不同水分状况及施磷量对水稻土中速效磷含量的影响

CHANGE IN AVAILABLE P CONTENT IN PADDY SOILS AS AFFECTED BY PHOSPHATE FERTILIZATION AND SOIL MOISTURE REGIME

通过室内培养试验研究了不同水分(淹水和60%田间持水量)及施P量对水稻土速效P及水层含P量的影响.结果表明,无论水分状况如何,土壤速效P含量随施P量的增加而呈明显增加趋势.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P2O560～120 mg/kg,而第四纪红壤性水稻土和黄泥土为P2O5120～180mg/kg.P肥施入土壤后,水溶性P主要存在于土壤溶液中,而分布于水层中的P相对较少.但在过量施P(P2O5>180 mg/kg)时,施肥后短期内(0～30天),水层中P浓度较高(0.05～0.3 mg/kg),如水分管理不当,则会造成P的损失.

An indoor incubation experiment was conducted to investigate dynamics of available phosphorus （P） content in paddy soils different in soil moisture regime （submerged or 60% water holding capacity） and submerging water layer as influenced by phosphate fertilizer application. The results indicated that soil available P content was obviously increased with the phosphate fertilizer application rate. 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. Soluble P was mainly distributed in soil solution and less in the water layer. However, a higher concentration of soluble P was found in the water layer of submerged paddy soils with excessive P addition （〉P2O5 180 mg/kg）. Thus, P loss is likely to occur under unsuitable water management.