Restoration of Abandoned, Degraded Agricultural Soil Using Composted Biosolid: Influence on Selected Soil Properties

One practice for reclaiming degraded agricultural soils under semiarid climate is to use organic amendment to improve the physical, chemical, and biological properties of the soil, therefore enhancing its fertility. A short-term field experiment was carried out to study the effects of different biosolid rates on selected soil properties and assess these as potential indicators of soil restoration. The organic waste was surface-applied once at three rates (30, 60, and 90 Mg ha(-1)) to an abandoned agricultural soil. Three years after the biosolid was applied several chemical and biological soil properties such as organic C (SOC), humified C fractions (THS-C), water soluble C (DOC), total nitrogen (N-k), basal respiration (CO2-E), and potential nitrogen mineralization (PMN) increased significantly in 60 Mg ha(-1) and in 90 Mg ha(-1) biosolid rates. The physical soil properties studied did not change with the biosolid treatments at least in this short-term experiment. The available heavy metals showed a slight increase in the biosolid treatments but the values obtained were below those considered phytotoxic. In spite of that the canopy cover was higher in the biosolid treatment plots than in the unamended soil which will contribute to soil restoration; the analysis of the biological properties did not show such a clear trend that they could be used as soil quality indicator under the condition of this study.