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Fraction of Net Radiation Utilized in Evapotranspiration from a Corn Crop
Author(s) -
Graham W. G.,
King K. M.
Publication year - 1961
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1961.03615995002500020026x
Subject(s) - evapotranspiration , lysimeter , crop coefficient , environmental science , water content , crop , bowen ratio , daytime , hydrology (agriculture) , soil water , agronomy , atmospheric sciences , soil science , ecology , geotechnical engineering , biology , engineering , geology
The ratio of daily evapotranspiration to net radiation was determined at various stages in the development of a corn crop. Measurements, made near the center of a 266‐ by 340‐foot corn plot near Guelph, Ontario are reported for 16 days of observation during the summer of 1958. Soil moisture in the plot was maintained at a level exceeding 75% available. There was good agreement between the daily evapotranspiration determined by a floating lysimeter and the daily evapotranspiration computed hourly from the vertical heat budget method. The ratio of evapotranspiration to net radiation (E/R n ) averaged 0.81 ± .09 for the daytime period on days following rain when a large area was equally moist. Low values of E/R n were associated with days of heavy cloud and high humidity. Values of E/R n greater than unity during the daytime were obtained on some days when the corn plot was irrigated and the surroundings were dry. Freezing of the crop reduced E/R n to 0.52. The stage of crop development prior to freezing did not have any effect on E/R n under the soil moisture conditions of this experiment.