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Is Soil Temperature Better than Air Temperature for Predicting Winter Wheat Phenology?
Author(s) -
McMaster Gregory S.,
Wilhelm Wallace W.
Publication year - 1998
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1998.00021962009000050006x
Subject(s) - phenology , air temperature , environmental science , agronomy , apex (geometry) , growing degree day , shoot , winter wheat , soil water , atmospheric sciences , biology , soil science , botany , geology
In predicting wheat ( Triticum aestivum L.) phenology, logic suggests that basing thermal unit accumulation on near‐surface soil temperature should give a better representation of shoot apex thermal unit accumulation than air temperature until internode elongation raises the apex above the soil surface. A study was undertaken to determine if predictions of winter wheat phenology are improved when based on measured near‐surface soil temperature rather than air temperature. Air temperature 1.5 m above the soil surface and soil temperature at crown depth (the position of the shoot apex before stem elongation) were collected for 23 site‐years across the U.S. Central Great Plains representing a range of cultivars, soils, management practices, and climates. Seven site‐years from different sites were randomly selected to calculate the mean thermal units from both seeding and 1 January to specific growth stages based on both air and soil temperature. These means were used to predict occurrence of growth stages for the remaining 16 site‐years. In no instance did soil temperature significantly improve prediction of winter wheat phenology. From these results, we conclude that the additional effort and expense of using soil temperature in predicting winter wheat phenology are not justified.