Abstract:
Irrigation water is scarce in semiarid environment and need to be used judiciously. Minimizing
water input in crop fields such as maize will help in saving water which would increase the
water productivity. Several approaches are employed to reduce irrigation water input in
agricultural areas. In this particular study, soil moisture based water application has been
employed to study the effect of deficit irrigation application in Arba Minch area. The study
was particularly conducted on Arba Minch University demonstration farm. The aim of this
study is to assess the role of different water applications and the responses of maize yield, under
the semi-arid environment like Arba Minch by planting two commonly grown varieties of
maize (BH-140 and BH-540). Both field and laboratory experiments were carried out to acquire
important data for analysis in this study. For the analysis, AquaCrop model was employed. To
carry out this, irrigation application based on current amount of soil moisture in the crop root
zone with 100, 75, 50, and 25% of the soil moisture deficit is satisfied for the designed
treatments. The soil moisture deficit is taken as the amount of soil moisture content between
the field capacity and the current soil moisture content. The results of the study showed that
large savings in irrigation can be possible using the soil moisture based approach when
compared to the previous studies. As a result, yields of BH-140 was from 8.93 t/ha to 5.65 t/ha
and for BH-540 from 8.84 t/ha to 5.76 t/ha. These were obtained with the overall water
application for BH-140 from 417.55 mm to 268.39 mm and BH-540 was 417.13 mm to 266.09
mm. Thus, for BH-140, the model showed NSE of 0.737 and RMSE of 0.534. Whereas for
BH-540, the model showed NSE and RMSE of 0.755 and 0.489 respectively. Also, water
productivity based on the total supplied water ranges from 2.717 kg/m
3
to 1.353 kg/m
for BH140
and
from
2.920
kg/m
3
to 1.385 kg/m
3
BH-540. Comparatively, better aboveground dry
biomass was observed for BH-540 in treatment T
5B
. Contrarily, the grain yield was better in
the case of BH-140 maize variety. Therefore, the model can effectively be used for maize
irrigation scheduling in the study area using the values calibrated in this study.
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