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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #354442
Title: Comparison of wheat yield simulated using three N cycling options in the SWAT model

Author
item HANEY, ELIZABETH - Texas Agrilife Research
item Haney, Richard
item White, Michael
item Arnold, Jeffrey

Submitted to: Open Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2018
Publication Date: 8/8/2018
Citation: Haney, E.B., Haney, R.L., White, M.J., Arnold, J.G. 2018. Comparison of wheat yield simulated using three N cycling options in the SWAT model. Open Journal of Soil Science. 8:197-211. https://doi.org/10.4236/ojss.2018.88016.
DOI: https://doi.org/10.4236/ojss.2018.88016

Interpretive Summary: This journal article compares different computer models for prediction of wheat yield using fertilizer inputs and comparing with actual wheat yield in the field. Models called SWAT-C and SWAT-flush provide the most accurate prediction of average wheat yield and can be used for wheat cropland yield assessment. SWAT-flush incorporates soil testing methods that mimic some of the natural processes that occur in the field. However, it is important to understand that none of the N-cycling routines included in the SWAT model predict annual variations in wheat yield with great certainty, due to the complicated reactions that plants and soil undergo over the course of the growing season. Further research is needed to determine the effectiveness of SWAT-C and SWAT-flush in determining average and annual yield under various farming regions with different management and with numerous agronomic crops.

Technical Abstract: The Soil and Water Assessment Tool (SWAT) model has been successfully used to predict alterations in streamflow, evapotranspiration and soil water; however, it is not clear how effective or accurate SWAT is at predicting crop growth. Previous research suggests that while the hydrologic balance in each watershed is accurately simulated with SWAT, the SWAT model over or under predicts crop yield relative to fertilizer inputs. The SWAT model now has three alternative N simulation options: (1) SWAT model with an added flush of N (SWAT-flush); (2) N routines derived from the CENTURY model (SWAT-C); and (3) a one-pool C and N model (SWAT-One). The objective of this study was to evaluate the performance of SWAT-flush, SWAT-C, and SWAT-One as they affect wheat yield prediction. Simulated yields were compared to wheat yields in a 28 year fertilizer/wheat yield study in Lahoma, OK. Simulated yields were correlated with actual 28-year mean yield; however, none of the available N cycling models predicted yearly yields. SWAT-C simulated average yields were closer than other N sub-models to average actual yield. Annually there was a stronger correlation between SWAT-flush and actual yields than the other submodels. However; none of the N-cycling routines were able to accurately predict annual variability in yield at any fertilizer rate. We found that SWAT-C or SWAT-flush are the most viable choices for accurately simulating long-term average wheat yields although annual variations in yield prediction should be taken into consideration. Further research is needed to determine the effectiveness of SWAT-C and SWAT-flush in determining average and annual yield in various farming regions and with numerous agronomic crops.