Residual Effects of Fertilization With Sewage Sludge Compost on Cropland

Composting municipal sludge is an ecological and economic efficient technology to exploit such residual organic products in order to increase agricultural yields and soil fertility. This study aimed to determine the improve of some chemical characteristics of soil after fertilization with composted sewage sludge associated or not with mineral fertilization after two years of application and the yields recorded after the first two years of treatment. The experimental field was organized using subdivided parcels method, studying two gradients: organic and mineral fertilization. Before application on land as organic fertilizer, chemical characteristics of compost were analyzed in laboratory. Also it was made a characterization of soil from experimental field before and after compost fertilization. In the first year of experimentation the highest soybean yield were recorded in variants with maximum dose of mineral fertilizer. The highest maize yield was obtained in the most intensive fertilization treatment of our experiment which consist of doses of compost equivalent to a nitrogen rate of 400 kg/ ha and mineral fertilization (N100P100). In the second year of experimentation we recorded significant increase yields at oat crops in variants with fertilization in maximum doses. Related to soybean crops, in this second year, the values of yields were increased only in organic or mineral fertilization, but not in association of them. Fertilizing with sewage sludge does not replace the chemical fertilization, but is used in association with it in order to satisfy the necessity of crops for the nutrients.