Predicting soil organic carbon dynamics of integrated crop-livestock system in Brazil using the CQESTR model

Authors: OLIVEIRA, JANAINA - Embrapa; Gollany, Hero; Polumsky, Robert - Wayne; MADARI, BEATA - Embrapa; LEITE, LUIZ - Embrapa; MACHADO, PEDRO - Embrapa; CARVALHO, MARCIA - Embrapa

Submitted to: Frontiers in Environmental Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2022
Publication Date: 3/21/2022
Citation: Oliveira, J.M., Gollany, H.T., Polumsky, R.W., Madari, B.E., Leite, L.F., Machado, P.L., Carvalho, M.T. 2022. Predicting soil organic carbon dynamics of integrated crop-livestock system in Brazil using the CQESTR model. Frontiers in Environmental Science. 10. Article 826786. https://doi.org/10.3389/fenvs.2022.826786.
DOI: https://doi.org/10.3389/fenvs.2022.826786

Interpretive Summary: Land degradation and reduction in productivity have resulted in losses of soil organic carbon in agricultural areas in Brazil. Our objectives were to i) evaluate the predictive performance of CQESTR model for a tropical savannah; and ii) examine the effect of integrated management systems, including Integrated Crop-Livestock System scenarios on soil organic carbon stocks. Two long-term paddocks, under similar soils and climate conditions were used in this study. In Paddock 4, the rotation was corn and 3.5/4.5 yrs pasture, while rotations in Paddock 5 included 2.5 yrs of soybean, dryland rice, and corn followed by 2.5/3.5 yrs pasture. Measured and CQESTR simulated values were significantly correlated (r = 0.94), indicating that the model captured spatial-temporal dynamics of soil organic carbon. Predicted soil organic carbon increased by 28% and 19% under current management for Paddock 4 and Paddock 5, respectively, by 2039. Both paddocks were under similar conditions; however, Paddock 4 had more time in the pasture phase with less disturbance than Paddock 5 (4.5 vs. 3.5 years pasture). Integrated Crop-Livestock System increased soil carbon sequestration compared to simple grain cropping systems under both no-till and conventional tillage due to high biomass input into the production system.

Technical Abstract: Land degradation and reduction in productivity have resulted in losses of soil organic carbon (SOC) in agricultural areas in Brazil. Our objectives were to i) evaluate the predictive performance of CQESTR model for a tropical savannah; and ii) examine the effect of integrated management systems, including Integrated Crop-Livestock System (ICLS) scenarios on SOC stocks. Two long-term paddocks, under similar edaphic and climate conditions were used in this study. In Paddock 4 (P4) the rotation was corn (Zea mays L.) and 3.5/4.5 yrs pasture (Urochloa ruziziensis), while rotations in Paddock 5 (P5) included 2.5 yrs of soybean (Glycine max L.), dryland rice (Oryza sativa L.), and corn followed by 2.5/3.5 yrs pasture (U. brizantha). Measured and CQESTR simulated values were significantly (0.0001) correlated (r = 0.94) with a mean square deviation (MSD) of 7.55, indicating that the model captured spatial-temporal dynamics of SOC. Predicted SOC increased by 18.0 and 12.04 Mg ha-1 at the rate of 0.90 and 0.60 Mg ha-1 yr-1 under current ICLS management for P4 and P5, respectively, by 2039. ICLS increased soil C sequestration compared to simple grain cropping systems under both no-till (NT) and conventional tillage (CT) due to high biomass input into the production system.