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Nitrogen Outputs from a Field‐Size Agricultural Watershed
Author(s) -
Lowrance Richard
Publication year - 1992
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/jeq1992.00472425002100040013x
Subject(s) - denitrification , loam , surface runoff , environmental science , mollisol , hydrology (agriculture) , agronomy , subsurface flow , tile drainage , nitrate , field experiment , nitrogen , leaching (pedology) , soil water , soil science , groundwater , chemistry , ecology , geology , biology , geotechnical engineering , organic chemistry
Nitrogen outputs from a 0.34‐ha field were measured for 1984 through 1987. The field consisted of Cowarts loamy sand (fine‐loamy, siliceous, thermic Typic Hapludult) managed in a summer row crop‐winter cover crop sequence. Outputs measured were subsurface flow, surface runoff, and denitrification. Monthly sampling of denitrification rates showed a high degree of temporal and spatial variability. Rates significantly increased with soil moisture and depth. Denitrification also increased after irrigation events. Nitrogen movement in subsurface flow was 97% NO 3 ‐N and was about 10 times that in surface runoff. Most subsurface flow and movement of N (77 kg NO 3 ‐N ha −1 ) occurred in December 1986 through February 1987 when 62 cm of precipitation fell in a 12‐wk period (December 1986–February 1987) following fertilizer application. This period accounted for one‐half the total subsurface nitrate movement for the 4‐yr study. Even though no crop was harvested in 1985, subsurface outputs of N were low in winter of 1985–1986. Soil NH 4 ‐N levels were significantly higher after the year without a harvest, indicating that more of the N in crop residue was found in the soil pool.