Marine Cozzolino
When we talk about agriculture, most minds imagine fields of wheat, corn, or lavender as far as the eye can see. Monoculture is currently the most visible form of agriculture in all landscapes. However, it is by no means the only form of farming that exists. In some arid regions, where nutrients are not present in sufficient quantities in the soil, new methods of cultivation could alleviate this problem.
Authors Sareban Hadi, Madani Ahad and Vazin Farshid at the Department of Agronomy, Islamic Azad University of Gonabad, Iran, published a paper on intercropping grain legumes this year. Published in the Egyptian journal of agriculture research, the paper "Encouraging farmers to adopt sustainable water and nutrient management in arid agroecosystems: problems, solutions and future studies" proposes solutions to nitrogen and phosphorus deficiency in dryland soils using intercropping methods.
In acidic soils, phosphorus and nitrogen are essential elements that are present in too small quantities. Intercropping consists of planting other elements at the same time as the main crop, in this case grain legumes. These legumes, used with sunflower, corn, cotton or other crops, could allow the introduction of missing nutrients. Indeed, legumes increase the H ions in the soil, which has the effect of acidifying the soil. And a more acidic soil allows phosphorus to be better dissolved. This is true in today's wheat/legume intercrops, where phosphorus uptake is higher than in monoculture. In addition, grain legumes play other beneficial roles by increasing soil organic matter, nutrient availability and water retention.
However, adding a component to the main crop is a challenge, as these new components should not "steal" water and nutrients from other plants. For water, the latter is mostly deep, so field crops have easy access to it, and the short roots of grain legumes cannot steal this resource from them; but the essential nutrients (nitrogen and phosphorus) are found in homogeneous quantities in the soil. If they are in short supply, and the legumes take them up, then the yield is lower for the farmers. The solution to this problem is to increase the number of nutrients in the soil, for example with bacteria that solubilize phosphate.
In conclusion, the insertion of grain legumes in cotton, maize or other crops in drylands increases the amount of H ions in the soil. These ions acidify the soil, and a more acidic soil dissolves phosphorus better. However, nitrogen fixation by grain legumes is not sufficient, and the addition of nitrogen fertilizer is necessary.
Sareban, Hadi, Ahad Madani, and Farshid Vazin. "Encourage farmers to adopt sustainable water and nutrient management in arid agroecosystems: problems, solutions and future studies." Egyptian Journal of Agricultural Research 99.2 (2021): 136-141.
