Effects of montmorillonite,kaolinite and basalt on soil carbon sequestration
To investigate the impact of basalt,montmorillonite,and kaolinite on soil physicochemical properties and carbon pool components,a field micro-plot experiment was conducted to assess their effects on soil particle structure,pH,and contents of available nutrients,dissolved organic carbon(DOC),microbial biomass carbon(MBC),or-ganic carbon,and inorganic carbon.It was shown that compared to the treatment using pecan shell organic fertilizer alone(H),the treatments of co-application of pecan shell organic fertilizer+basalt(BH),pecan shell organic fer-tilizer montmorillonite(MH),or pecan shell organic fertilizer+kaolinite(KH)significantly(P＜0.05)reduced soil MBC content by 8.7％,10.3％,and 9.7％,respectively.The BH treatment significantly increased soil pH value by 0.80 and elevated soil DOC,organic carbon,and inorganic carbon contents by 9.4％,3.6％,and 939.2％,respectively.The MH treatment significantly boosted the soil exchangeable calcium and magnesium content and cation exchange capacity by 77.3％,471.7％,and 80.2％,respectively,and increased the soil organic carbon and inorganic carbon contents by 2.5％and 543.2％,respectively.The KH treatment significantly enhanced the proportion of water-stable macroaggregates(particle size≥0.25 mm)by 2.3 percentage points,and raised the soil organic carbon and inorganic carbon contents by 2.8％and 646.3％,respectively.Except for the significant rise in available potassium content under BH and MH treatments,BH,MH and KH treatments had no significant impact on the contents of the other available nutrients(alkali-hydrolyzable nitrogen and available phosphorus).In conclusion,applications of basalt,montmorillonite,and kaolinite combined with organic fertilizer could stabilize the soil organic carbon,which achieved the synergistic stabilization of both organic and inorganic carbon,and the application of ba-salt combined with organic fertilize showed the best effect on the inorganic carbon sequestration.
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