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Soil Science Society of America Journal Abstract -

Prediction of the Calcium to Calcium Plus Magnesium Ratio in Soil-Grown Winter Wheat Forage


This article in SSSAJ

  1. Vol. 52 No. 1, p. 152-160
    Received: Jan 8, 1987

    * Corresponding author(s):
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  1. N. Rossi,
  2. P. H. Nye,
  3. D. L. Grunes  and
  4. C. A. Sanchirico
  1. Inst. of Agric. Chemistry and Forestry, Univ. of Basilicata, Potenza, Italy
    Dep. of Agric. Science, Univ. of Oxford, England
    USDA-ARS, U.S. Plant, Soil, and Nutrition Lab., Ithaca, NY 14853-0331
    Dep. of Agronomy, Cornell Univ., Ithaca, NY



The purpose of the research was to predict the Ca/(Ca + Mg) ratio in soil-grown winter wheat forage from a knowledge of (i) Ca/(Ca + Mg) in the soil solution, or from Ca/(Ca + Mg) calculated from exchangeable plus soluble ions in the soil, and (ii) Ca/(Ca + Mg) in the tops of plants grown in nutrient solutions of regulated Ca/(Ca + Mg). Winter wheat (Triticum aestivum L. ‘Centurk’) was grown in a controlled light-temperature chamber and harvested after 10, 20, and 30 d. The same Ca/(Ca + Mg) ratios were used in both nutrient solution and soil experiments. In the nutrient solution experiment, the Ca level varied from 5.90 to 0.78 mM, while the Ca + Mg equalled 6 mM. In the soil experiment, the amounts of liming materials for the different treatments (in mg kg−1 of soil-sand mixture) varied from 2 400 (CaCO3) + 0 (MgCO3) to 0 (CaCO3) + 2020 (MgCO3). Growth was similar in nutrient solution and in soil, and was unaffected by Ca-Mg treatment. Concentrations of Ca and Mg in tops and roots were higher in the plants grown in nutrient solutions than in the soil-grown plants. The observed and predicted Ca/(Ca + Mg) ratios in the tops agreed excellently. The concentrations of Ca and Mg at the root surfaces of the soil-grown plants were calculated using diffusion, mass flow, and root absorbing power. The calculated valuves differed little from those found in the bulk of the soil solutions. Implications for Ca and Mg deficiency of grazing ruminants are discussed.

Joint contribution of the USDA-ARS, Ithaca, NY, and Cornell Univ. Agric. Exp. Stn. This study was part of the program of the Center for Root-Soil Research, Ithaca, NY. Cornell Dep. of Agronomy Paper no. 1620.

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