Browsing by Author "Tumbo, Siza D"
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Item Impacts of Climate Variability and Change on Rainfed Sorghum and Maize: Implications for Food Security Policy in Tanzania(2015-04-15) Msongaleli, Barnabas M; Rwehumbiza, Filbert; Tumbo, Siza D; Kihupi, NgangaConcern about food security has increased because of a changing climate, which poses a great threat to food crop productivity. Climate change projections from the Coupled Model Inter-comparison Project phase 5 (CMIP5) and crop models were used to investigate the impacts of climate change on rain-fed cereal production. Calibrated and evaluated crop models simulated maize and sorghum yields over time periods and scenarios across central zone Tanzania with and without adaptation. Simulation outputs without adaptation showed predominant decrease and increase in maize and sorghum yields, respectively. The results showed that maize yields were predicted to decline between 1% and 25% across periods, representative concentration pathways (RCPs) and global circulation models (GCMs). However, sorghum yields were on average predicted to increase between 5% and 21%. Overall when adaptation is incorporated toward mid-century, yields are projected to increase for both crops. The yield projections variation between cereal crops highlights the importance of location and crop specific climate change impact assessments. Despite the uncertainties in predicting the impacts of climate change on rainfed crops, especially on cereals (maize and sorghum) which are important staple food crops in semi-arid Tanzania, the findings of this study enable policy makers to develop plans aimed at sustainable food security. In conclusion, the results demonstrate the presumption that sorghum productivity stands a better chance than maize under prospects of negative impacts from climate change in central zone Tanzania.Item UAV-based multispectral vegetation indices for assessing the interactive effects of water and nitrogen in irrigated horticultural crops production under tropical sub-humid conditions: A case of African eggplant(Elsevier, 2022) Mwinuka, Paul Reuben; Mourice, Sixbert K; Mbungu, Winfred B; Mbilinyi, Boniphace P; Tumbo, Siza D; Schmitter, PetraUAV-based multispectral vegetation indices are often used to assess crop performance and water consumptive use. However, their ability to assess the interaction between water, especially deficit irrigation, and nitrogen application rates in irrigated agriculture has been less explored. Understanding the effect of water-nitrogen in teractions on vegetation indices could further support optimal water and N management. Therefore, this study used a split plot design with water being the main factor and N being the sub-factor. African eggplants were drip irrigated at 100% (I100), 80% (I80) or 60% (I60) of the crop water requirements and received 100% (F100), 75% (F75), 50% (F50) or 0% (F0) of the crop N requirements. Results showed that the transformed difference vegetation index (TDVI) was best in distinguishing differences in leaf moisture content (LMC) during the vegetative stage irrespective of the N treatment. The green normalized difference vegetation index (GNDVI) worked well to distinguish leaf N during vegetative and full vegetative stages. However, the detection of the interactive effect of water and N on crop performance required a combination of GNDVI, NDVI and OSAVI across both stages as each of these 3 VI showed an ability to detect some but not all treatments. The fact that a certain amount of irrigation water can optimize the efficiency of N uptake by the plant is an important criterion to consider in developing crop specific VI based decision trees for crop performance assessments and yield prediction.Item Understanding Farmers Information Communication Strategies for Managing Climate Risks in Rural Semi-Arid Areas, Tanzania(International Journal of Information and Communication Technology Research, 2012) Churi, Ayubu J; Mlozi, Malongo R. S; Tumbo, Siza D; Casmir, RespickiusCrop production risk caused by climate variability cannot be managed in the absence of climate information. Despite the use of various communication strategies by rural communities in Tanzania, access and use of agricultural information is inadequate to cope with challenges in crop production. This study aims at assessing farmers information needs, examine communication strategies used and hence recommend information and knowledge sharing strategies for improved decision making. In addition, the study examined how modern ICT used together with tradition methods can reduce risks and improve crop productivity of smallholder farmers. A cross-sectional research design and simple random sampling techniques were used for the study. Interviews using structured questionnaires and focus group discussion were conducted to collect primary data from farmers and extension workers. Data were analyzed using descriptive statistics where Statistical Package for Social Science (SPSS) was used. The findings showed that smallholder farmers require climate, market and agricultural inputs information to make strategic and tactical farm-level decisions for managing climate variability and extreme events. Climate information was found to be important factor for making decisions. Radio was found to be an important communication channel by the respondents in the study area, for communicating climate information. In addition, the respondents used extension officers and fellow farmers to access climate, market and agricultural input information. Mobile phones were noted to be preferred by surveyed farmers for communicating agricultural information. The study concluded that, efforts to improve adaptation capacity of smallholder farmers in rural areas should target the extended use of information technology for improved access to climate information and advisories. Furthermore, development initiatives for managing risks of climate variability should focus on improving climate forecasts issued by Tanzania Meteorological Agent (TMA).