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Variations in Nitrate and Chloride Concentrations below Selected Agricultural Fields
Author(s) -
Lund L. J.
Publication year - 1982
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/sssaj1982.03615995004600050035x
Subject(s) - nitrate , chloride , nitrogen , cycling , environmental science , chemistry , environmental chemistry , zoology , agronomy , hydrology (agriculture) , geography , biology , geology , forestry , geotechnical engineering , organic chemistry
Nitrate‐nitrogen (NO ‐ 3 ‐N) and chloride (Cl ‐ ) concentrations below four agricultural fields were determined to evaluate the validity of assuming that the nitrogen (N) cycling systems were at steady state for purposes of calculating N balances. Eight or nine sites in the fields in the Santa Maria Valley of California were sampled two or four times to determine the spatial and temporal variations in NO ‐ 3 ‐N and Cl ‐ concentrations in the unsaturated zone. Significant spatial variations were found within all fields with mean field concentrations of NO ‐ 3 ‐N and Cl ‐ ranging from 40 to 136 mg/L and 4.5 to 7.1 meq/L, respectively. Temporal variations were less dramatic. Nitrate‐nitrogen and Cl ‐ concentrations did not change with time over the period of study below a field that had been cropped to artichokes ( Cynara scolymus ) for the previous 12 years. Differences did occur with time for the other fields. For two of the fields the changes in mean concentrations could be related to past management with decreasing NO ‐ 3 ‐N concentrations reflecting periods of less N fertilization.