Organic Matter Dynamics and Carbon Sequestration Rates for a Tillage Chronosequence in a Brazilian Oxisol
- João Carlos de M. Sáa,
- Carlos C. Cerriab,
- Warren A. Dick *ac,
- Rattan Lalad,
- Solismar P. Venske Filhoab,
- Marisa C. Piccoloab and
- Brigitte E. Feiglab
- a J.C.M. Sá, Universidade Estadual de Ponta Grossa, Cx. Postal 992/3, 84010-330, Ponta Grossa-PR, Brasil
b Universidade de São Paulo-Centro de Energia Nuclear na Agricultura, Av. Centenário 303, 13416-970, Piracicaba-SP, Brasil
c The Ohio State University, School of Natural Resources, 1680 Madison Avenue, Wooster, OH 44691
d The Ohio State University, School of Natural Resources, 2021 Coffey Rd., Columbus, OH 43210
Amounts and rates of C sequestration under no-tillage are not known for a major ecological region of south Brazil. These were assessed in a Brazilian Oxisol under a plow and no-tillage chronosequence located in Paraná State. The chronosequence consisted of six treatments: (i) native field (NF); (ii) 1-yr plow conversion of native field to cropland (PNF-1); (iii) no-tillage for 10 yr (NT-10); (iv) no-tillage for 20 yr (NT-20); (v) no-tillage for 22 yr (NT-22); and (vi) conventional tillage for 22 yr (CT-22). Soil samples were collected from five depths. No-tillage, compared with the NF treatment, caused a significant increase in soil organic C (SOC) storage. More than 60% of this increase occurred in the 0- to 10-cm soil layer. There was a decrease in the amount of SOC in the CT-22 compared with the NF soil treatment and 97% of this loss also occurred in the 0- to 10-cm layer. There was a close relationship between the SOC content and the amount of crop residues input (R 2 = 0.74, P ≤ 0.05). There were increased SOC concentrations in the finer particle-size fractions (<20 μm) of no-tillage surface soil compared with the NF or CT-22 soils. However, the percentage of SOC derived from crop residues in no-tillage treatments, as assessed by 13C natural abundance (δ), was generally greater in the coarse (>20 μm) than in the finer (<20 μm) particle-size fractions. The C sequestration rate for no-tillage was 80.6 g C m−2 yr−1 for the 0- to 20-cm depth and 99.4 g C m−2 yr−1 for the 0- to 40-cm depth. The no-tillage C sequestration potential for South Brazil was estimated as 9.37 Tg C yr−1Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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