nitrogen through root exudates and residues, making legumes a preferred precursor to many crops. Growing legumes is a cheap and affordable way to enrich soils with nitrogen. Including them in crop rotations creates favorable conditions for growing subsequent crops with reduced use of artificial nitrogen fertilisers.   Role of leghemoglobin and practical consequence Biological nitrogen fixation is a fascinating process. The rhizobium invades the roots of compatible host legume plants, leading to the development of specialized root structures that we know as nodules. In the nodule, the bacteria reduce N2 to ammonia using the nitrogenase enzyme complex, which is produced within the bacterium. For BNF to progress, the nitrogenase needs to be protected from oxygen. The root nodules protect the nitrogenasebased process from oxygen using an iron-linked protein called leghemoglobin. Leghemoglobin controls the concentration of free oxygen in the cytoplasm of infected plant cells, protecting nitrogenase from oxygen while at the same time enabling the provision of oxygen for respiration in root tissue to supply the energy required. A fascinating part of this is leghemoglobin is closely related to the hemoglobin in blood with an analogous function in transporting oxygen. Like hemoglobin, leghemoglobin is red when charged with oxygen. This explains why healthy root nodules are pink. The presence of a large number of nodules that are pink when split open is a reliable indicator of successful establishment of BNF in legumes crops (Figure 1).   Biological nitrogen fixation requires energy For BNF, the conversion of each molecule of N2 to two ions of ammonium NH4+ requires 16 molecules of ATP. The end result of this conversion requires energy from the host legume plant. Symbiotic nitrogen fixation uses about 4–16 % of host plant photosynthate in faba bean and soybean plants. This energy cost is one of the reasons why grain legumes crops are lower yielding than comparable cereal crops. However, under good growing conditions, faba bean and soybean compensate for the energy demanding BNF by boosting growth further.   Figure 2. Shape of nodules in legume plants. A: indeterminate; B: determinate.   Establishing the symbiosis Establishing the symbiosis begins with the removal of flavonoids by the bacterium from the host legume plant. This stimulates the synthesis of specific signaling molecules in the bacteria called „nod factors“. Nod factors are required for both bacterial invasion and nodule formation. The molecular structure of nod factors is specific to the different species of Rhizobium. The rhizobial bacteria attach to the tips of the root hairs, causing them to twist forming an ‘infection thread’ structure that allows the bacteria to reach the root cells of the host plant. The infection thread grows towards the centre of the root and the bacteria are released into the cells of the newly formed root nodule where the nitrogen fixation takes place. The bacteria stimulate the host plant cells to produce the leghemoglobin. The nitrogen that is fixed is then available to the whole of the host plant with the result that high yielding legume crops do not require fertiliser nitrogen. Legumes plants form two types of nodules: indeterminate ovoid shaped and determinate round shaped (Figure 2). The nodules are rich in iron and protein providing a rich source of food for larvae of certain weevils (Sitona lineatus and other Sitona species). The leghemoglobin is also so similar to mammalian blood that it is used in substitute meat products.   It is important to have the right bacteria The specificity of nod factors means that each legume has a specific type of symbiotic bacteria in the family Rhizobiaceae: Rhizobium leguminosarum for pea, faba bean, vetchling and lentil; Rhizobium phaseoli for common bean; Rhizobium ciceri for chickpea; Sinorhizobium meliloti for alfalfa and other medics, yellow melilot and fenugreek; Rhizobium trifolii for clover; Bradyrhizobium lupini for lupins; Mesorhizobium loti for sulla and trefoil; Rhizobium vigna for cowpea and other Vigna species, peanut; Rhizobium simplex for sainfoin; Bradyrhizobium japonicum for soybean (Figure 3).   Figure 3. Nodulated roots of soybean plants from the field.   Key practice points Establishing the symbiosis between the nitrogenfixing bacteria and the host legume plant is a key objective for every farmer growing legume crops. In addition to the natural route, significant BNF can be obtained by inoculating the seeds with an appropriate strain of the nitrogenfixing bacteria. Such inoculation is essential for soybean because European soils do not contain the required species. In contrast, European soils contain strains that infect pea, faba bean, common bean and clover, so the response to inoculation is very variable. In some situations, naturally occurring local strains of nitrogen fixing bacteria in the soil are lacking or have low nitrogen-fixing activity. This necessitates the introduction into the soil of selected strains of nitrogen fixing bacteria characterized by high nitrogen-fixing activity. How this is done for soybean is described in detail in the Legumes Translated Practice Note 1. The other practice points arising from these biological processes include the need to protect the root nodules. Pea and bean weevil (Sitona spp.) adults eat the leaves but this has little effect of the crop yield. The more significant damage is done by the larvae feeding on the nodules. Their control is important where infestation is high. Integrated pest management of Sitona spp. including the use of biocontrol and pheromonebaited traps is required is some situations. This must be done according to local best practice and regulations. Due to the energy demands of the process, ensuring that the crop grows well is fundamental to high rates of BNF, which in turn supports further crop growth. This positive cycle explains how high yielding legumes crops are produced under good growing conditions without any other nitrogen source.   Further information AgroBioInstitute, Agricultural Academy, Bulgaria supplies inoculants for soybean, alfalfa and bird‘s-foot trefoil. Other parts the Agriculture Academy supply basic seed of Bulgarian cultivars of soybean, alfalfa, beans, lentils and garden and fodder peas. Pommeresche, R. and Hansen, S., 2017. Examining root nodule activity on legumes. FertilCrop Technical Note. Research Institut of Organic Agriculture (FiBL) and Norwegian Centre for Organic Agriculture (NORSØK), Frick and Tingvoll. Available at https://orgprints.org/31344/ Von Beesten, F., Miersch, M. and Recknagel, J., 2019. Inoculation of soybean seed. Legumes Translated Practice Note 1. www.legumestranslated.eu

