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United States Department of Agriculture

Agricultural Research Service

Research Project: SOIL CONSERVATION SYSTEMS FOR SUSTAINABILITY OF PACIFIC NORTHWEST AGRICULTURE

Location: Soil and Water Conservation Research

Title: Cqestr Simulation of Management Practice Effects on Long-Term Soil Organic Carbon

Authors
item Liang, Yi
item Gollany, Hero
item Rickman, Ronald - RETIRED ARS
item Albrecht, Stephan
item Follett, Ronald
item Wilhelm, Wallace
item Novak, Jeffrey
item Douglas Jr, Clyde - RETIRED ARS

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 2008
Publication Date: September 1, 2008
Citation: Liang, Y., Gollany, H.T., Rickman, R.R., Albrecht, S.L., Follett, R.F., Wilhelm, W.W., Novak, J.M., Douglas Jr, C.L. 2008. CQESTR simulation of management practice effects on long-term soil organic carbon. Soil Sci. Soc.Am. J. 72:1486-1492

Interpretive Summary: CQESTR, pronounced sequester, is a carbon balance model. The name CQESTR is a phonetic condensation of the words carbon sequestration, which means carbon storage. CQESTR is process-based model uses readily available field-scale data to assess long-term effects of cropping systems or crop residue removal on soil organic carbon storage or loss in agricultural soils. It computes the rate of biological decomposition of crop residue or organic amendments as they convert to soil organic matter (SOM). Input data for SOM calculation include crop rotation, aboveground and belowground biomass additions, tillage, weather, and the nitrogen content of crop residues and any organic amendments. Our objective was to model SOM changes in agricultural soils under a range of climate and management systems using CQESTR. Four long-term experiments (Champaign, IL, >100 yrs; Columbia, MO, >100 yrs; Lincoln, NE, 20 yrs; Sidney, NE, 20 yrs) in US under various crop rotations, tillage practices, organic amendments, and crop residue removal treatments were selected for their documented history of the long-term effects of management practice on SOM dynamics. Regression analysis of 113 pairs of simulated and measured SOM data under diverse climate, soil texture and drainage classes, and agronomic practices at the four agricultural sites, resulted in a very significant (P < 0.001) linear relationship (r2 = 94%). CQESTR successfully simulated a substantial decline in SOM with 50 years of crop residue removal under various rotations at Columbia and Champaign. The increase in SOM following addition of manure was simulated well. However, the model underestimated SOM for a fertilized treatment at Columbia. Simulation results show that management practices that increase biomass contributions to the soil (fertilization, manure application, etc.), limit inversion tillage, and return root and shoot biomass to the soil annually promote soil organic C storage. Given the high correlation of simulated and observed SOM changes, the CQESTR model can be used to examine the expected effect of planned changes in agricultural management on soil C contents at the field-scale level. As such, CQESTR has potential to estimate the amount of crop biomass that can be harvested for bioenergy production while maintaining SOM at desired levels to sustain soil production capacity and limit erosion. It can also be an important tool to estimate impacts of crop residue removal for bioenergy production on SOM level and soil production capacity. [GRACEnet and REAP publication].

Technical Abstract: Management of soil organic matter (SOM) is important for soil productivity and responsible utilization of crop residues for additional uses. CQESTR, pronounced sequester, a contraction of ‘C sequestration’ (meaning carbon storage), is a carbon balance model that relates organic residue additions and crop management and soil tillage to SOM accretion or loss. Our objective was to simulate SOM changes in agricultural soils under a range of climate and management systems using the CQESTR model. Four long-term experiments (Champaign, IL, >100 yrs; Columbia, MO, >100 yrs; Lincoln, NE, 20 yrs; Sidney, NE, 20 yrs) in US under various crop rotations, tillage practices, organic amendments, and crop residue removal treatments were selected for their documented history of the long-term effects of management practice on SOM dynamics. CQESTR successfully simulated a substantial decline in SOM with 50 years of crop residue removal under various rotations at Columbia and Champaign. The increase in SOM following addition of manure was simulated well. However, the model underestimated SOM for a fertilized treatment at Columbia. Predicted and observed values from the four sites were significantly related (r^2 = 94%, n = 113, P < 0.001) with slope not significantly different from 1. Given the high correlation of simulated and observed SOM changes, CQESTR can be used as a reliable tool to predict SOM changes from management practices and offers the potential for estimating soil C storage required for C credits. It can also be an important tool to estimate impacts of crop residue removal for bioenergy production on SOM level and soil production capacity. [GRACEnet and REAP publication].

Last Modified: 7/22/2014