The Nutrient Dynamics On The Rhizosphere In Complex Ecosystem Of Triploid Populus Tomentosa-grass

In this paper, nutrient dynamics on the rhizosphere and non-rhizosphere in complex ecosystem of Triploid populus tomentosa-grass of conversion of cropland to forest (Triploid populus tomentosa - Lolium multiflorum Lam and Triploid populus tomentosa -natural grass) were studied by using peeling method. The main research results were as follows:1. There is acidification on the rhizosphere of Triploid populus tomentosa in certain degree. Soil pH were higher on the rhizosphere soil and non-rhizosphere soil in forest-herb model than that in natural grass model. It showed that Lolium multiflorum can improve soil pH in contrast with natural grass. The seasonal dynamics of soil pH on the rhizosphre soil showed a double-apices curve in the two kinds of model being highest in February, and being lowest separately in June and December or June and September In contrast the seasonal dynamics of soil pH on the non-rhizosphre soil showed a single-apex curve in the two kinds of model, and the maximum appeared between in January and February, and the minimum appeared in may. Soil pH on the rhizosphere soil and non-rhizosphere soil was significant positive correlation in forest-herb model, and also remarkable in natural grass model, but didn't reach remarkable level. The seasonal dynamics of soil pH on the non-rhizosphere soil showed remarkable positive correlation in two kinds of models.2. Organic matter cumulated on the rhizosphere soil of Triploid populus tomentosa.The difference of organic matter on the rhizosphere soil was not significant between two models, but significant on the non-rhizosphere soil in the first half year and all-year. Organic matter dynamics on the rhizosphere soil showed approximately a double-apices curve in forest-herb model being highest in April and August, and being lowest in December and July. However organic matter dynamics on the non-rhizosphere soil was not obvious, and the maximum and minimum appeared in April and July respectively. In natural grass model organic matter dynamics on the rhizosphere soil was not obvious either, being highest in April and July and lowest in December and June. Organic matter dynamics on the non-rhizosphere soil showed a single-apex curve and the maximum and minimum appeared in April or in February and August seperrately. Organic matter dynamics on the rhizosphere soil and non-rhizosphere soil in forest-herb model and natural grass model were not significant correlation.3. The total N showed cumulation on the rhizosphere and the fluctuations were less than 5% on the rhizosphere and non-rhizosphere soil in all-year. in the two kinds of models. The difference of total N on the rhizosphere soil was not significant in two models, but significant on the non-rhizosphere soil. Total N on the rhizosphere soil showed a very significant positive correlation.4. Hydrolytic N on the rhizosphere soil was depleted in all-year. As far as the first half year and all-year are concerned, hydrolytic N contents on the rhizosphere soil and...