Composition and Stability of Soil Aggregates among Different Soil Types of Tea Garden

Based on the field survey and laboratory analysis,the soil aggregate composition and stability characteristics in five soil types(yellow soil,red earth,moisture sandy soil,alpine meadow soil and purple soil) of tea garden in Wuyishan city were investigated.The results showed that the contents of soil macro-aggregates decreased with soil depth,but micro-aggregates increased correspondingly in the five soil types of tea garden.The contents of soil macro-aggregates(5 mm) were highest,accounting for 18.07%-89.23% of the total in yellow soil,alpine meadow soil and purple soil,the soil micro-aggregates(0.25 mm) were the highest,accounting for 37.16%-63.91% of the total in red soil and moisture sandy soil.The proportion of R0.25(water-stable aggregate 0.25 mm) was between 36.08% and 97.23%(sample means 73.60%).The mean weight diameter(MWD) and geometric mean diameter(GMD) of soil aggregates in alpine meadow soil of tea garden were significantly higher than those in other soil types,followed by those in yellow soil and purple soil,the lowest was in moisture sandy soil.The fractal dimension(D) changes in the opposite trend simultaneously.The soil aggregate composition and stability were significantly correlated with soil organic carbon,total N,total P,soil bulk density,soil porosity,sand and silt,but not significant correlated with C/N,total K,pH value and clay.