Changes in soil organic carbon stocks under agriculture in Brazil

Self Cite

SUMMARYSoil physical quality is an important factor for the sustainability of agricultural systems. Thus, the aim of this study was to evaluate soil physical properties and soil organic carbon in a Typic Acrudox under an integrated crop-livestock-forest system. The experiment was carried out in Mato Grosso do Sul, Brazil. Treatments consisted of seven systems: integrated crop-livestock-forest, with 357 trees ha -1 and pasture height of 30 cm ); integrated crop-livestock-forest with 357 trees ha -1 and pasture height of 45 cm ); integrated crop-livestockforest with 227 trees ha -1 and pasture height of 30 cm ); integrated croplivestock-forest with 227 trees ha -1 and pasture height of 45 cm ); integrated crop-livestock with pasture height of 30 cm (CL 30 ); integrated croplivestock with pasture height of 45 cm (CL 45 ) and native vegetation (NV). Soil properties were evaluated for the depths of 0-10 and 10-20 cm. All grazing treatments increased bulk density (ρ ρ ρ ρ ρ b ) and penetration resistance (PR), and decreased total porosity (ƒ t ) and macroporosity (ƒ ma ), compared to NV. The values of ρ ρ ρ ρ ρ b (1.18-1.47 Mg m -3 ), ƒ ma (0.14-0.17 m 3 m -3 ) and PR (0.62-0.81 MPa) at the 0-10 cm depth were not restrictive to plant growth. The change in land use from NV to CL or CLF decreased soil organic carbon (SOC) and the soil organic carbon pool (SOC pool ). All grazing treatments had a similar SOC pool at the 0-10 cm depth and were lower than that for NV (17.58 Mg ha -1 ).Index terms: agroforestry, soil organic carbon, multivariate analysis. A qualidade física do solo é um importante fator para a sustentabilidade dos sistemas agrícolas. O objetivo desta pesquisa foi avaliar as propriedades físicas do solo e o carbono orgânico em um Latossolo Vermelho distrófico, sob sistema de integração lavoura-pecuária-floresta. O experimento foi conduzido no Mato Grosso do Sul, Brasil. Os tratamentos consistiram de sete sistemas: integração lavoura-pecuária-floresta, com 357 árvores ha -1 e altura de pastejo de 30 cm ); integração lavoura-pecuária-floresta, com 357 árvores ha -1 e altura do pastejo de 45 cm (CLF 357-45 ); integração lavoura-pecuária-floresta, com 227 árvores ha -1 e altura do pastejo de 30 cm ); integração lavoura-pecuária-floresta, com 227 árvores ha -1 e altura do pastejo de 45 cm ); integração lavourapecuária, com a altura do pastejo de 30 cm (CL 30 ); integração lavoura-pecuária, com a altura do pastejo de 45 cm (CL 45 ); e vegetação nativa (NV). As propriedades do solo foram avaliadas nas profundidades de 0-10 e 10-20 cm. Todos os tratamentos com pastagem aumentaram a densidade do solo (ρ b ) e resistência à penetração (RP) e diminuíram a porosidade total (ƒ t ) e macroporosidade (ƒ ma ), em comparação com a NV. Os valores de ρ b (1,18-1,47 Mg m -3 ), ƒ ma (0,14-0,17 m 3 m -3 ) e PR (0,62-0,81 MPa) na profundidade de 0-10 cm não foram restritivos ao crescimento de plantas. A mudança de uso do solo a partir NV para CL ou CLF diminuiu o carbono orgânico (SOC) e o estoque de carbono orgânico (SOC...

