Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Vulnerability and adaptation options to climate change for rural livelihoods – A country-wide analysis for Uganda
Wichern, Jannike ; Descheemaeker, Katrien ; Giller, Ken E. ; Ebanyat, Peter ; Taulya, Godfrey ; Wijk, Mark T. van - \ 2019
Agricultural Systems 176 (2019). - ISSN 0308-521X
Crop suitability - East Africa - Household food security - Impact assessment - Multi-level

Rural households in sub-Saharan Africa earn a substantial part of their living from rain-fed smallholder agriculture, which is highly sensitive to climate change. There is a growing number of multi-level assessments on impacts and adaptation options for African smallholder systems under climate change, yet few studies translate impacts at the individual crop level to vulnerability at the household level, at which other livelihood activities need to be considered. Further, these assessments often use representative household types rather than considering the diversity of households for the identification of larger-scale patterns at sub-national and national levels. We developed a framework that combines crop suitability maps with a household food availability analysis to quantify household vulnerability to climate-related impacts on crop production and effects of adaptation options. The framework was tested for Uganda, identifying four hotspots of household vulnerability across the country. Hotspots were visually identified as areas with a relatively high concentration of vulnerable households, experiencing a decline in household crop suitability. About 30% of the households in the hotspots in (central) southwest were vulnerable to a combination of 3 °C temperature increase and 10% rainfall decline through declining suitability for several key crops (including highland banana, cassava, maize and sorghum). In contrast only 10% of the households in West Nile and central northern Uganda were negatively affected, and these were mainly affected by declining suitability of common beans. Households that depended on common beans and lived at lower elevations in West Nile and central north were vulnerable to a 2 to 3 °C temperature increase, while households located at higher elevations (above 1100–2000 m.a.s.l. depending on the crop) benefited from such an increase. Options for adaptation to increasing temperatures were most beneficial in northern Uganda, while drought-related adaptation options were more beneficial in the southwest. This framework provides a basis for decision makers who need information on where the vulnerable households are, what crops drive the vulnerability at household level and which intervention efforts are most beneficial in which regions.

How to increase the productivity and profitability of smallholder rainfed wheat in the Eastern African highlands? Northern Rwanda as a case study
Baudron, Frédéric ; Ndoli, Alain ; Habarurema, Innocent ; Silva, João Vasco - \ 2019
Field Crops Research 236 (2019). - ISSN 0378-4290 - p. 121 - 131.
East Africa - Intensification - Rainfed wheat - Resource-saving technologies - Yield gap - Yield-increasing technologies

As wheat demand is increasing in sub-Saharan Africa (SSA), domestic production is being encouraged. The potential to increase the productivity and profitability of wheat appears large in the region, but little is known about the concrete interventions needed to meet that potential. In this study, we selected a site in Northern Rwanda (representative of the cool humid climatic zone which accounts for most of the spring wheat production of SSA) and analysed the determinants of wheat productivity and profitability for 130 smallholder farms during two consecutive short rainy seasons, namely 2017A and 2018A (wheat is seldom grown during long rainy seasons: potato is the preferred crop then). Although wheat yields were found to be high when compared to typical yields in SSA (means of 3469 and 3052 kg ha −1 during the seasons 2017A and 2018A, respectively), large yield gaps were also found (1.977 t ha −1 on average, or 37.6% of the highest farmer's yield, defined as the average actual yields above the 90th percentile of this variable). Evidences presented in the paper suggest that wheat productivity could be increased through increased seeding rate (a 0.14% increase in wheat grain yield was found with a 1% increase in seeding rate), increased nitrogen (N) application combined with frequent weeding (a 0.02% increase in wheat grain yield was found with a 1% increase in N application and frequent weeding), and labour-saving technologies (e.g., herbicides and mechanization). If wheat profitability would also increase with frequent weeding and labour-saving technologies, it would decrease with increased input use in many cases. Indeed, seed, fertilizer and amendments represent most of the wheat production cost in the area. These results illustrate the importance of assessing the impact of narrowing the yield gap on profitability, not only productivity, as some yield-increasing technologies may not be desirable from an economic perspective. They also demonstrate that resource-saving technologies (input-saving e.g., precision agriculture, labour-saving e.g., mechanization) may be as much in demand by African smallholders as yield-increasing technologies, calling for a more balanced approach in current research and development initiatives on the continent.

