Affiliation:
1. Department of Ecology, Evolution, and Organismal Biology Iowa State University Ames Iowa USA
2. Department of Agricultural and Biosystems Engineering Iowa State University Ames Iowa USA
3. Department of Agronomy Iowa State University Ames Iowa USA
4. Department of Crop Sciences University of Illinois Urbana‐Champaign Urbana Illinois USA
Abstract
AbstractMuch of the US Corn Belt has been drained with subsurface tile to improve crop production, yet poorly drained depressions often still flood intermittently, suppressing crop growth. Impacts of depressions on field‐scale nutrient leaching are unclear. Poor drainage might promote denitrification and physicochemical retention of phosphorus (P), but ample availability of water and nutrients might exacerbate nutrient leaching from cropped depressions. We monitored nitrate, ammonium, and reactive P leaching across multiple depression‐to‐upland transects in north‐central Iowa, using resin lysimeters buried and retrieved on an annual basis. Crops included conventional corn/soybean (Zea mays/Glycine max) rotations measured at fields with and without a winter rye (Secale cereale) cover crop, as well as juvenile miscanthus (Miscanthus × giganteus), a perennial grass. Leaching of nitrogen (N) and P was greater in depressions than in uplands for most transects and years. The median difference in nutrient leaching between paired depressions and uplands was 56 kg N ha−1 year−1 for nitrate (p = 0.0008), 0.6 kg N ha−1 year−1 for ammonium (p = 0.03), and 2.4 kg P ha−1 year−1 for reactive P (p = 0.006). Transects managed with a cover crop or miscanthus tended to have a smaller median difference in nitrate (but not ammonium or P) leaching between depressions and uplands. Cropped depressions may be disproportionate sources of N and P to downstream waters despite their generally poor drainage characteristics, and targeted management with cover crops or perennials might partially mitigate these impacts for N, but not necessarily for P.
Funder
National Institute of Food and Agriculture
Subject
Management, Monitoring, Policy and Law,Pollution,Waste Management and Disposal,Water Science and Technology,Environmental Engineering
Cited by
2 articles.
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