EFFECTS OF TILLAGE AND DIRECT DRILLING ON SOIL TEMPERATURE IN WINTER

Continuous records of soil temperature were collected at 1 cm and 5 cm depth during two winters (1972–4) in cultivated and uncultivated (direct drilling) soil. When solar radiation levels were low, the observed large and irregular fluctuations in soil surface temperature appeared to be associated with advective heat flow. The stubble mulch on the uncultivated soil insulated the surface layers from temperature variation, resulting in less soil freezing than cultivated soil and fewer hours above 5° C. Some implications of these findings for cultivations for cereals are discussed.