Effects Of Sludge Compost On Physicochemical Properties Of Saline-alkali Soil And Growth Of Cool-season Turfgrasses

With the acceleration of urbanization and the strengthening of environmental protection awareness,the number and scale of construction of sewage treatment plants have been increasing in recent years.However,due to the incomplete construction of sludge disposal facilities,the shortage of investment,and the prominent problem of "heavy water and light mud",many sludge generated in the process of sewage treatment has not been properly disposed of.Saline-alkali soil is widely distributed in our country,and the saline-alkali soil in the northwest area accounts for about 60% of the country,which greatly affect land use.There are rich nutrients in the sludge.Land use after composting can not only effectively solve the problem of sludge disposal,but also improve the characteristics of saline-alkali land and promote plant growth.Greening can improve the green coverage rate.This study made use of the complementary physical and chemical properties and fertility of sludge compost and saline-alkali soil.Through the pre-planting test,reference to relevant standards and previous studies,the addition range of sludge compost test was determined and pot comparison test was conducted.Agrostis stolonifera,Poa pratensis and Festuca elata were used as materials.Salinized soil was used as blank control(CK)and nutritive soil as reference(S).Sludge compost mixed with saline-alkali soil dry weight ratio of 5%,10%,20%,40%,60% for experimental groups.To study the effects of sludge compost and saline-alkali soil composite matrix of different proportions on the growth of turfgrass,and the effects of planting turfgrass on composite matrix,explore the feasibility of application of composite matrix in greening lawn,and provide new ideas for sludge compost resource utilization and reducing the planting cost of turfgrass in saline-alkali soil matrix,and draw the following conclusions:(1)The heavy metal content of the tested sludge compost was determined to meet the A-level standards of the "Standards for Control of Pollutants of Agricultural Sludge"(GB4284-2018)and meet the experimental requirements.Sludge compost could effectively improve some physical and chemical properties of saline-alkali soil,including p H,salt content,bulk density,porosity,saturated water capacity and so on,and significantly improve the fertility level.According to the optimal standard value,previous studies and soil comprehensive evaluation index(SQI)analysis,the optimal application ratio of sludge compost is 10% and 20%.(2)Plant height,root length,fresh weight,dry weight,chlorophyll content,soluble sugar content,free proline content,malondialdehyde content and plateau quality of turfgrass planted on the mixed substrate of sludge compost and saline-alkali soil with different ratios were measured at 25 d and 45 d,and each index was quantitatively analyzed by grey relational analysis method.The results showed that applying appropriate amount of sludge compost in saline-alkali soil could effectively improve the quality and usability of turfgrass,and the effect was related to the application amount of sludge compost,the types of turfgrass and the growth time of turfgrass.The quality of Agrostis stolonifera,Poa pratensis and Festuca elata were the best under the conditions of sludge compost application ratio of 20%,10% and 20% respectively.The promotion effect of Agrostis stolonifera,Poa Pratensis and Festuca elata on the quality of Agrostis stolonifera was greater than that of Poa pratensis,and Festuca elata was the least.Under the condition of low sludge compost application rate,all indexes of turfgrass at 45 days were better than those at 25 days,whereas under the condition of high sludge compost application rate,all indexes of turfgrass at 45 days were deteriorated to varying degrees.(3)By measuring the physical and chemical indexes and fertility indexes of the mixed matrix of sludge compost and saline-alkali soil before and after the planting test,the results showed that planting turf grass could effectively reduce the p H value,salt content and bulk density of the mixed matrix,and improve the total porosity and saturated water capacity.Agrostis stolonifera,Poa pratensis and Festuca elata improved the mixed matrix the most when the dry weight ratio of sludge compost was 20%,10% and 20%,respectively.The improvement of Festuca elata was greater than Poa pratensis,and Agrostis stolonifera was weaker.