The Castor Cake Fertiliser is made from the leaves and flowers of the castor oil plant. The cake itself is a hard, black substance, while the liquid it is mixed with is a clear liquid that is slightly sticky to the touch. The liquid can be poured onto the cake, or mixed with water. The cake is then left to dry, until it becomes a black powder that can be used to improve soil conditions. The cake has been proven to increase the amount of earthworms and soil bacteria in the soil, which improves plant growth.