Study on quantity of microorganism and fertility of orchard soil with different plant ages

Soil microbiological characteristics are sensitive indicators of soil quality. In this paper, the quantitative distribution of the main soil microorganism, including bacteria, actinomycete, yeast and fungi, soil fertility including organic matter and Alkli-N, olsen-P and ailki-K were determined in three orchard soils with different plant ages in soil depth. The results showed that the amount of soil microorganism presented an obviously decreasing pattern in the vertical distribution. The amount of soil bacteria, actinomycete and organic matter in 15 year-old orchards were significantly higher than those of 7 or 15 year-old orchards, indicating that soil nutrient is correlated positively with the quantity and composition of bacteria and actinomycetes in soils. Therefore, soil microbial characteristics can reflect the changes in soil quality and thus can be used as bio-indicators of soil health.