This protocol describes how fertiliser solutions can be made and applied to already established plants in pot experiments. Before planting, fertiliser can be directly applied in solid form by evenly mixing it into the soil. This however cannot be done once the experiment has been initiated with plants already established. The fertiliser will hence have to be added to the soil with minimal disturbance and one way of doing this is by applying it in solution form. Adding fertiliser in solution form in pot experiments is particularly useful when second or third fertiliser applications have to be made for fertiliser applied in two or more split applications. Split applications of fertilisers are common for highly leachable fertilisers (e.g. urea), as this helps extend nutrient availability to growing plants. For various reasons, solid fertiliser application methods like banding or broadcasting are not suitable for pot experiments, hence the application of fertilisers to soils in established pot experiments in solution form. Fertiliser calculations are needed to determine the amount of fertiliser to add to pots. This protocol gives one example of a fertiliser calculation, but you will need to do your own reading for further understanding. See the attached document for guidance.