Evolution of soil fertility under the influence of organic fertilizers and erosion on slope lands in the Moldavian Plain

Abstract

The influence of long-term fertilization on wheat and maize yield and soil fertility has been investigated at the Agricultural Research and Development Station of Podu-Iloaiei since 1968. The experiments have studied the influence of mineral fertilization, manure and crop residues on production, in peas-wheat-maize crop rotation and on soil fertility, on 16% slope field. Investigations were carried out on a typical Cambic Chernozem, which prevails in the Moldavian Plain and have established the fertilizer rates ensuring efficient yield increases and increasing the content of organic carbon from soil. The soil on which the experiments were set up have a clay-loam texture (420 g clay, 315 g loam and 265 g sand), a neuter to weakly acid response and a mean nutrient supply. On weakly eroded soils, the annual application of crop residues, which resulted from peas, wheat and maize crops, together with the rate of N80P60, have resulted in maintaining the content of organic content from soil at values of 18.8 g/kg soil. On highly eroded soils, the increase in the organic carbon content of soil from 18.8 to 21.6 g/kg soil was recorded by the long-term application of the rate of N80P60+60 t/ha manure. On 16% slope lands, the use of a crop structure made of 25% maize, 25% perennial grasses and legumes, 25% peas and 25 % wheat has determined the diminution by 62% of soil losses by erosion and the reduction by 61% of water runoff and mineral elements, compared to maize continuous cropping.