H. B. Tukey was head of
Michigan State University (MSU) Department of
Horticulture in the 1950s. Working with S. H. Wittwer, they demonstrated that foliar feeding is effective. Radioactive
phosphorus and
potassium were applied to foliage. A
Geiger counter was used to observe absorption, movement and nutrient utilization. The nutrients were transported at the rate of about one foot per hour to all parts of the plants. A spray enhancer, called a surfactant, can help nutrients stick to the leaf and then penetrate the leaves'
cuticle. Foliar application has been shown to avoid the problem of leaching-out in soils and prompts a quick reaction in the plant. Foliar application of phosphorus, zinc and iron brings the greatest benefit in comparison with addition to soil where phosphorus becomes fixed in a form inaccessible to the plant and where zinc and iron are less available. == Use ==