Long-term effects of cropping system and mineral fertilization on production and soil fertility in the Moldavian Plain

Abstract

The investigations conducted during 2005-2010 at the Podu- Iloaiei Agricultural Research Station, Ia i county, have studied the influence of different mineral fertilizers rates on wheat and sunflower yield and soil agrochemical characteristics. In bean-wheat-maizesunflower- wheat crop rotation, applying mineral fertilizers resulted in getting mean yield increases, which varied according to rates, between 94 and 180% (1631- 3129 kg/ha) in wheat and between 38 and 101% (773-2063 kg/ha) in sunflower. The mean yield increases, obtained for each kg of a.i. of applied fertilizer, were comprised between 11.2 and 13.6 kg grains (N80P40 - N160P80) in wheat and between 9.2 and 9.7 kg grains (N40P40 - N120P80) in sunflower. In the soils from the Moldavian Plateau, which are poor in organic matter and nutrients, the proper use of different rotations and fertilizer doses may replace a part of high technological consumption, determined the improvement in the content of organic matter from soil and ensured better conditions for the capitalization of nitrogen fertilizers. On the Cambic Chernozem from the Moldavian Plateau, a good supply with mobile phosphorus in wheat and sunflower crops (37-72 mg/kg) was done in case of the annual application of a rate of N120P80, while a very good supply (72-91 mg/kg) was achieved at the rate of N140P100. After 44 years of experiences, in five year crop rotation, fertilization of sunflower, wheat and maize crops with high rates of mineral fertilizers (N160P80), resulted increased soil organic carbon content by 22, 7% (3.5 g C / kg soil), compared to the unfertilized control.