Do soil carbon sequestration and soil fertility increase by including a gramineous cover crop in continuous soybean?

Abstract

AbstractCover cropping is a farming practice that may improve C sequestration and soil fertility, but these effects can vary under different edaphoclimatic conditions. The effects of including a winter gramineous cover crop (CC) in continuous soybeans were evaluated in three long‐term experiments (8 yr) on one coarse‐textured soil and two fine‐textured soils in the Pampas region of Argentina. The impacts of CC on soil C sequestration, soil nutrient availability, soil organic C (SOC), and N contents of soil particle size fractions were also determined. The inclusion of CC only increased SOC stock by 3.1 Mg ha‐1 in the coarse‐textured soil (CTS). The labile C fraction in the 0–5‐cm depth increased in both the CTS and the fine‐textured soils (FTS) by 263% and 93%, respectively. Soil N also increased in the labile fraction by 119% and 112% when a CC was used in the CTS and FTS soils, respectively. Moreover, the inclusion of a CC decreased soil P availability in one experiment (4.9 kg ha‐1) and increased soil manganese in two experiments (11 kg ha‐1 on average). The inclusion of a gramineous CC in a soybean monoculture increased the C balance, particularly in coarse‐textured soils. Considering that soil N was similarly affected, the C/N ratio was not impacted.