石灰性土壤吸磷差异及其与土壤性质的关系

Phosphorus Sorption Characteristics of Calcareous Soils and Their Relationship with the Soil Properties

采用等温吸附法研究了24个农田石灰性土壤和4个石灰性生土的磷吸附能力及其与土壤基本理化性质的关系,进而采用通径分析和多元逐步回归分析确定了影响供试石灰性土壤吸附固磷能力的主要土壤性质。研究结果表明:28个供试石灰性土壤的磷等温吸附曲线都很好地拟合了Langmuir等温吸附方程,最大吸磷量(Xm)以4个石灰性生土最大;其次为7个大田褐土性土,9个大田石灰性褐土;8个蔬菜大棚石灰性褐土最小。土壤pH值、CaCO3、活性钙、活性镁、活性铝和小于0.002 mm的土粒均与最大吸磷量呈显著或极显著正相关,而土壤有机质、全氮、速效磷、速效钾和0.2～2.0 mm的土粒均与最大吸磷量呈极显著负相关。经通径分析和反向逐步回归分析可知,影响供试石灰性土壤吸附固磷能力的主要因素为有机质,其次为速效磷和活性钙,土壤有机质、速效磷、活性钙和小于0.002 mm土粒共同决定了供试石灰性土壤95%的最大吸磷量。供试土壤中,8个蔬菜大棚石灰性褐土有机质、全氮、速效磷、速效钾含量相对较高,而吸附固磷能力相对较弱。连年大量有机和无机肥料的投入不仅导致磷在土壤中大量积累,而且由于土壤肥力的逐步提高,其吸附固磷能力下降,土壤中累积的磷素迁移性增强,造成水环境污染的风险增加。

The P-adsorption characteristics of 28 agricultural calcareous soils and 4 immature calcareous soils and their relationship with the soil physic-chemical properties were studied by isotherm-adsorption method,and the major soil properties affecting P-adsorbing maximum（Xm） of the experimental calcareous soils were determined by path and stepwise multiple regression analyses.The results indicated that the phosphorus isothermal adsorption curves of the 28 experimental calcareous soils all properly fitted the Langmuir adsorption equation.The sequence of Xm was 4 immature calcareous soils,7 weakly developed cinnamon soils of farmland,9 calico cinnamon soils of farmland,and 8 calico cinnamon soils of plastics greenhouse from low to high.The Xm of the soils was positively and significantly or very significantly related to soil pH,CaCO3,active calcium,active magnesium,active aluminum,and the particles smaller than 0.002 mm respectively,but negatively and very significantly related to soil organic matter,total nitrogen,available phosphorus,available potassium,and particles from 0.2 to 2.0 mm respectively.The results of path and backward-stepwise regression analysis showed that the major soil properties affecting Xm of the experimental calcareous soils were organic matter firstly,and then available P and active Ca,and the model based on soil organic matter,available P,active Ca,and particles smaller than 0.002 mm explained 95% of the variation in Xm.The soil fertility index of organic matter,total N,available P,and available K of the 8 calico cinnamon soils from plastics greenhouse were relatively higher,but their capacities of phosphorus adsorption and fixation were relatively lower.Therefore,continual application of large quantity manure and fertilizers not only led to the fertilizer P build up in the soil,but the capacity of soil adsorbing and fixing P also decreased because of the gradual increase of soil fertility.The migratory aptitude of accumulated P would increases in the soil and the risk of water environmental pollution increased,too.