Effect of stubble height and tillage on winter soil temperature in central Alberta

Production of winter wheat in central Alberta may be risky due to winter-kill by low temperatures. Winter survival can be enhanced with a snow-trapping stubble. The effect of barley stubble height and tillage on snow depth and soil temperature was investigated during the winters of 1983–1984 and 1984–1985 on a Black Chernozemic soil at Lacombe, Alberta. Snow depth was measured only in 1984–1985 and was deepest under zero tillage with the tallest stubble (30 cm). Under zero tillage, stubble height had a significant effect on soil temperature. Soil temperatures under zero tillage with no stubble were the lowest and fluctuated greatly in response to air temperatures. Soil temperatures increased with an increase in stubble height and were highest at a stubble height of 15 or 30 cm. Soil temperatures in plots with stubble 15 cm tall were 3.9-5.3°C higher than in plots with no stubble. Under conventional tillage, stubble did not affect soil temperatures in 1983–1984, but in 1984–1985 soil temperatures in November and December were warmer when stubble was incorporated than when it was removed. Soil temperatures under conventional tillage were generally similar to temperatures under zero tillage with no stubble or with stubble of 7.5 cm. Although the soil temperatures during the course of this study did not go below the critical lethal limits of −20°C, the results indicated that stubble height and zero tillage may provide a solution to some of the problems associated with winter kill of winter wheat in central Alberta.