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Nitrogen Management for Corn and Groundwater Quality in Upper Midwest Irrigated Sands
Author(s) -
Struffert Anne M.,
Rubin John C.,
Fernández Fabián G.,
Lamb John A.
Publication year - 2016
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/jeq2016.03.0105
Subject(s) - loam , leaching (pedology) , agronomy , soil water , zea mays , urea , environmental science , nitrogen , chemistry , soil science , biology , organic chemistry
Groundwater contamination from NO 3 –N leaching in corn ( Zea mays L.) production with coarse‐textured soils poses an environmental concern. Our objectives were to evaluate NO 3 –N leaching in continuous corn (CC), corn after soybean ( Glycine max L.) (CSb), and soybean after corn (SbC) in irrigated sandy soils in Minnesota related to (i) N rate using best management practices of split‐N application, (ii) a split‐N application and single preplant applications of enhanced‐efficiency fertilizers (EEF), and (iii) residual N treatment in SbC. Urea (0–315 kg N ha −1 in 45‐kg increments) was broadcast as a split application (half at preplant and half at the V4 development stage) and polymer‐coated urea (ESN), ESN/urea, and SuperU at preplant at a rate of 180 kg N ha −1 on an Arvilla sandy loam soil. In May and June, 75% of the total drainage and 73% of the total NO 3 –N leached occurred. At the economic optimum N rate (EONR), season‐long NO 3 –N leaching rates were 86 and 106 kg NO 3 –N ha −1 for CC and CSb, respectively. In CC, reducing the EONR by 20% reduced grain yield by 4% and NO 3 –N leached by 9%, and a 25% reduction in EONR resulted in an additional 2% reduction for both, whereas no significant reductions occurred for CSb. Similar NO 3 –N leaching occurred with EEFs and the split‐N application. After 4 yr of no N application, we measured 9 to 20 mg NO 3 –N L −1 and leaching of 21 to 51 kg NO 3 –N ha −1 , highlighting the difficulty of meeting drinking water quality standards in corn cropping systems. Core Ideas Enhanced‐efficiency N fertilizers did not reduce nitrate amounts leached. Suboptimum N fertilizer rates reduce corn yield without enhancing water quality. Early spring precipitation, when crops are small, drives nitrate amounts leached.