Biochemical Behavior of Accumulated Phosphrus in Andosol and Their Availabilities for Crop Plants and the Perspectives for Recycle Use.

1)为了阐明土壤耕层水铝英石组分对土壤磷沿着变化的控制作用，采用沉淀法分离了试验田耕层和底土中小于2 μ m的粘粒组分，并测定了它们<27><29>的~（13）Al-和~（13）Si-固体核磁共振（NMR）谱。相对于<27>这些粘土组分的~ 1Al-NMR谱，Al（4）和Al（6）都存在，并且作为四配位Al指示剂的50-60 ppm附近的共振在表土中比在底土中增强得更高。与1H <29>Si-NMR谱相关，在底土中观察到的化学位移仅为-79 ppm，在表土中观察到约-90 ppm的附加峰，表明水铝英石结构随着栽培沿着发生了一些变化。但磷素累积行为与水铝英石结构变化之间的关系尚不清楚。2）采用选择性溶解法测定了耕层土壤水铝英石含量。连续施用农家肥的犁层抑制水铝英石含量随时间的推移，而它略有增加，没有应用。3）为了区分AM根系和AM菌丝对土壤中各种磷化合物的磷吸收作用，研究了AM根系和AM菌丝对土壤中各种磷化合物的磷吸收作用。使用“双罐系统--用尼龙网将根和菌丝隔室分开”。在根际和根表土壤中，不仅Ca-P，Al-P、Fe-P和Org-P也具有很强的移动的性，这些化合物对玉米和木豆也是有效的。绒球囊霉是一种活跃的AM真菌，采自土壤表层，即使在淹水条件下也能与水稻共生。

1) In order to elucidate the role of allophane fractions of plow layr in Andosol on controlling the phosphorus (P) behavior along with time, clay fractions (less than 2um) were separated from the top- and sub-soils of the experimental field by the precipitation method and ^<27>Al- and ^<29>Si- solid state nuclear magnetic resonance (NMR) spectra were measured. In relation to ^<27>Al-NMR spectra of these clay fractions, both of Al (4) and Al (6) were existed and the resonance around 50-60 ppm as an indicator of the four-co-oridinated Al was intensified higher in topsoil than in subsoil. As related the ^<29>Si-NMR spectra, the observed chemical shift in subsoil was only -79 ppm, and additional peak around -90 ppm was observed in topsoil, indicating that some changes in allophane structure were introduced along with the cultivation. However, the relationships between the behavior of accumulated P and the structure changes in allophane were still not clear.2) According to the selective dissolution method, allophane contents in topsoil were measured. Continuous application of farmyard manure to the plow layr suppressed allophane content with time, whereas it slightly increased without application. There was significantly possitive correlation between non-allophane Al content and Al-P fraction in topsoil which has been increasing with time for past more than 10 years.3) To distingwish the functions of Arbuscular Mycorrhizal (AM) root system and only the external AM hyphae on P absorption from various types of P compounds in topsoil, "double pot system -separation of the roots and hyphae compartment by a nylon net-" was used. Not only Ca-P but Al-P,Fe-P and Org-P were quite mobile in rhizosphere and hyphaesphere, and these compounds were also available for maize and pigeonpea. Glomus etunicatum, one of the active AM fungus, which was collected from topsoil in Andosol had high abilities to symbiose with rice even under submerged condition.