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

Blue flowering narrow-leafed lupin   The survey and respondents An online survey with conventional and organic farmers who cultivated lupin was conducted across Germany within the ‘Demonstration Network for Cultivation and Utilisation of Lupin’ between October and December 2019. In total, 67 farmers responded. Most farmers were from the states Brandenburg, Hesse, North Rhine-Westphalian, Lower Saxony, Bavaria and Saxony-Anhalt with 7-12 responses each. Since lupin is mainly produced on sandy soils with low soil pH in north-eastern Germany, the sample included farmers from this region and also farmers from western and southern areas where lupin production is novel. Conventional farmers were the largest group with a share of 64% (43), 36% (24) were organic farmers.   Lupin production and use Most of the conventional farmers (80%) reported producing only narrow-leafed lupin (Lupinus angustifolius L.). White lupin (Lupinus albus L.) was grown by 10%. Both species were grown by 7%. Many organic farmers (54%) reported producing only narrow-leafed lupin, while 25% produced white lupin. Both were grown by 13%. Only a very few farmers produced the yellow lupin (Lupinus luteus L.). This distribution reflects the general dominance of narrow-leafed lupin in Germany with 10 registered cultivars in 2022. Due to the disease anthracnose, caused by Colletotrichum lupini (Bondar), white and yellow lupin cropping stopped around 1995, and only the tolerant cultivar of white lupin is now grown (4 registered cultivars in 2022). The majority (54%) of the conventional farmers produced lupin for on-farm use only while 18% produced lupin as a cash crop only and 28% for both. This split for organic farms was even (32%, 36% and 32%, respectively). Lupin sold from conventional farms was mostly for feed (89%) and less often for food (17%) or seed (11%). Compared to the conventional farmers, more organic famers sold their lupin for food (47%) which reflects the higher market share for organic lupin-based food products e.g., meat replacements, meal, coffee, drinks. The larger share of organic lupin was sold for feed (67%).     Motivation for lupin production The most stated motivation of conventional farmers was to produce domestic protein feed (60%). Steadily increasing soybean prices support this motive. Agronomic motives, such as crop diversification and enhancing crop rotations were cited by 40%. Other motives arise from financial incentives from the Common Agricultural Policy and personal interest in the cultivation of lupin. Some farmers referred to drought tolerance of lupin and benefits for soil fertility as motives to grow the crop. Enhancing crop rotations and crop diversification was most important for organic farmers (48%). This reflects the crucial agronomic role legumes have in supplying reactive nitrogen on organic farming. Organic farmers also stressed domestic protein feed (42%).   Challenges in lupin production The main challenges perceived in lupin production were very similar from conventional and organic farmers. Drought is regarded as the greatest challenge by both groups. This is likely to be a consequence of the extreme weather conditions in 2018/2019. Weed infestation, particularly late infestation, is seen as another major challenge. This reflects the poor competitiveness against weeds and the limited options for weed control especially in the late growing phase. Other unfavourable weather conditions were seen as a medium issue by about50% of the conventional as well as organic farmers. More organic farmers (41%) than conventional farmers (16%) perceived anthracnose as a medium or major challenge for lupin cultivation. A similar picture but on a lower level was shown for an infestation risk with the lupin weevil (Sitona gressorius F. and Sitona griseus F.) – 24% of organic farmers named it as a challenge and 15% of conventional farmers. Other pests and diseases were only seen as a challenge by individual farmers. Further challenges farmers perceived with lupin cultivation could also be derived from farmers’ assessment of lupin yield and yield stability. Almost half of the conventional farmers assessed yield as poor and the other half as medium (48% and 52%, respectively). Organic farmers assessed lupin yield even worse with 65% describing the yield as poor and 35% as medium. Yield stability was also rated negatively by 63% of conventional farmers and by 67% of organic farmers. A question comparing lupin with other legumes also stressed the yield issues perceived by farmers: over 70% of conventional and organic farmers assessed lupin yield in comparison to other grain legume yields as lower.   