A Controlled Release Fertiliser (CRF) is a granular fertiliser for application to the soil where it gradually releases nutrients over a period of time. This leads to more efficient nutrient uptake by the plant and minimises nutrient leaching. In conventional fertilisers, the water soluble nutrients are released quickly as the fertiliser dissolves and are subject to leaching away from the roots, or in the case of nitrogen, volatilisation into the atmosphere. Impact CRF granular fertilisers have an insoluble substrate or a semi-permeable jacket of polymer sulphur-coated urea (PSCU) that controls the release of Nitrogen into the soil over a period of time.

Besides being more efficient in the utilisation of applied nutrients, CRFs also help reduce the impact on the environment and the contamination of the subsurface water. Indigrow CRFs should be applied either by topdressing the soil, or by mixing the fertiliser into the soil before sowing.