Chloride Fertility Management
Chloride is an essential plant nutrient and has a major role in plant water relationships, yet in the past, chloride was rarely considered when developing a fertility program. However, over the past 20 years, research in many areas of the Great Plains has demonstrated wheat yield and profit increases from chloride applications.
The beneficial effects of chloride applications are often, but not always, due to the suppression of various root and leaf diseases. It should be pointed out, however, that while the incidence or severity of these foliar diseases are reduced, fungicides often further reduce the detrimental effects of these diseases. Chloride applications on wheat do not replace the need for fungicides, especially for heavy disease pressure or susceptible varieties. Also, not all of the positive responses to chloride have been tied to disease suppression since grain yield increases have been noted in the absence of root and foliar diseases.
Chloride Sources / Application Method
The most common source of chloride is potassium chloride (potash 0), which contains about 45 percent chloride and liquid ammonium chloride solution. Other chloride sources, such as ammonium chloride and calcium chloride, could also be used but are not readily available and have potential compatibility issues with other fertilizer products.
Since the chloride ion is soluble in water and mobile in soils, chloride containing fertilizers can be applied before or after planting. Research to date has not indicated yield differences in method of application. Often, it is not possible to apply all of the chloride in drill-row applications because of the risk of germination damage. Preplant deep banding of chloride should perform well where equipment is available. The most practical methods of chloride application would be to include potassium chloride with a preplant N or P broadcast application or with topdress dry nitrogen programs.
Chloride Application Rate
South Dakota, North Dakota, and Kansas offer a chloride soil test based on the chloride content of the surface two feet of soil. Research generally indicates that 40 to 60 pounds of chloride per acre are required to optimize wheat production. If the soil test from the surface two feet is less than this amount, fertilizer chloride is recommended to provide the total of 40 to 60 pounds per acre. If a soil chloride analysis is not available, 20 to 30 pounds of chloride would be suggested on a trial basis. The inclusion of chloride in Great Plains wheat fertility programs should be considered since research has indicated relatively consistent and profitable wheat yield responses.