Study On The Degradation Mechanism And Potting Effect Of Biodegradable Polymer Materials Containing Multiple Nutrients

In recent years,due to urban expansion and soil erosion,the area of arable land has been continuously reduced,and the pressure on food has been increasing.Agricultural production has increasingly relied on the use of agricultural materials(including chemical fertilizers)to increase food production to reduce the pressure on arable land.However,traditional agricultural materials have low nutrient content,easy loss and low utilization rate.At this time,the development of new agricultural materials with high nutrient content,high element utilization rate,increased production and income,and green environmental protection is imminent.In order to improve the shortcomings of traditional agricultural materials,slow and controlled release materials have been developed and widely used.However,the various controlled release materials currently used also have deficiencies.For example,the shortcomings of urea-formaldehyde slow-release material include too long degradation cycle,low nitrogen utilization rate and single nutrient composition;the cost of coated slow-release material is high and the membrane material is not easy to degrade,which will cause environmental pollution.Based on this,people try to use biodegradable polymer materials as agricultural materials.Biodegradable polymer materials are rich in nutrients,and can be degraded by water and microorganisms in the soil to release nutrients,without degradation residues,and are environmentally friendly.In this paper,the biodegradable polymer composite materials with various nutrients developed by Shanxi Key Laboratory of Nanofunctional Composite Materials were used as the research object.The effects of different sodium silicate or boric acid additions on the composition and structure of the composite were studied respectively,and the degradation mechanism,nutrient slow-release characteristics and practical application effects were studied through tomato pot experiments.The specific research content and results are as follows:(1)The effect of adding sodium silicate on the composition and structure of biodegradeble polymer composite materials containing nitrogen,phosphorus,potassium and silicon(SiPSRF-1 and Si-PSRF-2)was studied.And the influence of the composition structure of Si-PSRF-1 and Si-PSRF-2 on its biodegradability,nutrient slow-release characteristics and pot application effect.The research results show that: adding sodium silicate will increase the content of low molecular weight PSRF in Si-PSRF-1 and Si-PSRF-2 and introduce silicic acid gel,and the more sodium silicate is added,the higher the content of low molecular weight PSRF and silicic acid gel.The increase in the content of low molecular weight PSRF will lead to an increase in the release rate of nutrients in Si-PSRF-1 and Si-PSRF-2;the hydrophobicity of the silicic acid gel will hinder the degradation of materials by water and microorganisms,resulting in a reduction of the nutrient release rate of Si-PSRF-1 and Si-PSRF-2 in the early stage.The application of silicon-containing polymer composite materials can effectively adjust the physical and chemical properties of the soil and increase the nutrient content of the soil,thereby providing sufficient nutrients for the growth of tomatoes;the application of silicon-containing polymer composite materials can promote the photosynthesis of tomatoes,thereby promoting the nutrients in the soil Absorption.The cumulative amount of tomato elements increased with the addition of sodium silicate.The application of silicon-containing polymer composites can effectively improve tomato yield and tomato quality.(2)The effect of the addition of boric acid on the composition and structure of biodegradeble polymer composite materials containing nitrogen,phosphorus,potassium and boron(BPSRF-1 and B-PSRF-2)was studied.And the tomato pot experiment was used to study the effects of the composition and structure of B-PSRF-1 and B-PSRF-2 on biodegradability,nutrient slow-release characteristics and pot application effects.The results show that BPSRF-1 with low boric acid content contains more high molecular weight PSRF and high crystallinity,so its degradation rate is slower in the early stage;when PSRF in the crystallization area is exposed to water,the degradation rate increases.B-PSRF-2 with high boric acid content contains more high molecular weight PSRF,and the early degradation rate should be slower than B-PSRF-1;however,excess boric acid will form more voids in B-PSRF-2 than BPSRF-1,resulting in an increased degradation rate of B-PSRF-2.Therefore,as the amount of boric acid added increases,the material's degradation performance and nutrient slow-release characteristics change nonlinearly.The application of boron-containing polymer composite materials can promote the development of tomato roots,thereby increasing the nutrient absorption rate of tomatoes,resulting in an increased utilization of nitrogen and phosphorus elements in the materials.The cumulative amount of tomato elements is proportional to theamount of boric acid added.The application of boron-containing polymer composite materials can effectively increase tomato yield,but has no significant effect on tomato quality.