Research on the Evolution Trend of Soil Nutrient of Different Tree Ages in Weibei Dry Plateau

[Objective] The evolution tendency of the orchard soil quality was verified and the theoretical basis of sustainable fruit tree production was discussed.[Method] The distribution characteristics of soil organic matter,available N,available P and Ca in soil profile on orchard of different tree ages in Weibei Dry Plateau were analyzed and studied.[Results]The results showed that the content of organic material in orchard soil in-depth was obviously reduced.With the age-increasing of the tree from 8-15 tree ages,the content of organic matter in orchard soil was reduced.Even though the available N and available P above 40 cm layers in the soil with different orchard ages were slightly increased,the capacity of N and P-providing was not high.The variation of exchangeable calcium content in soil upper layers was not obvious in the calcareous orchard soil which was rich in calcium.There was obvious reduction trendy in the exchangeable calcium content under 60 cm soil layers,which showed there was an acidification trend in soil.[Conclusion] In the Weibei area the key issue of nutrient management in orchard is the poor fertilization in depth dryland.Under the bad soil condition, the fertilizer efficiency could be given full play in the moderate deep fertilization.