Effects of different fertilization and sowing amounts on vegetation restoration and soil quality in alpine mining areas and comprehensive evaluation
The Muli coal mining area is located in the hinterland of the Qilian Mountains on the Qinghai-Tibet Plateau.After years of mining activity,excessive open-pit mining activities have encroached on swampy wetlands and a large amount of waste residue from mining has been landfilled.Soil affected by mining activity is infertile,which leads to difficulties in environmental restoration and high restoration costs.Therefore,it is crucial to conduct experiments to identify an efficient and low-cost ecological restoration plan.The experiment conducted forms part of a large-scale restoration program in Qinghai Province and comprised two-factors(fertilization and seeding rates),and three-levels of each.Specifically,the fertilization rates were:low fertilization,F1(sheep manure 165 m3·ha-1+organic fertilizer 7.5 t·ha-1+forage special fertilizer 75 kg·ha-1);medium fertilization,F2(sheep manure 330 m3·ha-1+organic fertilizer 15 t·ha-1+forage special fertilizer 150 kg·ha-1);and high fertilization,F3(sheep manure 495 m3·ha-1+organic fertilizer 22.5 t·ha-1+forage special fertilizer 225 kg·ha-1).The three seeding rates were:low seeding rate,S1(60 kg·ha-1);medium seeding rate,S2(120 kg·ha-1);and high seeding rate,S3(180 kg·ha-1).A total of nine restoration treatments were formed from the combinations of the three levels of fertilization and seeding rate,namely:low fertilization and low seeding rate(F1S1),low fertilization and medium seeding rate(F1S2),low fertilization and high seeding rate(F1S3),medium fertilization and low seeding rate(F2S1),medium fertilization and medium seeding rate(F2S2),medium fertilization and high seeding rate(F2S3),high fertilization and low seeding rate(F3S1),high fertilization and medium seeding rate(F3S2),and high fertilization and high seeding rate(F3S3).This experiment design therefore comprehensively evaluated the overall effectiveness of different restoration programs by exploring vegetation growth and soil quality changes in mining areas under various restoration treatments.Data were analyzed using grey relational analysis and the entropy weight TOPSIS method.The study results indicate that applying fertilizer and adjusting seeding rates significantly enhances vegetation restoration in the mining area(P<0.05).With medium and high fertilization treatments,vegetation cover exceeded 70%,vegetation density reached 8826-10447 plants·m-2,and aboveground biomass significantly increased to 445.51-559.47 g·m-2.Some restoration treatments also improved soil physical properties significantly(P<0.05).With medium and high fertilization treatments,soil bulk density averaged 0.94 g·cm-3.Moreover,increased fertilizer application led to a significant increase in soil moisture content,which reached 39.31%and 38.28%under F3S2 and F2S3,respectively.Soil saturated capacity and capillary water holding capacity also increased significantly(P<0.05)under high seeding rate treatments,with the highest values of 91.14%and 81.39%,respectively,under the F3S3 treatment.In terms of soil nutrient characteristics,medium and high fertilization treatments increased organic matter by an average of 26.23%,and the pH value averaged 7.5,indicating a slightly alkaline soil.Additionally,essential nutrients such as nitrogen,phosphorus,and potassium increased significantly with increasing fertilization(P<0.05).Through measured plant and soil indicators,grey relational analysis,and entropy weight TOPSIS analysis,it is evident that the restoration program with medium fertilization and high seeding rate(F2S3)offers dual advantages in both ecological and economic benefits.In conclusion,this study finds that 330 m3·ha-1 sheep manure,15 t·ha-1 organic fertilizer,150 kg·ha-1 specialized forage fertilizer,and a seeding rate of 180 kg·ha-1 in the Muli mining area of Qinghai Province can be recommended as the optimal combination for ecological restoration.
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