长期节水灌溉条件下保护地土壤无机磷分级及其有效性研究

菜田土壤长期节水灌溉试验结果表明,蔬菜保护地0~60cm土壤剖面中,无机磷组分均以Ca-P含量最高,Fe-P、Al-P和O-P含量在不同灌溉处理中表现不同。滴灌处理O-P含量略大于Fe-P,明显大于Al-P;渗灌土壤Fe-P稍大于O-P,但二者均明显大于Al-P;沟灌土壤Fe-P大于Al-P大于O-P,而后二者比较接近,差异不明显。3种灌溉处理各种形态无机磷随剖面加深逐渐降低。而且上层土壤各种形态磷相差较大,往下这种差异逐渐减小,至60cm土层时,O-P、Fe-P和Al-P趋于一点,Ca-P也与它们比较接近。从整个剖面无机磷变化趋势看,O-P比较稳定,变化不明显,其它3种形态无机磷变化较大,尤以Ca-P变化幅度最大。下层土壤各种形态无机磷含量比较低而且互相接近,说明下层土壤受施肥和人为因素影响比较小。

Effect of Long-term Water-saving Irrigation on Fraction of Soil Inorganic Phosphorus in Plastic Film Houses

The results of long-term water-saving irrigation in protected soil showed that the content of Ca-P is highest among the components of inorganic phosphorus along 060 cm soil profile, and the contents of Fe-PAl-P and O-P differed from different irrigation treatments. In drip irrigation the content of O-P was higher than that of Fe-P slightly, but higher than that of Al-P obviously. In subirrigation the content of Fe-P was higher than that of O-P slightly, and this two kinds of inorganic P were higher than that of Al-P obviously. the content of Fe-P was higher than that of Al-P and O-P, and the contents of Al-P and O-P were similar in furrow irrigation. All the kinds of inorganic P decreased with the deepened profile in the three irrigation treatments, moreover the difference between various form of inorganic P was greater in upper soil layers, but lessened gradually downwards to the lower soil layers, the contents of Ca-PFe-PAl-P and O-P went to one point in 60 cm. O-P content decreased slowly and the other inorganic P decreased rapidly, especially for Ca-P along the soil profile. The contents of various inorganic P being lower and similar to each other indicated the effect of fertilization and artificial activity on the lower soil layers is little.