Evaluation of availability of phosphorus reserved in Andisols for high yield of crop and savings of phosphorus resources.

以土壤胶体组成为参照，对土壤磷素肥力进行了评价。磷的吸附能力与活性铝(尿磷矿和铝腐殖质复合体)密切相关。以铝腐殖质络合物为主要活性铝的非透水阳离子对磷的吸附能力高于以铝腐殖质为主要活性铝的非透水阳离子。土壤速效磷含量随着土壤对磷的吸附能力的增加而降低。用EDTA-NaF溶液提取土壤中保留的总可溶性无机磷。在土壤全磷和速效磷水平相当的情况下，植物从氨基安替酚中吸收的磷高于非氨基安替酚(Truog和Bray法)。与不透性安迪索相比，非氨基安迪索需要更多的有效磷才能使植物生长良好。在土壤全磷含量相同的情况下，氨基苯甲酚的Truog-P和阴离子交换树脂浸提性磷的值高于非氨基苯甲酚，而非氨基苯甲酚的Bray-P和乙酸可提取磷的值高于等量的氨基苯甲酚。因此，必须根据土壤胶体组成的不同，通过提取方法来准确评价土壤磷的有效性。在低pH<5.3的低pH条件下，植物速效P含量下降。在低pH条件下，铝伤害抑制了根的伸长，导致植物对磷的吸收减少。

Phosphorus (P) fertility of Andisols was evaluated with reference to colloidal composition of soils. P sorption capacity was strongly correlated to active aluminum (allophane and Al-humus complex). Nonallophanic Andisols with major active aluminum of Al-humus complex showed a higher P sorption capacity per active aluminum than allophanic Andisols with major active aluminum of allophane. Soil available P content decreased with increasing of P sorption capacity of soil.Total soluble inorganic P reserved in soil was extracted by EDTA-NaF solution. Plant absorbed greater amounts of P from allophanic Andisol than nonallophanic Andisol with equal level of total soluble P and available P (Truog and Bray methods). Nonallophanic Andisol needed more available P for good plant growth with compared to allophanic Andisol. Allophanic Andisol showed higher value of Truog-P and anion exchange resin extractable P than nonallophanic Andisol with equal amount of total soluble P.However, nonallophanic Andisol showed higher value of Bray-P and acetic acid extractable P than allophanic Andisol with equal amount of total soluble P.It was concluded that the accurate evaluation of P availability of Andisols must be conducted by extraction methods in consideration for soil colloidal composition.Plant available P decreased in nonallophanic Andisol with low pH less than 5.3.Soil available P contents did not change within the pH range of 4.5 to 7.0. In low pH,the inhibition of root elongation by Al injury caused the reduction in P absorption of plant.