Studies on the correlation of soil enzyme activity of Gong-Chuan (Citrus umshiu MARC) root-area with soil nutrient content

Soil enzyme activity of Gong-Chuan root-area and the relations between the enzyme activity and the agrochemical properties in soils with different fertility were studied. The results indicate that the soil enzyme activity in high-yield orchard is notably higher than that of in low-yield orchard, and the soil enzyme activity is remarkably correlated with the nutrient content. It is also shown that the distributions of soil enzyme activity in soils have some regularity. The enzyme activity is highest in its level distribution area from the location of 4/5 radius of tree crown to that of the maximal radius, and in area inward or outwad from the above area the enzyme activity decreases gradually. The enzyme activity in its vertical distribution of soil of 0～20 cm depth is highest, and with the depth increasing, the enzyme activity decreases gradually.