Does addition of chloride as fertilizer improve grain yield? Well, that depends, at least according to Rick Engel, researcher with the Montana Agricultural Experiment Station. The following facts came from Fertilizer Facts Number 16, April 1997, "Correcting Physiological Leaf Spot Damage in Redwin’ and Other Winter Wheat Cultivars". Copies of this fact sheet are available on request.
§ Applying chloride containing fertilizers (e.g., 0/0/60, potassium chloride prevents/reduces leaf spotting in Redwin and other winter wheat cultivars.
§ Application rates of 20‑25 lbs/a chloride, or 40‑50 lbs/a of 0‑0‑60 material, are recommended.
§ Yield and economic return are increased by correcting and preventing leafspot problems with chloride fertilization.
Physiological leaf spot, a plant leaf necrosis that occurs on Redwin winter wheat planted on soils with low chloride levels, can result in reduced yield and reduced seed weight. This physiological leaf spot is believed to be the result of either some metabolic process or plant genetic weakness. In severely affected plants, the spots that typically appear on the flag leaf coalesce and result in premature leaf drop. Maintenance of a healthy flag leaf is essential to maximum yield.
§ Field studies have revealed that fungicides such as Tilt have no effect on leaf spot severity.
§ Not all winter wheat varieties are equally susceptible to leaf spot damage; CDC Kestrel', Promotory, Redwin, and Sierra are susceptible. Stephens and Manning are also affected.
At sites with soil chloride levels greater than 10 lbs/a (0 to 24" soil depth), damage due to physiological leaf spot is minor; as soil chloride drops below 10 lbs/a threshold, leaf spot severity increases exponentially.
§ Yield responses to applied chloride averaged 6.9 bu/a or about 10%; thousand kernel weight increases from applied chloride averaged 7.2%.
So, should you apply chloride as a fertilizer material when planting winter wheat this fall? That depends. If the soil is low in chloride and/or you have had a history of physiological leaf spot and you are planting one of the susceptible varieties listed here, you might benefit economically from 40 to 50 pounds of 0/0/60. Besides, some studies show that the addition of potassium, even on fairly high testing soils, results in reduced lodging. And, if you apply 0/0/60, potassium is the other component of the fertilizer.
Categories: Chloride, Wheat Fertility
Date: 1997