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.
Lowering nitrogen rates under the system of rice intensification enhanced rice productivity and nitrogen use efficiency in irrigated lowland rice
(cell Press, 2022) Mboyerwa, Primitiva Andrea; Kibret, Kibebew; Mtakwa, Peter; Aschalew, Abebe
Among the essential plant nutrients, nitrogen (N) is the most important and universally deficient in rice cropping systems worldwide. Despite different practices available for improvement of N management, nitrogen use effi- ciency (NUE) is still very low in rice, particularly under conventional management practices. This study was conducted to assess the effect of two crop management practices including the system of rice intensification (SRI) versus conventional management practices (CP) with four N application levels (60, 90, 120, and 150 kg N ha 1 ) and absolute control (i.e., without N application) on rice growth, grain yield, and NUE. Experiments were established in split-plot randomized complete block design in three replicates. Crop management practices and N levels were treated as the main effect of main-plots and sub-plots, respectively with replicate blocks treated as random factors. Results indicated that deploying of SRI increased rice grain yield by 17.5 and 52.4% during wet and dry seasons, respectively compared with the CP. Rice grain yield was significantly (p < 0.05) higher in SRI than in CP at all levels of N application compared. The application of N at 120 and 60 kg ha 1 resulted in the increase in rice grain yields by 49 and 46.5%, respectively, relative to the absolute control during wet and dry seasons. Nitrogen application had a significant effect (p < 0.05) on agronomic nitrogen use efficiency (ANUE) and partial factor productivity (PFP). Results also indicated that agronomic nitrogen use efficiency (ANUE) was higher (27.2 kg grain kg 1 N) during the wet season with an application of 60 kg N ha 1 . Furthermore, higher ANUE (23.8 kg grain kg 1 N) was recorded during dry season with an application of 90 kg N ha 1 . The significant (p < 0.05) interaction effects of treatments were recorded on PFP between SRI and 60 kg N ha 1 during the wet (116.7 kg grain kg 1 N) and dry (105.8 kg grain kg 1 N) seasons. This study revealed that ANUE and PFP decreased with N application at the levels of 120 and 150 kg N ha 1 under SRI and CP during the two cropping seasons. The findings of the present study provide potential information that rice grain yield and higher NUE could be achieved at low N inputs under SRI, and thus reducing costs resulted from fertilizer inputs without compromising other environmental benefits.
Potentials of system of rice intensification (SRI) in climate change adaptation and mitigation. A review
(JAPR, 2018) Mboyerwa, Primitiva Andrea
How to increase food production using less water is one of the greatest challenges of the future. Crops and livestock use 70 percent of all water withdrawals and up to 95 percent is some developing countries. Paddy alone consumes about 60 percent of it. By 2025, 1.8 billion people are projected to be living in countries or regions with absolute water scarcity. To ensure food security for the growing population, expansion of rice-cropped area and continuous intensification of rice cultivation would likely increase greenhouse gas emission. Data on trade-offs between rice yield increase, water management and reduction in greenhouse gas emissions are urgently needed for innovation in cropping techniques. Modification of current cropping technique might be a way to reduce greenhouse gas emissions from rice soils. In this respect, System of Rice Intensification (SRI) has been introduced as an efficient, resource saving, and productive strategy to practice rice farming. Water management practices proposed for the SRI, cycles of repeated wetting and drying, were found to be beneficial to rice plant growth through increased nutrient availability leading ultimately to higher grain yields. In many countries, SRI have been producing average yields around 8 t/ha, twice of the present world average. With good use of these methods and with build-up of soil fertility, in microbiological as well as chemical and physical terms, yields can surpass 15 t/ha, pushing beyond what has been considered a yield ceiling for rice. SRI is reported to reduce greenhouse gases emissions up to 40%, water saving 25-65%, reduction in incidence of major rice pests and diseases, resistance to storm damage and drought, high economic return and shorter crop cycle. These make SRI technology relevant to the climate change adaptation and mitigation.