Evaluation of the effectiveness of commonly used irrigation scheduling approaches on land and water productivity
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Tanzania Journal Agricultural of Sciences. 2008 Vol. 9 No.1, pp 79 -92
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.
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.
Keywords
Irrigation scheduling, Irrigation efficiency, Water productivity, Phaseotus vulgaris L., Common beans