红壤基质组分对磷吸持指数的影响

在红壤旱地肥料长期定位试验(始于1988年)中,选取了无机肥试验区的NPK、NP、NK、PK,有机无机配施试验区的CK、CK+猪厩肥(BM)及CK+花生秸秆(SR)等7个施肥处理土壤,测定了土壤磷吸持指数(Phosphate sorption index,PSI),分析了PSI与红壤最大吸磷量(Xm)的相关关系,讨论了土壤pH、有机质、黏粒、铁铝氧化物及无机磷酸盐等基质组分对PSI的影响。结果表明:长期施磷或配施有机肥均可显著降低红壤PSI值,随着土壤pH的升高、有机质及铁结合态磷酸盐(Fe-P)含量的增加,红壤PSI显著降低;土壤游离铁铝氧化物及黏粒含量越高,PSI也越大。PSI与Xm呈显著线性相关关系(Xm=0.5PSI+412.8,n=15,r=0.967**,p<0.01),因此,可以用PSI替代Xm来表征土壤固磷能力,亦可由PSI的大小来推断土壤磷的供磷能力。

Effect of soil matrix components on phosphate sorption index in red soil

Soil samples were collected form the 7 treatments (NPK, NP, NK, PK, CK, CK BM, and CK SR) of a long-term upland fertilzation field experiment, which started in 1988, for determination of phosphate sorption index (PSI) with soil maximum P sorption capacity (Xm), and hence discussions on effects of the soil matrix component, like soil pH, organic matter (OM), clay, iron-aluminium oxides and inorganic phosphates on PSI. Results show that long-term application of phosphorus fertilizer or combined application of organic and chemical fertilizer could significantly reduce PSI. Wih rising soil pH and organic matter and iron phosphate (Fe-P) content, PSI decreased markedly. But the higher the contents of free iron-aluminum oxides and clay in the red soil, the higher the soil PSI. Soil phosphate sorption index (PSI) showed a significant linear correlation with soil maximum P sorption capacity (Xm), (Xm = 0.5PSI 412.8, r = 0.967**, p < 0.01). Therefore, the former could used to replace soil maximum P sorption carpacity (Xm) to characterize soil phosphorus sorption capacity and soil phosphorus supply capacity as well.