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Zero tillage is sufficient to reduce nitrate pollution

© Cyril Kuhmar/TASS

Researchers from the Department of Earth Sciences School of science Indiana University-Purdue University Indianapolis (USA) conducted a meta-analysis for comparison of nitrate leaching under two different types of tillage: plowing and zero processing. It turned out that the rejection of the plowing does not reduce the groundwater pollution by nitrates, although it has other positive effects, writes portal Phys.org.

At zero processing crop residues (residues from the harvest in the fields, including the roots, lower stems, leaves) remain on the soil surface; disturbance to its integrity are minimized; pits are only small holes for fertilizer. This processing is performed on 20% of all arable land in the United States; this reduces soil erosion and reduces the erosion of topsoil into rivers and lakes. It was assumed that nitrate pollution with this method of agriculture must also decline .

Nitrates have become common water pollutants because of its high solubility in water and mobility of joints. Surface runoff and leaching are the main ways by which nitrates get into waterways from farmland. Additional factors influencing this process – aridity, variability of precipitation, the texture of the soil, the cultivated plants, the duration of treatment of the soil and composition of fertilizers.

“We found that no-tillage is not enough to improve water quality, said Wang Lixin, one of the authors of the study. We understand that at zero treatment increased the leaching of nitrogen”. The absolute content of nitrates in the surface runoff under zero and traditional tillage were about the same.

“Leaching of nitrate from soils long under no-till, increased due to frequent appearances of macropores, which are created by dead roots and earthworms,” sums up van.

Scientists came to the conclusion that the zero treatment should be supplemented with other methods such as cultivation soil cultivating crops, combination of crops or of alternating annual crops with perennial; this will help to keep nitrates in soil and reduce their leaching.

Material provided by the project of “1”.

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