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This article in AJ

  1. Vol. 65 No. 3, p. 351-354
    Received: Aug 18, 1972

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Relationships between Drouth and Corn Yields on Selected South Atlantic Coastal Plain Soils1

  1. Charles D. Sopher,
  2. Ralph J. McCracken and
  3. David D. Mason2



The objectives of this study were to determine the effects of drouth-days by physiological growth periods on corn (Zea mays L.) grain yields and to develop a one-figure drouth index suitable for expressing these effects. A drouth-day was defined as a 24-hour period when potential evapotranspiration exceeds rainfall plus the effective moisture storage capacity. The physiological growth periods were: two equal-length periods prior to tasseling; tasseling; and a maturity period. The study was conducted on two major North Carolina Soil Groups.

On the better drained (Udultic) soils of the Upper and Middle Coastal Plains, drouth-days accounted for 62.6% of the corn yield variation. The effects of drouth were detrimental in the second and fourth growth periods, and grain yields were reduced to zero after five drouth-days during the tasseling; period. For the very poorly drained (Aquultic) soils of the Tidewater Region, drouth-days accounted for 41.2% of the yield variation. Detrimental drouth-day effects were only present during the second and tasseling periods. The reduction of the effects of drouth-days on these soils was attributed to moisture extration from an underlying water table.

Using the derived regression coefficients for weights, the drouth-days by physiological growth periods were weighted and summed to develop a one-figure drouth-index. This index may be used as a single climatic variable in regression-correlation studies of the crop-soil ecological system.

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