Soil organic C affected by dry‐season management of no‐till soybean crop rotations in the tropics

• Published in: Plant and soil 2021-05, Vol.462 (1-2), p.577-590
• Main Authors: Rigon, João Paulo Gonsiorkiewicz, Calonego, Juliano Carlos, Capuani, Silvia, Franzluebbers, Alan J.
• Format: Article
• Language: English
• Subjects: Agricultural practices; Biomedical and Life Sciences; Carbon content; Carbon dioxide; Cereal crops; Cover crops; Crop production; Crop production systems; Crop residues; Crop rotation; Cropping systems; Crops; Crotalaria juncea; Ecology; Environmental aspects; Glycine max; Grain; Hemp; Intercropping; Life Sciences; Methods; Organic soils; Pennisetum glaucum; Plant Physiology; Plant Sciences; Regular Article; Residues; Seasons; Soil depth; Soil dynamics; Soil Science & Conservation; Soil surfaces; Soils; Sorghum; Sorghum bicolor; Sorghum bicolor bicolor; Soybean; Soybeans; Tillage; Tropical environments; Winter
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-021-04878-0

Aims Cover crop species selection for soybean ( Glycine max ) production under no-tillage (NT) management may affect soil organic C sequestration by altering the quantity and quality of C inputs, thereby affecting cropping system sustainability. If so, the underlying mechanisms for such regulation are still unclear. Methods We assessed changes in soil C and N fractions at 0-0.1 m depth and soil C stock at 0-0.6 m depth during the last three years of dry-season cover cropping in a soybean production system managed with NT for 9 years on a Rhodic Hapludox in Sao Paulo, Brazil. Dry-season management treatments were repeated yearly in a split-plot scheme. Main plots during the fall-winter were (1) ruzigrass ( Urochloa ruziziensis ), (2) grain sorghum ( Sorghum bicolor ), and (3) the intercropping of ruzigrass and sorghum. Subplots during spring prior to planting soybean were (a) pearl millet ( Pennisetum glaucum ), (b) sunn hemp ( Crotalaria juncea ), and (c) forage sorghum ( Sorghum bicolor ). Results Soil C and N fractions were affected according to crop residue characteristics of the rotations. Higher soil C stocks in 2012 and 2015 (7 % an average) were observed at 0.2–0.4 m depth by ruzigrass compared to sorghum. High crop residue input with ruzigrass in the fall-winter sequestered 0.61 Mg C ha − 1 yr − 1 at 0-0.1 m soil depth compared with lower C sequestration using grain sorghum (0.29 Mg C ha − 1 yr − 1 ). Conclusions The quantity and quality of crop residues impact its retention on soil surface controlling the dynamics of soil C and N fractions and can be considered relevant for soil C sequestration. These aspects could contribute to the mitigation of atmospheric CO 2 in crop production systems.