Potential Environmental and Health Impacts of High Land Application of Cheese Whey

Abstract

A laboratory scale experiment was carried out to study the transformation and transport of nitrogenous compounds in soils receiving high application rates of cheese whey (twice the nitrogen requirement for crops). The experimental apparatus consists of 36 soil columns constructed of 20 cm inside diameter PVC pipes. Three types of soil (sandy loam, loam and sandy clay loam) and three soil depths (60, 120, 180 cm) were studied. The average monthly rainfall for the summer period in Halifax was used. The nitrogen in the soil was subject to biological transformations and downward movement in the soil. There were indications of the mineralization and nitrification processes taking place in the soil. The soil type and depth appeared to affect these processes. The ammonia volatilization occurred during the first 75 days with most (90 %) of the NH₃ loss taking place during the first 30 days. The amount of nitrogen losses to the air is about 3.41 kg/ha (0.59% of the total nitrogen). The amount of organic nitrogen lost in the leachates was 3.0-4.14 kg/ha (0.52-0.71% of the total nitrogen) whereas the amount of inorganic nitrogen (ammonium nitrogen, nitrate nitrogen and nitrate nitrogen) lost in the leachates was 18.63-24.09 kg/ha (3.54-4.56% of the total nitrogen). The presence of nitrite nitrogen in the leachate at high concentrations is a potential health hazard. Although cheese whey has been reported to have the potential to improve soil conditions, excess application has the potential of degrading soils and causing health problems. Additional research is, therefore, needed to better characterize the physical and chemical characteristics of soils receiving continuous high applications of cheese whey and their impact on crop yield and the qualities of groundwater and air.