Compared to stipa bungeana grassland and fallow ground , the volume weight was smaller , total porosity and capillary porosity were higher , but non - capillary porosity was lower . 2 . achnatherum splendens height increased slow in the initial stages , fast from june to august and slow again after that
2.
And the major results and some new viewpoints were presented as follow : 1 ) sediment content of cn tillage system in runoff process is substantially low compared to st under rainfall with high intensity , showing cn bear the efficient capacity of control soil loss . nevertheless , when soil is saturated , the runoff intensity of both tillage systems is near , implicating cn has the limited function of reducing runoff . 2 ) based on the case analysis of observed all rainfall - runoff generation processes , a ) the initiation time hysteresis of surface runoff generation is notable when rainfall fall upon the unsaturated purple soils , which is attributed to the property of rapid water sorption and much non - capillary porosity
3.
Based on the principle of significant effect of soil fertility factors on forest growth , soil physical factors ( natural water content , bulk density , total porosity , capillary porosity , aggregate degree , coarse silt and physical clay ) , chemical factors ( om . total n , alkali - hytrolyzable n , total p , humus and ha / fa ) and biological factors ( urease , acidphosphotase , invertase and microbes ) were selected as evaluation index system of soil fertility . applying principal component analysis , soil ifi of subalpine coniferous forest was calculated
4.
The fractal dimension of the mixed forests were lower than the pure forests and grassland , and the soil weight diameter of the mixed forests were higher than the pure forests and grassland , which indicated that the mixed forest had best soil structure property in stability infiltration and water - holding ; the soil total porosity and the soil noncapillary porosity were different greatly between forest types , but the soil capillary porosity had little differ
5.
Soil saturated capacity , capillary capacity , total porosity and capillary porosity showed the trend of the " u " during the successional course of artificial forest , namely , they reduced on the early successional stages , after picea reached mature forest , soil porosity recovered slowly . the content of natural water was mainly affected by capillary porosity . from soil chemical properties analysis , the content of soil organic , humus , ha , fa and ha / fa of topsoil was more than that of bottom layer
6.
2 . the structure of purple soil is meliorated by sabaigrass . when contrast to bare land treatment and natural wild grassland treatment we knew that sabaigrass treatment and grass tree solid plating treatment reduced soil bulk density , enhanced soil capillary porosity , non - capillary porosity and porosity ratio , decreased soil sand grain content , enhanced soil clay grain and silt grain content so as to reduced the dispersal degree of soil , improved the aggregate capacity of soil , increased the amount of soil aggregate structure , meliorated the water permeability of soil , accelerated the form of good soil structure
मोबाइल