NUTRIENT AND PESTICIDE EFFECTS ON RUNOFF WATER QUALITY FROM AGRICULTURAL LANDS

Authors: Jones, Ordie

Submitted to: Conservation and Production Field Day Proceedings
Publication Type: Other
Publication Acceptance Date: 8/30/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: This handout is prepared for the Department of Energy (DOE) and the Pollution Prevention Technical team at Pantex Plant in Amarillo, Texas, they are sponsoring a Waste Reduction Information Exchange on August 30, 1995 at the Amarillo Civic Circle. Interpretive summary is not required.

Technical Abstract: Agrichemicals can potentially degrade and/or contaminate surface and groundwater supplies. In the Southern High Plains over 85% of the land area drains into approximately 20,000 playa basins, thus the potential of contaminating lakes and rivers downstream with agricultural runoff is greatly reduced. Extensive pollution of playa basins due to agrichemicals has not been reported. Trace amounts of triazine herbicides and aldicarb insecticide were detected in some of the water samples collected in 1992 from 99 playa basins. Three samples had triazine contents greater than 6 ppb and one sample had aldicarb content greater than 5 ppb (The Cross Section, May 1993). Nitrate and total phosphorus contents of the 99 samples averaged 2.9 and 0.4 ppm, respectively, indicating excellent water quality from a nutrient standpoint. Relatively high pesticide contents in 3% of the playas tested is of concern and emphasizes the need for applicators to comply with label directions for mixing and applying restricted-use pesticides. Nutrient and pesticide contents of runoff water were measured at Bushland, TX for 10 yrs from seven dryland-farmed watersheds using no- tillage and stubblemulch management. Nitrogen and P losses were extremely low for both tillage systems (<5 lb/ac N and <1 lb/ac P/yr). Atrazine degraded rapidly and did not accumulate in the soil or leach below the root zone. The maximum loss of atrazine measured in runoff during the 11-year period was 0.26% of the total application, which is very low. However, up to 1.5% of the propazine application was lost in runoff. Propazine accumulated in the soil profile, but was not detected below 2 ft. The ARS research at Bushland shows that dryland agriculture is not a significant contributor to water quality degradation in the Southern High Plains.