Potassium release kinetics and the effect of potassium fertilizer application on cotton growth, development, and yield in several Sonoran dessert soils of Arizona
AdvisorSilvertooth, Jeffrey C.
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PublisherThe University of Arizona.
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AbstractIn an effort to determine the agronomic necessity of K fertilization of cotton (Gossypium spp.) in Arizona, a five-year study was initiated in 1991, with a single field study near Gila Bend. Subsequent sites selected ranged from western (Yuma) to eastern (Safford) Arizona which totaled 11 site-years. Both Upland (G. hirsutum L.) and Pima (G. barbadense L.) cottons were cultivated, using soil and foliar applications of K. In 1992, study sites included the Safford Ag. Center (SAC), Maricopa Ag. Center (MAC), and a fanner cooperator site at Coolidge. In 1993, the experiment stations (SAC and MAC) were continued and Yuma Valley was added. The 1994 sites included only the experiment stations (SAC and MAC). In 1995, SAC and MAC were again maintained and a third location, a fanner cooperator site at Buckeye was added. Results from the study (12 site-years) indicated no lint yield increases due to K fertilization in all locations with either Upland or Pima cotton However, in 1995 at Buckeye, the result revealed a significant yield reduction due to the K foliar treatments. There were, however, no significant differences among the soil-only or the soil- plus-foliar treated plots at this location. Potassium (K) release kinetics of clay samples from 10 agricultural representative soils of Arizona was determined by successive extraction using a Ca-saturated cation resin. A preseason physical and chemical characterization of the soils showed all soils contain smectite-mica minerals. Four mathematical models (power function, Elovich, parabolic diffusion and first-order) were used to describe the nonexchangeable K release reaction involving 700-hour cumulative extraction time. Comparison of the models using the coefficient of determination (r²) and the standard error of the estimate (SE) indicated that the Elovich and the power function equations overall displayed the best fit. The first-order, and for the most part, the parabolic diffusion equation did not describe the K release very well. The constants a (initial rate) and b (release rate) for the Elovich and the power function equations, are at least in the order of magnitude as those found by others in several previous studies.
Degree ProgramGraduate College
Soil, Water and Environmental Science