ABSTRACT

Potassium nitrate (KNO3) Is primarily used for foliar applications on cotton but the fertilizer is considered expensive, and it must be dissolved in hot water at concentrations above 5% K20. We looked for another potassium source for foliar applications that would produce a comparable yield advantage as KNO3. This study compared foliar concentrations and rates of granular potassium chloride (KC1, 0-0-60) with KNO3 (13-0-44), with respect to dissolving time, X uptake, and leaf burn.

We found that KC1 dissolved four to eight times faster than KNO3 at equivalent K20 concentrations, allowing it to be prepared without hot water on the farm. Also, KC1 was more effective than KNO3 at 5.0%, 8.8%. and 11.7% K20 concentrations, based on leaf K uptake within 24 hours after application. Compared with KNO3, the KC1 treatments significantly increased K concentrations in the upper leaves, at all K20 concentrations. However, KNO3 produced less leaf burn.

Leaf K concentrations were highest with KC1 at the 6.8% K20 level. This treatment produced only trace amounts of leaf burn on punctures and/or broken leaves at the 4 gal/A rate. Potassium chloride concentrations above 8.8% K20 produced creator leaf burn and reduced leaf K uptake. A 4 gal/A rate of 0-0-9 (9% K20 as KCL.) is suggested as an alternative to 3-0-11 (as KNO3) for more effective foliar applications on cotton, and for a saving of more than $2.00 per application.