灌溉水平对■土磷素淋失的影响

利用渗漏池设施，研究了3个灌溉水平（600、900和1200 m3/hm2）对土磷素淋失的影响。结果表明, 淋溶到120 cm土体的磷量随灌溉量而增加，尤其是在耕层土壤Olsen-P含量达到约70 mg/kg 时有明显增加，但渗滤液中磷浓度在高灌溉时较低。在施化肥和有机肥条件下，各灌溉水平磷淋失的形态均以可溶性磷为主，3个灌溉水平可溶性全磷分别占总淋失磷量的66%、72%和75%； 颗粒磷约为总磷的30%。可溶性磷中可溶性有机磷和钼酸盐反应磷贡献各占约50%。适量施肥，控制灌溉量是防止磷素淋失的有效手段。

Impacts of irrigation regimes on phosphorus leaching in manural loessial soil

Irrigation is one of the critical factors which influence leaching loss of phosphorus in soils. Effects of the 3 irrigation regimes (600、900 and 1200 m~3/ha) on the leaching loss down to 120 cm soil depth were studied by using the refilled lysimeters. The results reveal that the phosphorus leaching losses were increased with the increase of irrigation amounts, and the leaching losses were increased obviously when soil Olsen-P reached to approximately 70 mg/kg. However, the P concentrations for all the tested P forms in the leachate are lowest under the highest irrigation amount. Under the inorganic phosphatic fertilizer plus diary manure application, phosphorus leaching is observed mainly in the form of dissolved phosphorus, and the proportion of total dissolved phosphorus to total phosphorus in the leachate is 66%, 72% and 75% under the 3 irrigation amounts, respectively. While, particulate phosphorus accounts for about 30% of the total leached P. Of the total dissolved phosphorus, both dissolved organic phosphorus and molybdate reactive phosphorus contributed about 50%. The better management of the phosphatic fertilizer plus organic manure disposal application with an optimizing irrigation amount would be an effective approach to prevent the phosphorus leaching loss from arable manural loessial soils.