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Interpretive Summaries:
2006 - Cotton and Soil Response to Application of Potassium
2005 - Cotton Response to Combinations of Nitrogen and Potassium
Cotton Response to Combinations of Nitrogen and Potassium, 2005
The objective of this study was to evaluate the effect of combinations of nitrogen (N) and potassium (K) fertilization on cotton yield, soil nutrients, and petiole nitrate (NO3-N) and K concentrations. This (2005) was the beginning of a 3-year field study at the University of Arkansas Cotton Branch Experiment Station in Marianna, Arkansas. Cotton cultivar ‘DPL444' was grown using cultural practices recommended by the University of Arkansas Cooperative Extension Service. Experimental treatments included five rates of N ranging from 0 to 160 lb/A (in 40 lb/A increments) as urea, and five rates of K2O ranging from 0 to 150 lb/A (in 30 lb/A increments) as potassium chloride (KCl).
Seed cotton yield increased with soil-applied urea. Seed cotton yield was 1,677 lb/A with no N fertilizer and 3,532 lb/A with 120 lb N/A. However, application of K did not affect seed cotton yield, regardless of rate, suggesting that native soil K was high enough to sustain optimum cotton yield, even at high N application rates. This is supported by the high soil test levels in samples collected before the application of any fertilizer. Petiole NO3-N and petiole K concentrations increased with increasing rate of N or K application and tended to decrease as the cotton plant developed.
In summary, application of N fertilizer almost doubled the seed cotton yield and increased the petiole NO3-N and K concentrations. Given the high soil test K levels measured at this study site, no yield benefit to application of K was observed across the wide range of N rates evaluated. AR-29F
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