Studies On Fertilizer Application On Rice Sown In Wheat-growing Soil With Wheat Straw Remained In Soil

Partially periodic intercropping of wheat with rice is a novel intercropping system in which rice seeds are sown into wheat-growing soil 20 days before the wheat is harvested with 30 cm height of wheat straw remained in soil and the other straw is also returned into soil after the wheat grain is threshed in fields. This cultivating system requires many new technologies, such as no tillage, aerobic nursery of rice seedlings and returning of all wheat straw. Field experiments were carried out to study the rice growth and development in this cultivating system with different fertilizer application treatments. The purpose of this study is to obtain a best fertilization practice in this new cultivation system. The results obtain are as follows.1. Fertilization had a great effect on the rice grain yields and the increments of the yields by fertilization were 59.4%~87.0% in different fertilization treatments compared with no fertilization (CK).2. Under the condition of same phosphorus and potassium application, rice ears per ha were increased with the increase of nitrogen fertilizer application rates while the number of grains per ear was largest in the nitrogen fertilizer application rate of 225 kg ha"1. Percentage of full grains and 1000-grain weight were a little bit decreased with the increase of nitrogen fertilizer application rates. The yields of rice grains were increased with the nitrogen application rates but no increments were found if the nitrogen fertilizer application rate was still increased from 225 kg N ha"1.3. Under the condition of same nitrogen fertilizer application, the number of rice ears was increased with the application rates of phosphorus and potassium fertilizers while the were no effects of phosphorus and potassium fertilizer application on total grains, percentage of full grains and 1000-grain weight. Application of phosphorus and potassium fertilizer did not affect the number of tillering but increased significantly the percentage of effective tillering, thus increasing the yield of rice grains.4. High yields of rice grain and high economic benefits could be obtained via a practiceof application of proper amount of nitrogen fertilizer together with phosphorus and potassium fertilizer.