Crichton cows at feed fence   Outcome Soybean meal can be replaced as a concentrated protein source for dairy cows without compromising milk yield or quality. There may be economic benefits depending on the price of soya and other protein sources. Switching to other high-protein feed ingredients is likely to reduce the carbon footprint. In future, milk buyers may reward farmers who do not use soya-based feeds.  Since imported soya is the main source of genetically modified products used in agriculture, switching makes production ‘GM-free’. Some of the alternatives (rapeseed meal and legume grains) can be home-grown, reducing the dependence on long supply chains. The information provided here can help the reader decide whether it is in their interests to remove soya from dairy rations, how it can be substituted, and how that might affect milk production.   What’s the problem with soya? A very large proportion of soya used in the European Union and the United Kingdom is imported from North- and South America. Despite a rapidly growing organic soya area in Central Europe, much organic soya used in organic systems comes from China or India. Particularly for soya from South America, there are a range of societal concerns now impacting on public policy and on food markets. This is evident also from the recent Farm-to-Fork Strategy that sets out the European Commission’s vision for the future of agrifood policy. Imported soya is acknowledged as a major link between the European economy and deforestation. It is also the major source of genetically modified products which are rejected in some dairy markets. For example, the German and Austrian dairy sectors are now almost ‘GM-free’. While soya production in Europe usually contributes to diversification of cropping systems, much of the imported soya is grown in simple systems based on soybean monoculture. Concerns about the link between soya and deforestation have been partially offset by the availability of certified sustainable soya. There is a growing interest in declaring and reducing the carbon footprint of food using alternative home-produced raw materials. While soybean meal is an expensive feed component on a per tonne basis, it is widely regarded as the cheapest and default source of concentrated plant protein. Hipro soya is 55% protein on a dry matter basis and so the rate of inclusion is relatively low. This creates more “space” in the ration to include, for example, cereals which are one of the cheapest sources of energy, or more forage. Soya is now the protein source of choice due to its high bypass protein or DUP (digestible undegradable protein) content. It is a particularly good source of ileal digestible lysine. Soya is however low in the essential amino acid methionine. Methionine has a key role in milk protein production and together with lysine, they are the first limiting amino acids for dairy cows.   Example of concentrate feed – purchased blend including rapeseed meal, protected rapeseed meal, distillers wheat dark grains, sugar beet pulp and palm kernel expeller.   What are the alternatives? The forage and the basic ingredients of the concentrate feeds, usually cereals, provide most of the protein in the diet. Soya or its alternatives supplement this foundation. There are many alternative concentrated protein sources. The most commonly used one is  rapeseed meal, which has been proven to fully replace soya with no detrimental effect  on milk yield or milk composition. Rapeseed meal is thought to be  underestimated in its metabolisable protein content compared to soyabean meal. Many farmers in the UK are replacing soya with rapeseed meal which has been processed (by heat or using chemicals) to improve the DUP content. This is perhaps more applicable to grass silage-based rations which are usually not short in rumen degradable protein. Rapeseed meal also has a more favourable methionine content and so it is likely to benefit milk protein content when substituting for soya. Other commonly used feeds include distillers dark grains (wheat or maize based) as a byproduct from ethanol production. This leaves the question of the suitability of the classical legume protein crops – pea, faba bean and lupin. Currently, these alternative grain legumes can also be considered but they are not always easy to source for industrial feed production, particularly in Scotland. This strengthens  their role in home-feed production. With this in mind, Table 1 sets out the basic nutritional information about these alternatives. More of these feeds need to be fed to come close to replacing the amount of protein provided by soya and therefore the total feed cost must be considered to ensure alternatives are cost-effective.     Going by the DUP content of feeds listed in Table 1, it is clear that using these feed ingedients to replace soya is likely to result in a lower supply of bypass protein in the diet.  This must be taken into consideration when diets are reformulated without soya. The most commonly used alternative feed in the UK is protected rapemeal, with available products having a DUP typically about 18-26% in the dry matter, with up to 75% of the crude protein content being DUP.   Key practice points There are a number of alternative feed sources, including other legume grains, that can be used to replace soya in dairy rations, although it may be harder to meet bypass protein requirements with some of these feeds. Careful formulation is required to balance amino acids. Methionine supplementation with a rumen protected source is recommended to maintain milk yield and milk protein content. The most common replacement for soya is protected rapeseed meal but others such as extracted rapeseed meal, distillers dark grains and grain legumes (peas, beans and lupins) can also be used alone or in combination. Care must be taken when replacing soya to account for any difference in energy and starch content of the alternative products used. Cost is an important consideration. Any change in production must be evaluated against the different ration costs  to assess whether the change is cost-effective or not.   Flowering pea   Further Information Watson, C., Reckling, Preissel, S., Bachinger, J., Bergkvist, G., Kuhlman, T., Lindstrom, K., Nemece, T., Topp, C.F.E., Vanhatalo, A., Zander, P., Murphy-Bokern, D., Stoddard, F.L., 2017. Grain legume production and use in European agricultural systems. Advances in Agronomy 144, 235-303. Cefetra Certified Soya. www.certifiedsoya.com Donau Soja Organisation provides on its website a daily price information about certified soya meals from European production (‘GM-free’). www.donausoja.org/en/dses-soya-bean-meal-prices/ Fraanje, W., 2020. Soy in the UK: What are its uses? www.tabledebates.org/blog/soy-uk-what-are-its-uses