Pods of white lupin grown in a field experiment   Reasons to stop lupin cultivation Farmers were asked whether they plan to stop or already have stopped lupin production. The majority of conventional and organic farmers stated the intention to continue production, 53% and 62% respectively. However, the other farmers which represent a considerable share, planned to stop or already have stopped lupin cultivation. The major reason to stop cultivation was related to the low yield reported by conventional (50%) and organic farmers (30%). This emphasis on low yields can most likely be traced back to very low yields in 2018 (national average of 0.95 t/ha) and 2019 (1.22 t/ha) which were lower than the national yield averages of 1.56 t/ha from 2011-2021. Organic farmers named also weed infestation (30%) and the increase of the lupin weevil (20%) as important reasons. The lack of pesticides was by 14% of conventional farmers mentioned as a reason for stopping lupin production. Missing financial incentives were also named by 14% of conventional farmers (there is no specific support programme for legumes in some German federal states). Individual conventional and organic farmers named a range of other reasons such as a poor availability and high costs of seed, high alkaloid contents, anthracnose, a limited farm area, poor gross margins, damage from wild animals esp. from birds, uneven ripening, pod shattering, and the ban of cultivation in water protection zones. While many farmers from this survey planned or already had stopped growing lupin, other farmers who were not part of the survey sample started to grow the crop (we only asked lupin growing farmers).   Figure 1. Lupin harvested area and production in Germany in 2011-2021   Changes needed to increase lupin cultivation When asked about changes that farmers perceive as necessary to increase lupin cultivation, most conventional farmers ranked the registration of certain pesticides high (72%). Second came financial incentives for protein crops (64%) followed by drought tolerant cultivars (42%) and higher producer prices (41%). Easier distribution channels and disease tolerant cultivars were seen as highly relevant by 22% and 18% of the respondents, respectively and only a few individual farmers perceived new agronomic cultivation techniques, improved mechanical weed management and solutions for controlling the lupin weevil as highly necessary. Organic farmers also perceived disease tolerant cultivars and higher prices (19%) as important conditions for increasing lupin cultivation. Moreover, financial incentives and drought tolerant cultivars were seen as relevant by 16% of the respondents. Similarly to the results from the conventional farmers, few organic farmers stated a high need for new cultivation techniques (13%) and solutions for lupin weevil (6%). Beyond the farm level, farmers saw the greatest potential for inducing change in plant breeding, with 62% of conventional farmers and 75% of organic farmers. Marketing, processing and research were ranked with a high potential by a relatively similar share of conventional farmers with 42%, 38% and 34%, respectively. For half of the organic farmers research had a high potential for change and only few saw this potential in processing (20%) and even less in marketing (7%).   Figure 2. Proportion (%) of conventional farmers citing different constraints as major and medium problems. Responses were given on a three-point response scale: major problem, medium problem, no problem (n=number of farmers who responded).   Conclusion The survey results present some key issues that farmers perceive for lupin production. Lupin is cultivated particularly for producing a domestic protein feed and due to its rotational benefits. Problems in lupin cultivation are especially associated with yield, tolerance to drought, and competition with weed which also caused farmers’ decision to stop lupin cultivation. Farmers demand cultivars that can deal better with extreme weather and have a higher tolerance against diseases. Action and progress in breeding is therefore perceived as highly relevant. Further factors named by farmers were economic determinants. Financial incentives are relevant to secure a profitable production and also an increase in producer prices were requested by farmers. The survey was conducted after two very dry years with low yields for lupin and other crops. In 2020 and especially 2021, lupin production increased again due to an increasing use of domestic grain legumes for feed and food, the farmer`s interest in growing lupin in regions other than the traditional ones, and the availability of new cultivars, especially white lupin. White lupin can achieve higher yields than narrow-leafed lupin on good soils. Since weather conditions were more favourable in recent years, average yields and harvested production increased.   Figure 3. Proportion (%) of organic farmers citing different constraints as major and medium problems. Responses were given on a three-point response scale: major problem, medium problem, no problem (n=number of farmers who responded).   Key practice points Lupin is mainly used for protein feed which is also the strongest motivation for production. Low yield, susceptibility to drought and competition with weeds are regarded as constraints. Breeding efforts for drought and disease tolerant cultivars are requested. Financial incentives and higher producer prices are needed.

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.

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.    

