A good crop fertility always starts from the ground up simply because the majority of nutrients crops require to produce economically viable crops are derived from the soil. Thus, plants roots are the primary organs responsible for nutrient uptake. But science has clearly shown that above ground plant parts can be very receptive and efficient at absorbing foliar applied nutrients. In fact, foliar nutrition can be a fantastic supplement to a sound soil applied fertility program.
Foliar nutrition applications should always be based on sound agronomic principle and with a specific goal or objective in mind. As such, foliar nutrition can be a very useful tool for supplementing soil fertility programs especially when soil or weather conditions are hostile to nutrient availability or uptake.