Preparation Of Multi-functional Microbial Humic Acid Slow Released Fertilizer

The drought in some parts of our agriculture and the decline of soil fertility have seriously hindered the further development of our agriculture,at the same time,there is an irrational use of fertilizer in agriculture.Based on the shortage of agriculture in China,the potassium humate made from weathered coal with low price was used as the main raw material in this thesis,the fertilizer with water absorption,water retention and slow release was prepared by aqueous solution polymerization,the optimum preparation technology was discussed and compared with the commercial water-retaining agent,the microbial humic acid slow-released fertilizer with various functions,such as water absorption,water retention,fertilizer release,soil improvement,crop quality and so on was prepared by mixing with beneficial microorganisms.The contents of the study are as follows.(1)Used weathered coal as raw material,the optimum extraction process of humic acid(HA)was discussed by alkali dissolved and acid out analysis method.,and potassium humate was prepared under this condition.The experimental results showed that the optimum extraction process of HA were as follows: the stirring temperature is 70?,the stirring time is 30 min,the mass fraction of KOH is 2%,the ratio of volume(mL)of the KOH solution to the mass(g)of coal sample was 10: 1,under these conditions the yield of potassium humate can reach up to 82.61%.The results of FT-IR,XRD,TGA,UV-Vis spectrum and solubility analysis showed that potassium humate has non-crystalline properties,and contains functional groups such as hydroxyl,carboxyl,etc.Its molecular weight and aromatization were low,and its solubility was good.(2)Used potassium humate(KHA),diatomite(DE),acrylic acid(AA)as raw materials,N,N'-methylene bisacrylamide(MBA)as crosslinking agent,potassium persulfate(KPS)as initiator,potassium humic-diatomite-polyacrylic acid type water retention fertilizer(Recorded as composite SM)was prepared.The experimental results showed that the optimum preparation conditions were as follows: the concentration of AA was 1.63 mol/L,compared to the mass ofmonomer AA the dosage of MBA was 0.3%,the dosage of KPS was 1.8%,the dosage of KHA was 20%,the dosage of DE was 10%,and the reaction temperature was 75?,the neutralization degree of AA was 65%.Under this condition,the absorbency of the compound to tap water is 506 times,the absorbency of 0.9% brine is 91 times.The FT-IR,XRD,TGA and SEM analysis showed that the potassium humic was reactioned with acrylic acid to form the structure of alkyl aryl ether and the synthesized material had microporous structure.(3)Used potassium humate(KHA),diatomite(DE),acrylic acid(AA)and urea as raw materials,N,N'-methylene bisacrylamide(MBA)as crosslinking agent,potassium persulfate(KPS)as initiator,a rich nitrogen and potassium of potassium humic-diatomite-polyacrylic acid-urea type water absorption and slow release fertilizer(Recorded as composite SM)were prepared.The experimental results showed that the optimized preparation conditions were as follows:compared to the mass of monomer AA the dosage of KHA was 20%,the dosage of MBA was 0.3%,the dosage of KPS was 2.2%,the dosage of DE was 10%,the dosage of urea was 20%,the reaction temperature was 80?,the neutralization degree of AA was 65%,the concentration of AA was 1.63 mol/L,under this condition the highest absorption rate of tap water can reach up to 395 times,and the slow-release rate of nitrogen was only 6.04% after 24 hours.The FT-IR,XRD,TGA and SEM analysis showed that potassium humate reacted with urea and participated in the polymerization reaction,and too much urea could change its space structure and act as filler.The results of urea slow-release performance test showed that the nitrogen release rate of SF was 36.33% after 28 days,which was lower than the demand of 75% after 28 days in our country,so it could be used as slow-release fertilizer.In order to investigate the application properties of SM and SF,the ionic resistance,absorbency,water retention effect in soil,the mobility in soil,water retention performance under different conditions and repeated water absorption were compared.The experimental results showed that the composite SM and SF has stronger resistance to metal ions than the water-retaining agent sold on the market,the absorbency of SM and SF is better than that of Ax brand water-retaining agent,when mixed with soil sample at 1:1000,the waterretention effect of SM and SF in soil is better than that of Hs and Ax brand water-retaining agent sold on the market,the moving distances of SM and SF in soil were 1.3 cm and 0.7 cm higher than that of Ax brand water-retaining agent respectively,the water retention properties of the four kinds of materials were not different under natural conditions,the repeated absorbability of SM and SF is similar to that of Hs and Ax brand water-retaining agent,which can satisfy the requirement of repeated water absorption.(4)Bacillus subtilis,Bacillus licheniformis and Bacillus glia were used as compound microbial fertilizer,the results of antagonistic experiment showed that there was no antagonism among them.The effect of different proportions of various strains on soluble phosphorus and nitrate nitrogen was investigated by inoculation culture.The results showed that the best mixture ratio of Bacillus subtilis,Bacillus licheniformis and Bacillus glia was 3:3:5.The pot experiment on the compound microbial fertilizer and the series of humic acid slow-release fertilizer was carried out.The results showed that the addition of microorganism and potassium humate can increase chlorophyll content,Vc content,soluble protein content and peroxidase activity of the tested crops.Effect on soil characteristics showed that,it can reduce soil capacity and increase soil water holding capacity and porosity.Moreover,the combination of microorganisms and products with strong water-absorbing and water-retaining capacity could significantly improve the water-holding capacity of soil.