THE EFFECTIVENESS OF PHOSPHORUS AND TYPES OF IRON OXIDES OF SEVERAL SOILS IN HUBEL AND HUNAN PROVINCES
Liu Fan; Li Xueyuan;Xu Fenglin;Wang Daizhang;Rong Yi(Huazhong Agricultural University, Wuhan 430070)
The phosphate adsorption characteristics, effect of supplying phosphorus to sorghum seedling and their relation to the constituents of soils distributing in Hubei and Hunan provinces were studied.Result indicated that phosphate adsorption and phosphorus affinity of yellow-brown soil and red soil were obviously larger than those of brown red soil. On the contrary, the desorbing ratio of phosphate and capacity of supplying phosphorus to sorghum seedling of the latter was stronger than those of the former. In yellow-brown soil and red soil, the type of iron oxides was goethite; in brown red soil, they were mixtures of goethite and hematite. Although the morphology of goethite that appeared as subrounded flat was similar to that of hematite, the specific surface areas of goethites adsorbing phosphate were larger than those of hematites. Therefore, the dissimilarity of iron oxide types was the main reason resulted in the distinct difference of phosphorus effectiveness in examined soils.