Take Another Look at Chloride?

Chloride deficiency in wheat

Chloride (Cl) is an essential plant nutrient that is required for proper plant growth and yield.  Since it is needed in relatively small quantities, it is classified as a micronutrient.  Nevertheless, it is a critical and frequently overlooked component of a complete soil fertility program.  In the West, there has probably been more emphasis placed on avoiding excess levels of Cl and salinity than on regularly occurring deficiencies.  However, evidence continues to mount that there are many regions where crops could benefit from additional Cl.

Chloride plays several important roles in plants, but the crop response usually comes from a classical nutrient response and/or suppression of fungal diseases.  While many crops respond favorably to applied Cl, wheat and other small grains are the crops that receive the most Cl in the West.  Some wheat varieties exhibit Cl deficiency symptoms, also referred to as physiological leaf spot, under low soil Cl conditions.  The symptoms are similar in appearance to tanspot or septoria with no associated pathogen.  Chloride has been proven to suppress septoria, leaf spot, stripe rust, tanspot and common and take-all root rots in wheat.  Adequate Cl is demonstrated by increased yield, higher test weights, and greater kernel plumpness.

How Do I Get Chloride?

Chloride is an anion and moves freely in the soil with water.  Rainfall near the ocean tends to deposit sufficient Cl, but wheat-producing regions more than 200 miles from the coast may respond to Cl fertilization.  Irrigation water usually supplies adequate Cl to meet plant needs, however regions with rain-fed cropping may not have sufficient Cl for top plant performance and yield.

Research has shown that there is no difference in crop response to various Cl-containing fertilizers.  The most common Cl source is muriate of potash (0-0-67; 47% Cl). It comes in several colors, depending on the geologic source and how it is processed. Other excellent sources of Cl include magnesium chloride and calcium chloride.

White potassium chloride

Red potassium chloride

Mixed color potassium chloride

Will Chloride Fertilization Pay?

Substantial profit can result from Cl fertilization where it is needed.  Like all plant nutrients, Cl responses will only occur where there is an insufficient nutrient supply.  An adequate Cl supply will benefit small grain production by accelerating plant development, reducing lodging, and improving disease resistance. 

Given the demonstrated yield and quality boost that Cl provides for many crops, it is time to reconsider whether your crops will benefit from providing some of this overlooked micronutrient to your fertilization program.