控释尿素养分速测及在田间土壤中氮素释放率研究

介绍了一种树脂包膜尿素工厂在线质检的养分速测方法,即,100℃快速浸提对二甲氨基苯甲醛分光光度法,建立了该方法与缓释肥料国家标准(GB/T23348-2009)中规定的25℃静水浸提凯氏定氮法测定结果之间的相关关系,验证了该速测方法预测计算肥料养分释放期的可行性;将控释尿素施用于田间土壤,实时监测土壤的温湿度状况,对比了控释尿素在25℃水与田间土壤中的氮素累积释放趋势。结果表明:(1)100℃浸提对二甲氨基苯甲醛分光光度法可以准确的预测树脂包膜尿素在25℃下的养分释放率和养分释放期。应用此法测定预测样品S1和S2的养分释放期的误差分别只有0.10d和1.75d,相对误差不超过2.3%。(2)控释尿素S1、S3分别在25℃水中与田间耕层土壤(75%相对含水量)中的氮素释放趋势基本一致。25℃静水与耕层土壤的温差(5℃)较小,不足以引起肥料在两介质中氮素累积释放率的显著差异。

Fast Measurement for Nutrition Release Rate of Controlled Release Urea and Study of Its Nitrogen Release Rate in the Field

As a kind of fast measurement of nutrition release rate, the 100℃ fast extraction and the colorimetry method of paradimethylaminobezaldehyde is introduced in order to guide on-line test of the quality of polymer coated urea (PCU) in factory. The correlated equations of PCU's release longevities measured both by this new method and by the standard method of 25℃ water extraction and Kjeldahl measurement prescribed in the Standard of Slow Release Fertilizer in China(GB/T 23348-2009)were established, validated and evaluated. Two kinds of controlled release urea(CRU) were used in the field, of which the temperature and humidity conditions were memorized real-timely. The nitrogen release trends of CRUs both in the 25℃ water and in the field were compared. The results showed that, the two kinds of PCU could be measured accurately by the colorimetry method of paradimethylaminobezaldehyde at 100℃. And by using regression equation of this measurement, the errors of release longevity of studied sample S1 and S2 were only 0.10d and 1.75 d respectively, and the relative errors were less than 2.3%. The CRUs' nitrogen release trends in the 25℃ water were as the same as in the field. The difference of temperature in the 25℃ water and in the 0-20 cm soil layer was so little (<5℃) that there was no significant difference of S1 and S3's cumulative nitrogen release rates in the different media.