Effects Of Straw Applying On Rice Yield, Quality And Environment

In order to effectively solve the straw open burning and disposal, and promote comprehensive utilization of straw, and environmental protection, an 3-year in-situ experiment in the field and soil micro pool culture experiment were conducted to study the wheat straw application on rice yield, population quality, grain quality, nitrogen utilization and ammonia volatilization, soil, soil nutrient status, environmental factors of ecological importance, on these basis the regulations on rice yield and quality, important ecological effects of environmental factors by the depth of straw, straw method, straw volume, applying with straw and nitrogen fertilizer, applying with straw and manure and inorganic nitrogen fertilizer were illustrated systematically.The main results were as follows:1. Making clear the effects of straw on rice yield, population quality and quality and its regulations.In the three ways of straw burying, cover and burn, the straw burying into field was better. In the three depth of 5 cm, 10 cm and 20 cm with straw burying, the rice yield of the depth of 5 cm with straw burying was the highest, the quality was better. With the range of straw application of 0-9000 kg/hm2, as the amount of straw increased, rice yield increased, the number of grains per panicle, seed setting rate and grain weight increased, while spike decreased, and the roughness, milled rice rate, milled rice rate and protein content increased, Chalky grain rate and chalkiness lowered, aspect ratio and gel consistency increased, amylose content decreased. When straw application of 6000 kg/hm2, the rice yield structure was relative coordinated, the yield was also high, the quality was better. At the condition of full straw application, the appropriate sowing rate of Yangfujing 8 was 67.5 kg/hm2, and nitrogen fertilizer application of 300 kg/hm2, the yield was highest, appearance quality of rice and cooking quality were better. In the different nitrogen application pattern, the pattern of basal: tillering: panicle for the 4:2:4 was better, the yield was highest, the roughness, milled rice rate and rate of milled rice was higher, chalky rice rate, chalkiness and amylose content were lower, gel consistency increased, quality improved noticeably.Applying with straw, manure and nitrogen fertilizer, tillers and maximum tiller number were appropriate, chlorophyll content was high, LAI was suitable, dry matter accumulation of heading - maturity was high, population quality, rice yield and quality were better. When the quantity of straw was 6000 kg/hm2, the quantity of manure was 4500 kg/hm~2, the quantity of nitrogen fertilizer was 240 kg/hm2, the effects were better.2. Revealing the cytology process of Rhizoctonia solani invading rice.Changes of microbe and organic matter content in paddy soil applied with straw, manure and nitrogen fertilizer were analyzed. Experimental plots in the rotations had 10 treatments, i. e. with or without straw, manure, nitrogen fertilizer and a control. The amount of straw was zero or 6000 kg/hm2, that of manure was zero, 1500 kg/hm2, 3000 kg/hm2, 4500 kg/hm2, or 6000 kg/hm2, that of nitrogen fertilizer was zero, 240 kg/hm2, 270 kg/hm2, 280 kg/hm2, 285 kg/hm2, 300 kg/hm2, or 330 kg/hm2. The results showed that with the range of nitrogen fertilizer application of 0-330 kg/hm2, increasing nitrogen fertilizer could promote the decomposition of straw at the situation of straw amending into soil. Each measure of straw, manure and nitrogen fertilizer could increase the bacteria, the fungus, ray fungi quantity in soil in some degree. The synthesis applying with straw, manure and nitrogen fertilizer could coordinate increase microbe quantity in soil, enhance the soil biomass nitrogen and organic matter content, and when the quantity of straw was 6000 kg/hm2, the quantity of manure was 4500 kg/hm2 , the quantity of nitrogen fertilizer was 240 kg/hm2, the effects were better. It indicated that a good amount of manure and nitrogen fertilizer could increase soil microbial numbers and organic matter content in straw amended agro-ecosystem, which was very important in improving soil fertilization.3,Clarifying the effects of the rice ecological environment by straw application in many respects.(1) In the aspect of nitrogen utilization and ammonia volatilization, straw application stimulated ammonia emission, and nitrogen fertilizer application significantly enhanced ammonia volatilization. At the conditions of applying with straw, manure and nitrogen fertilizer, nitrogen utilization efficiency of straw application was higher than that without straw application, nitrogen utilization efficiency of manure application was higher than that without manure application.(2) In the ecological environment, the pH value of surface water by straw buried and cover decreased, whereas the pH value of straw burning increased. Applying with straw, manure and nitrogen fertilizer had no apparent effects on pH value of surface water. In the initial after straw applying, the topsoil water oxidation reduction potential of clay and sand improved, after a long time as flooding, soil redox potential value lowered. Nitrogen fertilizer application could improve the oxidation reduction potential, straw and inorganic nitrogen fertilizer increased redox potential synergistically. The oxygen ratio of the field surface water by burying straw to field decreased, and that of the straw cover and burning was higher than and burying straw. Only organic manure, or inorganic nitrogen fertilizer application, or combined application could decreased the oxygen ratio. The early growth of rice, straw significantly increased the concentration of topsoil water DOC and IC. Application of inorganic fertilizers reduced the topsoil water DOC and IC concentration. In the condition of straw application, the application of nitrogen fertilizer could inhibit the dissolution of DOC and IC. (3) In the aspect of soil nutrition and fertility, compared with only straw application, straw application with nitrogen fertilizer and organic manure could increase soil organic matter content. Compared with straw cover and burning, the stability of the whole growth period of rice paddy soil N, P, K content by straw burned was favorable. With the advance of growth period of rice, straw application could alleviate nitrogen, phosphorus and potassium content decline in clay and sandy soil. Straw and inorganic nitrogen fertilizer combined application, or straw, manure and inorganic nitrogen fertilizer combined application could synergistically increase soil nitrogen, available phosphorus and potassium content, improve nutrient availability and soil fertility.