Predicting Crop Responses on High-Potassium Soils of Frigid Temperature and Ustic Moisture Regimes1
- Earl O. Skogley and
- Vincent A. Haby2
Results of 13 years of field research throughout Montana have demonstrated a relatively high rate of crop yield response to K fertilization when included in an N-P-K fertilizer program. Correlations between crop response to fertilizer K and ammonium acetate-extractable K have been too low for this method to be used as a soil test. Alternative extraction methods or proposed soil test techniques were investigated in search of a useful relationship. These included saturated paste extraction, equilibrium extraction with dilute solutions, extraction with HEDTA or DTPA, ion-exchange resin extraction, combination resin—ammonium acetate extraction, percentage-K saturation of the CEC, and free energy of exchange relations for various ionic ratios. No adequate soil test relationship was identified in these studies.
Soils of the northern Great Plains—Intermountain region are relatively high in extractable K and have frigid (cool) temperature regimes and ustic (semi-arid) moisture regimes. Under these conditions, chemical measurements which relate to the quantity of K in soil apparently do not have an adequate cause-and-effect relationship in the availability of K to plants.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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