长期施肥条件下石灰性潮土磷的吸附解吸特征

采用Langmuir方程、Freundlich方程及其扩展形式对长期施肥土壤磷的吸附和解吸特征进行了研究。结果表明，双面Langmuir方程和三种Freundlich方程能较好描述石灰性潮土壤对磷的吸附，方程决定系数r2均接近0.99。长期施用有机肥能减少土壤对磷的吸附，表现在土壤对磷的理论最大吸附量（Qm）降低以及吸附结合能常数K值下降。与长期施用化肥相比，长期施用有机肥土壤新吸附的磷也更容易解吸，土壤磷的解吸率从化肥处理的15%左右提高到20%以上。钾肥的施用增大了石灰性潮土对磷的吸附容量，磷的吸附结合能明显提高，意味着化肥钾的施用可能导致土壤磷向作物难利用方向转化，但有机肥与钾肥配合施用，钾肥的这种不良作用得到明显的改善。

A dsorption and desorption characteristics of soil phosphorus in calcareous fluvo-aquic soil under long-term fertilization

Langmuir, Freundlich and its extension equations were adopted to study the soil phosphorus adsorption and desorption characteristics in calcareous fluvo-aquic soil of long-term fertilization experiment. Results indicated that double-surface Langmuir equation and all forms of Freundlich equation could well describe phosphorus adsorbed by soil. Organic manure application could remarkably decrease phosphorus adsorption，which was shown by the decrease of Qm and K values in soil with organic manure addition for a long time. Phosphorus adsorbed by soil with organic manure addition was more easily released than by the soil with only mineral fertilizer application(phosphorus desorption rate was 20% and 15% for these two treatments, respectively). Qm value and K value were increased by potassium addition treatment, indicating that potassium addition promoted phosphorus transformation to more steady forms. This negative effect was evidently corrected by combined use of organic manure and mineral potassium fertilizer.