Abstract
Waterlogged conditions in hydromorphic soils during spring cause low temperatures which may restrict grapevine performance. Ridging is a soil preparation method that can improve internal drainage in the root zone. Temperature measurements showed that ridging tended to increase temperatures in the upper soil layers compared with unridged soil, but showed no significant difference in soil with ridges of varying width and height. During the later part of the growing season soil temperatures in the ridges exceeded 30°C. These high temperatures were, however, not maintained for long periods and may therefore not have had a negative effect on root activity. Soil temperature recorded during the entire growing season related well to soil water content. The soil temperature versus water content relationship improved with increasing soil depth. Temperature measurements showed that the diurnal rate of heat exchange was much higher in the upper layers of the ridged soil when compared with the unridged control. Accurate predictions of diurnal soil temperature cycles were made by using a sinusoidal function of time around the average daily soil temperature.