Nitrate leaching as influenced by cover cropping and nitrogen source.
1994
McCracken D.V. | Smith M.S. | Grove J.H. | MacKown C.T. | Blevins R.L.
To minimize groundwater contamination by NO3(-) and to maximize efficient crop N use, it is necessary to better characterize NO3(-) leaching in various cropping systems. Our objectives were to compare the contributions of hairy vetch (Vicia villosa Roth) and NH4+ N sources to NO3(-) leaching in corn (Zea mays L.) production, and to compare NO3(-) 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 NH4+ N source and a rye (Secale cereale L.) cover crop. Nitrogen, sometimes enriched with 15N, was applied to corn grown on a Maury silt loam (fine, mixed, mesic Typic Paleudalf) in lysimeters as vetch or NH4(+)-N at rates between 10.5 and 14.0 g N m-2 yr-1. Treatments (N source/cover crop) were: NH(+)-N/fallow, vetch-N/fallow, NH4(+)-N/ rye, and vetch-N/vetch; mean 3-yr cumulative NO3(-) leaching losses were 6.11, 4.85, 0.35, and 2.51 g N m-2, respectively. Total recovery of added 15N in leachate was <5% for all treatments, and the percentage of leached NO3(-) 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 NO3(-) and quantity of NO3(-) 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 NH4(+) N source/rye cover system leached consistently less NO3(-) than the vetch N source/vetch cover system, even though the fraction of water discharged was not consistently different.
اظهر المزيد [+] اقل [-]الكلمات المفتاحية الخاصة بالمكنز الزراعي (أجروفوك)
المعلومات البيبليوغرافية
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