Irrigated Agriculture and Water Quality in South

Abstract

Irrigated agriculture in the humid region has resulted in more intensive management including crop production and the associated increase in fertilizer and pesticide use. Multiple cropping in most of the southeast (Alabama, Florida, Georgia, and South Carolina) and Delta (Arkansas, Louisiana, and Mississippi) states increases the demand for water and agricultural chemicals. Pesticide usage in the 48 states and the District of Columbia totaled 299,829,159 kg of active ingredient (AI) by 1982. Agricultural chemicals may percolate to aquifers in some soils and geologic formations resulting in groundwater contamination. Groundwater fluctuations are related to irrigation. Groundwater quality data are used to show the trend in quality related to irrigated agriculture and cropping systems. Areas with specific groundwater problems such as salt‐water intrusion and pesticide levels are identified. A total of 17 pesticides have been reported in groundwater in the United States and four of these were found in the southeast and Delta states. Data show that less that 1% of wells sampled in the southeast and Delta states had nitrate concentrations exceeding 10 mg/L (drinking water standard). Degradation of surface water quality relative to irrigation is discussed.