| Frequent droughts and low fertilizer utilization are two key factors affecting crop yields.However,excessive use of traditional fertilizers has brought environmental problems,such as water pollution and land degradation.In this regard,degradable biomass fertilizers are greatly significant.In this study,mongolica sylvestris scale and potato starch were used as the main raw materials,and modified potato starch was grafted with acrylic acid to prepare an environmentally friendly hydrogel.Then,the fermented mongolica sylvestris scale particles were coated with a layer of hydrogel to synthesize a new water-retaining and slow-release fertilizer.The specific research contentsare as follows:1.Mongolica scale was used as raw material,urea was added as nitrogen source,the p H value of fermentation pile was adjusted by lime,and organic fertilizer starter was added to improve the fermentation maturity of mongolica scale.The effect of the addition amount of urea and organic fertilizer starter on its fermentation was discussed.When Z5(initial C/N30.6548 and 0.08% lime),Z9(initial C/N31.5644,0.08% lime)and Z10(initial C/N30.6548,0.08% lime and 0.2% organic fertilizer starter),the color was changed from dark yellow to dark brown,C/N was dropped to the matrix requirement,trace elements was increased,and pores also was increased significantly.2.Potato starch was as raw material,carboxymethyl potato starch sodium was prepared through etherification reaction.FT-IR showed that hydroxyl group in the native starch structure had been carboxymethylated.TG showed that the heat stability of potato starch was significantly improved after carboxymethylation.SEM showed that the carboxymethylation of potato starch,the oval shape of starch granules was broken,a lot of edges and corners appeared,and the small honeycomb holes on the surface disappeared.XRD showed that the diffraction peaks at 5.3°,15.2°,17.1° and 23° disappeared after carboxymethylation of potato starch,and the crystallinity was increased.The energy spectrum showed that Na appeared aftercarboxymethylation of potato starch,and its proportion was 8.53%.3.The single factor experiment method was used,the hydrogel was prepared by grafting carboxymethyl potato starch sodium with acrylic acid as the monomer.Comparing the effects of various reaction conditions on the water absorption performance,the optimum conditions were obtained: the amount of initiator was 3%,the amount of crosslinking agent was 0.3%,the amount of sodium carboxymethyl potato starch was 2.5g,and the degree of AA neutralization was 70%.The highest water absorption rate of hydrogel was 894.4g/g.SEM showed that the carboxymethyl starch sodium had a porous structure,and the surface presented a relatively uniform and loose three-dimensional network pore structure,which was beneficial to the improvement of the absorb liquid of resin’s ability.FT-IR showed that acrylic acid was successfully grafted onto carboxymethyl starch sodium.TG showed that the thermal stability of polymer was improved after the grafting of carboxymethyl starch sodium with acrylic acid.4.The scale granules of pinus sylvestris were coated with a layer of hydrogel by physical coating method.The results showed that within 40 days,the degradation rate of CMS/AA hydrogel in alkaline solution was 46.7%,and the degradation rate in acid solution was 35.4%.The dissolution rate method in distilled water was used to analyze the slow-release nutrient behavior of four mass ratio coatings of CMS/AA/FPR and a set of blank groups.Within 30 days,the slow-release nutrient of CMS/AA/FPR was increased by4.3%～6%.The pot experiment results showed that the prepared CMS/AA/FPR could provide the required nutrients for the plants and had the ability to retain water,which could promote the growth of plants. |
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