2.3. Irrigation control
The 90-V-notch weir method was used to measure and adjust
the water flow to the plots, as an equal quantity of water was supplied
using furrow irrigation over all experimental plots (Michael,
1978). Good tillage, plot and channels preparations were performed
to avoid outside drainage during irrigation. The 90-V-notch weir
was constructed across the approaching channel before starting
irrigation. The notch was 5 cm above the bottom of the channel and
the water was only allowed to pass through it. The height of water
over the 90-V-notch was measured in centimeters by using a ruler
after the constant and stable flow of water occurred. The amount
of water discharged was then calculated by measuring the time of
water flow into the plot in seconds with reading of the water height
over the 90-V-notch. Then return to the water discharge table to
know the discharge rate in liters per second. Then the total volume
of the water applied to each plot was counted from the discharge
table (Michael, 1978).