Crops and soils respond differently to residue cover management in no-till systems from the pampas region

DIAZ ZORITA, MARTIN; ALVAREZ, CRISTIAN; BRAMBILLA, C.; DUARTE, G.A.

Rio de Janeiro

Congreso; Rio18- 21 World Congress of Soil Science - Soil Science: beyond food and fuel; 2018

Brazilian Soil Science Society - Latin American Soil Science Society - International Union of Soil Science

The broad use of no-till systems in the pampas region helps to sustain productive soils by reducing soil erosion and maintaining its organic matter and related properties. However, the benefits of residue cover accumulation on crop yields can vary between crops that interact with the expected changes in soil fertility properties. Several studies suggest that residue cover could be partially removed impacting minimally on soil properties. Furthermore, under certain conditions, residue removal can improve wheat and other crops grain yields. Our objective was to determine the effects of residue cover removal or its accumulation on soil properties and grain production in a long-term (14 seasons) crop rotation with soybean, corn and wheat/double crop soybeans. The study, initiated in 2003, was performed in a Typic Haplustoll under no-till practices in the sandy pampas region of Argentina. The treatments compared 3 amounts of yearly chipped residue cover spread immediately before planting: (i) control leaving the field produced residues, (ii) reduced removing the coarse residues and (iii) increased duplicating the quantity of residues lying over the ground piling those removed in the second treatment. Grain production and crop yield components were yearly measured and soil properties were evaluated every 6 seasons. The experimental design was in randomized complete blocks with 3 replicates in 100 m2 plots, and the grain production data was analyzed based on repeated (seasons) measurements. The total removal of residues limited the productivity of summer crops, reducing corn grain yields by 13% and soybean crops by 3%. In seasons with low wheat production, the grain yields were reduced 10% in presence of the regular residue cover or 15% when the quantity of residues was duplicated. No significant changes were observed in double crop soybean yields. The cumulative grain production in the sequence with above ground biomass removal was 5.3% less than when the residue cover at planting was duplicated. In treatments with the removal of residues the soil organic matter contents were reduced but soil extractable P and K values increased in response to low crop productivity and nutrient uptake. However, when the residue cover was duplicated the changes in soil properties were smaller suggesting major risks on crop production and soil productivity properties after residue removal practices take place in the sandy pampas region.