Study of the changes of the rice yield and soil fertility on the paddy field under long-term no-tillage and ridge culture conditions

The changes of rice growth, its yield and the soil fertility with different tillage systems of 11 years were studied. The result showed that the amount of root, rate of white root and root activity in no-tillage and ridge culture treatment were higher than that in conventional tillage and rotation of paddy and upland treatments, and had an early tiller time. The plant height, stem diameter, spike length and grains per spike of no-tillage and ridge culture treatment were also higher than in conventional tillage and rotation of paddy and upland treatments, and the average yield of 11 years increased by 10.3% than conventional treatment, and by 11.3% than rotation of paddy and upland treatment. Furthermore, the long-term of no-tillage and ridge culture treatment improved the physic-chemical properties, the soil bulk density and the contents of soil nutrients increased. The same situation could be seen at the quantity of the soil microbe and the activity of soil enzymes when comparing the no-tillage and ridge culture treatment with the other mentioned ones. Moreover, in the up-layer soil of the no-tillage and ridge culture treatment, the loosely combined humus was higher by 0.194 percentage point than that of the conventional treatment, and by 0.238 percentage point than that of the rotation of paddy and upland treatment. On the other hand, the quantity of tightly combined humus in the former treatment was lower by 0.098 percentage point and 0.037 percentage point than that of the conventional treatment and the rotation of paddy and upland treatment, respectively.