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This article in AJ

  1. Vol. 73 No. 1, p. 25-28
    Received: Apr 24, 1980

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Potassium Response of Alfalfa in Solution, Sand, and Soil Culture1

  1. N. A. Romero,
  2. C. C. Sheaffer and
  3. G. L. Malzer2



Information on yield response to K by alfalfa (Medicago saliva L.) cultivars should be useful for determining the possibility of improving K utilization. Our objectives were to compare plant culture systems as methods of assessing K fertilization effects on alfalfa yield and K uptake, and to determine the effect of cultivar winterhardiness on yield. Growth chamber and glasshouse studies were conducted in which alfalfa cultivars were grown in sand and solution culture with nutrient solutions containing 0, 35, 60, 85, and 110 mg K/liter and in three soils receiving 0, 100, 200, 400, and 800 mg K/kg.

Sand culture was not effective in evaluating potential cultivar yield differences in response to K fertilization because K levels were insufficient for plant growth. Solution culture provided a wide range of K availability which allowed for evaluation of differential yield response by cultivars. Alfalfa yields for soil culture were less than for solution culture and K additions did not produce as wide a range of herbage K concentrations as solution culture.

In solution and soil cultures, cultivars differed in yield and in herbage K concentration responses to increasing K concentrations, but these responses were not related to cultivar winterhardiness. Cultivars also differed in herbage K concentrations at maximum dry matter yields and at the onset of K deficiency symptoms. Our results show that no relationship existed between cultivar winterhardiness level and yield response to K fertility. However, it may be possible to select cultivars which perform under low soil K fertility levels.

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