The effect of potassium fertilization on cereal crops grown on calcareous Manitoba soils

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Ewanek, John Norman
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Field experiments were conducted on calcareous soils with exchangeable potassium levels which ranged from 30 to 414 ppm to determine the effect of potassium fertilization on cereal growth. Barley plant matter samplings at 14, 21 and 28 days from seeding, and fifth leaf stage of growth indicated that the application of potassium fertilizer generally increased yield, potassium uptake and potassium concentration during early growth on all soils... Generally, potassium concentration in the barley and oat plants at the early stages was correlated to final yields. Final barley grain yields showed responses to one or more of the potassium treatments on 9 of the 10 soils studied; no responses occurred on the soil with 68 ppm exchangeable potassium. These responses although usually statistically non-significant were substantial, 2 bushels or more per acre. While wheat and oats showed some substantial, 3 bushels or more per acre, responses to potassium fertilization on soils with exchangeable potassium levels as high as 414 ppm, no consistant and uniform pattern of response was evident at exchangeable potassium levels greater than 84 ppm... With barley, potassium fertilization generally increased potassium uptake on soils with 414 ppm or less of exchangeable potassium and, with wheat, on soils with 102 ppm or less of exchangeable potassium. This was of interest because potassium uptake at harvest was found to correlate significantly with final grain and total yields... Results of a greenhouse experiment indicated that barley plants were more prone to damage from below freezing temperatures on soils low in exchangeable potassium, 67 ppm, than on soils high in exchangeable potassium, 210 ppm. The damage to the plants was reduced when the potassium concentration in the plant matter was increased with potassium fertilization.