The impact of saline soil amelioration on recovery of Suaeda glauca and soil physicochemical properties in degraded coastal wetlands
In order to investigate the effects of aligned soil improvement on the recovery of Suaeda glauca and the enhancement of soil quality,four treatments were set up in Yancheng,Jiangsu.Including(Ⅰ)ploughing+fertilization-ploughing 25 cm and fertilizing,application rate was 0.125 kg/m2,(Ⅱ)ploughing-only ploughing 25 cm,(Ⅲ)ploughing+covering-ploughing 25 cm and covering straw,the amount of the straw was 0.5 kg/m2,and(Ⅳ)ploughing+sawdust-ploughing 25 cm and improving with sawdust,the amount of the sawdust was 1 kg/m2.The study investigated the effects of various treatments on the growth index of Suaeda glauca,as well as the physicochemical properties and soil enzyme activities.Additionally,a comparison was made regarding how these treatments influenced the regulation of wetland soil structure,enhancement of soil fertility,and reduction of salinity.The results showed that the treatments had a significant promoting effect on the recovery of Suaeda glauca.There was no significant difference in the single plant growth index of Suaeda glauca among the four different treatments,but the number of plants per unit area and the biomass per unit area were significantly higher than that under the control(n=3,p<0.05).The treatments significantly enhanced soil looseness and reduced bulk density(BD)at a depth of 0-10 cm.In comparison to the control group,the total porosity(TP)of the soil increased by 5.77%,8.32%,11.62%,and 9.88%,respectively;but had little effect on the soil physical properties at the depth of 10-30 cm.Under improvement treatments,the content of soil organic carbon(SOC),total nitrogen(TN)and effective phosphorus(AP)of soil at the depth of 0-10 cm layer increased,with ploughing+fertilization treatment(I)demonstrating the most significant fertilizer effect.The organic carbon,total nitrogen and available phosphorus content increased by 21.90%,23.15%and 60.29%compared to the control group,while soil salinity was significantly reduced.However,the effective potassium content in the soil at all depths did not change significantly.Four improved treatments significantly increased soil urease(SUE)and alkaline phosphatase(ALP)activities at a depth of 0-10 cm.Specifically,SUE activity was found to be 1.40 times,1.05 times,1.72 times and 1.43 times that of the control group,and ALP activity was recorded as being 1.13 times,1.04 times,1.09 times and 1.06 times that of the control group.Similar trends were observed in the soil at 10-20 cm depth,but the two enzyme activities at 20-30 cm depth did not show significant differences.Correlation analysis revealed that ALP activity had a significant positive correlation with TP,SOC,TN,and AP(n=3,p<0.05),and significantly negatively correlated with potassium content(n=3,p<0.05).SUE activity was significantly positively correlated with TP,SOC and TN(n=3,p<0.05).Both enzyme activities showed a significant negative correlation with soluble salt content(n=3,p<0.05).Among the four improved methods tested,ploughing+covering treatment(III)significantly enhanced both pore conditions and enzyme activity within saline soils,with this improvement effect being particularly pronounced.