Maturing white lupin plant.   Lupinus albus cultivation Lupin is a promising crop for Greece. It can play a role in livestock feeding in particular. Lupin seeds have a high protein content (up to 44%) and they are also a rich source of calcium, iron, magnesium and phosphorus. Due to its nutritional profile, lupin represents a significant alternative to soybean. White lupin originates from the Mediterranean countries. It has the longest history of cultivation for human consumption of any lupin species, dating back to pre-Roman and Greek times. In the past, a cultivar of white lupin that was bitter was mainly cultivated in Greece. The bitterness is due to alkaloids which are toxic to humans and animals. Lupin seeds were immersed in the sea or were roasted to reduce the alkaloids. Sweet and semi-sweet cultivars with low levels of alkaloids (<0.05%) are now used. The most widely grown cultivar in Greece is the locally adopted cv. Multitalia which is semi-sweet. Climate and soil Spring-sown white lupin is well-adapted to the cool season. Lupin thrives in a temperature range from 14 to 25°C over a 110–125 day growing period. In warm climates such as in Greece, autumn sowing after the first rains is recommended. Sowing can continue until the end of November. Autumn sowing extends the growing season by about 60 days and brings the harvest forward so that the crop escapes severe mid-summer droughts and heat stress. This approach increases and stabilises yield. Autumn sowing of lupin also allows Greek farmers to grow two crops per year where there is irrigation.   Young white lupin.   White lupin requires slightly acid soils (pH 6–6.5), with an active calcium content of less than 3%. It has low demands in nutritional elements. Its deep root system forms large nodules where soil microorganisms (rhizobium bacteria) work symbiotically with the plant to fix atmospheric nitrogen and so enable plants to grow. Part of this nitrogen remains in the soil with legume residues for the next crop contributing further to the sustainability of crop rotations by reducing the need of synthetic nitrogen fertilizer. Water Under Mediterranean conditions, lupin grows in areas with rainfall of 380–450 mm. White lupin is quite drought tolerant, however the prolonged dry periods and high temperatures may cause significant yield reduction. Water supply from the soil at flowering and pod filling is critical for the plant development. Flood or overhead irrigation which results in water logging and soil flooding leads to problems with diseases. The optimum strategy for managing water is to gradually recharge the soil water reserve before severe drought strikes. For the best results, the cultivation strategy should tend towards recharging the soil moisture before depletion. This is where precision irrigation plays a role.   Testing precision irrigation We conducted an experiment from November 2019 to May 2020 near Larissa in Greece, looking at five different irrigation plans to determine the optimal irrigation protocol for lupin cultivation. Soil analysis before sowing provided information on soil texture and the supply of nutrients. These facts are needed because they can influence the irrigation scheduling and the final yield. For example, sandy soils need to be irrigated earlier than clay soils while soils richer in nutrients such as phosphorus and potassium can amplify a better yield. The selected fields had similar climate conditions, were of similar soil composition and nutrient concentration. We used the exact same fertilisation and cultivation techniques. The fields were sowed in mid-October, using the cultivar Multitalia. The crop stand developed well. There were long periods of drought during the winter and the total amount of rain was not enough to cover crop needs. Sensors in each field collected data on air temperature, wind, rainfall, external humidity, soil moisture, etc. The Drill and Drop type and Enviroscan type ground sensors measured soil moisture in different depths e.g., 10 cm, 20 cm, etc. Data are easily accessible via a web application where farmers see the parameters of interest and act accordingly. These sensors cover a large area, thus providing data for several fields minimising the cost of use.   Lupinus albus grains.   Crop responses We applied irrigation at different times according to soil humidity, making sure that the total amount of water was approximately the same (Table 1).     Irrigation increased yield significantly, from 11.5% to 30.76%, compared to the non-irrigated field. Field 1 was the control field and no irrigation was applied. Rain did not cover the crop needs and total yield was quite low at 2.6 t/ha. The treatments differ in the scheduling of the irrigation. Field 2 was irrigated to keep soil moisture levels high while fields 3 and 4 were irrigated to keep soil water levels at about 20% at 200 mm. This moderate water supply prevented extreme drought stress, maintained crop growth and avoided diseases associated with excessive irrigation. Field 5 was irrigated at the stage where plants were stressed due to a lack of adequate soil humidity. Despite receiving the biggest total amount of water, plants did not recover from the drought stress and the yield was lower than expected.   