DEW FORMATION AND THE DRYING PROCESS WITHIN A MAIZE CANOPY

The amount of dew-fall and dew-rise to a maize canopy during one night, and the drying time during the early morning, were estimated by using the Bowen ratio energy budget technique (BREB) and the soil diffusivity technique (SD). In addition, the distribution of the free liquid water within the plant community was measured at sunrise by using Leick plates and blotting papers. The course of the drying process within the plant canopy was also monitored by the blotting paper technique until the received night-time free liquid water within the canopy was evaporated. The calculated total amount of dew, estimated with the BREB and SD techniques, agreed with the measured amount to within 6%, though the measured drying process lagged about 1 hour behind the calculated one. Possible causes of this difference are the dripping effect and drainage down the stems, which were not included in the calculations. Initially, the drying process was faster in the upper layers of the canopy. Later, when the moisture distribution had become more or less even through the whole canopy, the drying rate became approximately uniform.