Probabilistic maize yield prediction over East Africa using dynamic ensemble seasonal climate forecasts
Ogutu, Geoffrey E.O. ; Franssen, Wietse H.P. ; Supit, Iwan ; Omondi, P. ; Hutjes, Ronald W.A. - \ 2018
Agricultural and Forest Meteorology 250-251 (2018). - ISSN 0168-1923 - p. 243 - 261.
Crop models - Dynamic crop forecasting - East Africa - Forecast lead-time - Probabilistic ensemble prediction - Rainfed agriculture
We tested the usefulness of seasonal climate predictions for impacts prediction in eastern Africa. In regions where these seasonal predictions showed skill we tested if the skill also translated into maize yield forecasting skills. Using European Centre for Medium-Range Weather Forecasts (ECMWF) system-4 ensemble seasonal climate hindcasts for the period 1981–2010 at different initialization dates before sowing, we generated a 15-member ensemble of yield predictions using the World Food Studies (WOFOST) crop model implemented for water-limited maize production and single season simulation. Maize yield predictions are validated against reference yield simulations using the WATCH Forcing Data ERA-Interim (WFDEI), focussing on the dominant sowing dates in the northern region (July), equatorial region (March-April) and in the southern region (December). These reference yields show good anomaly correlations compared to the official FAO and national reported statistics, but the average reference yield values are lower than those reported in Kenya and Ethiopia, but slightly higher in Tanzania. We use the ensemble mean, interannual variability, mean errors, Ranked Probability Skill Score (RPSS) and Relative Operating Curve skill Score (ROCSS) to assess regions of useful probabilistic prediction. Annual yield anomalies are predictable 2-months before sowing in most of the regions. Difference in interannual variability between the reference and predicted yields range from ±40%, but higher interannual variability in predicted yield dominates. Anomaly correlations between the reference and predicted yields are largely positive and range from +0.3 to +0.6. The ROCSS illustrate good pre-season probabilistic prediction of above-normal and below-normal yields with at least 2-months lead time. From the sample sowing dates considered, we concluded that, there is potential to use dynamical seasonal climate forecasts with a process based crop simulation model WOFOST to predict anomalous water-limited maize yields.
Farmers' use and adaptation of improved climbing bean production practices in the highlands of Uganda
Ronner, E. ; Descheemaeker, K. ; Almekinders, C.J.M. ; Ebanyat, P. ; Giller, K.E. - \ 2018
Agriculture, Ecosystems and Environment 261 (2018). - ISSN 0167-8809 - p. 186 - 200.
Adoption - Co-design - East Africa - Legumes - Nitrogen fixation - Phaseolus vulgaris - Smallholder

Climbing beans offer potential for sustainable intensification of agriculture, but their cultivation constitutes a relatively complex technology consisting of multiple components or practices. We studied uptake of improved climbing bean production practices (improved variety, input use and management practices) through co-designed demonstrations and farmer-managed adaptation trials with 374 smallholder farmers in eastern and southwestern Uganda. A sub-set of these farmers was monitored one to three seasons after introduction. About 70% of the farmers re-planted climbing beans one season after the adaptation trial, with significant differences between eastern (50%) and southwestern Uganda (80-90%). Only 1% of the farmers used all of the improved practices and 99% adapted the technology. On average, farmers used half of the practices in different combinations, and all farmers used at least one of the practices. Yield variability of the trials was large and on average, trial plots did not yield more than farmers' own climbing bean plots. Yet, achieved yields did not influence whether farmers continued to cultivate climbing bean in the subsequent season. Uptake of climbing beans varied with household characteristics: poorer farmers cultivated climbing beans more often but used fewer of the best-bet practices; male farmers generally used more practices than female farmers. Planting by poorer farmers resulted in adaptations such as growing climbing beans without fertilizer and with fewer and shorter stakes. Other relationships were often inconsistent and farmers changed practices from season to season. The diversity of farmer responses complicates the development of recommendation domains and warrants the development of a basket of options from which farmers can choose. Our study shows how adoption of technologies consisting of multiple components is a complicated process that is hard to capture through the measurement of an adoption rate at a single point in time.

Food availability and livelihood strategies among rural households across Uganda
Wichern, Jannike ; Wijk, Mark T. van; Descheemaeker, Katrien ; Frelat, Romain ; Asten, Piet J.A. van; Giller, Ken E. - \ 2017
Food Security 9 (2017)6. - ISSN 1876-4517 - p. 1385 - 1403.
Crop choice - District - East Africa - Food security - Household level - Smallholder farms
Despite continuing economic growth, Uganda faces persistent challenges to achieve food security. The effectiveness of policy and development strategies to help rural households achieve food security must improve. We present a novel approach to relate spatial patterns of food security to livelihood strategies, including the contribution of on- and off-farm activities to household food availability. Data from 1927 households from the World Bank Living Standards Measurement Study were used to estimate the calorific contribution of livelihood activities to food availability. Consumption of crops produced on-farm contributed most to food availability for households with limited food availability, yet the majority of these households were not food self-sufficient. Off-farm and market-oriented on-farm activities were more important for households with greater food availability. Overall, off-farm income was important in the north, while market-oriented on-farm activities were important in western and central Uganda. Food availability patterns largely matched patterns of agroecological conditions and market access, with households doing worst in Uganda’s drier and remote northeast. Less food-secure households depended more on short-cycle food crops as compared with better-off households, who focused more on plantation (cash) crops, although this varied among regions. Targeting interventions to improve food security should consider such differences in enterprise choice and include options to improve household market access and off-farm income opportunities.
Multi-century tree-ring precipitation record reveals increasing frequency of extreme dry events in the upper Blue Nile River catchment
Mokria, Mulugeta ; Gebrekirstos, Aster ; Abiyu, Abrham ; Noordwijk, Meine Van; Bräuning, Achim - \ 2017
Global Change Biology 23 (2017)12. - ISSN 1354-1013 - p. 5436 - 5454.
Climate variability - Dendroclimatology - East Africa - El Niño-Southern Oscillation - Extreme events - Famine and flooding - Indian ocean dipole - Little Ice Age

