The enriching point of available P depended on soil types, being P2O5 60 ~ 120 mg/kg in the paddy soil derived from Tertiary red sandstone, and P2O5 120 ~ 180 mg/kg in the paddy soils from Quaternary red clay and loess-like lake sediment.

• 土壤速效P出现富集的转折点因供试土壤而异,第三纪红壤性水稻土大致为P2O560~120mg/kg,而第四纪红壤性水稻土和黄泥土为P2O5120~180mg/kg。