| Based on determination of soil nutrients(organic matter,N,P,K and pH) and soil microoganisms(bacteria, fungi and actinomyces)and activity of the enzyme(invertase,urease, catalase)in four kinds of agroforestry landscape boundaries(forest-grassland,forest-farmland ,forest-grassland-forest and forest belt-farmland boundaries) in gully region of loess plateau,comparative analysis of siol nutrients, microoganisms and enzyme activity statistics were carried out.The main conclusions are as follows:1.Soil nutrient1.1 The soil nutrient distribution characters of forest-grassland boundary and neighboring region were different.The organic matter of average level in 0-40 cm soil layer was grassland > boundary > forestland,Available N was boundary > forestland > grassland ,Total N was forestland > grassland > boundary,Total P,K and pH were boundary > grassland > forestland,the difference was not significant.Available P and Available K were grassland > forestland > boundary,the difference was not significant.The content of organic matter,available P,available K of forestlsnd and grassland were higher in the late growing season (September),than that in early growing season(June or April),But the content of available N was the highest in the early growing season(April).1.2 The soil nutrient distribution characters of forest-grassland boundary and neighboring region were different.The organic matter,Total N,Total K and pH of average level in 0-40 cm soil layer were boundary > forestland > farmland,Available N was forestland > boundary > farmland,Total P was forestland > farmland > boundary,the difference was not significant.Available K and Available K were farmland > boundary > forestland,the difference was not significant.The amount of organic matter,total N,available P,and total P of forestlsnd and farmland were highest in the growing season (June), in early growing season(April)were the lowest.The amount of total K and available K were the highest in the late growing season(Septemper),in early growing season or growing season(June or April)were the lowest. 1.3 The soil nutrient distribution characters of forest-grassland-forest boundary and neighboring region were different.The organic matter,Total N,Available K of average level in 0-40 cm soil layer were forestland > grassland,the difference was not significant.Available N,Total P, Available P and Total K were grassland > forestland,the difference was not significant.pH was forestland > grassland.1.4 The soil nutrient distribution characters of forest belt-grassland boundary and neighboring region were different.The organic matter,Total N,Available N and Available K of average level in 0-40 cm soil layer were boundary > farmland > forestland, Total P farmland > forestland > boundary,the difference was not significant.Available P was farmland > boundary > forestland,Total K was forestland > farmland > boundary,pH was boundary > farmland > forestland,the difference was not significant.1.5 Horizontal distributions of soil nutrient across different boundaries showed"V"shape,inverse"V"shape and line shape along patch gradients of farmland (grassland)-edge-forestland and showed"V"shape,"W"shape and wave shape along belt transect gradients distribution.2. Soil microoganism2.1 Each kind of microoganism quantity exists obvious difference under four kinds of agroforestry landscape boundaries in soil.In the overall quantity,the bacteria was the highest,the fungi took second place,and the actinomyces was the lowest.The amount of microorganism in 0-20 cm soil layer of forestland was significantly much more than that of 20-40 cm.But the amount of microorganism in 20-40 cm soil layer of farmland was significantly much more than that of 0-20 cm.The amount of bacteria in 0-20 cm soil layer of forestland and grassland was more than that of 20-40 cm.But the amount of bacteria in 20-40 cm soil layer of farmland was significantly much more than that of 0-20 cm.2.2 The amount of fungi in 0-20 cm soil layer of forestland and farmland was less than that of 20-40 cm.The amount of fungi in different landscape boundaries was different in the grassland,the fungi in 0-20 cm soil layer of forest-grassland boundary was less than that of 20-40 cm,but the fungi in 0-20 cm soil layer of forest-grass-forestland boundary was more than that of 20-40 cm.This is because pH of 0-20 cm soil layer is smaller than that of 20-40cm, the fungus grows exuberantly under the acidic environmental condition.2.3 The amount of actinomyces in 0-20 cm soil layer of forestland in forest-grassland boundary was more than that of 20-40 cm,but 0-20 cm soil layer was less than 20-40 cm in other boundaries.In grassland were 0-20 cm soil layer more than 20-40 cm.In farmland ,The amount of actinomyces in 0-20 cm soil layer of forest-farmland boundary was less than that of 20-40 cm,the forest belt-farmland boundary was just opposite.3. Soil enzyme activity3.1 In vertical level,The activity of invertase,urease and catalase in 0-20 cm soil layer are more than that of 20-40 cm,The activity of invertase at different level showed small difference,But the urease and catalase showed big difference.3.2 On the landscape boundaries,The activity of invertase was the highest,the urease and catalase were weak.The activity of invertase in landscape boundary was forestland > grassland > farmland ,the urease was farmland > forestland > grassland,The activity of catalase showed little change, There was almost no difference among forestland,farmland and grassland.4. Correlation analysis of soil fertility4.1 The bacteria,fungi and actinomyces have the positive correlation with pH in forest-grassland boundary,But have the negative correlation in other landscape boundary.There was correlation between pH with other soil Nutrients, but the correlation was not significant.4.2 The activity of invertase,urease,catalase showed a negative correlation with pH,and a significant correlation with the organic matter,the total N,Available K. |
