六盘山北侧叠叠沟小流域土壤物理性质空间变异的研究

2005年6-10月,在宁夏六盘山北侧叠叠沟小流域的不同坡面设置了93个调查样点,研究了土壤物理性质随土层深度、坡向、坡位及植被类型的变化.结果表明:(1)随土深增加,土壤密度和石砾含量逐渐增大,而土壤总孔隙度、毛管孔隙度、非毛管孔隙度、土壤饱和持水量、毛管持水量和田间持水量却逐渐减小,但非毛管孔隙度在100 cm以下土层时因石砾含量加大却随土深增加而增大;(2)各项土壤水文物理性质基本上均是阴坡优于半阴半阳坡和阳坡,半阴半阳坡与阳坡差别不大;(3)随着坡位下降,土壤厚度、土壤密度、石砾含量、非毛管孔隙度逐渐增大,总孔隙度和毛管孔隙度逐渐减小,各种持水量指标基本上也是程度不同地减小,但上坡的持水量指标大于阴坡坡顶;(4)4种植被类型0～30 cm土层的土壤密度为天然灌丛＜天然草地＜乔木林地＜退耕地;石砾含量为退耕地最低,其它3种植被类型差别不大;总孔隙度、毛管孔隙度、饱和持水量、毛管持水量和田间持水量均是天然灌丛＞天然草地＞乔木林地＞退耕地;非毛管孔隙度则是退耕地＞乔木林地＞天然灌丛＞天然草地.其次,还建立了土壤物理性质与海拔、坡向、坡度、坡位、土壤深度、地表植被覆盖度等之间的回归方程.

The Soil Physical Characteristics in the Small Watershed of Diediegou Located on the North Side of Liupan Mountains

Based on field investigations,the variation of soil physical characteristics with soil depth,slope aspect,slope position,and vegetation types within the small watershed Diediegou located on the north side of Liupan Mountains,Ningxia,China was studied.The result shows:(1) The soil density and stone content increased with increasing soil depth;while total porosity,capillary porosity,non-capillary porosity,saturated water content,(capillary) soil water content,and field capacity of soil decreased with increasing soil depth.But the non-capillary porosity increased with soil depth in the range of deeper than 100 cm,since the stone content was getting higher in deeper soil layer.(2) All the soil physical properties measured in this study were basically better on the south slope than on the north slope and all other half-sunny slopes.There was very less difference between south slope and all other half-sunny slopes in term of research soil physical properties.(3) With lowering slope position,the soil thickness,soil density,stone content,and non-capillary porosity were gradually increasing;while the total porosity,capillary porosity,and all water-holding capacity indicators gradually decreasing,with an exception that the water-holding capacity on the up-slope was higher that on the slope top.(4) By comparing the averaged soil physical properties of upper soil layer(0~30 cm) among four main vegetation types,the soil density in abandoned farmland was the highest,the woodland the second,the grassland the third,and the shrub land the lowest.The stone content of soil in the abandoned farmland was the least,and there was less difference among all others land types.For the total porosity,capillary porosity,saturated soil water content,capillary soil water content,and field capacity,their order from high to low was shrub land,grassland,woodland,and abandoned farmland.For the non-capillary porosity,its order from high to low was abandoned farmland,woodland,shrub land,and grassland.Finally,the regression(equations) between the researched soil physical properties and altitude,soil aspect,slope gradient,slope position,soil depth,and ground vegetation coverage were established.