Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2015
Publication Date: 1/1/2016
Publication URL: http://handle.nal.usda.gov/10113/61878
Citation: King, K.W., Williams, M.R., Fausey, N.R. 2016. Effect of crop type and season on nutrient leaching to tile drainage under a corn-soybean rotation. Journal of Soil and Water Conservation. 71:56-58.
Interpretive Summary: Agricultural tile drainage has been identified as a primary pathway for offsite nutrient transport. However, an understanding of how nutrient transport differs under different crops and seasons is not clear. Long-term measurements of hydrology and water quality from tile drainage in Central Ohio indicate that there is no difference in nutrient transport under corn and soybean production. However, seasonal differences do occur and indicate that greater concentrations occur during the growing season while greater loads occur during the non-growing season. These findings have major implications for identifying and implementing best management practices in the Midwestern tile drained landscape. Cover crops and drainage water management were recommended to address the non-growing season losses.
Technical Abstract: Subsurface tile drainage is a significant pathway for nitrogen (N) and phosphorus (P) transport from agricultural fields. The objective of this study was to evaluate N and P leaching to tile drains under a corn- (Zea mays L.) soybean (Glycine max L.) rotation typical of agricultural management across the U.S. Midwest. Differences in nutrient concentrations and loadings between crop type and between growing (GS) and non-growing seasons (NGS) were assessed. From 2005-2012, hydrology and water quality were monitored at three end-of-tile locations that drained agricultural fields ranging from 7.7-25.6 ha in a headwater watershed in central Ohio, USA. Nitrate-N (NO3-N) and dissolved reactive P (DRP) were the primary (>75%) forms of N and P in drainage water. DRP concentration and loading was not significantly different between crop types, but differed significantly by season. DRP concentration was greater during the GS, while DRP load was greater in the NGS. In comparison, NO3-N concentration and load was dependent on the interaction between crop type and season, with the highest NO3-N concentrations observed during the GS under corn. Differences in N and P leaching to tile drains were attributed to the timing of nutrient application and differences in hydrology (e.g., discharge rate, flow pathways). Study results suggest that management practices, such as cover crops and drainage water management that target nutrient transport in the NGS, have the potential to decrease annual N and P loads. Adherence to recommended 4R stewardship practices may also help minimize nutrient leaching to tile drains under a corn-soybean rotation.