Abstract:
A field experiment was conducted to study the impacts of different irrigation schedules on
land and water productivity of a bean (Phaseolus vulgaris L.) crop. Three irrigation
scheduling methods were evaluated using a randomised complete block design., one based
on historical climatic data (water balance), a second one based on neutron probe soil
moisture measurements and the third one based on normal practices of farmers in the area
(farmer-managed schedule). Irrigation water applications and crop water use were
monitored throughout the growing season. The mean total water delivery under farmer-
managed plots was 735mm which is more than adequate for a bean crop whose water
requirement for maximum production varies between 300 and 500mm depending on
climate. There were significant differences (P<0.05) in irrigation water productivity (IWP)
and field water application efficiency (FAE) among treatments. The IWP and FAE of
farmer-managed schedule were significantly lower than the other treatments, but the F AE
of the control plot and climatic data plot did not differ significantly (P < 0.05). On the
other hand, there was no significant difference (P<0.05) in physiological water use
efficiency (PWUE) among treatments. Land productivity was significantly higher (P <
0.05) in the climatic data based schedule than the other methods. It would thus appear that
the water budget technique based on average climatic data is a suitable irrigation
scheduling criterion which saved irrigation water while achieving maximum yield,
optimum water productivity and field application efficiency. Low field application
efficiencies under farmers' management practices indicate a need for improvement in water
management strategies of individual farmers. This would go a long way to improving both
water and land productivities.
