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Nitrogen Management and Nitrification Inhibitor Effects on Nitrogen‐15 Urea: II. Nitrogen Leaching and Balance
Author(s) -
Walters D. T.,
Malzer G. L.
Publication year - 1990
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/sssaj1990.03615995005400010019x
Subject(s) - leaching (pedology) , nitrification , lysimeter , chemistry , urea , nitrogen , soil water , fertilizer , loam , agronomy , zoology , environmental chemistry , environmental science , soil science , biology , organic chemistry
Nitrification inhibitors (NI) may reduce N leaching losses, and should have the greatest effect on sandy soils where leaching potential is high. This study used 27 lysimeters to evaluate the effect of a NI, nitrapyrin [2‐chloro‐6(trichloromethyl) pyridine], on soil water percolation (SWP) and N leaching losses from an irrigated sandy loam soil (Typic Hapludoll) planted with corn ( Zea mays L.), and monitor the fate of a single application of 15 N‐enriched urea over a multiyear period. Urea was applied at 90 and 180 kg N ha −1 yr −1 for a 3‐yr period, with and without NI, and with and without incorporation. Urea + NI reduced SWP between planting and silking in 2 out of 3 yr when growing degree days (GDD) were high. After silking, SWP was reduced when urea + NI was incorporated and leaching load was high. A twofold increase in N rate resulted in an average of 3.4 times more N leached over 3 yr. The NI influenced time of N loss but not total N loss. Leaching losses of fertilizer‐derived N (FDN) were delayed 25 to 50 d when urea + NI were incorporated. The leaching load required to reach the maximum rate of FDN loss was higher with urea + NI. Leaching losses of fertilizer N were three times greater when determined by the difference method than by isotope‐ratio analysis. Differing results with these two calculations are attributed to isotope dilution with indigenous soil N as a result of microbial activity. Nitrification inhibitors may reduce the potential for nonpoint‐source pollution by delaying NO 3 leaching, but will be most effective if coupled with proper N rates and conservative irrigation water management.