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ARS Home » Pacific West Area » Pendleton, Oregon » Soil and Water Conservation Research » Research » Publications at this Location » Publication #319232

Research Project: Improved Soil Managment Practices for Tilled Summer Fallow in the Pacific Northwest

Location: Soil and Water Conservation Research

Title: Predicting carbon dynamics in integrated production systems in Brazil using the CQESTR model

Author
item Oliveira, Janaina - Embprapa
item Gollany, Hero
item Polumsky, Robert - Wayne
item Leite, Luiz - Embprapa
item Madari, Beata - Embprapa

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/20/2015
Publication Date: 7/17/2015
Citation: Oliveira, J.M., Gollany, H.T., Polumsky, R.W., Leite, L.F., Madari, B.E. 2015. Predicting carbon dynamics in integrated production systems in Brazil using the CQESTR model. Meeting Abstract. World Congress on Integrated Crop-Livestock-Forest Systems, Brasilia, Brazil, July 12-17, 2015.

Interpretive Summary: Process-based carbon models are research tools to predict management impact on soil organic carbon (SOC) and options to increase SOC stocks and reduce CO2. The CQESTR model was used to examine the effect of soil management practices, including integrated crop-livestock system (iCLS), and various scenarios on soil carbon dynamics over time and to validate its use for tropical ecosystems. The study was conducted at Embrapa Rice and Beans Research Center, in a tropical savannah ecosystem. The land was under native vegetation until 1950s and has been in iCLS since 2000. Crop rotations included corn (Zea mays L.) as summer crop and 3.5 or 4.5 years in pasture (Urochloa sp.) in Paddock 4, and 2.5 years crop phase [soybean (Glycine max L.), dryland rice (Oryza sativa L.) and corn] followed by 2.5 or 3.5 years in pasture (Urochloa sp.) in Paddock 5. The measured and simulated values for relatively small number of observed values were significantly (P = 0.001) correlated (r = 95.5%) with the MSD of 2.11 indicating that the model captured spatial-temporal dynamic of SOC in the topsoil (0-10 cm) for the iCLS very well despite limited SOC data. However, CQESTR did not predict SOC accumulation trend for the 10-30 cm layer. This underestimation could be due to lack of site specific grass or crop root biomass and root distribution under tropical conditions. Additional data is required to develop suitable coefficients and parameters to calibrate the model to improve the CQESTR prediction of SOC stabilization process in the subsoil layers of tropical soils.[GRACEnet Publication]

Technical Abstract: Process-based carbon models are research tools to predict management impact on soil organic carbon (SOC) and options to increase SOC stocks and reduce CO2. The CQESTR model was used to examine the effect of soil management practices, including integrated crop-livestock system (iCLS), and various scenarios on soil carbon dynamics over time and to validate its use for tropical ecosystems. The study was conducted at Embrapa Rice and Beans Research Center, in a tropical savannah ecosystem. The land was under native vegetation until 1950s and has been in iCLS since 2000. Crop rotations included corn (Zea mays L.) as summer crop and 3.5 or 4.5 years in pasture (Urochloa sp.) in Paddock 4, and 2.5 years crop phase [soybean (Glycine max L.), dryland rice (Oryza sativa L.) and corn] followed by 2.5 or 3.5 years in pasture (Urochloa sp.) in Paddock 5. The measured and simulated values for relatively small number of observed values were significantly (P = 0.001) correlated (r = 95.5%) with the MSD of 2.11 indicating that the model captured spatial-temporal dynamic of SOC in the topsoil (0-10 cm) for the iCLS very well despite limited SOC data. However, CQESTR did not predict SOC accumulation trend for the 10-30 cm layer. This underestimation could be due to lack of site specific grass or crop root biomass and root distribution under tropical conditions. Additional data is required to develop suitable coefficients and parameters to calibrate the model to improve the CQESTR prediction of SOC stabilization process in the subsoil layers of tropical soils.[GRACEnet Publication]