Growing pulses really works, everywhere in the world, whatever the crop: yields are improved by 20% on average. 48% in Africa. Details from Mathilde Fontez, editor-in-chief of the magazine Epsiloon.
franceinfo: An international study today demonstrates the effectiveness in boosting the yields of a type of crop, the cultivation of leguminous plants, beans and peas?
Mathilde Fontez: Beans, peas, but also lentils, clover, alfalfa, broad beans. This category of plants has a particular power, which we have known for a long time, even if biologists have not yet succeeded in completely unraveling its mysteries: they store nitrogen from the air, to deposit it in the soil, via their roots. They are therefore fertilizers for the soil since nitrogen is what is consumed by most crops. Basically, legumes are a natural fertilizer.
Where did the idea of cultivating them to restore the level of nitrogen in the soil come from?
That’s the idea yes. And it is already widely practiced: crop rotation with legumes is recognized as a key strategy for sustainable agriculture, or organic crops. Beans are planted to better grow corn, or wheat later.
But there, a study demonstrates for the first time the effectiveness of the technique on a large scale. The researchers, an international team, collated the field studies in 53 countries. They accumulated 12,000 yield observations, nearly 500 experiments, between 1959 and 2020. And what they find is that the gain in yield is quite remarkable: Legumes increase yields, at constant surface, by 20% on average.
So does it work?
It works yes. Everywhere. For all crops, be it corn, rice, wheat, beets. And the researchers detail the variations. For example, the increase in yield is less strong on soils where chemical fertilizers, nitrogen fertilizers, are used. This was expected: when the soil is enriched with nitrogen, inevitably, the contribution of legumes, in proportion, is less great.
But their use is still beneficial to performance. And that’s a surprise: for researchers, it’s probably the effect of crop rotation on the ecosystem of the field: legumes break disease cycles, they prevent pests and pathogens from proliferating. And on soils that are low yielding: soils cultivated organically, or African soils, there, the increase is impressive. It reaches 43% in Africa.
In their conclusion, the researchers bluntly say that “legume-based rotations offer a critical pathway to improve global agricultural production.” Although this may initially reduce the area of the main crop, the yield gains quickly compensate for this loss. A real sustainable solution then…