Spatial And Temporal Variations Of Apple Orchard Soil Biological Properties In Different Slope Position In The Loess Plateau

To explore the transformation law of slope soil biological properties with time andspace,as well as its impact on apple production on tundra transition area of the LoessPlateau,we studied the soil moisture, soil enzyme activity, soil organic matter, total N, soilrespiration rate and microbial biomass in different slope positions and soil depth of the area indifferent seasons by field investigation,laboratory analysis and mathematical statistics.Aftervariance and correlation analysis,conclusions gained are as follows:(1) soil moisture varied with season: the soil moisture was stable during2010Novemberto2011May,then decreased significantly in July and rebound after; soil moisture increased asthe increasing depth on the same slope position;soil water content shows a growing trendfrom the top to the base of slope.(2)the soil urease activity in2010May, July and September were significantly higherthan that in2010November and2011March; soil invertase activity in March,May, July andSeptember of2011were significantly higher than that in2010November;alkalinephosphatase in the top and base of slope in May, July and September of2011weresignificantly higher than that in November and2011March, while in the middle slope showed2011May> July>September> March>November2010; soil catalase activity changed littlewith season indicating that there is a significant positive correlation between enzyme activityand temperature; soil urease, invertase, alkaline phosphatase and catalase activity decreasedgradually with increasing soil depth. Soil enzyme activity in the top and base of slope werehigher than that in the middle.(3) soil respiration rate in different slope position was consistent,showed that July>September> May> March2011> November2010; soil respiration rate in three slopepositions were all decreased with increasing soil depth; except for May, soil respiration rate inthe top and middle of slope were slightly higher than that in the base. (4) soil microbial biomass, organic matter and total N showed a significant seasonalvariation, peaked in July and bottomed in November; soil microbial biomass, organic matterand total nitrogen in the soil profile decreased gradually with increasing depth,in which20-40cm soil layer decreased significantly over the topsoil. The content in0-20cm soil layervaried severe while in subsoil (20-40cm,40-60cm)remained stable;soil organic matter andmicrobial biomass carbon, total soil nitrogen and bicrobial biomass N in the same layer weresignificant related among the three slope positions.(5) The correlation analysis showed that soil organic matter in the0-60cm soil layer weresignificantly related with other indicators;microbial biomass carbon, nitrogen and enzymeactivity were significant difference;soil urease,invertase and alkaline phosphatase havesignificant difference while catalase activity related little worse with the other threeenzymes,as well as microbial biomass.