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This article in AJ

  1. Vol. 63 No. 6, p. 836-839
    Received: Oct 27, 1970

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Potassium Effects on Regrowth of Alfalfa (Medicago sativa L.)1

  1. E. L. Kimbrough,
  2. R. E. Blaser and
  3. D. D. Wolf2



Field experiments were conducted to investigate the relationship of K in alfalfa (Medicago saliva L.) plant tissues on dry-matter yields and other growth characteristics at different stages of maturity.

Yield increases were highly correlated with increases in percent K in alfalfa leaves or herbage (leaves and stems). The correlations of percent K in tissue with the dry-matter yields were highest when sampling in a bud stage of growth, and declined with advancing maturities with later samplings. Sampling for K at the time of harvesting underestimated the percent K needed for high yields; herbage that had accumulated for 18 days (bud stage) averaged 143% more in K than at 39 days (full bloom).

The percent K in leaves and herbage was augmented by K fertilization, but the herbage was higher than leaves in K. The percent K in herbage declined sharply with advancing maturity; this did not occur for leaf tissue.

Yields and LAI's increased faster with liberal than with low K. The faster regrowth rates with high as compared with low K may make it possible to shorten cutting intervals, and make an additional cutting during the season. During advanced maturities after 32 days of growth, the LAI's generally stabilized or declined because of leaf losses.

Factors that influence the percent K in tissue should be considered when associating K composition with yields of alfalfa.

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