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针对脲甲醛养分释放与作物生长曲线不匹配的问题,该研究采用蛋白水解物来改善脲甲醛的氮素释放率。土柱淋洗结果表明,蛋白水解物降低了脲甲醛初期的氮素释放率,加快了脲甲醛在后期的氮素释放率。在当量尿素与甲醛的摩尔比为1.2时,蛋白水解物水解度越小,氮素释放率越快。到第7周,蛋白水解物改性脲甲醛的氮素释放率和未改性的脲甲醛相比,氮素释放率提高了58.9%。采用傅里叶红外光谱、X射线衍射、热重和扫描电镜分析了蛋白水解物和蛋白水解物改性脲甲醛的结构,发现:蛋白水解物的活性基团能够与甲醛反应,并与尿素聚合,以嵌段的方式引入到脲甲醛的分子结构中;蛋白水解物水解度越低,改性脲甲醛结晶度降低的越多;和未改性的脲甲醛相比,改性的脲甲醛的最大分解温度有所降低,并且改性后的脲甲醛疏松多孔。因此,可以通过蛋白水解物的水解度来调控改性脲甲醛的氮素释放率,进而适应不同作物的生长周期,提高氮肥的利用率。
In response to the problem of urea formaldehyde release and crop growth curve mismatch, this study used protein hydrolysates to improve the urea nitrogen release rate. Soil column leaching results showed that the protein hydrolyzate reduced the initial nitrogen release rate of urea formaldehyde and accelerated the release rate of urea formaldehyde in the late stage. When the molar ratio of urea to formaldehyde is 1.2, the lower the degree of hydrolysis of the protein hydrolysates, the faster the nitrogen release rate. By the 7th week, the nitrogen release rate of proteolysis modified urea formaldehyde increased by 58.9% compared with that of unmodified urea formaldehyde. The structure of the modified urea formaldehyde was analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry and scanning electron microscopy. The results showed that the active groups of the protein hydrolyzate reacted with formaldehyde and reacted with urea , Which is introduced into the molecular structure of urea formaldehyde in a block manner. The lower the degree of hydrolysis of the protein hydrolyzate, the more the crystallinity of the modified urea formaldehyde is reduced. Compared with the unmodified urea formaldehyde, the modified urea formaldehyde The maximum decomposition temperature decreased, and the modified urea formaldehyde porous. Therefore, the degree of hydrolysis of the protein hydrolysates can be used to regulate the nitrogen release rate of the modified urea formaldehyde so as to adapt to the growth cycle of different crops and improve the utilization rate of nitrogen fertilizers.