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Soil carbon as affected by cover crops under no‐till under tropical climate
Author(s) -
Rosolem C. A.,
Li Y.,
Garcia R. A.
Publication year - 2016
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/sum.12309
Subject(s) - cover crop , agronomy , crotalaria juncea , soil carbon , sorghum , environmental science , topsoil , no till farming , soil fertility , crop rotation , soil water , legume , green manure , crop , biology , soil science
In tropical, low‐fertility soils, crop yields are dependent on soil carbon, and cropping systems under no‐till can increase soil C stocks. Plant residues supplied by cover crops in no‐till systems may improve aggregate stability and soil carbon, which may be further increased with the introduction of a legume in the cropping system. This research studied the effects of cover crops in rotation with soybean under no‐till on soil carbon and nitrogen, in Botucatu, Brazil, for 3 yr. The cover crops were millet ( Penninsetum americanum Leek), cober crop ( Sorghum bicolor × Sorghum sudanense ) and sunn hemp ( Crotalaria juncea L.), grown in the spring. Fallow without cover crops was used as a control. Grain sorghum ( Sorghum bicolor L. Moench) and soybean ( Glycine max (L.) Merril) were grown in fall–winter and summer, respectively. Generally, cover crops increased soil carbon contents, but soil N was only increased by sunn hemp in the particulate organic C fraction. An increase in the labile carbon fraction in the topsoil layers was closely related to cover crop root development. Fallow in spring should not be recommended in degraded soils with lowcarbon stock. Labile‐fractioned soil organic carbon and total carbon levels are more efficiently increased by grasses than by legumes in the short term, and grasses cropped in spring increase soil C/N ratio. Conversely, the introduction of a legume (sunn hemp) maintained a more stable C/N ratio, that is around 10, which would be more effective in increasing soil C in the long term.