The Activities Of The Rhizosphere Soil Culturable Microbial And Enzymes Under Potato Continuous Cropping

In the study, It was conducted to determine the number of culturable microorganisms and enzyme activities in the rhizosphere soil, where potato (Kexin 1) was successively cropped one and two and three years respectively. The traditional plate method and the MPN method were used to research the culturable microorganisms.The results show that: Successive cropping of potato significantly affected the microbial flora and enzyme activities in the rhizosphere soil. With the successive cropping years increasing, the number of bacteria decreased and showed significant difference, the number of fungi went up firstly and then came down, just liked a"Inverted Saddle"but there was no difference. The number of actinomycetes just had little change. The number of aerobic cellulose-decomposer, ammonifiers and nitrite bacteria had increased in varying degrees. In the rhizosphere soil which cropped potato for one year, two years and three years, The total quantity of aerobic cellulose-decomposer were as 123.24%,225.67% and 341.74% times as CK. The total quantity of ammonifiers were as 127.41%, 139.84% and 176.11% times as CK. But there was no nitrite bacteria in the soil of CK. The number of aerobic azotobacter decreased with the successive cropping years increasing but was higher than CK and as 311.21%,120.77% and 46.07% times as CK respectively.Continuous growing of potato would cause decrease of the activities of invertase.However, the activites of urease ,neutral phosphatease and catalase did not. have significant difference among different rotations.