A kind of chitosan slow release fertilizer microsphere and preparation method thereof

Abstract

The invention provides chitosan controlled release fertilizer microspheres and a preparation method thereof. The controlled release fertilizer consists of biodegradable chitosan, polyvinyl alcohol, sodium alginate and a chemical fertilizer. The preparation method comprises the following steps: dissolving chitosan in an acetic acid solution; dissolving the chemical fertilizer and polyvinyl alcohol in the chitosan acetic acid solution; adding an ion crosslinking agent to obtain microspheres; and putting the microspheres in a sodium alginate solution for ultrasonic vibration to form the chitosan controlled release fertilizer microspheres. In the process of crosslinking to form the microspheres, fertilizer molecules are adhered and wrapped in crosslinked network micropores of the chitosan microspheres, so that the solubility and releasing capacity of the fertilizer molecules are changed and nutrients are slowly released along with degradation of the chitosan microspheres. At the same time, a sodium alginate electrolyte membrane is wrapped on the surfaces of the microspheres, thereby reducing the burst release phenomenon of nutrients generated in the initial release stage. The controlled release fertilizer is simple in preparation process, relatively low in cost, environmentally friendly and non-toxic and suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of slow-release fertilizers, in particular to a slow-release fertilizer microsphere prepared by mixing chitosan and chemical fertilizers and a preparation method thereof. Background technique [0002] my country is a large agricultural country. With the improvement of agricultural production technology and the increase of output, the dependence on chemical fertilizers is getting higher and higher. However, the contribution rate of traditional chemistry to food growth is only 46.3%, which is far below the level of developed countries in the world. The low fertilizer utilization rate is a problem that has always troubled people. The main reason for the low fertilizer utilization rate is the leaching and volatilization of fertilizers. A large amount of fertilizer leaching will not only reduce soil fertility and crop quality, but also cause a lot of economic losses. It will also cause environmental pollution. Therefore,...

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Problems solved by technology

[0005] Chinese Patent Publication No. CN103254024A discloses a slow release fertilizer of attapulgite mineral powder, which is prepared by fermentation of attapulgite mineral powder and poultry manure, which can reduce pollution and optimize the soil environment, but attapulgite is used as Slow-release agent, if the amount is small, the slow-release effect will not be obvious, and if the amount is too large, the nutrient release rate will be too slow, and the attapulgite soil has strong water absorption. Apply this slow-release fertilizer to the soil, and the attapulgite soil will quickly absorb the soil The moisture in the fertilizer dissolves the fertilizer, and the long-term slow-release effect cannot be achieved

[0006] The Chinese Patent Publication No. CN102826920A discloses a compound slow-release fertilizer with perlite as the carrier. The slow-release fertilizer takes perlite as the carrier, mixes and sprays sulfuric acid, nitrogen fertilizer, and potassium fertilizer aqueous solution on the perlite particles, and sprays phosphorus at the same time. The powder fertilizer forms a ternary recombination slow-release fertilizer, which uses the adsorption of perlite to release the fertilizer slowly; because perlite has strong water absorption, it can easily absorb water in the soil to dissolve and release the fertilizer loaded in the pores, slowly The release rate is relatively fast, and the effect of long-term release of nutrients cannot be achieved, so it is not suitable for the growth of crops with a long growth period.

Chitosan is a biodegradable polymer material with good adsorption properties. After it is completely degraded, it can be used as a biological micro-fertilizer to improve soil and regulate plant growth; however, chitosan is easily soluble in In the aqueous solution with low pH, a large amount of chitosan will be lost, and it cannot be directly used to prepare slow-release fertilizers. Therefore, it is necessary to modify chitosan to improve its application value in the field of slow-release fertilizers.

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