A soil column study of the impact of municipal effluent irrigation on two Manitoba soils

Abstract

Changes in chemical and some physical properties of the Roblin and the Erickson soils were studied on soil columns in a greenhouse under simulated average year and dry year rainfall and simulated day length period for the growing season in Roblin, Manitoba. Historical weather data were used to simulate the rainfall in an average year and in a dry year. Theoretical day length hours for the growing period in Roblin were obtained from meteorological tables. Evapotranspiration demand of brome grass in the greenhouse was compared with that expected in field conditions. The physical changes in the soil columns were measured in terms of bulk density, water stability index of soil aggregates and the amount of root mass. The chemical changes were measured in terms of the major and minor nutrient concentration, pH and salinity in the individual horizons of the soil columns. The water stability index of the soil aggregates was reduced considerably. Bulk densities of individual horizons did not change significantly. Salinity and pH of the soil horizons increased. Concentration of major nutrients changed in most of the cases. The Sodium Adsorption Ratio (SAR) of the saturation extracts of each soil horizon increased substantially. Trace element concentration did not change substantially. Concentration of boron and manganese was higher in the leachates as compared to that in the effluent. Average crop yield was the order of 3.0 tonnes per hectare per cut. A linear relationship was observed between the amount of effluent applied within the evapotranspiration range of the crop and the yield of dry matter. The plant tissues were slightly deficient in nitrogen and phosphorus.