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Nitrate Losses in Subsurface Drainage from a Corn–Soybean Rotation as Affected by Fall and Spring Application of Nitrogen and Nitrapyrin
Author(s) -
Randall G. W.,
Vetsch J. A.
Publication year - 2005
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/jeq2005.0590
Subject(s) - loam , drainage , agronomy , plough , soil water , hydrology (agriculture) , spring (device) , environmental science , crop rotation , crop , geology , soil science , biology , ecology , mechanical engineering , geotechnical engineering , engineering
Substantial amounts of NO 3 from agricultural crop production systems on poorly drained soils can be transported to surface water via subsurface drainage. A field study was conducted from the fall of 1993 through 2000 on a tile‐drained Canisteo clay loam soil (fine‐loamy, mixed, superactive, calcareous, mesic Typic Endoaquoll) to determine the influence of fall vs. spring application of N and nitrapyrin [NP; 2‐chloro‐6‐(trichloromethyl) pyridine] on NO 3 losses from a corn ( Zea mays L.)–soybean [ Glycine max (L.) Merr.] rotation. Four anhydrous ammonia treatments (fall N, fall N + NP, spring preplant N, and spring N + NP) were replicated four times and applied at 135 kg N ha −1 for corn on individual drainage plots. Drainage occurred in all seven years. Seventy‐one percent of the annual drainage and 75% of the annual NO 3 loss occurred in April, May, and June. Fifty‐four percent of the NO 3 lost in the drainage occurred during the corn phase and 46% during the soybean phase. Annual flow‐weighted NO 3 –N concentrations for the fall, fall + NP, spring, and spring + NP treatments averaged 14.3, 11.5, 10.7, and 11.3 mg L −1 during the corn phase but annual NO 3 –N concentrations were still ≥10 mg L −1 in three of six years for the spring preplant treatment. Averaged across the six rotation cycles, flow‐normalized NO 3 –N losses ranked in the order: fall N > spring N + NP > fall N + NP > spring N. Under these conditions, NO 3 losses in subsurface drainage from a corn–soybean rotation can be reduced 14% by spring N and 10% by late fall N + NP compared with fall‐applied N. Nitrate losses were not appreciably reduced by adding NP to spring preplant N.