Study On Application Effect And Related Mechanism Of Kaolin Modified Water Absorption Biodegradable Polymer Sustained Release Material

In recent years,the population has grown rapidly,and the cultivated area have been continuously reduced because of the ecological problems such as soil erosion,the food problem has become increasingly prominent.Water and nutrients are two important factors affecting plant growth.In order to adjust the balance of water and nutrients,our laboratory has developed a kind of kaolin-modified biodegradable polymer sustained-release material with water absorption and water retention function,but its performance is not specifically study.Therefore,this paper studies the practical application effect of the material,the degradation properties and nutrient release properties of kaolin modified water absorption biodegradable polymer sustained-release materials were studied.The effects of the materials on soil environment and plant growth were further studied.Finally,the leaching characteristic of nutrients in soil was studied by leaching experiments.In order to more realistically reflect the performance advantages of kaolin modified water-absorbing biodegradable polymer sustained-release materials,four experimental treatments were set up for horizontal comparison:PSRF（N,P,K biodegradable organic polymer sustained release material）,SI-PSRF/SAP_KL（kaolin modified biodegradable polymer water-absorbing slow-release material）,PSRF+SAP_KL(kaolin modified water-absorbent resin SAP_KL and PSRF simple physical mixing),CK（no material treatment）.The effects of different materials were compared by tomato pot experiment and laboratory soil column leaching experiment.The specific research contents are as follows:（1）The degradation performance and nutrient release properties of different materials in soil-plant ecosystem were studied by tomato pot experiment.The results show that the introduction of water-absorbing components in the polymer sustained-release material can effectively improve the degradation performance and nutrient release properties of the material;the combination of the water-retaining agent SAP_KL and the polymer sustained-release material PSRF is different,and the nutrient release mechanism is also different.PSRF+SAP_KL is a simple physical mixture.SAP_KL can adsorb and desorb small molecules released during PSRF degradation,which has a certain retarding effect on the release of nutrients.However,SAP_KLL is difficult to degrade in soil,resulting in the poor degradation of materials.SI-PSRF/SAP_KL is a composite material with a semi-interpenetrating network structure.The molecular chain containing nutrient elements is interspersed in the crosslinked network structure,and the crosslinked network can hinder the small interspersed inside the structure through physical action.The release of molecules plays a better nutrient-releasing effect.At the same time,the cross-linked network structure in the composite is easily degraded by microbial attack,so it also has better degradation performance,and is superior to PSRF and PSRF+SAP_KL two materials in nutrient sustained release and degradation performance.（2）The effect of different materials in soil was studied,such as soil pH,oxidation reduction potential（ORP）,electrical conductivity（EC）,cation exchange capacity（CEC）,total organic carbon（TOC）,activated organic carbon（AOC）,soil water content.Etc.Physicochemical properties and the effects of changes in nutrient content in the soil.The results show that the application of polymer sustained-release materials can significantly reduce the pH value of alkaline soil,the better the nutrient sustained-release property of the material,the more obvious adjustment of soil pH;the polymer sustained-release material with water-absorbing component can increasing the EC value and CEC value of the soil significantly increased the activity of urease and catalase in the soil,while the microbial activity was beneficial to increase the permeability of the soil,thereby increasing the soil ORP value;the addition of sustained-release materials can significantly improve soil TOC,AOC content.Among them,SI-PSRF/SAP_KL can better improve soil physical and chemical properties.（3）The effects of different materials on plant physiological indexes,nutrient absorption,yield and fruit quality were studied.The results show that the addition of water-absorbing components to the polymer sustained-release material can provide water and nutrients for plant growth,and effectively promote the absorption and utilization of nutrients by plants,especially in the fruiting stage,the plant fruit is fully developed.Yield and fruit quality are effectively improved.（4）The effects of different materials on soil nutrient leaching were studied.The results show that the introduction of water-absorbing components in polymer sustained-release materials can effectively reduce the leaching rate of nitrogen and phosphorus in soil,and the effect of SI-PSRF/SAP_KL is most obvious.