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As interesting as a sack of beans

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​​​​​​​​Pulses, such as lupins, peas or beans provide high-quality protein for human and animal nutrition. Their cultivation supports humus formation, increases biodiversity in agricultural landscapes and can reduce greenhouse gases. Still, they are planted on no more than 1.7 percent of Europe’s arable land. Researchers from ZALF in Brandenburg are determined to change this and bring pulses back to our fields​.

People in the Middle Ages already knew how to maintain the fertility of their fields: By cultivating different crops in turns, they achieved more stable yields over the long term. This knowledge seems to be outdated in the age of highly specialized farming. Lucrative crops, such as rapeseed, maize, wheat and barley, dominate Europe‘s arable land and have almost completely replaced pulses such as peas, field beans and lupins. However, this profit-driven specialisation in agriculture had its repercussions on the environment. In the European Union, almost two thirds of all natural habitats are overfertilised, with consequences for biodiversity and water quality, for instance. The intensive use of synthetic nitrogen fertilisers is one of the main causes of nitrous oxide formation in the soil. When released into the atmosphere, nitrous oxide is around 300 times more harmful to the climate than carbon dioxide. But the problems are not limited to Europe alone. Up to 70 percent of our domestic cattle, pigs and chickens are given protein supplement feed from the US and Latin America. More than one million hectares of rainforest has been cleared for this purpose. »We can counteract these problems by growing more pulses in our domestic fields again,« say scientists from the Institute of Land Use Systems at ZALF. Agricultural engineers Dr. Johann Bachinger and Moritz Reckling have been investigating the potential of lupine, peas, soybean and co. for many years.​

 

Pulses are all-rounders

»25 years ago, I first planted lupines on the test field at ZALF right in front of our institute’s doorstep,« explains Bachinger. Since then, he has been involved in national and European research projects on the cultivation of pulses. Moritz Reckling has been working at ZALF since 2011 as a research associate and shares his colleague’s passion: »Pulses are true all-rounders,« he says. »As so-called deep-rooting plants, they improve the soil, their flowers provide food for bees and they provide valuable protein.« What’s more, they also have a positive effect on the climate: »Thanks to an ingenious symbiotic relationship, pulses can fix nitrogen from the air and thus act as natural fertilizer factories. Using a messenger substance, they attract bacteria that get caught in their root hair and form small nodules together with the plant. These bacteria fix atmospheric nitrogen and make it available to the plant in the form of fertiliser,« says Bachinger. But how can these positive effects be translated into measurable and calculable benefits for agriculture? »We have carried out a feasibility study for the cultivation of pulses in five European areas, including Brandenburg and regions in Italy and Scotland. It was found that their integration in crop rotations can reduce nitrogen fertilizer consumption by up to 38 percent and the release of nitrous oxide by up to 33 percent. Even higher savings can be achieved by cultivating legume-grass mixtures or lucerne which, like pulses, belong to the plant family of legumes.​ »Consumption of nitrogen fertilisers can thus be reduced by up to 58 percent and nitrous oxide emissions by up to 52 percent,« says Reckling. These figures are impressive.​ 

But farmers are reluctant to adopt large-scale cultivation schemes. Increased disease and pest infestation rates are considered to pose a risk, for instance, for pulses and result in yield fluctuations. »However, our research has shown that the fluctuations are similar to those seen in potato cultivation,« explains Bachinger. In order to eliminate risks and increase the competitiveness of legume cultivation, researchers at ZALF are conducting ongoing field trials. They want to identify the ideal cultivation method for legumes in rotation with other crops. The researchers consider plant breeding to be another way of increasing predictability for agriculture. »Whilst many new cultivars for wheat are launched on the market every year, new development on legumes has been quite rare for years,« says Reckling. »We need new, robust varieties that are tolerant to fungal attack and disease, withstand drought and are better positioned to cope with the effects of climate change.« But the scientists also identified an obstacle of a logistical nature: »In most of the European regions studied, the necessary local infrastructure is not sufficient to enable an economically viable cultivation of pulses.« Thanks to decades of focussing on importing protein crops, the factories needed for further processing along with large-scale customers, such as livestock farms, are now located mainly near major international ports. »But this problem does not exist with leguminous species such as clover and lucerne. They are harvested and can be used as animal feed right away. This immediately made them a genuine economic alternative in all the regions studied,« says Reckling.​​

 

​​Growing interest in pulses​

»Despite the challenges, the potential of legumes speaks for itself,« the researchers agree. Politicians too are increasingly recognizing this and responding to it. In order to draw attention to the underestimated crops, the United Nations declared 2016 the International Year of Pulses. In 2012, the German Federal Ministry of Food and Agriculture (BMEL) launched the protein crop strategy in order to strengthen the position of domestic legumes in economic competition. The researchers at ZALF also actively support a comeback of pulses: »In order to support agriculture, we developed the ›ROTOR‹ cultivation system planner. It can be used to calculate, for instance, yield expectations, nitrogen and humus balances as well as weed infestation risks for the respective site,« explains Reckling. »In order to ensure the practical relevance of our results, we continuously carry out investigations with farmers in our region. But the researchers are also breaking entirely new ground: »For four years now, we have been cultivating the economically most promising type of pulses, i.e. soybean, on our test fields. In warm areas, such as Brandenburg or southern Germany, we are already recording remarkable yields,« says Reckling. »We are working intensively with farmers on a comeback of pulses in our domestic fields«, Bachinger takes an optimistic look into the future.»Their reintegration into the European agricultural landscapes would not only contribute to more sustainable farming, but also reduce dependence on imported protein plants.«​

 

Text by Jana Schütze 

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