| Tailings are related to the good development of mining and are a potential resource that can be utilized.In recent years,with the advancement of urbanization and the high development of material civilization,mining industry has developed vigorously.However,the continuous accumulation of tailings has triggered a series of environmental problems,seriously threatening the safety of people’s lives and property,hindering the sustainable development of mining industry,making the treatment and utilization of tailings hot attention.This study took the soil of Kunyang Phosphate Mine in Jinning District,Kunming City,Yunnan Province as the research object,selected the waste phosphorus tailings of the mining area as the main improvement material,and used the biochar and organic fertilizer as the auxiliary materials,and used the soil culture test to screen out the best proportion of each component in the modifier,and took Chinese cabbage and pepper as the planting objects,and explored the best amount of the modifier in the soil through the pot experiment,An experiment was designed to study the effect of storage time on the improvement effect of soil conditioner.The main research conclusions are as follows:(1)There is no heavy metal contaminated soil in the study area.Taking the“Soil Nutrient Grading Standard”as a reference,the main problems in the soil of the mining area are low organic matter content,alkaline nitrogen content,and cation exchange capacity.(2)In soil culture experiments,the application of soil amendments could improve various nutrient indicators in the original soil,and different components of soil amendments had different effects on improving various nutrient indicators in the soil.In the process of improving soil with amendments,the presence of phosphorus tailings would have an inhibitory effect on the improvement of cation exchange capacity,alkaline nitrogen content,organic matter content,and available potassium content in the soil by the amendments;Promote the improvement of soil p H and available phosphorus content by amendments.(3)Taking the “Soil Nutrient Grading Standard” as a reference,when designing specific scoring rules to select the optimal ratio of each component in soil amendments,the highest score of B3O2-25% is 74,which is 85% higher than the original soil sample score;The optimal ratio of each component in the developed soil amendment is phosphorus tailings: biochar: organic fertilizer=15:3:2.(4)As the storage time of soil amendments increased,when biochar was added as an auxiliary material,the cation exchange capacity of the amendments decreased by45.39%,the alkaline nitrogen content decreased by 18.60%,the effective phosphorus content decreased by 6.59%,the organic matter content decreased by 23.96%,and the available potassium content decreased by 8.66%.After the amendment was applied to the soil,the cation exchange capacity increased by 112.23%,the alkaline nitrogen content decreased by 24.77%,the effective phosphorus content decreased by 24.98%,the organic matter content increased by 6.17%,and the available potassium content increased by 0.96%;When organic fertilizer was added as an auxiliary material,the cation exchange capacity of the modifier increased by 10.71%,the alkali hydrolyzed nitrogen content increased by 18.30%,the effective phosphorus content increased by9.42%,the organic matter content increased by 2.31%,and the available potassium content increased by 10.24%.After the modifier was applied to the soil,the cation exchange capacity of the soil increased by 6.30%,the alkali hydrolyzed nitrogen content decreased by 17.21%,the effective phosphorus content increased by 4.12%,and the organic matter content increased by 25.40%,The content of available potassium increased by 9.68%.As the placement time of amendments increases,the changes in nutrient indicators in soil are not only related to the changes in the indicators of the amendments themselves,but also influenced by the interaction between the amendments and the soil.(5)In the pot experiment,compared with the blank group,the addition of amendments increased the organic matter content in the soil of Chinese cabbage by179.46%,cation exchange capacity by 13.41%,alkali hydrolyzed nitrogen content by172.27%,effective phosphorus content by 46.52%,and available potassium content by170.02%.The germination rate of Chinese cabbage decreased,and the fresh weight and dry weight of Chinese cabbage increased by 29.52% and 35.20% respectively;Compared with the blank group,the addition of amendments increased the organic matter content in chili soil by 64.93%,cation exchange capacity by 26.31%,alkaline nitrogen content by 38.13%,effective phosphorus content by 59.67%,and available potassium content by 125.04%.The germination rate of chili peppers was improved,with an average plant height increased of 162.50%,a maximum plant height increased of 24.14%,a fresh weight increased of 258.27%,and a dry weight increased of 277.78%.The addition of soil amendments could reduce the germination rate of Chinese cabbage,but could promote its growth and increase its fresh and dry weight;The addition of improvers could increase the germination rate of chili peppers,shorten the germination cycle of their seeds,promote chili pepper growth,and increase the plant height,fresh weight,and dry weight of chili peppers.(6)When evaluating the optimal amount of soil amendments added to the soil,the comprehensive evaluation of soil nutrient indicators in pot experiments,as well as the weighting of plant fresh weight and dry weight,were used for scoring.The optimal amount of soil amendment in different plant potted experiments was different.Among them,the optimal amount of soil amendment in Chinese cabbage potted experiment was 3%,and its comprehensive score increased by 52.87% compared to the blank;The optimal amount of soil amendment added in pepper pot cultivation was 6%,and its comprehensive score increased by 244.11% compared to the blank. |
