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Nitrate Leaching as Influenced by Cover Cropping and Nitrogen Source
Author(s) -
McCracken Daniel V.,
Smith M. Scott,
Grove John H.,
MacKown Charles T.,
Blevins Robert L.
Publication year - 1994
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1994.03615995005800050029x
Subject(s) - vicia villosa , cover crop , leaching (pedology) , lysimeter , agronomy , loam , secale , cropping system , environmental science , nitrogen , chemistry , crop , soil water , biology , soil science , organic chemistry
To minimize groundwater contamination by NO − 3 and to maximize efficient crop N use, it is necessary to better characterize NO − 3 leaching in various cropping systems. Our objectives were to compare the contributions of hairy vetch ( Vicia villosa Roth) and NH + 4 N sources to NO − 3 leaching in corn ( Zea mays L.) production, and to compare NO − 3 leaching losses in a corn production system utilizing hairy vetch as a N source and winter cover crop with leaching losses in one utilizing an NH + 4 N source and a rye ( Secale cereale L.) cover crop. Nitrogen, sometimes enriched with 15 N, was applied to corn grown on a Maury silt loam (fine, mixed, mesic Typic Paleudalf) in lysimeters as vetch‐ or NH + 4 ‐N at rates between 10.5 and 14.0 g N m −2 yr −1 . Treatments (N source/cover crop) were: NH + 4 ‐N/fallow, vetch‐N/fallow, NH + 4 ‐N/rye, and vetch‐N/vetch; mean 3‐yr cumulative NO − 3 leaching losses were 6.11, 4.85, 0.35, and 2.51 g N m −2 , respectively. Total recovery of added 15 N in leachate was <5% for all treatments, and the percentage of leached NO − 3 derived from labeled N sources was generally <15%. In the winter‐fallow lysimeters, effects of N source on the fraction of water input discharged, concentration of NO − 3 , and quantity of NO − 3 leached varied with year and time of year; differences in N‐source availability and mulch effects were sometimes indicated. Generally, cover crop effects were larger than N‐source effects. The NH + 4 N source/rye cover system leached consistently less NO − 3 than the vetch N source/vetch cover system, even though the fraction of water discharged was not consistently different.