磷缓释复混肥的制备及其氮、磷缓释性评价

在实验室条件下制得不同程度磷缓释的复混肥(磷缓释肥),分别测定以水为淋洗剂和以2%柠檬酸溶液为淋洗剂时在特定淋洗装置下水溶性氮、磷及有效磷随时间的溶出率,采用双曲线方程Xt=b a/t对肥料的累计养分溶出率进行分段拟合,在此基础上引入缓释指数评价各养分缓释特性。结果表明:磷缓释肥对磷的缓释作用强于氮,对有效性磷的缓释作用强于水溶性磷;其水溶性氮、磷缓释指数(SR IWN、SR IW P)和有效磷缓释指数(SR IAP)与肥料中加入的缓释剂硫酸镁相对含量(X)具有很好的正相关,其直线相关系数为0.7414、0.8958和0.9829,后两者分别达到显著和极显著水平;2%柠檬酸溶液几乎能溶出肥料中全部有效磷,从而证明了自制磷缓释肥的有效性。

Preparation of phosphorus slow-release compound fertilizer and evaluation on its nitrogen and phosphorus slow-release effect

Different phosphorus slowrelease compound fertilizer(PSF) and their check fertilizer(CK) are prepared in laboratory,the nitrogen and phosphorus dissolving percentage of PSF and CK are measured under specified leaching apparatus when water and 2% citric acid water solution employed as leaching solvent respectively,hyperbolic curve equation X_t=ba/t is used to fit the curve of accumulated nutrient dissolving percentage in different leaching stage,and slowrelease index(SRI) is introduced in evaluation of the slowrelease effect of each kind of nutrient.The results show that the slowrelease effect of phosphorus is stronger than that of nitrogen and slowrelease effect of available phosphorus is stronger than that of water soluble phosphorus;the SRI is of water soluble nitrogen,water soluble phosphorus and available phosphorus have positive relationship with the relative content of additive,the linear correlation coefficient are 0.7414,0.8958 and 0.9829 respectively;almost all of the phosphorus(TP) in PSF can be dissolved by 2% citric acid water solution,this proves TP in PSF prepared by the simplified method was available.