Soil aggregation according to the dynamics of carbon and nitrogen in soil under different cropping systems

• Main Author: Seben Junior, Getulio de Freitas
• Publication Date: 2016
• Other Authors: Cora, Jose Eduardo [UNESP], Lal, Rattan
• Format: Article
• Language: eng
• Source: Repositório Institucional da UNESP
• Download full: http://dx.doi.org/10.1590/S0100-204X2016000900065; http://hdl.handle.net/11449/165373
• topic: carbon sequestration; carbon stocks; cover crops; crop rotation; soil aggregates; soil organic matter

The objective of this work was to evaluate total soil carbon and nitrogen, as well as their contents in particulate and mineral-associated C fractions; to determine C stock and sequestration rates in the soil; and to verify the effect of C and N contents on soil aggregation, using different crop rotations and crop sequences under no-tillage. The study was carried out for nine years in a clayey Oxisol. The treatments consisted of different cropping systems formed by the combination of three summer crops (cropped until March) corn (Zea mays) monocropping, soybean (Glycine max) monocropping, and soybean/corn rotation and seven second crops (crop successions). Soil samples were taken at the 0.00-0.10-m layer for physical fractionation of C and N, and to determine soil aggregation by the wet method. Soybean monocropping increased C and N in particulate C fraction, while the crop systems with corn monocropping x pigeon pea (Cajanus cajan), corn monocropping x sun hemp (Crotalaria juncea), and soybean monocropping x corn as a crop succession increased total C in the soil. Greater rates of soil C sequestration were observed with soybean/corn rotation and with soybean monocropping, as well as with sun hemp as a second crop. The increase in total N increases soil C stock. Soil aggregation was most affected at particulate C fraction. Increases in soil N promote C addition to particulate fraction and enhance soil aggregation.