室内变温与设施土壤条件下树脂包膜控释肥氮素释放特征研究及预测模型构建

At present，the lack of system research and contrast of the nitrogen release dynamics for controlled release fertilizer of resin coating under indoor changeable temperature culture and greenhouse soil conditions，so that the response mechanism of nitrogen release rate changing with temperature was not clear in field conditions，and furthermore the indoor conventional testing method (25℃water soak method) was difficult to reflect the actual release rate of controlled release fertilizer of resin coating. While the other models constructed were rarely combined with the actual conditions of field，at the same time parameters of complex，which affected the practical application. This project is based on the theory of chemical reaction dynamics，with the research mode of combining the indoor temperature cultivation and the actual conditions of field，and nitrogen release dynamics'similarities and differences of controlled release fertilizer of resin coating would be system researched，and the response relationship would be clear and definite. Furthermore，the regression analysis，nonlinear least square method，and the temperature transformation into day method would be used to construct mathematical model that least parameters were input，and the prediction of nitrogen release rate in fields was accurate. In order to realize the synchronization of nutrient supply and crop uptake，and provide scientific basis for controlled release fertilizer recommendation fertilization system in the field conditions and development of new kinds of coated controlled fertilizer。

针对目前缺乏室内变温和设施土壤条件中树脂包膜控释肥料氮素释放动力学特征的系统研究与对比，导致其氮素释放速率在田间条件下随温度变化的响应机制尚不明确，从而使得室内常规测试方法（25℃恒温水浸泡法）很难反映包膜控释肥料在田间的实际释放过程，而其它模型预测方法的构建又很少结合大田实际条件，同时参数复杂从而影响实际应用等问题。本项目基于化学反应动力学理论，采用室内变温培养与田间实际条件相结合方式，系统研究树脂包膜控释肥氮素释放动力学特征异同，探明其响应关系，进而利用回归分析、非线性最小二乘法、温度变换日数法等方法构建输入参数少、可较准确预测树脂包膜控释肥在田间实际溶出率的数学模型，以实现其养分供应与作物吸收同步，为建立田间变温条件下的树脂包膜控释肥推荐施肥系统及开发新型包膜肥料提供科学依据。

目前设施蔬菜生产中对控释肥料的需求量越来越大，考虑到经济和环境的双重效益，采用简单易行的方法预测控释肥料的养分溶出量成为迫切需要解决的问题。本项目采用室内培养实验模拟田间变温条件结合田间自然温度条件下的设施蔬菜生长实验，以2种不同释放类型、释放期的控释肥料（L45d和S45d）为试材，开发出了简单、较准确预测田间条件下控释肥料氮素释放的模型。（1）室内变温培养与设施番茄种植条件下L45d和S45d控释肥料氮素释放曲线都近似表现为抛物线型和S型，氮素释放显著的受温度影响。（2）变温培养条件下，30%、40%田间持水量显著抑制了氮素释放速率，氮素累积释放量只有约50%，而相同时段内60%、100%、120%土壤田间持水量的氮素累积释放量达到了80%以上，且三者之间无显著差异，但与前两者差异显著，说明控释肥料应用于设施蔬菜种植体系，不是水分而是温度主要决定了氮素释放过程。（3）根据氮素释放曲线形状，SUGIHARA和LOGISTIC模型被选择用来描述氮素释放过程，利用一级动力学方程和最小二乘法，建立了抛物线型控释肥料预测模型中Nm（控释肥最大氮释放百分率）与释放速率k的计算方法，并通过引入温度变换日数法，设置参数ψ（累积释放期为50d～75d时，ψ取值近似于1.2，大于90d时，ψ取值近似于1.4），在改进SUGIHARA模型的基础上建立了抛物线型控释肥料预测模型。（4）通过设置参数ω（累积释放期在35～75d的取值为1.0），采用回归分析结合分段取值法，在改进LOGISTIC模型的基础上建立了S型控释肥料预测模型。（5）分别采用设施春茬番茄和秋茬黄瓜种植试验，修正和验证了预测模型的准确度，达到了较好的效果，预测误差小于20%。控释肥料预测模型的建立对于控释肥料的质量提升、精准施用、推广应用、环境风险阻控具有切实可行的指导意义。