Study On The Effect Of Management Measures On Soil Quality In Gully Area Of Loess Plateau

With the development of the industry,in order to simply pursue the yield,the orchard management measures are extensive,and the soil quality degradation is serious.In this paper,Mafang Town,Yongshou County,Shaanxi Province,is selected as the research area.The soil quality of five typical soil management measures in this area,including conventional,no tillage,composting,green planting and intercropping,is selected as the research object.By setting up field test plots,the status and change rule of 23 soil physical,chemical and biological indexes under the five soil management measures are compared and analyzed The non-linear and linear evaluation method was constructed with the minimum data set,and the soil quality comprehensive evaluation index and soil degradation index were calculated.The main results are as follows:(1)The influence of orchard management measures on soil physical properties:the average soil moisture content of 0-60cm of orchard soil of five management measures is 12.48%,compared with that of conventional management measures,the soil moisture content of no tillage,composting and green planting orchard management measures is increased,while that of intercropping management measures is reduced by 3.25%;the soil bulk density,compactness of orchard soil of each management measures The electrical conductivity increased with the increase of soil depth;the porosity decreased with the increase of soil depth,with a range of 53.09%-44.39%;the pH value of soil was between 7.93-8.36,with a trend of first increasing and then decreasing,and the pH value of soil changed greatly under composting and green planting measures.The soil mechanical composition of the five measures is sand content>silt content>clay content,and the sand content is more than 65%.The silt content shows the trend of increasing first and then decreasing,with the variation range of 19.18%-25.49%.The obvious fluctuation occurs in the soil layer of 20-30cm.The soil mechanical stability aggregate content(DR0.25?MWD and GMD all increased with the increase of soil depth.The average value of DR0.25 was over 72.73%,and the change range of MWD and GMD was between 1.07-1.18 and 1.02-1.41.In the composition of soil water stable agglomerates,the range of<0.25mm microaggregates is 46.3%-66.73%,occupying the dominant level,and the content of all levels increases with the decrease of the diameter of the agglomerates.(2)Effects of orchard management measures on soil chemical properties:compared with conventional measures,the other four measures have positive effects on soil nutrient accumulation;under each measure,organic matter content,available nitrogen,phosphorus,potassium,total nitrogen,phosphorus,potassium and nitrate nitrogen all decrease with the increase of soil depth on the vertical profile,and the change trend of ammonium nitrogen content is inverted V-shaped.The results of correlation analysis showed that except for the ammonium nitrogen,there were significant correlation between the soil organic matter,available nitrogen,available phosphorus,available potassium,total nitrogen,total phosphorus,total potassium and nitrate nitrogen,while there was significant correlation between the ammonium nitrogen and the total nitrogen content of the soil,and the correlation coefficient between the ammonium nitrogen and other indicators did not reach a significant level.(3)Effects of orchard management measures on soil biological characteristics:compared with the conventional measures,the other four measures promoted the increase of soil enzyme activity,and the soil enzyme activity among the measures reached a significant level(P The activity of hydrogenase in soil profile showed a trend of decreasing increasing decreasing.The results of correlation analysis showed that urease,sucrase,alkaline phosphatase and other enzyme activity indexes were significantly correlated,and hydrogen peroxide was significantly correlated with alkaline phosphatase.A total of 45955 soil animals belonging to 42 groups of 23 orders,11 classes and 4 phyla were isolated from 5 management measures.Among them,there are three dominant groups,accounting for 35.52%of the total capture density;there are 11 common groups,accounting for 54.37%and the rest 28 groups constiture rare groups,accounting for 10.11%;the vertical distribution characteristics of soil animals show obvious apparent aggregation,the dominance index,evenness and diversity index show opposite trends,and the composting measures have the most abundant and uniform diversity of soil animals.The results of RDA showed that 95.58%of the soil environmental factors were accumulated to explain the relationship between soil environment and soil animal community,which indicated that the ordination axis could explain the relationship between most of the soil animal groups and soil environmental factors.(4)Effects of orchard management measures on soil quality:Based on the soil quality evaluation method of the minimum data set,the selected soil quality index results show that the soil quality levels of the five management measures are respectively at the low,medium,medium,high,medium and medium levels,and the comprehensive index of orchard soil quality in the gully area of the residual tableland is between 0.4-0.6,which belongs to the medium level and non-linear The model was t=0.7225m+0.0289(R2=0.9227,P<0.001).Compared with the conventional orchard,the soil degradation indexes of no tillage,composting and green planting are all positive,which shows that these three measures are beneficial to the improvement of soil quality in the soil profile,and the degradation trend of soil quality in the deep layer of 30-50cm under the intercropping management measures should be paid attention to.