The purpose of this study is to determine the effect of pH, soil water content, and organic matter availability on soil P pools and Fe minerals in acid sulfate soils which are common in coastal areas and paddy rice fields. An acid sulfate soil (original pH 3.2 or adjusted to pH 5.5) was amended with mangrove root pieces to achieve an organic carbon addition of 50% or 150% of native soil organic carbon. Then, the soil was incubated for 12 weeks with 4 weeks each in submerged, and then moist and then again submerged conditions. At the end of each 4-week period, soil P pools (labile P, moderately labile P, non-labile P, and residual P), oxalate extractable Fe/Al, and potential phosphate P sorption were measured. During the submerged periods, addition of mangrove roots decreased the redox potential and increased oxalate extractable Fe, but only at pH 5.5, indicating that reducing microbes were constrained by the low pH of the original soil. Labile phosphate was up to twofold higher with mangrove roots than in the unamended control, with greatest increase at 150% OC and pH 5.5. The increase in labile phosphate was likely due to release of bound P by Fe reduction and of P released from mangrove roots. Mangrove root addition enhanced phosphate sorption during the first 8 weeks, suggesting that mangrove roots provided more P binding sites in cell walls. Raising the pH to 5.5 and addition of organic matter can enhance P availability in acid sulfate soils by providing P and enhancing soil P release.

这项研究的目的是确定pH值，土壤含水量和有机质的利用对沿海地区和水稻田常见的酸性硫酸盐土壤中的P池和Fe矿物质的影响。将酸性硫酸盐土壤（原始pH值3.2或调整为pH 5.5）用红树林根块进行修正，以使有机碳的添加量达到天然土壤有机碳的50％或150％。然后，将土壤孵育12周，浸没后分别浸润4周，然后再潮湿和浸没。在每4周的结束时，测量土壤P库（不稳定的P，中等不稳定的P，非不稳定的P和残留P），草酸盐可萃取的Fe / Al以及潜在的P吸附磷。在淹没期间，添加红树林根系会降低氧化还原电位并增加草酸盐可提取铁的含量，但仅在pH 5.5时，表明还原微生物受到原始土壤pH值的限制。红树林根部的不稳定磷酸盐最多比未经改良的对照高两倍，在150％OC和pH 5.5时最大。不稳定磷酸盐的增加可能是由于减少铁释放结合的磷和从红树林根部释放的磷。在开始的8周内，添加红树林根可增强磷酸盐的吸收，这表明红树林根在细胞壁中提供了更多的P结合位点。将pH值提高到5.5并添加有机物可以通过提供磷和增加土壤P的释放来提高酸性硫酸盐土壤中P的利用率。在OC浓度为150％和pH值为5.5时增加最大。不稳定磷酸盐的增加可能是由于减少铁释放结合的磷和从红树林根部释放的磷。在开始的8周内，添加红树林根可增强磷酸盐的吸收，这表明红树林根在细胞壁中提供了更多的P结合位点。将pH值提高到5.5并添加有机物可以通过提供磷和增加土壤P的释放来提高酸性硫酸盐土壤中P的利用率。在OC浓度为150％和pH值为5.5时增加最大。不稳定磷酸盐的增加可能是由于减少铁释放结合的磷和从红树林根部释放的磷。在开始的8周内，添加红树林根可增强磷酸盐的吸收，这表明红树林根在细胞壁中提供了更多的P结合位点。将pH值提高到5.5并添加有机物可以通过提供磷和增加土壤P的释放来提高酸性硫酸盐土壤中P的利用率。