Effects Of Different Flex Cropping Modes On Soil Enzymes Activities And Soil Microbial Community Structure

Flax is a kind of traditional and significant oil-bearing crops. With oil flax has been appreciating in recent years,the crop acreage is proliferating in a single planting structure and widespreadly continuous cropping(TC) model,which results in a series of disadvantages for oil flax planting,such as the serious disturbance of the plant growth,the aggravation of plant diseases and insect pests damaging,the decline of the quality and the yield.In order to illuminate the the variation mechanisms of agriculture soil microenvironment under different cropping model, for which could provide theory basis and pratical experience for the flax planting and the preference of cropping model,this research setted a group of long-term experiments in a semiarid hilly area of Yuzhong, Gansu Province, studied the influence of cropping model on soil enzyme activity, soil nutrient, rhizosphere bacteria and the fungal genetic diversity.The experiments conducted under four models:oil flax—wheat rotation(TR), flax/ wheat intercropping(TI),continuous cropping of flax(TC),, uncultivated(TU).The main results of the experiments are as follow:1、 The type of corpping model had a remarkable effect on soil enzyme activity. Different corpping models in different growth period of 0 ~ 20 cm arable layer had a remarkable effect on soil catalase, urease, alkaline phosphatase and invertase activity. Soil catalase activity and sucrose enzyme activity in the whole growth period showed the same change trend, the activity of seedling stage were lower than the flowering period, the average is 2.07mg·(g·h)-1 and 23.58 mg·(g·d)-1 respectively. Both enzymes activity rised in the flowering period, while enzymes activity declined in harvest time. Soil urease activity first decreased and then increased, and it in flowering period was significantly lower than that in harvest time. However,the alkaline phosphatase activity was constantly decreasing. Uncultivated(TU) model had a relatively stable numerical value is in different periods, changed roughly linearly, and in seedling time it was slightly below than it in flowering period and after harvest.2、The activities of soil enzyme activity descended with the increasing of soil depth under each corpping model. The soil enzymes activity reducted significantly in the layer of 20-40 cm, and the differences under different models was negiligible.When the soil depth reaches 40-60 cm, various enzyme activity continued to fall, no significant differences between the treatments. This is mainly because of different plant roots introduced by the different corpping models and stratified distribution of soil organic matter.3、The relevancies of different soil enzyme activity and different soil physicochemical characters varied greatly. Soil enzyme activity and soil physical and chemical properties and some nutrient elements are closely related, the relationship among different enzyme activity and soil physical and chemical properties. Hydrogen peroxide enzyme activity and soil p H showed significant negative correlation, the effective zinc content, and available k content, unease activity and total phosphorus content show significant positive correlation, and the effective zinc content were significantly negative correlation; Alkaline phosphates activity and total phosphorus, available potassium content were showing significant positive correlation, and with effective zinc content showed significant negative correlation, the effective manganese content; Invertase activity was not seen with the soil physical and chemical properties have a significant correlation between indicators.4、The type of corpping model had signifcant influence on the structure of the soil microbial community. Through setting the field test and the combination of high throughput sequencing field test methods under different planting patterns for crop rhizosphere soil microbial community structure changes, the result shows that different planting patterns on crop rhizosphere soil microbial community structure is different.High-throughput sequencing results show that the dominant four types of bacteria in soil and four kinds of processing the mutual influence between different, The results showed that:The percentage of Proteobacteria is TR<TI<TU≈TC;The percentage of Acidobacteria is TC<TI≈TU<TR;The percentage of Actinobacteria is TR<TC<TU<TI;The percentage of Chloroflexi is TC<TR≈TI<TU.The dominant four kinds of fungi in soil and four kinds of processing the mutual influence between different, The results showed that:The percentage of Ascomycota is TC<TR<TU<TI;The percentage of Zygomycota is TI<TC<TR<TU;The percentage of Basidiomycota is TR≈TU<TI<TC.So thatthe results Show different planting patterns on crop rhizosphere soil microbial community structure influence each are not identical.5、The change of soil microbial diversity under different corpping model. By high-throughput sequencing,under different planting patterns crop rhizosphere soil microbial community diversity index of each are not identical, to analyze data of shannon and Simpson index, the result shows that the Simpson index of bacteria is TR<TU<TI<TC;the Simpson index of fungi is TR<TI<TU<TC;the Shannon index of bacteria is TR<TI<TU<TC;the Shannon index of fungi is TR<TU<TI<TC. The results above demonstrated the change law of soil enzyme activity, soil nutrient, soil bacteria and fungus structures,diversity of the soil microbial under different corpping models in paramos zones. Additionally,this article proposed that the oil flax—wheat rotation(TR) model and oil flax/ wheat intercropping(TI) model could have positive impact on partial correlation factors of the agriculture soil microenvironment,to a variable extent.All of these discoveries could provide theory basis and pratical experience for the oil flax planting in paramos zones.