土壤中钙键和铁/铝键结合的有机碳差异的比较

为研究矿质元素在有机碳矿化中所起的作用,以棕壤、黄棕壤、红壤为供试土壤,比较了不同利用方式和施肥处理土壤中钙键、铁/铝键结合的有机碳的差异。结果表明,从北至南的地带性土壤(棕壤、黄棕壤和红壤)系列中,全钙及与有机碳结合的钙依次降低,钙键结合的有机碳占有机碳总量的比值依次升高;铁/铝键结合的有机碳及其占全碳的比值依次升高。与自然土壤相比,耕作土壤在不施肥条件下,钙键有机碳、铁/铝键有机碳占有机碳总量的比值增加,且铁/铝键有机碳占有机碳总量比值的增加率始终比钙键有机碳占有机碳总量比值的增加率要高;覆膜比不覆膜时铁/铝键有机碳占有机碳总量比值的增加率比钙键有机碳占有机碳总量比值的增加率高得多。这表明,与全土有机碳相比,有机碳矿化稳定性由高到低依次是铁/铝键有机碳、钙键有机碳、全土有机碳。

Comparisons of Ca-Bound and Fe/Al-Bound Organic Carbon in Soils

For studying the function of the mineral elements in the mineralization of soil organic carbon, the contents of Ca- and Fe/Al-bound organic carbon in soils (Brown earth, Yellow-Brown soil and Red soil) with different utilization and fertility leves were determined. The Ca-bound organic carbon (Ca-C) was extracted by 0.5M Na2SO4(pH7.0),and Fe/Al-bound organic carbon (Fe/Al-C) by 0.1M Na4P2O7(pH13).The Ca-C and Fe/Al-C were detected by High TOC II (Elementar, Germany).The result showed that the ratio of Ca-C to the total organic carbon (TOC) and the ratio of Fe/Al-C to TOC increased in the soils from North to South. Compared with native soils, the ratio of Ca-C to TOC and the ratio of Fe/Al-C to TOC in the infertile soils increased significantly. Under the condition of film-covered soil, the ratio of Ca-C to TOC and the ratio of Fe/Al-C to TOC increased more greatly than uncovered soil. Compared with native soil, the increased ratio of Fe/Al-C to TOC is always higher than the increased ratio of Ca-C to TOC in the lower fertility treatment. We concluded that the stability of mineralization of soil organic carbon decreased as follows: Fe/Al-C > Ca-C > organic carbon of whole soil.