折光率法在控释尿素释放率和肥效期检测中的应用

Application of refractive index method to test nutrient release rate and longevity of controlled release urea

【目的】以尿素测定标准化学方法,即对二甲氨基苯甲醛(PDAB)比色法检验折光率法测定控释尿素养分释放率及肥效期的准确性和可靠性,为折光率法应用于快速准确评价控释尿素肥效期提供理论依据。【方法】以3种肥效期的控释尿素PCU1、PCU2和PCU3为材料,采用25℃恒温静水培养控释尿素,分别用PDAB比色法和折光率法测定尿素释放率和肥效期,并对2种方法的测定结果进行相关分析和校验研究,评价25℃下折光率法测定控释尿素养分释放率和肥效期的准确性和可靠性。【结果】折光率法测得的不同肥效期控释尿素释放特征曲线与PD-AB比色法的测定结果几乎重合,说明折光率法不会改变控释尿素的累积释放规律。2种方法测得的控释尿素释放曲线Richards方程的拟合特征参数No、k、ti无差异,释放率测定结果呈极显著线性正相关,相关系数均为0.999,标准误分别为0.09,0.16和0.10,二者之间无统计差异。当养分累积释放率为80%时,3种控释尿素PCU1、PCU2和PCU3的肥效期分别仅相差0.97,3.14,8.96d。【结论】折光率法测定控释尿素养分释放率和肥效期的准确度和精度高,适用于检测不同肥效期控释尿素的养分释放率和肥效期,可用于评价控释尿素的控释性能。

【Objective】 The purpose of this study was using paradimethyl-aminobenzaldehyde（PDAB） colorimetric method to verify the accuracy of refractive index method（RIM）,and use the method to simply,rapidly determine the nutrient release rate and longevity of controlled release urea.【Method】 Still pure water dissolving incubation was used to study the nutrient release rates and longevities of three kinds of controlled release urea：PCU1,PCU2 and PCU3,which were examined by PDAB and RIM.Then correlation analysis and verification method were applied to evaluate the accuracy and reliability of RIM at a temperature of 25 ℃.【Result】 Results showed that the nutrient release characteristics curves measured by RIM and PDAB were identical.And there was no difference between Richards equation specific parameters tested RIM and PDAB.Nutrient release rates tested by the two methods were very significantly linearly correlated with a correlation coefficient of 0.999,and there was no statistic difference.The differences of measured and predicted longevities of three controlled release urea were 0.97,3.14,and 8.96 d,respectively.【Conclusion】 Refractive index method had high accuracy and precision to determine the nutrient release rate and longevity of controlled release urea.It is applied to test the nutrient release rate and longevity,and performance of controlled release urea.