AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335
Winter 1998, No. 5
Response to fertilization depends on soil chloride levels. Soils testing 30 pounds per acre or less, in the upper 2 feet, have a high probability of responding to added chloride. Soils testing between 30 and 60 pounds per acre have a fair chance of crop response. Those testing above 60 pounds per acre are not likely to respond.
Plant tissue analysis may be a better predictor of chloride deficiency than soil analysis. Cereal plants need 0.4 percent in their tissue from the boot to flowering stage to achieve their full yield potential. If plant concentrations fall below that, yields decline. As a rule of thumb … response to chloride occurs 80 percent of the time when plant chloride is less than about 0.1 percent.
One of the ways chloride increases yields is by helping plants suppress and tolerate leaf and root diseases like tanspot, leaf rust, spot blotch, or root rot. Chloride also controls physiological leaf spotting that occurs in some winter wheat, durum wheat and barley varieties. This leaf spotting looks similar to tanspot but is not caused by pathogens.
Another way chloride increases yields is by improving the kernel weights. Chloride prolongs the grain-fill period and quickens the kernel growth rate, causing larger, mature kernels. The end result…better test weights.
It’s not just yield. Chloride also accelerates plant development. A good supply of chloride can help winter wheat mature 5 to 7 days earlier and spring wheat 1 to 5 days earlier. Chloride also strengthens stems, helping to reduce lodging.
Chloride is easy to manage. Whether it's applied as a pre-plant, banded at seeding, or top-dressed after crop emergence, the response is the same. There is little difference among application methods and among chloride sources. Muriate of potash is the most common source; it contains 47 percent chloride and also supplies potassium, another essential plant nutrient.
Chloride fertilization can be greatly beneficial, but is it economic? The answer is yes! Research shows chloride fertilization can be highly profitable if responses can be predicted and other nutrients have not been neglected. When soil and tissue tests are low and disease pressure is great, chloride fertilization pays.
Chloride may be the nutrient to take your crop to the next level of production and profitability.