Fertiliser dissolution is usually carried out in a differential pressure tank. Fertiliser concentration at tank outlet is essential information for the correct control of optimum fertilisation. To enable optimisation, a fertiliser concentration equation was derived from the continuity equation with a source term. The source term described fertiliser dissolution using the initial dissolution rate and a decay rate of dissolution. An analytical equation was obtained from the fertiliser concentration equation for a traditional fertilisation process. The analytical equation fitted experimental data well, providing significantly good quantitative predictions. The equation reduces to the standard exponential form when the source term disappears. The influence of the fertiliser dissolution and outflow on concentration variation is discussed. An optimum fertilisation method considering dissolution is further proposed to provide constant fertigation flux and optimum fertiliser concentration based on the fertiliser concentration equation. The optimum fertilisation method controls a flux division of the fertigation system. Fertiliser dissolution is analysed for its influences on the flux division and fertiliser concentration at tank outlet under optimum conditions. Fertiliser dissolution increases the optimum fertilisation time, and leads to reduced inlet flux compared with the optimum fertilisation case without fertiliser dissolution. Environmental impact assessment is discussed by comparing optimum fertilisation to traditional fertilisation. The optimum fertilisation method could offer positive to fertiliser management and environmental protection by avoiding the excessive nitrogen and phosphorus losses found in traditional fertilisation.

肥料溶解通常在压差罐中进行。储罐出口处的肥料浓度是正确控制最佳肥料的重要信息。为了优化，从带有源项的连续性方程中导出了肥料浓度方程。源术语使用初始溶出速率和溶出度的衰减率描述了肥料的溶出度。从传统的施肥过程中的肥料浓度方程式中获得了一个解析方程式。解析方程很好地拟合了实验数据，从而提供了很好的定量预测。当源项消失时，该方程式简化为标准指数形式。讨论了肥料溶解和流出对浓度变化的影响。根据肥料浓度方程，提出了考虑溶解的最佳施肥方法，以提供恒定的施肥流量和最佳肥料浓度。最佳施肥方法控制施肥系统的通量分配。在最佳条件下，分析了肥料溶解对通量分配和罐出口肥料浓度的影响。与没有肥料溶解的最佳施肥情况相比，肥料溶解增加了最佳施肥时间，并导致入口通量减少。通过将最佳施肥与传统施肥进行比较，讨论了环境影响评估。