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Potential soil potassium supply capacity as related to wheat potassium demand

Qian, P., J.J. Schoenau and G. Li. 1998. Communications in Soil Science and Plant Analysis 29: 635-641


We examined soil potassium (K) supply capacity as related to wheat response to K fertilization, using a cation exchange membrane (CEM) burial technique to measure potential K supply rate.  A growth chamber experiment was conducted to determine soil and plant response relationships.  Canadian Prairie Spring wheat (Triticum aestivum var. Biggar) was grown on three soils of different initial K fertility with three rates of added K.  Wheat response to K fertilization was well related to the amount of exchangeable K and K supply rate in the soil.  Soils with high initial K supply rate demonstrated an adequate K release rate which was associated with low response to added K fertilizer.  A soil K supply rate less than 5 μg cm-2 hr-1 represented soil K supply power that is less than optimal for wheat nutrition.