| Due to the characteristics of my country’s energy resources "rich in coal,poor in oil,less gas",the coal chemical industry using coal as raw material has developed rapidly in my country.The rapid development of coal chemical industry produces a large amount of waste gasification slag at the same time.Gasification slag is the waste slag produced in the gasification process of coal-water slurry,including coarse slag and fine slag.At present,the gasification slag is mainly disposed of in landfill and open-air storage.The gasification slag is stored on the surface,which occupies a large area of land,and is blown by the wind,causing dust to fly and pollute the air;burying it underground may cause soil pollution and water pollution.Therefore,comprehensive utilization of gasification slag was urgent and necessary.The purpose of this study was to explore the resource utilization of gasification slag in agriculture.The research uses gasification slag as raw material and chemical fertilizer to make organic-inorganic compound fertilizer,and selects specific gasification slag particle size and the ratio of gasification slag to chemical fertilizer through experiments to make gasification slag compound fertilizer with slow nutrient release.The effects of particle size of gasification slag and nutrient ratio on nutrient release,soil properties and fertilizer efficiency were discussed.The main findings are:(1)The physicol properties of gasification slag with different particle sizes were obviously different.The reserch on the properties of gasification slag showed that within the research range,the specific surface area and organic matter content of coarse slag with different particle sizes increased with the decrease of coarse slag particle size,and the specific surface area and organic matter content of fine slag with different particle sizes decreased with the decrease of particle size.The content of total phosphorus and total potassium in gasification coarse slag were higher.In addition,the contents of alkali-hydrolyzed nitrogen,available phosphorus,available potassium and organic matter in fine slag were higher.The organic matter content of 0.50 mm～ 0.25 mm gasification fine slags was 39.16% higher than that of 1.00 mm～0.50 mm gasification coarse slags.(2)Both the particle size and addition proportion of gasification slag affected the nutrient release of gasification slag compound fertilizer.The water immersion test showed that when the proportion of gasification slag was 15%,the compound fertilizer with the particle size of gasification slag from 0.50 mm to 0.25 mm had the most obvious retarding effect on the release of nitrogen,phosphorus and potassium in fertilizer.When the addition ratio of gasification slag was 30% or 45% and the particle size of gasification slag was 0.25 mm ～ 0.15 mm,the delaying effect of fertilizer nutrients was better.When the particle size of gasification slag was 1.00 mm ～ 0.50 mm or 0.25 mm ～ 0.15 mm,the slow-release effect of ammonium nitrogen,phosphorus and potassium was 15% > 30% >45%.When the particle size of gasification slag was 0.50 mm ～ 0.25 mm,the slow-release effect of ammonium nitrogen,phosphorus and potassium was 15% > 45% >30% by adding amount of gasification slag.(3)Gasification slag compound fertilizer can effectively delay the release of nitrogen,phosphorus and potassium from fertilizer in soil.The soil column leaching test showed that after leaching for 15 days,nitrogen of S30,S45(the particle size of gasification slag was 0.25 mm～0.15 mm,and the proportion of gasification slag was 30%and 45% respectively),M15 and M45(the particle size of gasification slag was 0.50 mm to 0.25 mm,and the proportion of gasification slag addition was 15% and 45%,respectively)decreased by 18.39 percentage points,16.67 percentage points,10.64 percentage points and 22.20 percentage points,respectively;compared with that of the same nutrient fertilizer.Potassium content decreased by 20.88 percentage points,1.80 percentage points,29.97 percentage points and 7.19 percentage points,respectively;The phosphorus in S45 decreased by 2.37 percentage points,1.28 percentage points,0.97 percentage points and 1.34 percentage points,respectively,compared with the same nutrient fertilizer,M15,M45 and S30.(4)Different environmental conditions had a certain effect on the nutrient release of gasification slag compound fertilizer.Nutrient release experiments under controlled pot culture conditions showed that,within the research range(Soil water content is 40%,60%,80%),with the increase of soil water content,the cumulative release of gasification slag compound fertilizer increased;within the research range(p H value of soil is 5,7,8),with the increase of soil p H,the cumulative release of slag compound fertilizer increased.(5)The application of gasification slag compound fertilizer can improve the chemical and biological properties of the soil at the fertilization site.On the 45 th day of Pakchoi,the contents of soil organic matter,ammonium nitrogen and nitrate nitrogen in the fertilized part of M15 were increased by 4.64%,3.26% and 11.46% respectively compared with HF(isonutrient fertilizer treatment);the content of soil organic matter and ammonium nitrogen in the fertilized part of S45 was higher than that of HF Compared with HF,the content of soil available phosphorus and available potassium in the fertilization part of S45 increased by 19.44% and 2.89%,respectively;the content of soil available phosphorus and available potassium in the fertilized part of M15 increased by87.50% and 87.50%,respectively,compared with HF.2.73%.During the whole growth period of Pakchoi,compared with CK(No fertilizer treatment or blank treatment),the application of gasification residue compound fertilizer could increase the activities of soil urease and alkaline phosphatase at the fertilization site,but there was no significant difference with HF treatment.(6)Application of gasification slag compound fertilizer can promote the growth and yield of Pakchoi.During the harvest period,the Pakchoi height of S45 increased by 1.11 cm and 2.21 cm,respectively,compared with HF and M15.The gasification residue compound fertilizer could increase Pakchoi yield.The Pakchoi yield was M15>S45>HF>CK,and the yield of M15 and S45 increased by 4.92% and 4.32%compared with that of HF,respectively.In conclusion,gasification slag compound fertilizer has a certain slow-release effect on fertilizer nutrients.Compared with the same nutrient fertilizer,the application of gasification slag compound fertilizer could improve the soil nutrient content and soil enzyme activity,promote the growth process of Pakchoi and increase Pakchoi yield.Thus,it is feasible to prepare gasification slag compound fertilizer from gasification slag. |
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