Utilization Of Dredging Silt From The North Canal River On Preparing Mineral Compound Fertilizer And Planting Experiment

Each year,a large amount of financial and material resources spent on the phenomenon of accumulation of dredging silt in the North Canal River.The silt is directly piled up on the ground,occupying land resources,which is in urgent need of comprehensive utilization.The dredged silt has the problem of low organic matter content and the nutrient elements could not be absorbed directly by plants and soil.To improve dredging silt usage in fertilizer,this paper collected dredging silt from the North Canal River as main raw materials,adopting the method of microorganism fermentation and sintering respectively,preparing dredged silt-garden waste biomass-lignite humic acid mineral compound fertilizer and dredged silt mineral compound fertilizer.The planting experiments were carried out,and explore the feasibility of dredged silt mineral compound fertilizer.It provides a new way for comprehensive utilization of dredged silt.Specifically carry out the following work:(1)The dredged silt of the North Canal River was collected,and the physical index,nutrient index,pollutant concentration limit and hygienic index were detected.The indexes basically met the National Standard for land improvement of silt(GB/T 24600-2009).Therefore,the dredged silt could be used as raw material to prepare mineral compound fertilizer.(2)To improve the dredged silt organic matter content,using dredge silt,garden waste biomass and lignite humic acid as raw materials,the mineral compound fertilizer was prepared by using the method of microorganism fermentation,in order to explore how the different ratio of raw materials and fermentation conditions on the dredged silt-garden waste biomass-lignite humic acid compound fertilizer minerals affect the organic matter content and total nutrients.The study showed that when the fermentation conditions were C/N=30,the initial water content was 50%,and the ventilation rate was 0.6 L/min,comparing with the dredged silt,the organic matter content increased from 3.90% to 36.50%,and the total nutrient content increased from4.50% to 9.05%.(3)To increase the contents of K2 O and MgO in dredged silt,the dredged silt was used as raw material and the activators K2CO3 and MgO were added to prepare dredged silt mineral compound fertilizer through sintering method.The influence of different sintering temperatures and time on the composition and dissolution of the dredged silt mineral compound fertilizer was investigated.The result showed that when the sintering condition was 900℃ for 60 min,the release of K2 O in K2 MgSi3O8 mineral compound fertilizer in 20 g/L citric acid for 1,28 and 112 days were in line with the national standard of slow-release fertilizer(GB/T 23348-2009).The contents of As,Cd,Pd and Cr were in line with the National Standard for fertilizer heavy metals(GB/T 23349-2009).Compared with dredged silt,K2 O increased from 3.57% to 29.80%,and MgO increased from 2.30% to 8.55%.(4)The efficiency of dredged silt-waste garden biomass-lignite humic acid mineral compound fertilizer and dredged silt mineral compound fertilizer were verified through pot experiment of small rapeseed and field planting experiment of oilseed rape in the greenhouse,Beijing,Daxing District.The pot experiment showed that when the dredged silt-waste garden biomass-lignite humic acid mineral compound fertilizer content was 2%,the fresh weight and dry weight of rape were 2.5 times and 8.9 times higher than that of the group without fertilizer.When 2% dredged silt-waste garden biomass-lignite humic acid mineral compound fertilizer and2% dredged silt mineral compound fertilizer were mixed,the fresh weight and dry weight of rape were increased by 3.5 times and 10.9 times than that of the group without fertilizer.Field planting experiments showed that the fresh weight of oilseed rape increased by 0.5 times compared with the unapplied group when the silt-waste garden biomass-lignite humic acid mineral compound fertilizer was added by 2%.The soil organic matter test showed that the application of mineral compound fertilizer is beneficial to improve soil fertility.