Biosolids valorization in degraded soils

Abstract

Advances in the sanitation of the watershed have taken place in the Metropolitan Region (MR) since the beginning of operation of large treatment plants. These processes generate a byproduct denominated biosolid; that is a stabilized sludge, it contains nutrients and organic matter and is an important source of essential elements for soils improvement and vegetal species development. The search of alternatives for biosolid handling and management indicates that agricultural valorization represents one of the most preferred options worldwide. Supported by this fact, this work outlines the use of biosolids in degraded soils in a real operational scale in three agricultural properties in the Melipilla province, Santiago Metropolitan Region. Biosolids were transported and applied in the spring of 2006, before the start of the production cycle of the selected farms. Biosolids, soil and subsurface water were environmentally monitored until the subsequent harvest and analyses on the yield and operating procedures were carried out. The results obtained confirmed the feasibility of the use of biosolids in degraded soils. It was noticed a tendency in the rise of parameters in the soils such as organic matter, nitrogen, phosphorus and sulfur with regard to their original conditions. As regard subsurface waters, the amount of nutrients in the soil-water system did not present negative analytical impacts associated with the use of biosolids. For the yield of crops associated with biosolids, there was an increase from 30% to 70% in regard to the regular fertilization based on inorganic fertilizers.