The evolution of chemical and biological characteristics in Cambic Chernozem, under the influence of crop rotation, fertilizers and soil erosion

Abstract

Investigations conducted at the Agricultural Research and Development Station of Podu-Iloaiei, Iaşi County, during 2004-2008, have followed the influence of different crop structures and different fertilization methods on crop yield, erosion and soil fertility. Within the experiment, the following rotation schemes have been followed: wheat and maize continuous cropping, 2-year rotation (wheat-maize), 3-year rotation (peas-wheat-maize) and 4-year rotation + reserve field cultivated with legumes and perennial grasses (alfalfa + Lolium or Sainfoin + Bromus). The use of 3 and 4 year- rotations with annual and perennial meliorate plants has resulted in yield increases of 25 – 30 % (632 – 768 kg/ha) in wheat and 24-28% (973-1161 kg/ha) in maize, as compared to continuous cropping. The fertilization of wheat and maize crops at the rate of N60P40+30 t/ha manure has determined the increase by 3.0 g/kg (17.9%) in the content of organic carbon from soil, as compared to the rate of N100P80. The use of peas-wheat-maize-sunflower rotation + reserve field grown with legumes and perennial grasses has contributed to the increase by 2.2 g/kg (13.4%) in the content of organic carbon. The use of 4-year rotation + reserve field cultivated with perennial grasses and legumes on slope lands, poor in organic matter has determined the increase by 47% in soil potential and by 34% in enzyme potential, as compared to wheat-maize rotation. On 11% slope lands, the use of soybean-wheat-maize rotation + two reserve fields cultivated with perennial grasses has determined the diminution of soil losses by erosion at 0.985 t/ha, and on 16% slope lands, peas-wheat-maize rotation + two reserve fields, cultivated with perennial grasses has determined the diminution in soil erosion at 1.371 t/ha. On 16% slope lands, the crop structure, which determined the diminution in mean soil losses by erosion until 1.371 t/ha/year included 20 % straw cereals, 20% annual legumes, 20% row crops and 40 % perennial grasses and legumes.