TITLE:
Comparison of Wheat Yield Simulated Using Three N Cycling Options in the SWAT Model
AUTHORS:
Elizabeth Brooke Haney, Richard Lee Haney, Michael James White, Jeffrey George Arnold
KEYWORDS:
SWAT Model, Yield Prediction
JOURNAL NAME:
Open Journal of Soil Science,
Vol.8 No.8,
August
30,
2018
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.