Foliar applied potassium nitrate beneficial in terms of cotton seed yield and lint yield

This study was performed to evaluate the response of cotton (Gossypium hirsutum L.) yield and yield characteristics to foliar K at three silty loam field locations in Arkansas (USA) from 1999 through 2002. The Mehlich 3 extractable (1:7) soil test values for these three locations ranged from 270 to 376 kg K ha-1, which is considered to be in the high range for cotton production in Arkansas. Foliar KNOwas applied at 11,2 kg KNO3 ha-1 for four consecutive weeks starting one week after first flowering with a pressurized CO2backpack sprayer calibrated to deliver 93,5 L ha-1. The foliar potassium nitrate treatment had a statistically significant effect on the number of seeds per hectare. Foliar KNO3 increased the number of seeds ha-1 by 13% compared to the untreated control. Across the five site years, foliar K numerically increased lint yield by only 4% (1285 vs. 1337 kg/ha), with a majority (171 kg) of this increase occurring at one site year (Table 1). The results suggest that foliar KNO3 applications typically do not increase yields when soil test K levels are adequate, or when recommended rates of K are soil-applied.

Table 1. Effect of foliar applied potassium nitrate on cotton lint yield.



Coker, D. L., D.M. Oosterhuis, and R. S. Brown. 2009. Cotton yield response to soil-and foliar-applied potassium as influenced by irrigation. Journal of Cotton Science, 13: 1-10.

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