Die abhängigkeit und schätzung von temperaturdifferenzen zwischen einem sommerweizenbestand und der klimahütte

Abstract

The daily maximum and minimum air temperatures and soil temperatures (at 5em, 20 cm soil depth under canopy) of a stand of spring wheat in flat terrain in N-Germany were compared during two growing seasons with the extreme temperatures of a 2-m standard screen and at 5 cm and 20 cm under bare soil, respectively. The mean maximum (minimum) air temperatures of the stand were 2.7°C higher (1.2°C lower) than the screen values. The mean maximum (minimum) temperatures of the soil at 5 cm and 20 cm depth were 7.0°C and 3.8°C lower (0.7°C and 1.2°C lower) than the temperatures of the bare soil of the station. Rainfall greatly diminished the differences. After statistical elimination of some of the meteorological elements, the maximum temperature differences could be calculated from total daily global radiation, soil moisture and rainfall, using multiple regression methods. The differences in the minimum temperatures were calculated from the grass minimum, wind at sunrise and rainfall. Global radiation was successfully substituted for by the daily duration of sunshine. A test of the regression formulae (coefficients of determination up to 71%) on independent data leads to the conclusion that climatological data may be used for spatial purposes of calculating maximum and minimum air and soil temperatures in wheat stands.