黄土高原不同土壤质地农田土壤碳、氮、磷及团聚体分布特征

Distribution of soil organic carbon,total nitrogen,total phosphorus and water stable aggregates of cropland with different soil textures on the Loess Plateau,Northwest China

结合野外观测和室内分析,研究了黄土高原不同土壤质地农田土壤碳、氮、磷含量及其生态计量学特征,以及土壤团聚体分布状况,以揭示土壤质地对区域农田土壤肥力的影响,以及土壤团聚体对肥力的调控作用.结果表明:黄土高原农田土壤大团聚体含量、主要养分含量及其生态计量比值均随土壤质地由细变粗(壤质黏土→黏壤土→砂质壤土)逐渐降低;土壤pH值和微团聚体含量则呈现出相反的变化趋势.随土壤黏粒含量增加,大团聚体含量、有机碳、全氮和全磷含量,以及C/P和N/P显著增加,土壤pH和微团聚体含量显著降低.土壤有机碳、全氮和全磷含量,以及C/P和N/P随大团聚体含量的增加显著增加.表明区域尺度上农田土壤肥力状况取决于土壤质地,并受土壤大团聚体的调节.

In this study, combined with field investigation and laboratory analyses, we assessed the distribution of soil organic carbon, nitrogen, phosphorous contents and their stoichiometrie ratios, and the distribution of soil water stable aggregates along a soil texture gradient in the cropland of the Loess Plateau to understand the effect of soil texture and the regulation of soil aggregates on soil fer- tility in cropland. The results showed that, with the change from fine soils to coarse soils along the texture gradient （loam clay→clay loam→ sandy loam） , the contents of maeroaggregates, organic carbon, nitrogen, phosphorous and their stoichiometric ratios decreased, while pH value and micro- aggregates content showed an opposite changing pattern. The contents of macroaggregates, organic carbon, nitrogen, phosphorous, and C/P and N/P were significantly increased, but pH value and microaggregates content were significantly decreased with increasing the soil clay content. Further- more, the contents of organic carbon, nitrogen, phosphorous, and C/P and N/P increased with the increase of macroaggregates content. These results indicated that soil fertility in croplands at a re- gional scale was mainly determined by soil texture, and was regulated by soil macroaggregates.