Key practice points Lupin thrives in a temperature range from 14 to 25°C for a period of 110–125 days from spring sowing and about 180 days from autumn sowing. In Greece, October sowing is recommended in order to avoid the high summer temperatures. Soil analysis helps determine the nutrient availability. Irrigation strategy should tend towards recharging the soil water before depletion impacts on the crop. Data from sensors covering a large area can be easily accessed via the web. Understanding what happens in the plants` root system enables us to make better decisions. In case of low winter rainfall, lupin needs irrigation to produce a high and economically viable yield. Excessive water accumulation during flowering stage can stress the plants. Irrigation where soil water contents are high is not advised. Irrigation should be used in advance to prevent extreme drought stress. Crops that have been subject to extreme drought stress do not recover fully when irrigated. Improved water use efficiency saves resources.   Further information Gresta, F., Wink, M., Prins, U., Abberton, M., Capraro, J., Scarafoni, A., Hill, G., 2017. Lupins in European Cropping Systems, in: Murphy-Bokern, D., Stoddard, F.L., Watson, C.A. (Eds), Legumes in Cropping Systems. CAB International, pp. 88-108. Cowling W.A., Buirchell B.J, Tapia M.E., (1998). Lupin, Lupinus L., International Plant Genetic Resources Institute IPGRI. Dalianis Konstantinos. 1993. Legumes for Grains and Forage. Stamoulis Publications, AthensPapakosta - Tasopoulou Despina. 2012. Special Agriculture, Grains and Legumes. Modern Education, Athens. Biala K, Terres J, Pointereau P, Paracchini M. Low Input Farming Systems: an Opportunity to Develop Sustainable Agriculture - Proceedings of the JRC Summer University - Ranco, 2-5 July 2007. EUR 23060 EN. Luxembourg (Luxembourg): OPOCE; 2008. JRC42320. The main sources for soil monitoring are the ground sensors in the field (figure below) for monitoring the plant condition every hour. Data are accessible by a terminal device in a form of table (Table 2).   Soil sensors Drill and Drop (a,b) Enviroscan (c,d).

Figure 1. The white lupin   Decision-making aids White lupin (Figure 1) is the most valuable protein crop after soybean for animal feed and human nutrition due to the high protein content and good amino acid profile. The yields are usually around 3 t/ha, typically varying from 2 to 4 t/ ha. Advantages over soybeans include above all the possibility of sowing in March (frost down to -5 °C is no problem), a better precedingcrop or break-crop effect, and clearly visible flowers which are attractive for pollinators. Lupin thrives well in acidic, low phosphorus soils. Disadvantages of white lupin are the risk of losses due to anthracnose, problems with late weed infestations, and a relatively late harvest (mid to late August). The marketing of lupin also requires care.   Anthracnose Avoiding anthracnose is key to success. Anthracnose is a leaf-spot disease transmitted through the seed (Figure 2). The use of visually clean certified seed is the foundation of control. All cultivars available so far are susceptible to the disease. In Germany, the less susceptible cultivar “Frieda“ has been approved since 2019. This cultivar has proven itself in cultivation in 2019 at two trial locations in Switzerland. The French cultivar ”Sulimo“ has also proven to be less susceptible and very high-yielding (at two locations and in three trial years). From 2020 on, ”Celina”, which according to the breeder is less susceptible, will be available, but we have no experience with it, yet. The risk of anthracnose is reduced in dry summers and on windy or open sites with soils with pH values below 7.   Figure 2. The dreaded anthracnose disease leads to localised twisted growth of whole plants at flowering time (left) and to black, twisted pods at maturity (right). The worst disease patches can be removed from the field by hand at flowering time.   Site and sowing Calcium carbonate content of the soil: Lupin is very sensitive to the calcium carbonate content (CaCO3, lime and chalk) in soil. Field testing at the Research Institute of Organic Agriculture FiBL shows that viable cultivation is possible where soil lime or chalk levels are below 3 %. Trying the crop first on a small scale will help identify viable sites where lime or chalk levels are between 3-10 %. Cultivation with lime or chalk levels above 10 % is not possible. Since soils with a higher lime content generally also have higher pH, soil pH is used as an indicator of the suitability of a site. As a general rule, the soil pH should be lower than 7. Studies from France have shown that especially the lime in the fine clay and silt fractions prevents lupin from absorbing