| Aiming at the problems of ordinary urea-formaldehyde slow-release materials such as largescale industrial production that is difficult to be simple and fast,simple nutrition,and slow release,and the establishment of scientific and effective development of biodegradable polymer slow-release fertilizers through crop yield or quality evaluation the research method is not clear,and the existing production prediction model is not perfect enough.On the one hand,this paper developed a series of modified urea-formaldehyde biodegradation that can be used in agriculture and horticulture through a new type of large-scale industrial production of reactive extrusion preparation process polymer slow-release materials,their composition structure and morphology,mechanical properties,processing properties,biodegradability and nutrient release characteristics were studied.On the other hand,by comparing the effects of different biodegradable polymer slow-release materials on soil performance,plant yield and physiological indicators,key impact indicators were obtained,and statistical analysis methods were used to evaluate soil fertility quality.Finally,the yield prediction model was carried out Optimized.The main research contents and results are as follows:The precursors of urea-formaldehyde(UF),methylolurea(MU),poly(butylene succinate)(PBS)and potassium dihydrogen phosphate(MKP)are used as raw materials to prepare new nitrogen binary slow-release material UF/PBS and ternary nanometer slow-release material containing nitrogen,phosphorus and potassium(NPK)UF/PBS/MKP.Through the analysis of the structure and micro-morphology of the slow-release material,the relevant preparation mechanism is obtained: MU generates UF with different degrees of polymerization through high-temperature melt polycondensation in the extruder,and the UF/PBS slow-release material and the UF and PBS are obtained.PBS is mixed at the molecular segment scale;MKP crystals are dissolved in the water generated during MU polycondensation to form UF,but then,due to the evaporation of water at high temperatures,MKPs are precipitated,due to the "cage effect" of the UF and PBS molecular chains and their interaction with UF and the hydrogen bonding interaction between MKP is perfectly limited to the nanometer scale,so as to obtain the ternary nano sustained release material UF/PBS/MKP.Through the research on the processing and mechanical properties of slow-release materials,it is found that the processing performance of urea-formaldehyde-based biodegradable polymer slow-release materials is close to that of pure PBS,and has excellent tensile and compression properties.The biodegradation and nutrient release performance of urea-formaldehyde-based sustained-release materials in real soil and water were studied through leaching soil burial degradation experiment and still water release experiment.The results show that the biodegradation rate of the prepared slow-release materials UF/PBS and UF/PBS/MKP and the slow-release of the nutrients contained can be easily adjusted and controlled by changing the raw material ratio.This study has important practical application prospects for expanding the application of urea-formaldehyde-based biodegradable polymer slow-release materials in the fields of agriculture and horticulture.Through field corn planting experiments,the effects of nutrients released by different biodegradable polymers on plant and soil indicators were studied.The results showed that: the application of biodegradable polymers significantly improved corn yield and quality;GRF(biodegradable polymer slow and controlled release silicon fertilizer)and PVA+INF(poly(vinyl alcohol))and inorganic fertilizer compound fertilizer)significantly improved the soil water content(more influence on the yield than nutrient elements),so the yield was the highest;maize grains treated with BRF(biodegradable polymer slow-controlled release boron fertilizer)),WRF(biodegradable polymer slow-release microfertilizer)and OM+INF(organicinorganic compound fertilizer)of element and organic matter have better quality,which is because trace elements and organic matter carried in organic fertilizer are beneficial to grain growth and enrichment of nutrients.After applying biodegradable polymer,the content of organic carbon and NPK in the soil increased significantly.Correlation studies have shown that soil NPK and organic carbon content showed positive correlation with maize yield while the water content of 60-100 cm soil layer during grain filling and maturity has a negative correlation with corn yield.Therefore,the continuous supply of NPK and organic carbon throughout the corn growth cycle,as well as the later control of corn moisture,can significantly increase corn yield.By evaluating yield and quality of soil fertility quality,principal component analysis of soil indicators revealed that soil NPK and organic carbon were the key indicators affecting soil fertility quality,which confirmed that NPK and organic carbon content were the key indicators affecting soil and yield.Finally,by properly selecting the input data and parameter adjustments of the prediction model,the accuracy,efficiency,and stability of yield prediction are improved,and the model is optimized. |
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