Study On Effect Of Soil Properties On Phosphorus Fertilizer Availability And Phosphate Adsorption-Desorption

Availability and adsorption-desorption of soil phosphorus were studied with 17 soil samples collected from different sites in China, and total phosphorus, available phosphorus, water-soluable phosphorus, phosphorus adsorption capacity and desorption capacity were analyzed with seven phosphorus level and five culture time. The main results showed that:1. Phosphorus fertilizer level is the most significant factor influenced on available phosphorus, adsorbable phosphorus and desorption phosphorus. There were positive linear correlativities between amount of phosphorus and adsorption capacity, desorption capacity, Olsen-P and water-soluable P; while adsorption ratio and desorption ratio decreased with phosphorus fertilizer level increased.2. The balance time of phosphorus transformation in soil was about seven days. Absorbable phpsphorus ratio and desorption phosphorus ratio approached fixed value after phosphorus transformation balance. Means that a certain proportion of fertilizer phosphorus was adsorbed after applied into the soil.3. Phosphorus adsorption and desorption curves in soil obeyed the Langmuir equation. Desorption capacity was far less than adsorption capacity, phosphorus of adsorbed could been desorbed down partly. Compared the characteristic parameters of adsorption K, Qm and MBC in different soils, phosphorus adsorption capacity was large in Qiyang, Hangzhou and Jiaxing, was small in Langfang, Zhengzhou and Dezhou, and the ability is medium in other soils. In general, the MBC of southern soils was larger than that of northern soils, the MBC of acid soil was larger than that of Calcareous soil.4. The Soil properties pH, Iron, Aluminum, CEC, Organic carbon, Calcium carbonate, Clay, Total P, Available P and Water-soluable P had influence on phosphorus adsorption-desorption and effective process of phosphorus. The mechanism of phosphorus adsorption-desorption and effective process of phosphorus was very complex.5. The exogenous phosphorus had 48.7% percentage was adsorbed after applied into the soil, in the adsorbed phosphorus contents, about 13.5%-61.5% phosphorus contents could be desorbed down; had 16%-20% percentage existed in the form of available P, among the available P, the proportion of water-soluable P was 5%-10%.6. Established the soil water-soluable P forecasting model to predict water-soluable P contents in soils and provide guidance for farmland fertilization.