Effects Of Different Mulching Measureson Soil Physical And Chemical Properties,Microbial Community Characteristics In Weibei Apple Orchard

Due to its unique geographical location and environmental conditions,the Loess Plateau has become the major producing region of apple production in China.However,there are many disadvantages of orchard management methods?clean tillage?in this area,mainly reflected in the large surface exposed and large amount of fertilizers.In case of heavy rainfall,water and nutrients may be lost because of surface runoff,continuous growth and consumption leads to a series of problems such as lack of soil organic matter and decline in fruit yield and quality.This study takes the Weibei dryland orchard as the research object,The soil physicochemical properties,soil microbial comminities and diversities are determined under cornstalk mulch?CM?,sawdust mulch?SM?,forest soil mulch?FSM?and clear tillage without cover?CK?treatment.To further analyze and compare the yield,quality and photosynthetic characteristics of fruit under different coverage measures,and to explore the comprehensive benefits of different coverage models.At the same time,in order to select suitable for the promotion of the area,some suggestions are put forward in view of the shortage of resources in the Loess Plateau producing area.The coverage model or alternative resources provide some theoretical support for the rational application of orchard surface cover measures in dryland apple cultivation.The main conclusions of this study are as follows:?1?Different coverage treatments significantly increased soil moisture content of 0-20 cm,and CM had the best effect,which increased by 16.9%⁴8.46% compared with the control.Compared with the control,the different coverage treatments could significantly reduce the soil bulk density of 0-10 cm soil layer,and CM effect was the best.It decreased by 13.67% and 14.93% from 2017 to 2018 respectively.Meanwhile,the different coverage treatments were lower than the control soil pH trend.?2?Different coverage treatments could increase soil organic matter,total nitrogen and ammonium nitrate nitrogen content,and the nutrient content decreased gradually with the growth period during the growth period.The improvement of soil organic matter content was the best with CM,and increased by 43.81% and 43.65% respectively compared with the control in 2017-2018.The total nitrogen was improved by CM and SM and FSM was the second.On the whole,the soil nitrate nitrogen showed an increase with the depth of the soil layer,and the soil ammonium nitrogen showed a decrease with the increase of the soil depth.Different coverage treatments increased or significantly increased soil urease,sucrase and catalase activities,and the soil urease activity was significantly improved by CM.The soil catalase activity was significantly improved by FSM.?3?Coverage measures have significant effects on soil bacterial and functional microbial gene abundance.The coverage of soil bacteria?16S rRNA?gene increased by 18.21% ? 78.89% compared with the control treatment.At the same time,the coverage could increase soil ammoxidation?AOA,AOB?and denitrification?nirS,nirK?to a certain extent compared with the control treatment and nitrogen-fixing?nifH?functional microbial gene abundance promoted soil nitrogen cycling.Using Illumina high-throughput sequencing technology to study the community structure,composition and diversity of soil bacterial flora under different coverage measures,The results of Alpha diversity showed that the coverage treatment improved the abundance and diversity of soil bacterial communities compared to the control.The overall performance was SM > CM / FSM > CK;Beta diversity analysis showed that the diversity of the soil bacterial community structure can be significantly changed by mulching measures.SM changed the structure more than the control among them.The species annotations were carried out at the level of door and class classification.The results showed that the dominant bacteria in the soil were the Proteobacteria,Acidophilus and Actinobacteria;?-proteobacteria,Subgroup₆,?-proteobacteria and ?-proteobacteria are the dominant species.?4?The yield and quality of apples covered by each treatment within two years were improved to varying degrees.Compared with the control,the average fruit weight in 2017 and 2018 increased by 8.3% and 16.2%;the hardness increased by 3.1% and 13.1%,respectively;the soluble sugar content increased by 7.0% and 9.7%,respectively.In addition,the coverage treatment increased the net photosynthetic rate,vegetative weight and chlorophyll SPAD value of the fruit trees compared to the control.In summary,the orchard cover treatment is obviously better than the clearing and no-covering in the improvement of soil physical and chemical properties,soil microbial richness and diversity,fruit tree photosynthetic efficiency and yield quality optimization.It is better to be promoted in the region.