Changes in Soil Physical Properties Due to Organic Waste Applications: A Review

Abstract Land application of organic wastes such as animal manure, municipal wastes, and sewage sludge could alter the soil physical properties. Repeated substantial applications of waste increase the soil organic matter percentage. The available data on effects of waste applications on soil physical properties such as bulk density, water holding capacity at both field capacity and wilting point, and saturated hydraulic conductivity were summarized. Based on data from 12 different sources, 21 soil types, 7 waste types, and 8 crop types, a linear regression analysis of observed increases in soil organic C as a result of waste applications on percent reduction in bulk density indicated a highly significant relationship ( r 2 = 0.69**). The results of an exponential multiple regression analysis of percentage sand and increase in organic C percentage on the percent increase in water holding capacity indicated that approximately 80% of the observed variations in percent increases in water holding capacity, at both field capacity and wilting point, could be attributed to variations in soil texture and soil organic C increases. The data on hydraulic conductivity as well as on infiltration rates are very limited and are not sufficient for quantitative analyses. The limitations of the available data were discussed in terms of identifying future research needs.