Browsing by Author "Dibwe, Mohamed"

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    Effects of rotational irrigation on water use effiency, growth and yield of direct seeded lowland rice
    (University of Dar es Salaam, 1984) Dibwe, Mohamed
    An experiment to study the effects of rotational submerging irrigation during the vegetative growth phase in rice culture was set out at Dakawa rice farms during the rainy season of 1983. Four irrigation intervals, that is daily; 4 days; 8 days; and 12 days; and three flooding levels that is 5 cm; 10cm; and 15 cm were tested in a split-plot design to find out the optimum irrigation schedule and flooding level to achieve the maximum output from a unit amount of irrigation water. Results from the experiment revealed that field capacity to soil saturation at pre-tillering followed by rotational submerging (5cm) irrigation at 8 days irrigation interval between tiller initiation and panicle initiation stages; and finally continuous submerging (5cm) irrigation to maturity resulted into the lowest water requirement and highest efective rainfall. Tiller mortality was higher with higher irrigation frequency than lower frequency while less irrigation frequency favoured weed growth. There was no significant difference in grain yield. Therefore, the continuous deep submerging irrigation during vegetative growth phase appeared to be the most wasteful irrigation practice at Dakawa rice farms. As such the main effects of rotational submerging irrigation were to reduce pumping and irrigation costs, and increase effective rainfall utilization. These findings are discussed in terms of improving water management practices in large scale farms and their subsequent implications in grain yield