Effect Of Returning Whole Straw Associated With Chemical Nitrogen And Organic Fertilizer On Rice Yield Formation

An 3-year in-situ experiment was conducted to study returning whole straw associated with chemical nitrogen and organic fertilizer for yield formatting of rice (cv. Changyou 1 and Wujing 15)at Jiangyan's Shengao Shuangxu farm, Jiangsu province during 2005-2007. As follows are the main results.1. The effect on yield and yield components by straw returning, organic fertilizer and nitrogen-fertilizer:(1) Straw returning makes rice yield increased notably. Straw returning under blank fertilizer increased rice yield at 9.37kg/mu, and increasing effect is 2.4%. Straw returning under nitrogen-fertilized increased rice yield at 30.57kg/mu, and increasing effect is 5.7%.The significantly differences show straw returning combining with chemical nitrogen fertilizer makes better increasing effect. From the yield components, straw returning under blank nitrogen decreased ears per area at 3.0%, increased the grains per ear at 3.8%, decreased the weight of 1000 grain at 0.4%, seed-setting rate decreased 0.9%; while straw returning under chemical nitrogen fertilizer, rice ear per area increased 2.7%, the grains per ear decreased 0.3%, the weight of 1000 grain increased 0.2%, seed-setting rate increased 0.2%. (2) The effect of using organic fertilizer in rice for yield is remarkable. Applying organic fertilizer under blank nitrogen, the rice yield increased 35.83kg/mu, 9.2%, Adding organic fertilizer and straw returning, the rice yield increased 69.18kg/mu,17.2%. applying organic fertilizer associated with straw and chemical nitrogen fertilizer, average yield increased is 37.21kg/mu,6.8%. From the yield formation, organic fertilizer has little effect on seed-setting rate and the weight of 1000 grain but remarkable effect on ear number, especially when no nitrogen-fertilizer is used, ear number increased notably, and grains per ear is also affected to some extent. The increase of the ear number and grain number resulted into notable increase in the mount of spikelets per mu.2. The straw returning under blank nitrogen decreased tiller and peak seedlings (main stems plus tillers). The peak seedling decreased of changyou 1,wujing15, was 13400/mu,11.26% and 18200/mu, 13.48% respectively, In applying rate 19kgN/mu, the adding of chemical nitrogen effectively decreased influence of the straw returning on tillering, and promoted tiller to some extent. The peak seedling increased under straw returning and chemical nitrogen fertilizer for changyou 1 and wujing 15 increased 3600/mu,1.62%,and 900/mu,0.24% respectively; the final ear forming increased 13200/mu, 8.88%, and 3700/mu, 2.36% respectively. To sum up, straw returning in blank nitrogen fertilizer can restrain tiller, while straw retureing is combined with chemicai nitrogen fertilizer, it can promote tiller. (2)The adding of organic fertilizer can promote tiller. In non- nitrogen, when organic fertilizer is used ,compared with no using of organic fertilizer, the final ear forming of changyou 1 and wujing 15 increased 20900/mu,21.78%, and 17200/mu,16.92% respectively. In the fertilized zone(16kgN/mu), when organic fertilizer is used, compared with no using of organic fertilizer, the final ear forming of changyou 1 and wujing 15 increased 22500/mu,15.54%, 18600/mu, 12.53% respectively.3. The effect on dry matter accumulation by straw returning, organic fertilizer, nitrogen-fertilizer:(1) In non-fertilizer, when straw is returning the total dry matter accumulation of changyou 1 and wujing 15 increased 62.21 kg/mu,9.43%, and 44.00 kg/mu,5.51%. In the fertilized, the values under straw rerurning are approximate to or a little bigger.(2)The adding of organic fertilizer can increase dry matter accumulation, especially in jointing stage, increased over 30%.4. The effect on Rapid Viscosity-analyzer (RVA) value by straw returning, organic fertilizer, nitrogen-fertilizer:(1) Peak value and viscosity under straw returning are higher.(2) Breakdown value under straw returning are bigger, and the adding of organic fertilizer can also increase breakdown value.(3)Generally, the changing trend of setback value is that the value under straw returning are smaller ,and organic fertilizer is more smaller .5. Nitrogen fertilizer using efficiency is 0.2-0.5 percentage points higher when straw is returned than when no straw is returned, and this efficiency is 1-5 percentage points higher when organic fertilizer is combined than when no organic fertilizer is combined. Moreover, the bigger the proportion of organic fertilizer is, the higher the fertilizer using efficiency is.