| Directing at the aimless and excessive application of fertilizers,the destruction of soil structure,the lower fertilizer utilization,Current state is vigorously promoting modern agriculture development road of fertilizer saving and efficiency improvement.Humic acid liquid fertilizer is a new type of fertilizer,which can improve the soil and enhance the fertilizer utilization.Using with the integrated management of irrigation and fertilizer,it will be water-saving,fertilizer-saving and more efficient.Firstly,the optimum condition to prepare humic acid by different concentrations of HNO3 and H2O2 oxidizing weathered coal was studied in the paper.Secondly the soluble humates were prepared by double activator method using alkali and H2O2.What’s more,in the preparation technology research of humic acid liquid fertilizer,basing on humic acid activated solution added in macroelements and trace elements,and the trace elements were keeped steady by using chelator.Finally,the paper dicussed the regularity of soluble humic acid concentration change after the humic acid activated solution diluted by fertilizer solution was discussed.(1)In the preparation technology research of humic acid by using different concentrations of HNO3 and H2O2 to oxidize weathered coal,taking the content of free humic acid,acidic groups,-COOH,-OH of the product as indicators,and the optimum process conditions of nitro humic acid(NHA)are as follows:the reaction time was 60min,the reaction temperature was 80℃,the coal-acid ratio(m/V)was 1:0.6(converted into pure HNO3),HNO3 concentration was 28%,the optimum concentration of H2O2 was 48%.The original weathered coal,NHA and the product oxidized by H2O2(OHA)were respectively characterized by laser particle size analyzer,FTIR and GPC.The results showed that:the medium diameter of products from small to large were NHA,OHA,the original weathered coal.The chemical structure of OHA and NHA were changed,and the new functional group and the active site increased.The original weathered coal,OHA and NHA molecular weight were 396.82×104,2.0398×104 and 0.77754×104.(2)The optimum process conditions for preparing soluble humates are as follows:alkali quantity was 45 ml,H2O2 quantity was 10 ml,the reaction temperature was 95℃,the reaction time was 60min.The content of soluble humates in humic acid activated solution could be reached 72.20 g/L.The soluble humates were characterized by laser particle size analyzer and thermogravimetric analysis(TGA).The results showed that:the soluble humates had narrow diameter distribution and high activity.(3)The conclusions were obtained in the preparation technology research of humic acid liquid fertilizer containing macroelements and chelated trace lelements.A single chelator EDTA could meet requirements in experiment.The optimum process conditions are as follows:pH was 8.0,the reaction temperature was 40℃,the reaction time was 70min,chelated ratio[n(EDTA:Zn2+)]was 1.2:1,the product met the standards NY 1106-2010 "water-soluble fertilizers containing humic-acid "requirement.(4)The paper had explored the regularity of soluble humate concentration change after the humic acid activated solution diluted by fertilizer solution,drawn the curves of concentration change and established regression equations.The model can provide theoretical and technical support for the industrial production of humic acid liquid fertilizer.The regression equations of soluble humate concentration change after the humic acid activated solution diluted by 11-4-7、9-3-5、12-4-8 fertilizer solution are as follows:(?)... |
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