Abstract
Aim of study: To evaluate soil organic carbon (SOC) sequestration and stock over the succession of maize to winter cover crops under a short-term no-tillage system.Area of study: A subtropical area in Southern Brazil.Material and methods: The experiment was implemented in 2013. The treatments were: seven winter cover crops single cultivated (white-oats, black-oats, annual-ryegrass, canola, vetch, fodder-radish and red-clover); an intercropping (black-oats + vetch); and a fallow, with maize in succession. Soil samples were collected after four years of experimentation, up to 0.60 m depth, for SOC determination.Main results: SOC stocks at 0-0.6 m depth ranged from 96.2 to 107.8 t/ha. The SOC stocks (0-0.60 m depth) were higher under vetch and black-oats, with an expressive increase of 23 and 20% for C stocks in the 0.45-0.60 m layer, compared to fallow. Thus, SOC sequestration rates (0-0.60 m depth), with vetch and black oats, were 1.68 and 0.93 t/ha·yr, respectively.Research highlights: The establishment of a high-quality and high C input cover crops in the winter, as vetch or black-oats in succession to maize, are able to increase SOC stocks, even in the short term.
Highlights
Soil organic matter (SOM) is responsible for ensuring soil organic carbon (SOC) accumulation and plays an essential role in soil physical, chemical and biological characteristics (Zanatta et al, 2019)
Changes in SOC stocks are result from the balance between C input, mainly from plant residue or animal manure, and C output, which occurs through decomposition (CO2 emissions), leaching and erosion processes (Poeplau & Don, 2015)
There were significant variations in SOC concentrations in depth, where red clover resulted in the lowest concentrations at 0.3-0.45 m layer; and vetch and black oats resulted in the highest SOC concentrations at 0.45-0.60 m layer
Summary
Soil organic matter (SOM) is responsible for ensuring soil organic carbon (SOC) accumulation and plays an essential role in soil physical, chemical and biological characteristics (Zanatta et al, 2019). Only the use of a no-tillage system does not guarantee the soil's full potential in sequestering C, requiring diverse and efficient crop systems with high residues production (Conceição et al, 2013) In this sense, the use of cover crops instead of fallow periods is an essential tool that increases the potential of the no-tillage system as a conservationist practice in sequestering SOC (Poeplau & Don, 2015; Veloso et al, 2018). The use of cover crops instead of fallow periods is an essential tool that increases the potential of the no-tillage system as a conservationist practice in sequestering SOC (Poeplau & Don, 2015; Veloso et al, 2018) This is due to the large amount of SOC input via plant roots, which contributes more effectively than the aboveground residue to SOM pool (Rasse et al, 2005; Kätterer et al, 2011). Results from a meta-analysis (Poeplau & Don, 2015) shows that cover crops in agricultural areas promoted SOC sequestration of 0.32 ± 0.08 t/ha·yr
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