Influence of crop rotation and long-term fertilization on wheat and maize yield and soil fertility in the Moldavian Plain

Abstract

Investigations, set up in 1968, were carried out on a Cambic Chernozem with a slope of 14%. They have shown the influence of different crop rotations and fertilization on soil erosion and fertility. The mean yield increases in wheat, during 1980-2007, were between 23 and 26 % (646 – 736 kg ha−1), due to crop rotation and between 57 and 101 % (1099 – 1949 kg ha−1), due to applied fertilizer rates. On slope lands from the Moldavian Plain, a good supply in mobile phosphorus for field crops (37-72 mg kg−1) was kept in case of the annual application of a rate of N100P80, and a very good supply in mobile phosphorus (69-78 mg kg −1) and mobile potassium (over 200 mg kg−1) was found at a rate of N60P40+30 t ha−1 of organic manure, applied in 3 or 4 -year crop rotations with legumes and perennial grasses. The total carbon mass on Cambic Chernozem from the Moldavian Plain has registered significant increases at higher than N140P100 rates, at organo-mineral fertilization and in 4-year crop rotation + reserve field cultivated with perennial grasses and legumes. In maize continuous cropping and wheat-maize rotation, very significant values of the carbon content were found only in organo-mineral fertilization, in 4-year crop rotation + reserve field cultivated with perennial grasses and legumes, and at N140P100 fertilization. The mean annual losses of nitrogen, phosphorus and potassium, once with water runoff and eroded soil on 14% slope fields were of 19.9 kg ha−1 in maize continuous cropping, 11.9 kg ha−1 in wheat-maize rotation and 8.1 kg ha−1 in rotation peas-wheat-maize-sunflower + two reserve fields cultivated with perennial grasses and legumes.