Relationships between Drouth and Corn Yields on Selected South Atlantic Coastal Plain Soils1
- Charles D. Sopher,
- Ralph J. McCracken and
- 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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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