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Cover crops can reduce nitrogen loss

Cover crops can reduce nitrate pollution without increasing the salinity or reducing yield, according to researchers.

Cover crops are minor crops that do not aim to increase the production.

The study of the Research Group on Agricultural Systems (AgSystems) of the UPM in collaboration with the group of Soil Quality and Environmental Applications have concluded that its use during intercrop period can reduce the amount of free nutrients in soil fixed to its biomass.

Therefore, cover crops are presented as an interesting alternative to fallow because their use could reduce the contamination of aquifers.

However, the accumulated water and nutrients increase the risk that pesticides and even the nutrients can be produced (with the consequent contamination of aquifers). If the fallow periods and the accumulation coincide with strong or extended periods of rainfall, the risk increases even more.

An interesting alternative to reduce these risks is the introduction of cover crops or capture. These minor crops are not intended to produce fruit or grains but to reduce the amount of free nutrients in the soil (fixing them to their biomass) during intercrop periods.

In order to analyze the efficiency of these cover crops as well as possible negative effects on the main crop (the maize in this case), researchers of the UPM have developed diverse essays by using different types of cover crops during six consecutive years at the “La chimenea” land of the IMIDRA and in the “Campos de Prácticas” at the School of Forestry. These essays were monitored; they analyzed its development and crop coverage as well as the soil moisture at different stages of depth for each treatment.

As a result of these essays, they concluded that cover crops are truly efficient for the control and nitrate leaching, mainly for the species of the gramineae family, and even though none of the species presented yield reduction of the following maize, legume species presented beneficial effects in terms of production.

They also studied the risk of increased soil salinity that can affect the maize production when leaching is reduced. In this sense, it was observed that although there is a reduction in the amount of salts because of the leaching, the total balance of salts continues being negative in the system despite introducing cover crops. They did not observe any increase of soil, even reducing the surface layers; this allowed them to enhance the conditions for sowing and germination of maize. The study1,2,3 was funded by the Research National Plan and the European Commission.

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