Premium
Groundwater Quality Beneath Irrigated Vegetable Fields in a North‐Central U.S. Sand Plain
Author(s) -
Stites Will,
Kraft G. J.
Publication year - 2000
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/jeq2000.00472425002900050018x
Subject(s) - groundwater , aquifer , environmental science , hydrology (agriculture) , agriculture , pesticide , groundwater pollution , water quality , pollution , nitrate , soil water , coastal plain , geology , agronomy , ecology , soil science , biology , geotechnical engineering , paleontology
Abstract The dramatic expansion of irrigated agriculture since about 1970 in the north‐central USA has been accompanied by NO 3 and pesticide pollution of groundwater. The expansion has been concentrated in areas with sandy soils and shallow water tables, such as the Wisconsin central sand plain. In some parts of this sand plain, most wells contain detectable pesticide residues and NO 3 ‐N concentrations that exceed the 10 mg L −1 U.S. drinking water maximum contaminant level (MCL). To evaluate the effects on groundwater quality of this agricultural system, we monitored solutes 23 times during a 2‐yr period in the upper 3 m of the aquifer beneath and immediately upgradient of four irrigated vegetable fields. Groundwater beneath fields had significantly greater concentrations of most solutes and lower pH than upgradient groundwater. Especially pronounced were Ca, Cl, K, Mg, and NO 3 differences, with concentrations 5 to 26 times greater under fields. Nitrate N concentrations averaged 21 mg L −1 under fields, compared with 1 mg L −1 upgradient. Pesticide residues were ubiquitous beneath fields, and generally persisted for many months after application. Pesticide concentrations often exceeded Wisconsin preventive‐action limits (PALs), but seldom exceeded federal MCLs. Even when agricultural management approximated best management practice (BMP) recommendations, the NO 3 concentration beneath these fields approached double the MCL, indicating a need for new approaches to control agricultural groundwater pollution.