脱硫石膏配施不同有机物料对盐渍土活性有机碳及酶活性的影响OA

China has extensive areas of saline-affected soils,and their amelioration is crucial for expanding cultivated land and ensuring food security.Through field experiments,this study investigated the effects of co-application of desulfurization gypsum with biochar or cattle manure on labile organic carbon fractions,structural characteristics of dissolved organic carbon(DOC),and soil enzyme activities in salined soils of the Yellow River delta.The experiment comprised four treatments:control of no desulfurization gypsum or organic materials added(CK),desulfurization gypsum application alone(G),combined application of desulfurization gypsum and biochar(GB),and combined application of desulfurization gypsum and cattle manure(GM).Results demonstrated that compared with CK,the G and GM treatments significantly increased the contents of DOC,readily oxidizable organic carbon(ROC),hot water-extractable organic carbon(HEOC),and total organic carbon(TOC)by 5.31%and 24.34%,6.06%and 54.55%,2.12%and 9.24%,6.88%and 57.27%,respectively(P<0.05).The GB treatment significantly reduced DOC and HEOC contents,compared to CK,but notably enhanced TOC content.Both G and GM treatments significantly improved the soil carbon pool management index relative to CK.UV-Vis spectral analysis of DOC revealed that G and GM treatments significantly decreased SUVA₂₅₄,SUVA₂₆₀,and SUVA₂₈₀values,while markedly increasing E250/E365 and E253/E203 ratios,compared to CK.Compared with CK,invertase activity,β-glucosidase activity,geometric mean enzyme activity,and total enzyme activity in G and GB treatments increased by 19.63%and 29.43%,91.08%and 57.08%,18.46%and 18.62%,and 19.01%and 18.18%,respectively(P<0.05),whereas catalase activity decreased by 7.52%and 16.37%(P<0.05).Correlation and grey relational analyses indicated that catalase activity played a significant role in influencing DOC and HEOC contents,while polyphenol oxidase activity was crucial in affecting DOC structural parameters.In summary,the combined application of desulfurized gypsum and cattle manure could increase the labile organic carbon content in salined soil,while reducing the molecular weight of DOC,the degree of humification,and the proportion of hydrophobic components.This made it an effective measure for enhancing organic carbon in the saline soils of the Yellow River delta.