ガウス補正法による溶出モデル式の改良 : 樹脂系被覆肥料の溶出機構と反応速度論的解析による溶出評価(第3報)

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We studied the release of nutrients from individual granules of three kinds of coated urea having different coating characteristics. Twenty granules were immersed individually in 10 mL of water and incubated at 30℃ for 84 d. Urea released in the solution was determined intermittently and the data were fitted to the first-order reaction model originally proposed by ISHIBASHI et al. (1992). 1) The release of urea from the individual granules obeyed the simple first-order reaction model. There were comparatively wide variations in the release rate constant (k) and in the lag period (t_<au>) : the coefficients of variation for k were from 37.5 to 59.6%, and those for t_<au> from 21.1 to 47.8%. 2) All the nutrient release curves were exponential, indicating that the sigmoidal curves found with mass samples were caused by the variations in k and t_<au> values. 3) We propose a new nutrient release model, assuming that t_<au> varied according to the normal (Gaussian) distribution. Curves obtained with this model fitted far better to the observed values, particularly to those for the coated urea having larger t_<au> values.
社団法人日本土壌肥料学会の論文
1997-10-05