用缓释指数评价化学缓释肥的缓释特性及其生物效应

Slow-Release Effect and Biological Availability of Chemical Slow-Release Fertilizers Evaluated by Slow-Release Index(SRI)

在实验室条件下,采用简化的工艺制备了对氮、磷、钾三元素均有部分缓释作用的复混肥(化学缓释肥),用特定淋洗装置测定肥料各养分随时间的溶出率,通过双曲线方程Xt=b-a/t对其养分累计溶出率与时间的关系进行拟合,以方程常数b和a计算出的缓释指数(SR I)来定量评价肥料缓释特性,同时进行盆栽试验,探讨了缓释指数与复混肥中相应缓释添加剂百分含量(X)之间、各复混肥处理的油菜产量与复混肥中缓释添加剂总含量(X')之间的关系。结果表明:各养分的缓释指数(SR I)与相应缓释添加剂含量(X)均有很好的线性正相关;各化学缓释肥处理的油菜产量随缓释添加剂总含量(X')增加而增加;化学缓释肥以较少的荚数获得更高的产量。这预示着通过肥料的室内淋洗试验得到的缓释指数SR I不仅可以用来评价肥料的缓释性能,且在一定程度上可预测肥料的增产效应。

The slow -release compound fertilizer （NPK -SF） was prepared by simplified chemical method in laboratory in which nitrogen, phosphorus and potassium could be partly slow -released. The dissolving percentage of N, P and K in NPK -SF and control fertilizer （CK） was measured under the specified leaching apparatus. Hyperbolic curve equation （ Xt = b - a/t） was used to fit the accumulated nutrient dissolving percentage and the slow - release index （SRI） calculated from b and a values of the equation was used to evaluate the nutrients slow release properties of NPK - SF quantitatively. At the same time, pot experiments of the fertilizer on rapeseed were conducted. The relationship between SRI and additive content （X） of each nutrient in the NPK -SF, yield of rapeseed and total additive content （X′） was analysed. The result showed ： SRI had good liner positive correlation with additive content （X） of corresponding nutrient in the NPK - SF. The yield increased as total additive content （X′） increased and the higher yield of p - NPK - SF was obtained with less number of pod compared to p - CK. This indicated that the SRI could not only be used to evaluate of the slow - release properties of slow - release compound fertilizer and predict the additive content in the fertilizer, but it could also be used to predict the increment of yield in certain range.