Location: Agroecosystem Management ResearchTitle: Comparison of measured and modeled effects of residue removal on soil organic carbon Author
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/22/2014
Publication Date: N/A
Citation: N/A Interpretive Summary: Crop residues are being used as livestock feed and may be used for biofuel production in the future. Removal of residue from fields has the potential to negatively affect soil quality. These negative effects may be difficult to measure as they often occur slowly over long time periods. Models may help with assessing management effects on soils but they must be validated using available long-term data. CQESTR is a model that uses management practices and site weather to estimate changes in soil carbon. We compared CQESTR estimated changes in soil carbon to measured changes in soil carbon in two studies in eastern NE. These studies included rainfed vs. irrigated continuous corn under various tillage, N fertilizer rates, and residue removal rates. Changes in soil carbon estimated with the model agreed very well with changes measured in these studies after ten years.
Technical Abstract: Soil organic carbon (SOC) is an important soil property strongly influenced by management. Changes in SOC are difficult to measure through direct sampling requiring long time periods and intensive sampling to detect small changes in the large, highly variable pool. Models have the potential to predict management induced changes in SOC but require long-term data sets for validation. CQESTR is a processed-based model that uses site weather, management, and crop data to estimate changes in SOC. Crop residue removal for livestock feed or future biofuel feed stock use is a current management practice potentially affecting SOC. CQESTR estimated changes in SOC were compared to measured changes for two residue removal studies in eastern NE. The rainfed site compared SOC changes in no-tillage continuous corn grown under two N-rates (135 and 202 kg ha-1) and two residue removal rates (none and 50%). The irrigated site compared SOC changes in continuous corn grown under no-tillage or disk tillage and three residue removal rates (none, 50 and 80%). After 10 years under these management scenarios CQESTR estimated SOC agreed well with measured SOC (r2 = 0.93 at the rainfed site and r2 = 0.82 at the irrigated site). These results are consistent with other CQESTR validation studies.