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This article in SSSAJ

  1. Vol. 21 No. 4, p. 357-359
    Received: Oct 1, 1956
    Accepted: Apr 16, 1957

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Seedling Emergence of Wheat, Grain Sorghum, and Soybeans as Influenced by Soil Crust Strength and Moisture Content1

  1. R. J. Hanks and
  2. F. C. Thorp2



A technique was devised for studying plant seedling emergence through soil crusts where soil crust strength, soil moisture content, and soil type could be varied independently. Wheat, grain sorghum, and soybeans were studied with crust strengths from 0 to 1,400 millibars (as measured by the modulus of rupture) and soil moisture content from field capacity to ¼ available (¼ of the available water remaining in the soil). Preliminary tests were made to determine the reliability of the modulus of rupture as a measure of crust strength with respect to seedling emergence.

Wheat seedling emergence was not influenced by seed spacing or crust thickness for a wide range of crust strength as measured by the modulus of rupture. It was concluded from this study that the modulus of rupture is a good measure of crust strength as related to seedling emergence of wheat and similar plants.

Soil crust strength limiting seedling emergence for the plants studied was dependent on the soil moisture content. At a given crust strength, seedling emergence was lowest where the soil moisture content was lowest. At constant moisture content, seedling emergence decreased with increasing crust strength for the plants and soils studied. However, partial seedling emergence occurred on all treatments even where crust strength was as high as 1,400 millibars.

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