EFFECTS OF TILLAGE AND EVAPORATIVE DEMAND ON THE DRYING CHARACTERISTICS OF A SILT LOAM - AN EXPERIMENTAL-STUDY

Evaporation from undisturbed cores of a silt loam (typic Hapludalf) collected from four tillage treatments (ploughing to a depth of 30 cm (P), ploughing followed by harrowing (P + H), ploughing, harrowing and rolling (P + H + R) and no tillage (UNT) plots) was studied in a laboratory-controlled environment at five rates of evaporative demand. The results showed that at high evaporative demands, the evaporation was generally high compared with cumulative water losses at both low and moderate demands. More cumulative evaporation occurred from the more open surface structures at higher evaporative demands and most of these losses occurred during the first stages of evaporation. At low evaporative demand, cumulative evaporation was highest on untilled soil after 30 days of drying. The ability of tillage-induced open surface structure in reducing evaporation was more effective at lower than higher evaporative demands.