The Preparation Of Turf Cultivation Base Material From River Sediment

A vast amount of river sediment has been produced annually as a result of the large-scale development of water environment treatment projects in China.Therefore,there is an urgent need to develop resource utilization methods for river sediments.At the same time,turf planting causes severe topsoil stripping and nutrient loss,damaging the natural soil.The use of river sediment to prepare turf planting substrates is an effective way to solve the aforementioned problems.In this study,river sediment,fly ash,and herbal residues were used as the main substrate materials.A response surface method was applied to analyze the effect of different substrate formulations on the overall quality of turf through field trials with extreme vertex design experimental treatments.A mixture regression model was established to screen the optimal matrix formulas for turf planting.The physical and chemical properties of the matrix formula and its influence on the stoichiometric ratio of carbon,nitrogen,and phosphorus above the turf were analyzed to provide a theoretical optimal matrix formula.Finally,the safety and economic evaluation of the application of the optimal matrix formula was conducted to provide a reference for the industrial utilization of river sediments.The main findings of this study are as follows.1.The stepwise regression analysis method of the mixture was adopted to obtain the polynomial regression equation for the comprehensive quality of turf,which is:Comprehensive quality U(x)=2.966X+3.18Y-6.01Z+37.4XZ,R2=0.8321**X: River sediment;Y: Fly ash;Z: Herbal residue.When the comprehensive quality of turf is greater than eight(the best comprehensive quality),the optimal matrix formula is: river sediment 60.00% ～71.88%,herbal residue 28.12% ～ 40.00%,and fly ash 0%.Increasing the proportion of herbal residues in the matrix formula can continuously improve the overall quality of turf.With the increase in proportion of fly ash and river sediment,the comprehensive quality of turf continues to decline.The negative impact of fly ash on the comprehensive quality of turf is more significant than that of river sediment.2.The polynomial regression equation of p H value,organic matter,alkalidecomposable nitrogen,available phosphorus,and available potassium was established using the mixed material stepwise regression method.Based on the above model,the nutrient content of the optimal matrix formula can be predicted as: p H value: 7.04 ～7.12;organic matter: 111.27 g/kg ～ 130.58 g/kg;alkaline nitrogen: 130.97 mg/kg ～158.90 mg/kg;available potassium: 839.53 mg/kg ～ 1,116.86 mg/kg;the effective phosphorus content cannot be accurately predicted due to the extremely poor fit of the regression model.The optimal matrix formula contains rich organic matter,nitrogen,phosphorus,potassium,and other nutrients.The physical conditions of the optimal substrate,such as bulk density and porosity,are more suitable for plant growth.The contents of Cd and Ni are relatively low,which has a reduced negative impact on plant growth.In addition,the optimal substrate formula produced a lower carbon to nitrogen ratio,carbon to phosphorus ratio,and nitrogen to phosphorus ratio of the upper part of the turf;the ratio ranges are 42.79 ～ 43.7,331.86 ～ 338.25,8.13 ～ 8.66,respectively,indicating that turf growth rate is higher.3.With reference to GB4284-2018 "Agricultural Sludge Pollutant Control Standards",the pollutant content of the optimal matrix formula was much lower than the standard requirements,indicating that the use of the optimal matrix formula to plant turf satisfied environmental safety requirements.Based on the annual production of the two seasons of turf,the cost per mu of turf produced by the optimal formula substrate was 5,279 Yuan,and the profit was 2,624 Yuan.Compared with the traditional turf planting mode,the cost increased by 1,058 Yuan,and the profit reduced by 1,026 Yuan.When the cost of planting the sod is included in the backfill soil full scale,the cost and profit differences between the two models is not evident.In addition,the application of an optimal substrate to produce turf achieved the utilization of river sediment and protected the cultivated soil and ecological environment,while also presenting significant ecological and social benefits.