SoilChem土壤胶体表面化学CAS.ppt

Conclusion The depletion intensity was by the bottom or the middle part of roots. * Conclusion The nonlinear regression equation with three times of x and t could describe the phosphate distribution in the rhizosphere against the growing time (t) and the distance from the root plane (x). * Questions and Discussion 1. 什么是永久电荷和可变电荷？ 2. 电荷零点的概念及其影响因素？ 3. 试述土壤中永久电荷和可变电荷的来源及其与土壤肥力的关系。 * Questions and Discussion 4. 活度与养分位的联系与区别？ 5. 有效养分包括哪些形态？受什么因素影响？ 6.试述土壤中养分离子运移的主要方式及其定量描述公式 。 * Any Questions ? * * Relative Contribution (%): Pmr =(Pm/Pt) * 100 Pdr =(Pd/Pt) * 100 P-P uptake by plant Qw-water uptake of plant Cp -p concentration in the effective water of soil Calculation the relative contribution of Mass flow and Diffusion * General distribution characteristics of phosphate in Wheat Rhizosphere There was a depletion zone by the soil-root interface, which shows that diffusion is the major process for supplying phosphate to plant. RESULTS AND DISCUSSION * A. Depletion Rate The ratio of C/Co C-phosphate content in near root soil or rhizosphere Co- phosphate content in the primary soil or bulk Soil The depletion can defined by two indices: * B. Depletion Range The width of the depletion zone. The depletion can defined by two indices: * The main range of depletion zone was about 2-3 mm near the root surface, In which the distribution curve had a sharp gradient, the C/Co changed about 20%, from 75% at 0.2 mm near the root surface to 95% at 2-3 mm apart from the root plane. P distribution properties Diffusion in the soil for 15 days, * The range of the depletion zone could spread for 5 mm or so near the root surface, But in the range of 3-5 mm apart from the root surface the locus of the distribution curve changed gently, and the C/Co changed only 5% nearly. P distribution properties Diffusion in the soil for 15 days, * Frequently, the highest depletion rate of phosphate was not just at the root surface but at a distance of