Study Of Effects Of Straw Returning And Reducing Fertilizer Application On Crop Yield And Soil Nutrients

Double cropping rice is one of important cropping patterns in China. As doublecropping rice production exists problems of low straw utilization ratio and excessivefertilization, it has become the main headstream of the agricultural non-point sourcepollution. With the spreading of optimized fertilization technology, optimized fertilizationis replacing traditional fertilization and become the main fertilization method. To make thebest of straw resources and discuss the feasibility of reducing fertilizer application on thebasis of optimized fertilization, we carried out a study of effects of straw returning withreducing fertilizer application on yield and soil nutrient of double cropping rice.To direct physical production better, the study was chosen to carry out plotexperiments in field condition. Through the study of effects of straw returning withreducing fertilizer application on the basis of optimized fertilization on double croppingrice in Tongcheng city, these conclusions were obtained:1.Compared with optimized fertilization, the effects of strew returning with optimizedfertilization, strew returning with optimized fertilization and straw decomposing inoculant,strew returning with reducing fertilizer application on course of development and growth,stems and tillers’ dynamic, accumulation of dry matter, stem length and thousand seedweight of double cropping rice were not so apparent, but differed with disease index ofsheath blight, number of productive ears, number of grain per ear and maturing rate.Optimized fertilization with straw returning (OFS) and optimized fertilization with strawreturning and decomposing inoculant (OFSDI) reduced disease index of sheath blight andnumber of grain per ear significantly of early rice; optimized fertilization with reducingnitrogen and straw returning (RNS) and optimized fertilization with reducing phosphateand straw returning (RPS) reduced number of productive ears significantly of early rice;optimized fertilization with reducing potassium and straw returning (RKS) reducedmaturing rate obviously of late rice.2.Compared with optimized fertilization, the effects of strew returning with optimizedfertilization, strew returning with optimized fertilization and straw decomposing inoculant,straw returning with reducing fertilizer application on single season yield and total yieldwere different. RPS and optimized fertilization with reducing nitrogen、 phosphate andpotassium and straw returning (RNPKS) had no significant reduction effect on the yield ofeither early season rice or late rice, and the reducing rate was-0.27%~3.83%; OFS, OFSDI, RNS and RKS significantly reduced the yield4.79%~10.27%of early season rice, whileincreased inapparently-0.67%~5.33%of late rice; OFSDI, RNS, RPS, RKS and RNPKShad not apparently reduced1.50%~3.06%of the total yield of double cropping rice, whileOFS reduced4.79%significantly.3.Compared with optimized fertilization, the effects of strew returning with optimizedfertilization, strew returning with optimized fertilization and straw decomposing inoculant,straw returning with reducing fertilizer application on nutrient contents in the plant andkernel of the double cropping rice in the two seasons differed a lot.4.Generally speaking, the optimized fertilization’s output-input ratio was highest,which was respectively2.57in early rice,2.61in late rice and2.59in double seasons. Andcompared with optimized fertilization, OFS, OFSDI, RNS and RPS reduced output-inputratio0.02~0.91; RKS reduced early rice’s output-input ratio0.38, increased late rice’soutput-input ratio0.06, and reduced output-input ratio0.16of double seasons; RNPKSreduced early rice’s output-input ratio0.04, increased late rice’s output-input ratio0.00, andreduced output-input ratio0.02in double seasons.5.Compared with optimized fertilization, the effects of strew returning with optimizedfertilization, strew returning with optimized fertilization and straw decomposing inoculant,strew returning with reducing fertilizer application on soil nutrient differed with reducednutrient types. Besides of the markedly reducing effect on the content of available P in soilby straw returning with reducing fertilization application, OFS, OFSDI, RNS, RPS, RKSand RNPKS all maintained or markedly increased soil nutrient contents such as organicmatter, total nitrogen and available potassium.Compared with optimized fertilization, the effects of strew returning with optimizedfertilization, straw returning with optimized fertilization and straw decomposing inoculant,straw returning with reducing fertilizer application on soil enzymes activity were different.OFS, RNS, RPS, RKS and RNPKS reduced urease activity significantly in soil, RKSincreased the invertase activity significantly in soil, RNS reduced the cellulose activitysignificantly in soil, OFSDI had no obvious effect on the three kinds of enzymes activity.6. The results of this study indicated that it was practical to carry out straw returningwith reducing N for10%or P for10%or K14.29%separately or simultaneously on thebasis of optimized fertilization only under the consideration of rice’s yield and soilnutrients, and that would not cause apparent negative effects on the rice yield and soilnutrients. But to consider the economic benefit and output-input ratio, the optimizedfertilization is still the best choice.