The Activities Of The Rhizosphere Soil Culturable Microbial And Soil Nutrient Under Potato Continuous And Rotation System

Experiments conducted for potato plants in continuous and rotation (Kexin-Ⅰ) system in order to investigate the number of microorganism changed from rhizosphere and non-rhizosphere soil. Number of microorganism, potato plants nutrient content, and plants biomass were determined in two-year experiments. Results showed that:1. Potato plants growth presented slow and weak, the tuber yield and plants mass accumulation decreased significantly in continuous planting system but increased in rotation planting system; plants total nitrogen, phosphorus and potassium content in continuous planting system less than these in rotation planting system.2. The number of microorganism from root soil significantly influenced with the increases of continuous planting years. For bacterium and actinomycetes and Aerobic Azotobacter from root soil, the number significantly decreased, for both fungi and Aerobic cellulose-decomposer number significantly increased, but in2plantings were conducted during3years condition, the number of Aerobic cellulose-decomposer significantly higher than in5years continues planting condition. With the increases of continuous planting years, the B/F value and soil fertility decreased significantly, and the soil changed from "bacterium type" to" fungi type". There was no any changes observed about the number of the ammonifiers bacteria in the condition of continuous planting potato4yeas, and nitrite bacteria number significantly decreased; But continuous5years its number was higher than that of in the condition of plant different crops during5years.3. Soil pH value was much higher than that of CK treatment, but there were no differences among continues and rotation treatments. With the increases of continuous planting years, soil organic matter, soil total nitrogen and soil available phosphorus content decreased, and the minimum value of soil organic matter and soil available phosphorus content got in the condition of2plantings set up during3years. For the available potassium, different from the above data measured, its content increased with the increases of continuous planting years and higher than the data from rotation planting svstem. 4. Through correlation analysis, there was no correlation was between soil temperature and microorganism number, and there was a significant positive correlation between bacterium number and the tuber fresh weight in every sampling stages. significant correlations also covers actinomycetes number and soil total nitrogen content, actinomycetes number and soil available phosphorus content, actinomycetes number and soil organic matter, bacterium number and soil available phosphorus content, fungi number and soil pH, Aerobic cellulose decomposing bacterium and soil pH. And there was no correlation between soil available potassium and bacterium number.