硫包衣尿素氮素释放特性及其评价方法研究

Study of Characteristics of Nitrogen Release from Sulfur-Coated Urea and Method of Evaluation

采用静水释放法研究了38℃下6种不同硫包衣尿素氮素释放特性,并对不同硫包衣尿素的初期养分释放率、7d静态氮溶出率和微分溶出率进行了比较,探讨了硫包衣尿素氮素释放特性及其评价方法。结果表明,6种不同肥料的氮素释放曲线基本可分为"S"形、倒"L"形和直线形,其氮素累积释放率(质量分数)达到80%所需要的时间分别为48,85,32,80,41和23d;其氮素释放率与时间的关系可用抛物线扩散方程和一级动力学方程进行拟合,且效果较好;硫包衣尿素的初期养分释放率和7d静态溶出率可用于养分释放性能的综合评价。

The static water release method is used to study the nitrogen release characteristics of six different sulfur-coated urea products at 38 ℃, a comparison is made of the initial nutrient release rate of the products, 7 d static nitrogen dissolving rate and differential dissolving rate, and an inquiry is made into the nitrogen release characteristics of sulfur-coated urea and the method of evaluation. The results indicate that the nitrogen release curves of the six different products may basically be divided into the ＂S＂, inverse ＂L＂ and linear types, and time required for the cumulative nitrogen release rate （mass fraction） to reach 80% is 48,85,32,80,41 and 23 d, respectively. The relationship of the nitrogen release rate with time may be fitted with the parabolic diffusion equation and the first-order kinetics equation, with good effect. The initial nutrient release rate of the products and the 7 d static dissolving rate may be used to evaluate comprehensively the nutrient release properties.