Objective  To ascertain the conditions of soil nutrients, microbial quantities, enzyme activities of pomegranate orchards with different age stages and their correlations, the references were provided for soil scientific management of pomegranate orchards.

  Method  soil samples were collected from pomegranate orchards with different age stages, then the soil nutrients, microbial quantities, enzyme activities were determined and their correlations were analyzed.

  Result  ① The contents of available nitrogen (N) in the soils of the early stage of fruiting and the full bearing period were significantly higher than that of the growing period, but the contents of available N were very low on the whole according to the classification standards for soil nutrients in The Second Soil Census of China. The contents of rapidly available phosphorus (P) and potassium (K) in the soils increased significantly with the age stages. The contents of rapidly available P were high in the soils of all the orchards, and the contents of rapidly available potassium (K) was low only in the soils of the growing period. ② The microbial quantity increased with the age stages, and the number of bacteria increased significantly. The numbers of fungi and actinomycetes in the soils of the early fruiting period and the full bearing period were significantly higher than those of the growing period, however, there was no significant differences in the numbers of fungi and actinomycetes between the early fruiting period and the full bearing period. ③ The activities of urease, sucrase and alkaline phosphatase increased significantly with the age stages, while the activities of catalase decreased significantly with the age stages. ④ According to the correlation analysis, the activities of urease, sucease and alkaline phosphatase were positively correlated with the numbers of bacteria and fungi in the soils, whereas the activities of catalase was negatively correlated with the numbers of them, and surcease was the only one whose activities were significantly correlated with the number of actinomycetes of the four enzymes. The activities of the four enzymes were significantly correlated with available N, rapidly available P and K. The numbers of fungi and actinomycetes were all significantly correlated with available N, rapidly available P and K, while the number of bacteria was very significantly correlated with rapidly available P and K but not significantly correlated with available N.

  Conclusion  There are some differences in the soil nutrients, microbial quantities and enzyme activities of the pomegranate orchards in different age stages, and the microbial quantities and enzyme activities are closely related with soil nutrients. Thus, the pomegranate orchards should be managed scientifically according to their age stage. Meanwhile, the microbial quantities and enzyme activities could be regarded as indicators of soil fertility, and it could provide theoretical reference for the soil management of the pomegranate orchards in different age stages.