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Nitrate Movement and its Distribution in the Soil Profile of Differentially Fertilized Corn Watersheds
Author(s) -
Schuman G. E.,
McCalla T. M.,
Saxton K. E.,
Knox H. T.
Publication year - 1975
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/sssaj1975.03615995003900060042x
Subject(s) - watershed , baseflow , hydrology (agriculture) , leaching (pedology) , water table , soil horizon , environmental science , nitrate , fertilizer , zoology , soil water , groundwater , agronomy , geology , soil science , geography , biology , streamflow , ecology , drainage basin , cartography , geotechnical engineering , machine learning , computer science
Nitrate movement within the 6.1‐m soil profile of a watershed in southwestern Iowa, fertilized at 448 kg N/ha per yr, resulted in a 720‐kg/ha increase in NO 3 ‐N below the corn root zone during the 3‐year study. The NO 3 ‐N concentration of the baseflow from the watershed increased during this period, indicating that some of the leached NO 3 ‐N reached the ground water. The watershed fertilized at the recommended N rate (168 kg/ha per yr) did not increase the quantity of NO 3 ‐N below the corn root zone; however, some NO 3 ‐N leaching did occur. Between April 1971 and April 1974, the accumulation of NO 3 ‐N in the profile of the excessively fertilized watershed moved from the 1.0‐ to 3.1‐m depth. Three‐fourths of NO 3 ‐N movement occurred between June 1972 and April 1973 when 80 cm of precipitation caused 21 cm of percolation below the corn root zone (183 cm). The watershed fertilized with 168 kg N/ha per yr did not show any zones of significant NO 3 ‐N accumulation in the soil profile at any of the sampling dates. The depth to the water table on the lowest contour sampled on the excessively fertilized watershed was 4.6 and 4.9 m in April 1973 and April 1974, respectively. The average NO 3 ‐N concentration for these two sampling dates at the water table depth increased from 3.7 to 12.9 ppm. The average NO 3 ‐N concentration at the water table depth on the normally fertilized watershed was 2.0 and 4.5 ppm in April 1973 and April 1974, respectively, with a water table depth of 3.0 m.