Potential Air and Groundwater Pollution from Continuous High Land Application of Cheese Whey

Abstract

Experiments were performed, using eighteen 280 cm deep soil columns with 20 cm inside diameter, to determine the relative amounts of nitrogenous compounds leached and volatilized from soils receiving high application rates of cheese whey during two seasons. Three soils (loamy sand, sandy loam and sandy clay loam) and two cheese whey application rates (560 and 840 kg-N ha^-1), that provided twice and three times the nitrogen requirement for corn crop, were investigated. The leaching and volatilization processes were monitored over a period of five months each season. The concentrations of nitrogenous compounds in the leachates obtained from three soils decreased with time and the soil type and whey application rate did not have any significant effect on the soil removal efficiency of these compounds. However, higher concentrations were observed in the second season of application. The decline in the ammonium nitrogen concentrations in the absence of plants and the initial increase in the nitrite nitrogen and nitrate nitrogen concentrations indicated that the nitrification process had taken place. The organic nitrogen losses in the leachates were 3.02-4.14 kg h^-1 (0.54-0.74 % of the initial total nitrogen). The total inorganic (NH₄, NO₂, NO₃) nitrogen losses in the leachates were 59-76 mg which is higher than the initial concentration of 55 mg indicating that the mineralization process had taken place. Volatilization of NH₃ was independent of soil type and whey application rate. About 3.41 g^-1ha^-1 (0.59 % of the initial total nitrogen) of nitrogen was lost to the atmosphere through volatilization Nitrite and nitrate are highly soluble and easily leach out of soil solution. Therefore, continuous application of cheese whey at higher rates may result in ground water contamination and eventually becomes a threat to human and animal health.