The effects of fertilizer treatments on agrochemical properties of dark chestnut soil and the productivity of an irrigated crop rotation.

摘要

In field trials carried out near Inguletsk, Ukraine in 1992-97, the effects of the following fertilizer treatments on soil fertility and crop yield were investigated for a rotation of barley + lucerne [Medicago sativa], lucerne, lucerne, winter wheat + oil radish, soyabeans and maize cultivated on dark chestnut medium loam soil: conventional (150 kg mineral fertilizers + 10 t manures/ha); alternative (100 kg mineral fertilizers + 10 t manures/ha + green manures + crop residues + nitrogen fixing bacteria); and organic (10 t manures/ha + green manures + crop residues + nitrogen fixing bacteria). The effects of different tillage methods (mouldboard ploughing and/or blade cultivation to varying depths) and different levels of irrigation were investigated. Increases in nitrate nitrogen and mobile phosphorus in soil were greatest in the conventional treatment, increasing by 4.5-5.6 and 1.3-1.5 times respectively. Crop yields were greatest with this treatment, with different methods of tillage not having a significant effect on crop yield. Humus content of soil was maintained at a level of 2.06-2.08%. The alternative treatment increased nitrate nitrogen and mobile phosphorus by 8.7-15.7 and 5.6-14.5% respectively, and increased humus content of soil by0.02-0.05%. Crop yields were 2-10% less than those obtained in the conventional treatment, with highest yields being obtained with mouldboard ploughing and combined tillage methods. For all treatments, highest crop yields were obtained with optimal levels of irrigation (8.3-8.4 t/ha). The organic treatment was least effective, with yields for individual crops being reduced by ?1% as compared with other treatments, and by 21-27% over the whole rotation as compared with the conventional treatment. For the alternative and organic treatments, blade cultivation reduced crop yields by 5-25% as compared with mouldboard ploughing.