Plants take up chlorine (Cl) as the chloride (Cl–) anion. It’s active in energy reactions in the plant. Most Cl- in soils comes from salt trapped in parent materials, marine aerosols and volcanic emissions. Classified as a micronutrient, Cl- is required by all plants in small quantities.
Research has shown that chloride (Cl-) diminishes the effects of fungal root diseases such as take-all and common root rot on small grains. It also helps suppress infections of small-grain fungal leaf and head diseases. Researchers have correlated lowered incidences of stalk rot in corn to adequate Cl-.
Chloride can be broadcast preplant or top-dressed with N. The most practical source is potassium chloride (KCl), which contains about 47 percent Cl. Preplant, at seeding, and top-dressed applications have all been effective. Higher rates should be applied preplant or topdress. Chloride is highly mobile in the soil and should be managed accordingly.
Chloride can negatively affect crops such as tobacco, some soybeans varieties, potatoes and some tree crops. Effects vary with crop varieties or root stock and intended crop use.
Symptoms of deficiency can vary across crop species, but similarities exist for how nutrient insufficiency impacts plant tissue color and appearance. Nutrient deficiencies are commonly associated with the physical location on the plant
(i.e., whether the symptoms are primarily observed on older versus newly formed plant tissue), but these symptoms can spread as the severity of the deficiency progresses.