Abstract
Playas on the Southern High Plains are sites of active ground-water recharge to the Ogalalla aquifer and are used in agricultural and municipal waste management systems. The effectiveness of a playa for containing effluent from a commercial dairy operation was studied. Four drill core holes, positioned in the annulus and alternating wet and dry zones of a playa, provide surface and subsurface samples where dairy surface discharge enters the playa. Chemical and physical analyses performed on the core samples include nitrate-N, ammonium-N, pH, conductivity, and soil texture. Chloride distributions on two of the core profiles were compared to nitrate. Results indicate elevated nutrient levels in the top two meters of the heavy clay floor of the alternating wet and dry playa region, but not below that depth. A comparison of nitrate-N and chloride distribution suggests that denitrification processes probably eliminate most nitrate-N in this portion of the playa. This suggests that nitrate-N, once it reaches the central region of the playa, is contained long enough to denitrify. However, movement of nitrate-N is found at the playa annulus. Another concern arises with the transport of chloride from the playa as indicated by its distribution below the playa center.
