| Crop straw is a kind of precious natural resources, and also the largest amount of agricultural waste. Early studies suggest that the main application of straw to the field is to provide nutrients to the soil, improve soil fertility, thereby reducing the amount of fertilizer application. With the people of straw utilization in agriculture more in-depth understanding, on straw decomposition, changes the dynamics of nutrient release, and straw burning on atmospheric environment influence aspects do a lot of research,, study on the influence of soil microbial community structure attracts more and more attention of scholars.This paper selects the wheat, rice, corn, rapeseed and Vicia faba 5 kinds of common agricultural crops straw, using the litterbag method, research in dryland and paddy soils under the environment, 5 kinds of crop straw respective rot solution characteristics, effect on soil aggregate composition and organic carbon distribution characteristics and microbial community structure, the main analysis of the straw accumulative decay rate and decay rate, nutrient explain a cumulative release rate, soil aggregate composition, organic carbon distribution and its contribution rate, soil PLFA total and microbial flora distribution, microorganism relative demeanor and population characteristics of difference, obtains the following conclusion:1. 5 kinds of crop straw decomposition rate of the early stage fast, stable late in the trial period of wheat, rice, rape and broad bean straw decomposition rate difference is not big, but corn straw is significantly lower than the other four kinds of straw. The cumulative decomposition rate of straw accumulated in dryland farming was the rice > corn > wheat > rape > broad bean, and the paddy field was corn > rice > broad bean. Compared with the environment of dryland farming and paddy field, the decomposition rate of the 5 kinds of straw is all shown as dryland farming; Crop straw, the cumulative release rate of 4 kinds of nutrients can be seen, the change of carbon and nitrogen is close to the law of change of phosphorus and potassium. Comprehensive point of view, crop straw in Dryland environmental decay release of carbon, nitrogen, phosphorus and potassium nutrients rapid phase respectively 10~90d, 10~60d, 10~60d, Five at the end of the trial the final straw carbon cumulative release rate ranged from 65.57~87.46%, the maximum amount of nitrogen release of rape straw, the cumulative release rate ranged from 55.00~69.79%, the largest amount of phosphorus release of faba bean straw, the cumulative release rate was 80.08~96.66%, the largest volume of potassium release of rape straw, the final cumulative release rate ranged from 89.73~98.98%, corn straw maximum emission; rapid stage of paddy field decomposition release of carbon and nitrogen, phosphorus and potassium were 10~60d, 10~30d, 10~60d, 10~30d, five kinds of straw at the end of the trial the final cumulative carbon release rate ranged from 49.78~69.20%, the largest amount of nitrogen release of rice straw, the final cumulative release rate ranged from 90.74~97.13%. The largest amount of phosphorus release of faba bean straw, the cumulative release rate was 33.15~77.04%, the maximum amount of potassium release of corn straw, the final cumulative release rate change Amplitude 77.54~90.45%, the maximum release amount of wheat straw. Five kinds of crops straw nutrient release speed sequence are K> P >N > C, the end of the trial of C, N, P, K nutrient release in addition to the size of the faba bean straw is P > K > N> C, the rest of the four kinds of straw is P > k > C > N, thus it may be known, crop straw over buried field decomposing phosphorus release most, followed by potassium, carbon and nitrogen release relatively few.2. Dryland farming and paddy field, consisting of six soil in different size aggregates were < 0.05 mm in diameter percentage content of most, followed by 0.05~0.25 mm > 0.25 mm in the least and three particle diameter percentage in soil aggregates of six treatments were significantly different(P < 0.05). Dryland soil over buried straw can improve soil aggregates > 0.25 mm grade percentage, which rape straw improve, showed that straw over buried returning to aggregates in Dryland Soil Micro aggregates to large and medium-sized aggregate conversion. At the same time, 5 kinds of straw mulching could significantly improve the percentage content of 0.05~0.25 mm grain size aggregates in dryland farming soil, which showed that the straw mulching and straw mulching could also be beneficial to the transformation of micro aggregate. Returning straw to field can increase the content of 0.25 mm in soil aggregate of paddy soil, but the effect is not as good as dryland farming.3.Under the dryland farming, 5 kinds of straw can increase the content of organic carbon in soil aggregates and faba bean stra w effect is remarkable, broad bean and wheat straw also can significantly improve the micro aggregate and powder clay aggregate and soil organic carbon content, the effects of corn straw on soil aggregate organic carbon content. In addition to corn, the re maining 4 kinds of straw can improve the contribution rate of organic carbon in large aggregates, the most significant effect of rape straw. Rice, broad bean and rape straw can significantly improve the contribution rate of micro aggregates of organic carbon. In paddy field, straw mulching could increase soil aggregate organic carbon content and its contribution rate, wheat and broad bean straw could significantly increase the content of organic carbon in micro aggregates. In addition, straw mulching could increase the organic carbon content in the aggregate, but the distribution of organic carbon content in the 3 particle size of aggregate was not affected by the returning of straw to field.4. Experiments were detected in 33 PLFA markers, dryland soil PLFA total amplitude for 8.35~25.15 nmol- 1, order of magnitude for rape > bean > corn > rice > wheat, 5 kinds of straw over buried field can improve the PLFA content, including rape, broad bean processing are without straw 2.18, 2.08 times significantly. Padd y soil PLFA total amplitude was 4.04~2.219 nmol- 1, the size of the order for rice > corn > wheat > rape > beans, wheat, rice and corn straw turn buried after returning on the soil microflora PLFA amount and without straw had no significant difference, rape, broad bean straw but reduces the paddy soil, bacteria PLFA content. 5 kinds of straw the flora quantity of PLFA is higher than that without straw treatment, in addition to the treatment of fungal PLFA bean straw amount were significantly higher than those without straw, bean processing total bacteria and PLFA were significantly lower than other treatments, each treatment between actinomycetes and gram positive bacteria, gram negative bacteria(G+)(G-) no significant difference; microorganism group PLFA ratio analysis showed that straw burying of microbial soil stress than paddy soil, rape straw burying of small dryland soil microbial stress, wheat, corn straw and Green Bean Stalk in paddy soil stress is smaller; rice, wheat and corn, rapeseed was significantly increased paddy soil microbial species richness index and dominance index. Principal component analysis showed that the horsebean stalk on dryland soil microbial community structure influence, rapeseed green stalk and wheat straw on soil microbial community structure in the paddy field effect. The principal component analysis showed that the main components of the broad bean green straw influenced the soil microbial community structure in the dryland farming, and the soil microbial community structure of rape and wheat straw was the biggest influence on the soil microbial community structure in the field of PLFA. |
PDF Full Text Request