|Bauer, Philip - Phil|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/11/1996
Publication Date: N/A
Citation: N/A Interpretive Summary: Potassium deficiency is occurring throughout the cotton growing areas of the world. Current soil testing methods do not always predict when there will be a yield response to added potassium fertilizer. This research was conducted to determine if measuring the ability of the soil particles to replenish the soil water with potassium as plant roots take up this nutrient could predict when growers would get a yield response to added fertilizer. We found that when the ability of the soil to convert potassium from a form that is readily available to plants to a less available form was low, there was a greater chance of getting a yield response to potassium fertilizer. This finding is an important first step to scientists working on developing improved soil testing methods for potassium fertility to cotton because it indicates that further research on this method of soil testing is warranted. It may ultimately result in improved efficiency in the use of potassium fertilizer.
Technical Abstract: Potassium deficiency is widespread in cotton growing areas around the world. The objectives of this study were 1) to develop a method whereby we can predict cotton response to K fertilization across the US Cotton Belt using the K buffering capacity (KBC), 2) to determine the relationship of commonly measured soil physical and chemical properties to KBC for a number of diverse cotton-producing soils, and 3) to compare soil extractants and K fertilizer recommendations used across the Cotton Belt. Locations were chosen to represent the major soil types across the Cotton Belt. Treatments were 0, 50, and 100 lb K20/A. When K fixation was <100%, there was a 44% probability of yield response to K. When K fixation was between 100 and 110%, probability of yield response was 23%; and above 110%, probability of yield response was 0%. Potassium fixation was positively correlated with CEC, and was more highly correlated with Mehlich-3 and ammonium acetate extractable K than with Mehlich-1 extractable K. The use of K fixation percentage as a predictor of cotton yield response to K fertilization shows promise across the Cotton Belt and merits further research.