Premium
EPIC Tile Flow and Nitrate Loss Predictions for Three Minnesota Cropping Systems
Author(s) -
Chung S.W.,
Gassman P.W.,
Huggins D.R.,
Randall G.W.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.303822x
Subject(s) - tile drainage , tile , environmental science , hydrology (agriculture) , surface runoff , zoology , agronomy , soil water , soil science , geology , geography , ecology , biology , geotechnical engineering , archaeology
Subsurface tile drains are a key source of nitrate N (NO 3 –N) losses to streams in parts of the north central USA. In this study, the Erosion Productivity Impact Calculator (EPIC) model was evaluated by comparing measured vs. predicted tile flow, tile NO 3 –N loss, soil profile residual NO 3 –N, crop N uptake, and yield, using 4 yr of data collected at a site near Lamberton, MN, for three crop rotations: continuous corn ( Zea mays L.) or CC, corn–soybean [ Glycine max (L.) Merr.] or CS, and continuous alfalfa ( Medicago sativa L.) or CA. Initially, EPIC was run using standard Soil Conservation Service (SCS) runoff curve numbers (CN2) for CC and CS; monthly variations were accurately tracked for tile flow ( r 2 = 0.86 and 0.90) and NO 3 –N loss ( r 2 = 0.69 and 0.52). However, average annual CC and CS tile flows were underpredicted by −32 and −34%, and corresponding annual NO 3 –N losses were underpredicted by −11 and −52%. Predicted average annual tile flows and NO 3 –N losses generally improved following calibration of the CN2; tile flow underpredictions were −9 and −12%, whereas NO 3 –N losses were 0.6 and −54%. Adjusting a N parameter further improved predicted CS NO 3 –N losses. Predicted monthly tile flows and NO 3 –N losses for the CA simulation compared poorly with observed values ( r 2 values of 0.27 and 0.19); the annual drainage volumes and N losses were of similar magnitude to those measured. Overall, EPIC replicated the relative impacts of the three cropping systems on N fate.