Regulation Effect Of Straw Returning Mode Into Field On Soil Microorganism And Growth Properties In Maize

In this study, the different modes of cultivate and straw returning field were chosen, and two methods-traditional microbial pure culture technology and phospholipid fatty acid spectra analysis method were combined in order to understand the ecology status of soil with different straw application pattern when under condition of rotation and continuous cropping from microorganism angle; combined the two parts closely related to soil which are underground root system and above ground plant together, comprehensive analysis straw mulching and straw deeply burring’ effects on maize growth and development, morphological index, dry weight accumulation, ear leaf photosynthetic fluorescence characteristics, photosynthetic and carbon and nitrogen metabolism activity of key enzyme, grain-filling rate, main characters of roots, grain yield and efficiency of water application under different planting pattern, to provide science basis for rationally conducting straw turnover, and achieve win-win situation for soil and crop, to establish theoretical basis for the sustainable development of agriculture. The results showed that:1、With different straw applying pattern in the same soil, straw deeply burring has a higher decomposing rate than straw mulching; while comparing to the amplification of T2 to T1, CT2 to CT1 has a lower increase. the maize straw nutrient release rate was 28.6%~41.9%(N),52.0%~68.9%%(P),60.2%~81.3%(K). In the rotation soil, straw applying pattern had little effect on straw nutrient release rate. In the continuous cropping soil, the nitrogen and phosphorous release rate of straw deeply burring treatment was significant higher than straw mulching, no big influence on potassium release rate.2、With the rotation pattern, the main microorganism, microorganism physiological groups, enzymatic activity in soil are higher than that in long time continuous cropping pattern. With long time continuous cropping pattern, comparing to straw mulching, straw deeply burring showed a better chance at increasing the carbon content in microorganism, soil bacteria, actinomycetes and microorganism physiological groups(ammonifying bacteria, aerobic nitrogen fixer, nitrifying bacteria) and declining the soil fungi number,increasing soil urease and invertase activity. Under the condition of the rotation, straw turnover declined soil bacteria number, had little influence on soil actinomycete、ree-living nitrogen fixing bacteria and ammonifier number; straw deeply burring significantly increased the number of soil aerobic cellulose decomposing bacteria and nitrobacteria in the middle and later growth periods.3、With the rotation pattern, straw turnover could decline the aerial root number, and there is no significant difference between root dry weight of soil horizon from 0~20cm and different straw applying mode. While with the continuous cropping planting pattern, straw turnover could increase the aerial number and the root dry weight of soil horizon from 0~20cm, and comparing the two straw applying pattern, straw deeply burring has a more significant effect. With the deeper of soil horizon, the root dry weight gets lower. The root dry weight is much higher with the rice and wheat rotation pattern than long time continuous cropping planting pattern.4、The root activity is higher with rotation cropping planting pattern. Under the rotation pattern, straw turnover significantly decline the root activity in VT tassling stage and the nitrate reductase activity, there isn’t significant difference in other periods, these indexes including the root activity, the nitrate reductase activity, soluble sugar content, soluble protein content, SOD and POD activity, didn’t change much with the two straw applying pattern. With long continuous cropping pattern, straw deeply burring is a better way to increase the soluble protein and soluble sugar content, protective activity in middle and later growth periods.5、There isn’t significant correlation between straw turnover and the height of maize,ear height or ear height coefficient. Straw buried deeply could significantly increase the accumulation of dry matter in the middle and later growth periods( tasseling stage VT-milk ripe stage R3). In the continuous cropping mode, straw buried deeply could increase more transfer rate of corn stalk、sheath、tassel and its’ contribution to grain, and showed a better performance in average Pn,Tr and Gs,Fv/Fm,ΦPSII and qP than straw mulching deeply after maize tasseling 0-50 days.Under the rotation mode, straw turnover has little influence on the gas exchange parameters(Pn,Tr and Gs), chlorophyll fluorescence parameters(Fv/F and ΦPSII) and activity of photosynthetic key enzyme(PEP and RuBPcase) of ear leaf.6、The average grain filling rate is out of sync with maximum grain filling rate. With the planting pattern of the rotation, straw turnover doesn’t have so much influence on grain filling rate, however. With the planting pattern of maize long time continuous cropping, both straw mulching and deeply buried can increase grain Rmax,Rave,Tmax and T, especially the T2 treatment of buried deeply.7、The average yield、average efficiency of water application and average efficiency of rainfall showed a opposite effect. With the planting pattern of rice and wheat rotation, there isn’t significant correlation between straw turnover and these three index, is a reduction effect; under the condition of long time continuous cropping, there isn’t significant variation between straw mulching and CK, straw buried deeply could significantly increase the maize yield、efficiency of water application and efficiency of rainfall.