Browsing by Author "Mboyerwa, Primitiva Andrea"

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Effect of water, crop and nitrogen management practices on water productivity, yield and greenhouse gas emission in irrigated lowland rice, eastern Tanzania
(2022) Mboyerwa, Primitiva Andrea
Rice (Oryza sativa L.) is one of the most important grain crops for more than 50% of the world’s population, providing approximately 20% of total energy intake for humans (Muthayya et al., 2014). • Rice is also the largest consumer of water among all crops (Deng et al., 2021; Bouman and Tuong , 2001). • The water productivity of rice is lower than those of other crops (Kumar and Rajitha, 2019). • In Tanzania, about 90% of rice is grown under continuous flooding (CF), a practice that requires large amounts of water with less productivity (Katambara et al 2013; FAO, 2012) and contribute to emission of greenhouse gas emission ( Methane, carbon dioxide and nitrous oxide (Adounkpe et al .,2021). • Water productivity of rice that ranges from 0.1 to 0.14 kg m−3 has been recorded in Tanzania, which is lower when compared to 0.60–1.60 kg m-3 in other parts of the world (Najmuddin et al .,2018). • On average, 2500 liters of water is used, ranging from 800 liters to more than 5000 liters to produce one kg of rice (Najmuddin et al .,2018;Bouman and Tuong 2001). By 2025, 15–20 million ha of irrigated rice is estimated to suffer from some degree of water scarcity (Bouman and Tuong, 2001). • Alternate wetting and drying (AWD) irrigation practice has been demonstrated to provide advantages in terms of reducing water use and increasing crop productivity. • In addition to water, nitrogen is one of the most important nutrients that determine rice yields (Zhang et al., 2021, Djaman et al., 2018; Saito et al., 2015); its deficiency is a limiting factor for sustainable rice production. • However, the use of N fertilizer is generally inefficient, and the average apparent recovery efficiency of N fertilizer is about 33% for rice globally (Zhang et al., 2021).
Evaluation of growth, yield and water productivity of paddy rice with water-saving irrigation and optimization of nitrogen fertilization
(MDPI, 2021) Mboyerwa, Primitiva Andrea; Kibret, Kibebew; Mtakwa, Peter W; Aschalew, Abebe
Rice production in Tanzania, with 67% of its territory considered semi-dry and having average annual rainfall of 300 mm, must be increased to feed an ever-growing population. Water for irrigation and low soil fertility are among the main challenges. One way to decrease water consumption in paddy fields is to change the irrigation regime for rice production, replacing con- tinuous flooding with alternate wetting and drying. In order to assess the impact of different irri- gation regimes and nitrogen fertilizer applications on growth, yield, and water productivity of rice, a greenhouse pot experiment with soil from lowland rice ecology was conducted at Sokoine Uni- versity of Agriculture, Tanzania during the 2019 cropping season . The experiment was split-plot based on randomized complete block design with 12 treatments and 3 replications. Water re- gimes were the main factors comparing continuous flooding (CF) and alternate wetting and drying (AWD) with nitrogen fertilizer levels as the subfactor, comparing absolute control (no fertilizer) with 0 (P and K fertilizers), 60, 90, 120, and 150 kg Nha−1. Alternate wetting and drying (AWD) significantly improved water productivity by 8.3% over CF (p < 0.05). Water productivity (WP) ranged from 0.6 to 1.5 kg of rice per m3 of water. Average water use ranged from 36 to 82 L per season, and water saving was up to 34.3%. Alternate wetting and drying significantly improved yields (p < 0.05) by 13.3%, and the yield ranged from 21.8 to 118.2 g pot−1. The combination of AWD water management and 60 kg N ha −1 nitrogen fertilization application was found to be the optimal management, however there was no significant difference between 60 and 90 kg N ha −1, in which case 60 kg N ha −1 is recommended because it lowers costs and raises net income. Nitrogen levels significantly affected water productivity, water use, and number of irrigations. Nitrogen levels had significant effect (p < 0.05) on plant height, number of tillers, flag leaf area, chlorophyll content, total tillers, number of productive tillers, panicle weight, panicle length, 1000-grain weight, straw yield, grain yield, and grain harvest index. The results showed that less water can be used to produce more crops under alternative wetting and drying irrigation 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 strate- gies
Evaluation of water productivity and agronomic performance of paddy rice through water saving irrigation and nitrogen fertilization
(2020) Mboyerwa, Primitiva Andrea; Kibret, Kibebew; Mtakwa, Peter W; Aschew, Abebe; Uphoff, Norman T
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.