Evaluation of water productivity and agronomic performance of paddy rice through water saving irrigation and nitrogen fertilization
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Date
2020
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Abstract
Tanzania with 945 million hectares of land area and annual rainfall of 300 mm on 67% of
its territorial land is considered as a semi-dry region in the world. Rice production in Tanzania
needs to be increased to feed a growing population, whereas water for irrigation is getting scarce.
One way to decrease water consumption in paddy fields is to change the irrigation regime for rice
production and to replace continuous flooding with alternate wetting and drying. In order to
investigate the effect of different regimes of irrigation and nitrogen fertilizer on yield and water
productivity of hybrid rice, two greenhouse pot experiments comprising soils from upland and
lowland production ecologies were conducted at Sokoine University of Agriculture, Tanzania
during crop seasons of 2019. The experiment was arranged in split plots based on completely
randomized block design with 3 replications. Water regimes were the main factor comparing
continuous flooding (CF) and alternate wetting and drying (AWD) wit nitrogen fertilizer levels as
the sub-factor including absolute control , 0, 60, 90, 120 and 150 kg/ha. Alternate wetting and
drying (AWD) improved water productivity in both upland and lowland production ecologies
compared to CF. AWD increased yield under lowland production by 13.3% while in upland there
was 18.5% decrease in yield. The average water use varied from 31.5 to 84 L pot-1 under upland
trials, while in lowland trials it was 36 to 82.3 L. Higher yield and lower water application led to
an increase in WP varying from 1.2 to 1.8 kg cm-3 under upland trials, and 0.6 to 1.5 kg cm-3 under
lowland trials. The variation in water productivity among treatments was mainly due to the
differences in the yield, water and nitrogen levels used in the production process. Both sets of
trials recorded water saving up to 34.3% and 17.3% under lowland and upland trials, respectively.
Under upland trials, the yield varied from 39.9 to 124.1 g pot-1 and in lowland trials yield was from
20.6 to 118.2 g pot-1 representing paddy rice. The measurements showed that less water can be
used to produce more crops under alternative rice growing practices. The results are important for
water-scarce areas, providing useful information to policy makers, farmers, agricultural
departments, and water management boards in devising future climate-smart adaptation and
mitigation strategies.
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Journal Article
Keywords
Water saving, Irrigation, Water productivity, Grain yield, Rice