脲甲醛合成模型的建立及优化产品对油菜生长的影响

Establishment of Urea-formaldehyde Synthesis Model and the Effects of Optimized Products on Rape Growth

旨在探究脲甲醛的养分控释特性与反应因素的响应关系及其对油菜(Brassica campestris L.)生长的影响,为脲甲醛精准合成和科学施用提供依据。采用响应曲面法中心复合设计建立了缓释有效氮、活性系数与摩尔比、反应温度、反应时间的响应模型,并应用盆栽试验探究了模型优化脲甲醛产品对油菜产量、氮肥利用率及生理性状的影响。结果表明:(1)脲甲醛肥料缓释有效氮和活性系数主要受尿素甲醛摩尔比影响,其次是反应时间。(2)采用响应曲面法建立了脲甲醛缓释有效氮和活性系数的二次多项式数学模型并对其有效性进行验证,均达到了显著水平(缓释有效氮P<0.05,活性系数P<0.01),最终确定了具有最高AI且缓释有效氮最大的脲甲醛合成的最佳工艺参数为:U/F为1.48,反应温度为45.26℃,反应时间1.71h,在此条件下缓释有效氮可达12.63%,活性系数67.86%。(3)与等量尿素处理相比,优化脲甲醛产品与尿素7∶3掺混显著增加油菜产量23.93%~24.50%,单施全量脲甲醛产量差异不显著;减氮20%条件下,与全量尿素施肥处理比较,优化脲甲醛和尿素掺混处理显著提高油菜产量8.38%。本试验条件下,根据响应模型优化合成的脲甲醛和尿素掺混施用可满足油菜整个生育期的氮素需求,提高油菜产量和氮肥利用率。

In order to provide evidence for the fine synthesis and scientific application of urea-formaldehyde（UF）,the study was to investigate the relationships between the nutrient release characteristics of UF and the driving factors,and the effects of optimized products on rape（Brassica campestris L.）growth.The response surface methodology was used to investigate the response of urea formaldehyde molar ratio（U/F）,temperature and time to the slow available nitrogen and activity index（AI）of UF.Meanwhile,the nitrogen（N）release rate of UF and soil N supply were measured in the rape pot experiment.The results showed that the quadratic polynomial mathematical model of the slow available N and AI of UF were established and both of them were significant.The slow available N and AI of UF fertilizer were mainly affected by U/F（X1）,followed by reaction time（X2）.The optimal parameters for UF production,which with the highest AI and maximum slow available nitrogen content were：U/F 1.48,reaction temperature at 45.26 ℃ and reaction time for 1.71 h.Under these conditions,the slow-release effective nitrogen reached 12.63%,with AI as 67.86%.Meanwhile,the N release rate of UF in soil was slowly and soil inorganic N contents were increased with UF fertilization,especially in the later rape growth period.Compared with treatments of urea at the same rates of N application,the mixture of urea application and UF at 7∶3 ratio increased rape yields by 23.93%-24.50%.However,nearly the same yield occurred with single fertilization of UF.Moreover,even the rate of N application was reduced 20%,the mixture treatment still increased the rape yield by 8.38% compared to the high amount urea treatment.Eventually,the mixture of Urea and UF,were the best mode for gaining greatest yields of rape and higher N use efficiency.