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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Soil Management and Sugarbeet Research » Research » Publications at this Location » Publication #328384
Title: Simulating soil organic carbon in a wheat–fallow system using the Daycent model

Author
item BISTA, PRAKRITI - Oregon State University
item MACHADO, STEPHEN - Oregon State University
item Del Grosso, Stephen - Steve
item GHIMIRE, RAJAN - New Mexico State University
item Reyes-Fox, Melissa

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2016
Publication Date: 3/9/2017
Citation: Bista, P., Machado, S., Del Grosso, S.J., Ghimire, R., Reyes-Fox, M.A. 2016. Simulating soil organic carbon in a wheat–fallow system using the Daycent model. Agronomy Journal. 108(6):2554-2565. doi:10.2134/agronj2016.04.0202.

Interpretive Summary: Crop management practices that contribute to soil organic carbon (SOC) sequestration can improve productivity and long-term sustainability. We present a modeling study on influence of various long-term crop residue and nutrient management practices on SOC dynamics under conventional and no-till management systems near Pendleton, OR. Model performance was evaluated by comparing modeled and observed data from 1931 to 2010. The model was very accurate at representing crop yields and SOC levels. DAYCENT projected that conventionally tilled winter wheat-summer fallow systems, except when manure was added, lost 866 to 2192 g C m-2 SOC from 1931 to 2080. Manure addition led to gains of 496 g C m-2 SOC in the same period. The conversion to no-tillage from 2011 onwards, however, minimized SOC loss by 17 to 47% under different winter wheat-summer fallow systems. No-tillage conversion in manure amended plots resulted in SOC gain by more than 300%. This study suggested that adoption of a no-tillage system and the addition of organic amendments can improve the long-term sustainability of dryland winter wheat-summer fallow systems.

Technical Abstract: Crop management practices that contribute to soil organic carbon (SOC) sequestration can improve productivity and long-term sustainability. We present a modeling study on influence of (>80 years) various long-term crop residue and nutrient management practices on SOC dynamics under conventional and no-till management systems. The DAYCENT model was used to simulate the impact of six treatments: fall crop residue burning (FB0), no burning of crop residue with 0 (NB0), 45 (NB45) and 90 (NB90) kg N ha-1, pea vines (PV), and cattle manure (MN) addition, on grain yield and SOC under a conventionally tilled dryland winter wheat (Triticum aestivum L.)-summer fallow (WW-SF) systems, near Pendleton, OR. Model performance was evaluated by comparing modeled and observed data from 1931 to 2010. After minimal parameter adjustment. The model was very accurate with R2 values of 0.93, 0.95 and 0.99 for the mean of observed and modeled grain yield, residue yield, and SOC, respectively. The strong positive correlation (r = 0.71 to 0.91) in different treatments between observed and modeled SOC indicated that model closely simulated the observed values. The paired t-test results demonstrated no significant bias between observed and modeled SOC for five out of six treatments. DAYCENT projected that conventionally tilled WW-SF systems, except MN, lost 866 to 2192 g C m-2 SOC from 1931 to 2080. MN gained 496 g C m-2 SOC in the same period. The conversion to no-tillage from 2011 onwards, however, minimized SOC loss by 17 to 47% under different WW-SF systems. No-tillage conversion in MN resulted in SOC gain by more than 300%. This study suggested that adoption of a no-tillage system and the addition of organic amendments can improve the long-term sustainability of dryland WW-SF systems.