The long-term effects of crop rotation and fertilization on yield and soil fertility in the Moldavian Plain

Abstract

The investigations conducted during 1995-2009 at the Podu- Iloaiei Agricultural Research Station have studied the influence of different organomineral fertilization rates on wheat yield and soil agrochemical characteristics. Within the experiment, the following rotation schemes have been followed: 2- year rotation (wheat-maize) and 5-year rotation (bean – wheat – sunflower – wheat - maize). The organic fertilizers, applied together with mineral ones (N50P50+60 t manure/ha), have improved soil chemical characteristics and determined mean yield increases in wheat of 122% (1918 kg/ha), as compared with the unfertilized control. In the intensive rotations with cereals, with high annual consumption of nutrients, maintaining a good soil supply with organic carbon and mineral elements was done only by the organo-mineral fertilization (N50P50 or N100P100 + 40 t manure/ha). In 5-year crop rotation, the content of organic carbon from soil has diminished by approximate 2.1 g/kg/year in unfertilized control and by 0.90 g/kg/year at the rate of N120P80.