[Study on dynamic change law of N, P and K in Panax notoginseng plant soils with different interval year].

Objective: To study effects of different interval year on Panax notoginseng plant soils macro element content.

Method: The dynamic change of total N, P, K and available N, P, K in soil from Mabai, Matang, Gumu and Panlong was determined under different planting patterns (new soil, interval 5 years soil and continuous cropping soil).

Result: Contents order of soil total N, P and available N, P were interval 5 years soil > continuous cropping soil > new soil. No significant quarter change on soil total N was found, but the other three showed inverted "v" curve, and the peak value appeared on April 2010. Content of soil total K did not change significantly, but the available K content order was new soil > continuous cropping soil > interval 5 years soil, the quarter change was similar as soil available N or P. The soil total N, P, K and available N, P, K were different of the 4 monitoring sites under the 3 interval planting modes. There was a significant correlation between soil total P and available P under all these 3 interval planting modes, but N and K. The propitiation of N-P-K of new soil, interval 5 years soil and continuous cropping soil were 1: 0.4: 2.4, 1: 0.4:1.4, 1:0. 4:2.0, respectively.

Conclusion: Continuous cropping pattern induce the accumulation of P, but deficient of K. The imbalance proportion of N, P and K was one of the incentives of continuous cropping induced obstacles. Strengthen the research of optimum proportion of soil N, P and K, and then eliminate continuous cropping obstacles by means of formulated fertilization is the future research direction.