Why "Liquid" fertilization is better terminology than "Foliar" fertilization

When applying fertilizer to turfgrass plants, there are two general types of application: liquid and granular. Granular products are applied in a dry form, while liquid products are applied as a spray application.

The term foliar fertilization is often used to describe liquid applications made to the leaves, or foliage, of turfgrass. But this can be misleading,with the implication that all the applied fertilizer is being taken up by the foliage.

The reality is that only about 50% of the fertilizer applied to turfgrass foliage enters the plant through the leaves. And in many cases much less than 50% is absorbed by the leaves. Research by Branham et al. found that 14 to 37% of the applied nitrogen was taken up by turfgrass leaves in Illinois. Research at Arkansas by Stiegler et al. found uptake of 31 to 56% of foliar-applied nitrogen.

These results are similar to the experimental results of Jörg Schönherr¹ who has done extensive research into foliar uptake of nutrient ions. Uptake is the highest at 100% humidity, so once the liquid solution has dried on the leaf, foliar uptake of the applied nutrients ceases.

Even with the limited foliar uptake, I still prefer liquid applications to granular applications. With liquid applications, precise doses of nutrients can be spread evenly at low rates to all areas of the sward. It is impossible to get such even distribution of nutrients when applying granular products.

When I was the superintendent at Shanghai Links, we made liquid fertilizer applications to all areas of the course as the main source of nutrients. We would allow the fertilizer to dry on the leaves, so we would get some uptake by the foliage, and we would then apply enough water to rinse the remaining fertilizer from the leaves and into the upper reaches of the soil, where the remaining nutrients could be absorbed by the roots.