Cotton Growth in an Acid Fragipan Subsoil: II. Effects of Soluble Calcium, Magnesium, and Aluminum on Roots and Tops

Soileau, J. M.; Engelstad, O. P.; Martin, J. B.

Cotton Growth in an Acid Fragipan Subsoil: II. Effects of Soluble Calcium, Magnesium, and Aluminum on Roots and Tops

1969

Soileau, J. M. | Engelstad, O. P. | Martin, J. B.

Greenhouse and laboratory studies were made to evaluate the effects of soluble Ca, Mg, and Al on cotton (Gossypium hirsutum) growth in highly acid fragipan subsoil (Dickson series). Growth response was not related to soil pH, per se. The high level of soluble Al inherent in the Dickson subsoil greatly inhibited cotton growth by inducing morphological damage to the root system and by depressing uptake of Ca. Yield reductions were accompanied by Al concentrations above 0.2 and 0.02% in roots and tops, respectively. Severe Ca deficiency symptoms in tops and roots were observed where Ca was maintained at inherent subsoil levels and Al was either neutralized with base or was leached from the soil system. Although all treatment yields were not related to Ca or Mg concentrations in plant tissue, results suggested that the native levels of exchangeable Ca and Mg in Dickson fragipan subsoil may be limiting for cotton growth. Whether or not the “inherent” deficiency of Ca is entirely or only partly Al-induced was not conclusively determined; however, this question may be relatively unimportant in view of the other harmful effects of high levels of soluble Al on cotton growth.

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