Irrigation scheduling of maize crop by PAN evaporation method in Mardan[Pakistan]

The experiment was conducted using Randomized complete block designwith four pan levels i.e. 0.5 Ep, 0.75 Ep, 1.00 Ep, 1.25 Ep and one controltreatment. Soil moisture content was determined up to 1 m depth bygravimetric method. The first soil sampling for moisture estimation wasperformed at the time of crop sowing. Subsequent moisture was carried outbefore and after each irrigation event. Moisture samplings were also carriedout after each successive rainfall. Final moisture sampling was determined atthe time of crop harvest. A cutthroat flume was installed in the watercoursefor applying the measured quantity of irrigation water to the plots. Soilphysical properties (soil bulk density, wilting point ad field capacity), actualmanagement allowed deficit, application efficiency and water use efficiencywere also determined for all the plots. Potential evapotranspiration (Etc) forresearch site and maize evapotranspiration (Etc) was also determined by panevaporation method. Maize evapotranspiration (Etc) for whole the growingseason was found to be 451 mm. Total irrigation depth applied were 278, 132,197, 263 and 328 mm for T0, T1, T2, T3 and T4 plots respectively. Only threenumber of irrigation was applied to maize during the research period becauseof heavy rainfall. The actual average management, allowable deficit was rangedbetween 0.31-0.40, 0.46-0.58 and 0.38-0.49, which was high about 38-48%, 11-29%25-42% due to early irrigation before reaching their desired MAD level. Thehighest value of MAD was observed in T0, and T2 plots before all threeirrigation, while the lowest value was observed in T3, T2 and T4 plots duringthe research period. Average application efficiency of each irrigation wasrecorded between 50-81, 38-4 and 56-76% due to small application of irrigationwater. Highest application efficiency vas observed in T1 plots while the lowestvalues were observed in T3 and T4 plots through out the growing period. Thewater use efficiency was noted from 5.04 kg/ha/mm to 17.74 kg/ha/mm becauseof high and low depth of water stored in root zone. The statistical analysisshowed that. There was significant difference among different irrigationdepths applied on grain yield of maize. The highest yield of 2993 kg/ha wasobtained in T2 plots which were irrigated according to 0.75 0f panevaporation. The lowest grain yield of 1993 kg/ha was obtained in T0 plotswhich were irrigated according to farmer method.