The availability of potassium to plants from several calcareous and non-calcareous Manitoba soils

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Bailey, Loraine Dolar
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The soils of Manitoba could be divided into two broad groups, calcareous and non-calcareous, based on their percent calcium carbonate equivalent. Previous field and greenhouse experiments had indicated that there existed differences in the relative ease of availability of soil potassium from these soils to plants. Also that the NH4OAc extractable potassium determined on these soils did not adequately describe the amount of potassium in these soils available to plants. An investigation, including greenhouse and laboratory experiments, was conducted to investigate these problems. It was found that the differences with respect to the the availability of potassium to plants from these two groups of soils were dependent on the texture of the soils compared. Thus for equivalent levels of NH4OAc and NaCl extractable potassium, the coarser textured soils in both groups supplied approximately equal amounts of potassium to corn... It was also observed that an equilibrium condition appeared to be operating in the soil potassium system of these soils. NH4OAc solution extracted more potassium that the NaCl solution, which in turn extracted more potassium than the H2O solution from fine textured soils in both soil groups... Corn was found to take up more magnesium from both groups of soils than calcium... In both greenhouse experiments it was found that banding the potassium in to the soils below the seeds, gave a better yield of plant material than mixing the potassium throughout the soil. The amount of potassium taken up by the plants from the banded source of potassium was larger than the amount they took up from the diffused source.