Preparation And Application Of Microencapsulation Soil Conditioner

Fulvic acid（FA）,as a kind of soil conditioner,provides many benefits for plants by improving their drought tolerance,promoting nutrient absorption,stabilizing soil p H value and reducing fertilizer loss.At present,the research shows that FA application on soil and leaf surface is beneficial to seed germination,seedling growth and root development of crops.FA can improve soil fertility and degenerate soil.However,FA is easy to lose water and may lose its function in a short time.In order to maintain its long-term soil conditioning effect,it is necessary to use carriers to achieve the purpose of sustained release.In this paper,core-shell polymer microspheres were prepared to achieve sustained drug release.The main contents of this paper are as follows:First,the biopolymer potassium alginate（PAL）and chitosan（CS）were used as the shell materials,and the porous calcium carbonate as the core.FA was added to calcium carbonate microspheres,and potassium alginate（PAL）and chitosan（CS）were assembled in aqueous solution.PAL/CS/FA-Ca CO₃microspheres were prepared by layer by layer self-assembly.The surface morphology,encapsulation efficiency and drug release behavior were investigated.The results showed that PAL/CS/FA-Ca CO₃ microspheres were formed by self-assembly of PAL and CS,and the particle size distribution was between 2-6μM.The analysis of drug release behavior showed that the degradation degree of Ca CO₃ microspheres was different under different p H value,and the release process was delayed to different extent.The results also showed that the BET specific surface area of PAL/CS/FA-Ca CO₃microspheres decreased and the pore volume increased in the process of biodegradation and nitrogen adsorption desorption.Compared with the traditional soil conditioners,PAL/CS/FA-Ca CO₃ microspheres have broad application prospects.Second,microgel membranes were prepared by using N-isopropyl acrylamide（NIPAM）to prepare poly N-isopropylacrylamide（PNIPAM）microgel and PNIPAM hydrogel mixture by emulsion polymerization.The PAL/FA microspheres prepared by emulsification were combined with attapulgite（ATP）and PNIPAM microgel membrane to prepare PNIPAM/PAL/ATP-FA microspheres.PNIPAM/PAL/ATP-FA microspheres were prepared by emulsification and attapulgite（ATP）.The morphology,temperature sensitivity,drug release and plant growth of PNIPAM/PAL/ATP-FA composite microspheres were analyzed by SEM,continuous drug release at different temperatures and plant planting.The results showed that the particle size distribution of PNIPAM/PAL/ATP-FA composite microspheres was relatively uniform and had obvious temperature sensitive effect.With the addition of PNIPAM and PAL in the microspheres,the effect of slow-release was more obvious at 35℃than at 25℃.In addition,in the process of plant planting,the plants with faster release of PAL/FA microspheres were relatively slender.In addition,the performance of PNIPAM/PAL/ATP-FA composite microspheres with the slowest drug release showed that the roots of plants were relatively developed and strong.In conclusion,the advantages of the microspheres have broad application prospects in the field of drug release and soil conditioner.