| Peat is an organic mineral resource formed by the transformation and accumulation of plant residues in swamps,and it has a certain improvement effect on coastal saline soil.In this paper,taking the coastal saline soil as the research object,setting up a soil culture experiment to analyze the physicochemical properties and soil enzyme activities of coastal saline soil after peat treatment,and at the same time combining the chemical groups and microstructure characteristics of raw peat and modified peat to explore the improvement effect and mechanism of raw peat and modified peat on coastal salt soil,the main test results are as follows:1.Both acid and alkali modification can change the physicochemical properties of the original peat,increase the specific surface area and pore volume of the peat,and improve the cation exchange capacity;under scanning electron microscopic observation,the surface of the modified peat is more smooth and flat.Among them,the acid modification method can improve the cation exchange capacity and specific surface area of peat more,acid modification method increased specific surface area of peat 10.77 m2/g,cation exchange capacity by 204.28 mmol/kg,and the alkali modification method can change the microstructure of peat more,so that the peat surface bulge can be reduced.In the infrared spectroscopy,the acid-modified method was able to introduce acidic groups such as carboxyl and nitro into the peat;the alkali-modified peat did not occur any new group introduction phenomenon,and the characteristics of the spectra were more similar with those of the original peat.2.In the greenhouse soil cultivation test,the application of modified peat and raw peat can affect the physicochemical properties of coastal saline soil,which can enhance soil conductivity,cation exchange capacity,and soil organic carbon content,and ease soil water evaporation.Acid-modified peat improves soil water-holding capacity and enhances effective soil phosphorus content,but the salinization of the soil is aggravated by the introduction of excess potassium ions during the modification process;alkali-modified peat is most effective in lowering the pH of coastal salt soils and enhances the ion exchange capacity of the soil,yet it is less effective than acid-modified peat and original peat in enhancing soil nutrient macronutrients;compared to the other two,the enhancement of ion exchange performance and improvement of soil structure of original peat is most helpful and enhances the soil carbon and nitrogen content,compared with CK,alkaliolysis nitrogen content was increased by 36.93%-106.22%,although it reduces the effective soil phosphorus content.3.Analysis of soil enzyme activities after 196 d of soil cultivation revealed that both acid-base modified peat and original peat can affect the enzyme activities in coastal salt soils.Except for alkaline phosphatase,acid-modified peat generally inhibited enzyme activities in coastal saline soils,and among the three peats,acid-modified peat showed the smallest increase in alkaline phosphatase activities but the best inhibition of urease activity,compared with CK,the urease activity was decreased by 22.86%-28.33%.The effect of alkali-modified peat on soil enzyme activities was similar to that of original peat,in that it promoted the activities of conversion enzymes such as alkaline phosphatase,cellulase,and sucrase,and inhibited the activity of urease,whereas the effect of raw peat on these enzymes was less effective than that of alkali-modified peat,and original peat inhibited the catalase activity.In the correlation analysis of soil indicators after 196 d of soil culture,the physicochemical indicators of pH,effective phosphorus,and avaliable potassium were significantly correlated with enzyme activities such as catalase,sucrase,and cellulase.4.Take these remediation effects and peat properties into consideration synthetically,alkali modified peat show the best effect on costal saline soil in this experiment. |
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