Response of Maize (<i>Zea Mays</i> L.) to Supplementary Irrigation Under Rain Fed Agriculture at Jimma Agricultural Research Center, South West Ethiopia

Maize is the most extensively produced crop in both Africa and Ethiopia in terms of both land area and production. However, low soil fertility, non-agronomic methods, disease, pests, weeds, and insufficient water, negatively affect its yield. Although there are a lot of maize farming in the Jimma Zone, the yield is very low. The variability of rainfall is one of the causes of the low production, and it has to be supplemented through irrigation. This study was initiated with the objective of determining the effect of supplementary irrigation on the production and productivity of maize (Zea mays L.) under rain-fed agriculture. The field experiment was carried out for three consecutive years, from 2020 to 2022, on the maize (Zea mays L.) crop at the Jimma agricultural research center. The plots were laid out in a randomized complete block design (RCBD) consisting of eight treatments in three replications. The results of the analysis of variance showed that, the different levels of supplementary irrigation had a highly significant (P < 0.05) effect on ear height, but there was no significant difference on plant height. Grain yield and 100 seed weight were significantly (p<0.05) influenced by the application of different levels of supplementary irrigation. The pooled mean analysis indicated that the highest grain yield of 10623.1 kg ha^-1 and 100 seed weight of 56.19 gm/plot were recorded from the application of full irrigation (100% ETc). However, the plot with rain fed has given the lowest grain yield (5216.5 kg ha^-1) and the lowest 100-seed weight (41.97 gm /plot). In this study, there was a 49.1% yield increment between the fully supplied and the rain-fed maize. The result of partial budget analysis of maize showed that, the highest marginal rate of return and maximum net benefit of 16118 % and 255465 ETB were recorded from one SI at flowering stage and full Supplementary irrigation, respectively. The lowest net benefit (125984 ETB) was obtained at a rain fed treatment. Even though the marginal rate of return was lower, for a sustainable production of maize a full supply irrigation can be recommended.