施磷对不同生育期棉田土壤磷素吸持特性的影响

以两种质地棉田土壤为材料,研究不同施磷处理对不同生育期棉田土壤磷吸附与解吸的影响.结果表明:各生育期磷素等温吸附曲线与Langmuir,Temkin和Freundlich方程拟合度均达极显著水平,尤以Freundlich方程拟合度最高,相关系数均在0.96以上;磷的吸附饱和度(DPS)、零净吸附浓度磷(EPC_0)、吸附量、解吸量和解吸率随施磷量的增加均呈增长趋势,而标准需磷量(SPR)呈下降趋势;以Freundlich方程估算原状棉田土壤各个生育期的需磷量,壤质棉田苗期、花铃期和吐絮期的需磷量(按含P_2O_5 46%的磷肥折算)分别为143.7,137.4 kg/hm~2和160.2 kg/hm~2,砂壤质棉田苗期、花铃期和吐絮期的需磷量分别为106.6,251.1 kg/hm~2和173.0 kg/hm~2.

Effects of Phosphorus Application on Phosphorus Adsorption and Desorption of Cotton Field Soil at Different Growing Stages

In this paper,the effects of phosphorus application on phosphorus adsorption and desorption of soils in two different cotton fields are studied.The results show that there is an extremely significance between the phosphorus isothermal adsorption curves of loam soil at various growth stages of cotton and the fittings with the Langmuir equation,Temkin equation and Freundlich equation,especially with the Freundlich equation,and the correlation coefficients are higher than 0.96.Phosphorus adsorption saturation(PAS),net phosphorus concentration at zero adsorption(PCA_0),phosphorus absorption,phosphorus desorption and phosphorus desorption rate increased with increasing the amount of applied phosphate fertilizer,while the standard phosphorus requirement(SPR)decreased.The results estimated with the Freundlich equation show that the SPRs(in accordance with the conversion of phosphate fertilizer containing 46% P_2O_5)at the seedling stage,the flowering-boiling stage and the boll-opening stage of cotton in loam cotton field were 143.7,137.4 and 160.2 kg/hm~2,and the SPRs at the seedling stage,the flowering-boiling stage and the boll-opening stage in sandy loam cotton field were 106.6,251.1 and 173.0kg/hm~2,respectively.