Abstract:
Evaluation of the effects of supplementary irrigation on maize crop productivity under rain fed
agriculture was carried out at Arba Minch University Demonstration site. The aim of the
research was to study the effect of supplementary irrigation under rain fed for maize crop, in
order to provide necessary information in decision making on irrigation management. The
experiment was laid out in a Randomized Complete Block Design (RCBD), and investigated in
the cropping season of the year 2015 GC. There were two main treatments (Rain-fed (R) and
Rain-fed with supplementary irrigation (SI), and each have three replications. The time of SI was
not scheduled to prove moisture stress free condition throughout the growing season. All
management practices were the same with exception of water added to (SI). Data analysis was
done for variance and LSD at 5% level of significance. Result showed significant response grain
yield weight (t/ha), plant height, leaf length, leaf width (m). Maize average yield under rain-fed
was 2.88t/ha whereas, under 10, 25 and 50%ETc supplementary irrigation with rain fed the
grain yields were 3.06t/ha, 3.38t/ha and 3.99t/ha respectively. Supplementary irrigation was
considered only during the critical water stress conditions due to inadequacy of rainfall and
when soil moisture was below 20%. Supplementing rain-fed agricultural production system by
10% of ETc was increased the yield by 6% whereas, supplementing by 25 and 50%ETc during
critical water stress periods was increased the yield by 17 and 39% respectively. This represents
huge potential of supplementary irrigation to improve the productivity of rain-fed agriculture.