iron from the soil, which the nodules need for nitrogen fixation. The result is a nitrogen deficiency which is indicated by yellowish leaves and poor growth (calcium chlorosis). The susceptibility to  anthracnose is also increased on such a soil. Plants from inoculated seeds should have a strong dark green colour reflecting high rates of nitrogen fixation facilitated by adequate iron supplies. Inoculation: Biological nitrogen fixation in lupin, as in soybean, depends on symbiosis with a strain of Bradyrhizobium that is not normally found in soils where no lupin cultivation took place in the preceding years. Therefore, lupin responds to seed inoculation. This allows the roots to form nitrogen-fixing nodules together with the bacteria, and nitrogen fertilisation is not necessary. Experiments have impressively shown that inoculation can easily lead to a doubling or tripling of the yield. The most common of these inoculants is a black peatbased powder containing living bacteria. It can be ordered together with the seed in the seed production. It is however best mixed with the seed immediately before sowing until the seeds are fully dark-stained. Since UV light kills the bacteria, the inoculant and the finished inoculated seeds should be protected from sunlight and stored in a cool place (see also Inoculation of soybean seed).   Figure 3. Weed control is particularly important for the prevention of late weeds. The crop can be weeded mechanically in the early stages.   Cultivation and harvest Cultivation: The stale seedbed technique provides a foundation of weed control both in conventional and organic crops. Tined weeding within three days after sowing can also be used. Special care should be taken not to disturb the seed. Inter-row cultivation can be used approx. 4-6 weeks after sowing (Figure 3) in a way similar to soybean (see also Practice Note 2). Ideally, inter-row cultivation should be carried out in the afternoon when plant turgor is low to avoid injury. The crop can be effectively inspected for anthracnose under dry conditions approximately 8 weeks after sowing, at the beginning of flowering. At this time the first patches of anthracnose might become visible. Removal of the infected plants by hand can help prevent the disease from spreading even more rapidly from these patches. Harvesting: White lupin matures late, usually at the end of August/beginning of September. In very hot years (such as 2015 and 2018) they could be harvested in the first week of August. Rainfall in July and August can delay harvest, especially when it stimulates the late production of new side shoots. The right time for threshing is reached when the seeds in the pods „rattle“ when shaken and when most of the straw is brown (Figure 4). The pods of white lupin are clearly more shatter-resistant than those of blue lupin. The seeds are large, so the combine concave must be as wide open as possible. The threshing drum speed should be set at the lowest level, and the fan speed should be high for rapid straw separation. The moisture content of the crop should be at or below 14 %. Low temperature drying (below 35 °C air temperature) should be used if drying is necessary.   Figure 4. In flower, pods filing, and ripe white lupin   Further information Dierauer, H., Böhler, D., Kranzler, A., Zollitsch, W., 2004. Lupins. Leaflet (German). Research Institute of Organic Agriculture FiBL, Frick. www.fibl.org/de/shop/1308-lupinen.html Dierauer, H., Clerc, M., Böhler, D., Klaiss, M., Hegglin, D., 2017. Successful cultivation of grain legumes in mixed cultivation with cereals (German). Research Institute of Organic Agriculture FiBL, Frick. www.shop.fibl.org/chde/1670-koernerleguminosen-mischkulturen.html Duthion, C., 1992, Comportement du lupin blanc, Lupinus albus L, cv Lublanc, en sols calcaires. Seuils de tolérance à la Chlorose. Agronomie 12, 439-445. www.hal.archives-ouvertes.fr/hal-00885488/document Gresta, F., Wink, M., Prins, U., Abberton, M., Capraro, J., Scarafoni, A. & Hill, G., 2017. Lupins in European cropping systems. In: Murphy-Bokern, D., Stoddard, F. and Watson, C. 2017. Legumes in cropping systems, p. 88-108, Wallingford: CABI Publishing. Websites and videos Pages on the cultivation of organic lupins in German and French on the web platform Bioaktuell.ch, Research Institute of Organic Agriculture FiBL, www.bioaktuell.ch/pflanzenbau/ackerbau/koernerleguminosen/biolupinen.html. The website of the German lupin network is a valuable resource: www.lupinen-netzwerk.de/Kategorie/anbau/allgemeines/. Forschungsinstitut für biologischen Landbau FiBL, 2020. Lupinenanbau – Erfolg mit neuen Sorten. YouTube-Kanal FiBLFilm. German (English subtitles can be chosen under “settings”) www.youtube.com/watch?v=ELyQAP6gT4g&feature. Research Institute of Organic Agriculture FiBL, 2020. Machine demonstration: Mechanical weed control in soya. https://www.legumehub.eu/is_article/machine-demonstration-mechanical-weeding-in-soy/

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