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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #316573

Title: Success and challenges met during the calibration of APEX on large plots

item Baffaut, Claire
item Ghidey, Fessehaie
item SENAVIRATNE, ANOMAA - University Of Missouri
item Kitchen, Newell
item Sudduth, Kenneth - Ken
item Lerch, Robert

Submitted to: Annual International SWAT Conference
Publication Type: Abstract Only
Publication Acceptance Date: 4/24/2015
Publication Date: 6/24/2015
Citation: Baffaut, C., Ghidey, F., Senaviratne, A., Kitchen, N.R., Sudduth, K.A., Lerch, R.N. 2015. Success and challenges met during the calibration of APEX on large plots [abstract]. Annual International SWAT Conference. Session C3.

Interpretive Summary:

Technical Abstract: As the APEX model is increasingly considered for the evaluation of agricultural systems, satisfactory performance of APEX on fields is critical. APEX was applied to 16 replicated large plots established in 1991 in Northeast Missouri. Until 2009, each phase of each rotation was represented every year for three cropping systems: mulch-till corn-soybean, no-till corn-soybean, and no-till corn-soybean-wheat. Discharge and water quality were monitored from 1997 to 2002 during the growing season of the corn phase of each rotation. After parameterization of the model for each plot using measured weather, topographic, and soil data, and parameter values derived from another APEX application on similar soils, sensitivity analysis was conducted for all global (PARM file) and selected control parameters. The most sensitive parameters were then optimized using the PAROPT software based on data from one plot per cropping system, and validated based on data from the other plots within the same cropping system. Results showed good simulation of average crop yields. Model performance for runoff was excellent; it was satisfactory for herbicide and dissolved nutrients. However, exceptionally low corn yields caused by drought were overestimated. Similarly, exceptionally high corn yields were underestimated. Additional challenges were encountered when simulating a cover crop inter-seeded between corn rows, causing very low simulated corn yields. Overall, these results confirm the usefulness of APEX to evaluate current cropping systems but highlight the need to better understand drought-related and crop competition processes in order to evaluate the effects of climate change and advanced alternative cropping systems.