Soil Temperature Limitation to Water Use by Field-Grown Winter Wheat
- J. M. Wraith * and
- A. H. Ferguson
Modification of crop water use patterns in response to the field soil temperature regime has important agronomic and environmental implications. A 2-yr field study was conducted to ascertain how soil temperature modification influenced seasonal soil water depletion for a winter wheat (Triticum aestivum L.) crop near Bozeman, MT. Soil surface cover materials including clear plastic, white metal, and styrofoam were applied in the fall after germination and plant establishment. Soil temperature and water content profiles were monitored throughout the winter and spring growing seasons. Soil water depletion was significantly accelerated for those treatments having relatively warmer soil temperatures. Differences of up to 65 mm of cumulative soil water depletion were observed between warm and cool treatments during spring. Significant water extraction from a given depth within the soil profile did not occur until the soil temperature reached 10 to 11 °C during 1985. Repeated rainfall during 1986 obscured any relationship between minimum soil temperature and water uptake in the upper soil profile, but the same relationship as during 1985 was noted at greater depths. Although the nature of our field data does not allow determination of whether cold temperatures constrained root growth, root water uptake, or both of these processes, our field results substantiate conclusions drawn by other investigators using controlled-environment techniques. It is clear that cultural practices or climatic changes affecting seasonal soil temperature can impact soil water utilization by winter wheat in thermally limited growing areas.
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