Foliar feeding is a technique of feeding plants by applying liquid

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

directly to the

leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

. Plants are able to absorb essential elements through their leaves. The absorption takes place through their

stomata In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is b ...

and also through their

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rel ...

. Transport is usually faster through the stomata, but total absorption may be as great through the epidermis. Plants are also able to absorb nutrients through their bark. Foliar feeding was earlier thought to damage

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

es, but has become standard practice.

Effectiveness

H. B. Tukey was head of

Michigan State University Michigan State University (Michigan State, MSU) is a public land-grant research university in East Lansing, Michigan. It was founded in 1855 as the Agricultural College of the State of Michigan, the first of its kind in the United States. It ...

(MSU) Department of

Horticulture Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...

in the 1950s. Working with S. H. Wittwer, they demonstrated that foliar feeding is effective. Radioactive

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...

and

potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...

were applied to foliage. A

Geiger counter A Geiger counter (also known as a Geiger–Müller counter) is an electronic instrument used for detecting and measuring ionizing radiation. It is widely used in applications such as radiation dosimetry, radiological protection, experimental p ...

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 A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

. 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

Foliar feeding is generally done in the early morning or late evening, preferably at temperatures below , because heat causes the pores on some species' leaves to close.

References

{{reflist Horticulture Leaf vegetables Fertilizers de:Dünger#Mineralstoffaufnahme durch das Blatt