Section: Soil Organic Carbon Concentration and Poolcontrasting

confidence: 68%

Physical quality of an Oxisol under an integrated crop-livestock-forest system in the Brazilian Cerrado

Neto

Andrioli

Almeida

et al. 2014

Self Cite

“…This phenomenon was also discussed by Bayer et al (2011) in a study of soil in Rio Grande do Sul and by Zinn et al (2005) for Oxisol in the Cerrado biome region. These authors reported a correlation between C sequestration rates and the soil texture.…”

Section: Balancesupporting

confidence: 63%

“…Therefore, the C stock in the 0-20 cm layer was 21.1 % greater for LVTA than for LVTM. This difference between soils was primarily related to the texture (Zinn et al, 2005). In contrast, in the surface layer (0-5 cm), no significant difference was observed in the C stocks of the two soils.…”

Section: Stockmentioning

confidence: 73%

Carbon balance and crop residue management in dynamic equilibrium under a no-till system in Campos Gerais

Ferreira¹,

Sá

Harms³

et al. 2012

SUMMARYThe adoption of no-tillage systems (NT) and the maintenance of crop residues on the soil surface result in the long-term increase of carbon (C) in the system, promoting C sequestration and reducing C-CO 2 emissions to the atmosphere. The purpose of this study was to evaluate the C sequestration rate and the minimum amount of crop residues required to maintain the dynamic C equilibrium (dC/ dt = 0) of two soils (Typic Hapludox) with different textural classes. The experiment was arranged in a 2 x 2 x 2 randomized block factorial design. The following factors were analyzed: (a) two soil types: Typic Hapludox (Oxisol) with medium texture (LVTM) and Oxisol with clay texture (LVTA), (b) two sampling layers (0-5 and 5-20 cm), and (c) two sampling periods (P 1 -October 2007; P 2 -September 2008). Samples were collected from fields under a long-term (20 years) NT system with the following crop rotations: wheat/soybean/black oat + vetch/maize (LVTM) and wheat/maize/ black oat + vetch/soybean (LVTA). The annual C sequestration rates were 0.83 and 0.76 Mg ha -1 for LVTM and LVTA, respectively. The estimates of the minimum amount of crop residues required to maintain a dynamic equilibrium (dC/dt = 0) were 7.13 and 6.53 Mg ha -1 year -1 for LVTM and LVTA, respectively. The C conversion rate in both studied soils was lower than that reported in other studies in the region, resulting in a greater amount of crop residues left on the soil surface.Index terms: C sequestration rate, soil texture, subtropical soils.(1) Received for publication in July 25, 2011 and approved in July 10, 2012.(2) Posgraduate student (PhD)

“…Soil C stocks in conventional tillage systems were generally smaller than in no-till systems. The lower SOC stocks in CT derive from the higher rates of decomposition of SOM in these systems (Lovato et al, 2004;Zinn et al, 2005b).…”

Section: Validationmentioning

confidence: 99%

Changes in Soil Organic Carbon and Nitrogen Stocks in Long-Term Experiments in Southern Brazil Simulated with Century 4.5

Weber

Mielniczuk

Tornquist

2016

ABSTRACT:The Century model has successfully simulated soil organic matter dynamics in many agroecosystems. However, initial applications in southern Brazil produced mixed results. The objective of this study was to calibrate and validate Century 4.5 to simulate soil carbon (C) and nitrogen (N) dynamics under diverse soil management practices in subtropical Brazil. Soil C and N data from two long-term experiments established on a degraded Acrisol in the early 1980s were used. Treatments were conventional or no-tillage; grass or grass/legume cropping systems; and corn with or without mineral N fertilizer. The calibration process iteratively modified model parameters to match simulated values of C additions and Soil Organic Carbon (SOC) and Soil Organic Nitrogen (SON) stocks to field data measured throughout the 25 years of the experiments. Improved fit between measured and observed data was obtained after key parameter changes. Soil C and N stocks were simulated accurately after these modifications were implemented. Other experimental treatments were used to validate the model. Century successfully simulated increases in C and N stocks under no-tillage cropping systems including legumes. However, the model overestimated Soil Organic Matter (SOM) decomposition in treatments with low N availability, like oat/corn without N fertilizer. Overall, Century version 4.5 showed adequate performance in simulating C and N trajectories of contrasting cropping systems commonly found in southern Brazil. The few discrepancies between measured and modeled SOC stocks do not preclude using Century in regional-scale applications to assess impacts of agricultural practices on soil C and N in southern Brazil.