Climate-related environmental and humanitarian crisis are important challenges in the Great Horn of Africa (GHA). In the absence of long-term past climate records in the region, tree-rings are valuable climate proxies, reflecting past climate variations and complementing climate records prior to the instrumental era. We established annually resolved multi-century tree-ring chronology from Juniperus procera trees in northern Ethiopia, the longest series yet for the GHA. The chronology correlates significantly with wet-season (r = .64, p < .01) and annual (r = .68, p < .01) regional rainfall. Reconstructed rainfall since A.D. 1811 revealed significant interannual variations between 2.2 and 3.8 year periodicity, with significant decadal and multidecadal variations during 1855-1900 and 1960-1990. The duration of negative and positive rainfall anomalies varied between 1-7 years and 1-8 years. Approximately 78.4% (95%) of reconstructed dry (extreme dry) and 85.4% (95%) of wet (extreme wet) events lasted for 1 year only and corresponded to historical records of famine and flooding, suggesting that future climate change studies should be both trend and extreme event focused. The average return periods for dry (extreme dry) and wet (extreme wet) events were 4.1 (8.8) years and 4.1 (9.5) years. Extreme-dry conditions during the 19th century were concurrent with drought episodes in equatorial eastern Africa that occurred at the end of the Little Ice Age. El Niño and La Niña events matched with 38.5% and 50% of extreme-dry and extreme-wet events. Equivalent matches for positive and negative Indian Ocean Dipole events were weaker, reaching 23.1 and 25%, respectively. Spatial correlations revealed that reconstructed rainfall represents wet-season rainfall variations over northern Ethiopia and large parts of the Sahel belt. The data presented are useful for backcasting climate and hydrological models and for developing regional strategic plans to manage scarce and contested water resources. Historical perspectives on long-term regional rainfall variability improve the interpretation of recent climate trends.

Global and local forces in deindustrialization : the case of cotton cloth in East Africa’s Lower Shire Valley
Frederick, Kate - \ 2017
Journal of Eastern African Studies 11 (2017)2. - ISSN 1753-1055 - p. 266 - 289.
cotton cloth - Deindustrialization - East Africa - global - local
Numerous scholars have suggested that nineteenth-century industrial decline in the global “periphery” was driven by externally wrought global forces that promoted cash-crop agriculture and dis-incentivized local industry, particularly strong global demand for tropical agricultural commodities and increasing competition with imports of cheap, factory-produced manufactures from industrializing regions. To what extent did global market forces affect production choices, and to what degree did local forces guide outcomes? The deindustrialization process is investigated through a case study of Malawi’s Lower Shire Valley, where the Mang’anja cloth industry declined – and cash-crop production began – in the second half of the nineteenth century. I demonstrate that changing production choices were not directly motivated by global market opportunities. Indeed, other cloth-producing sub-Saharan African regions faced nineteenth-century global forces but did not deindustrialize. Rather, economic change in the valley was stimulated by local factor-endowment shifts precipitated by both global and local forces. Labour declined sharply due to slave raiding and famine, while supplies of fertile land increased due to environmental change. Within this altered context, Mang’anja villagers responded by abandoning labour-intensive cloth production in favour of cash-crop cultivation. In more labour-abundant African regions, on the other hand, cloth production continued to thrive alongside cash-crop exports. The mechanisms behind deindustrialization can only be understood through careful local-level examination of the local contexts that influenced responses to broader global processes.
Smallholder farmers’ attitudes and determinants of adaptation to climate risks in East Africa
Shikuku, Kelvin M. ; Winowiecki, Leigh ; Twyman, Jennifer ; Eitzinger, Anton ; Perez, Juan G. ; Mwongera, Caroline ; Läderach, Peter - \ 2017
Climate Risk Management 16 (2017). - ISSN 2212-0963 - p. 234 - 245.
Climate risks - East Africa - Farmers’ attitudes - Livelihood-based adaptation - Rasch analysis

Adapting to climate risks is central to the goal of increasing food security and enhancing resilience of farming systems in East Africa. We examined farmers’ attitudes and assessed determinants of adaptation using data from a random sample of 500 households in Borana, Ethiopia; Nyando, Kenya; Hoima, Uganda; and Lushoto, Tanzania. Adaptation was measured using a livelihood-based index that assigned weights to different individual strategies based on their marginal contributions to a household's livelihood. Results showed that farmers’ attitudes across the four sites strongly favored introduction of new crops, changes in crop varieties, and changes in planting times. Farmers disfavored soil, land, and water management practices. At lower levels of adaptation (25% quantile), adaptation index correlated positively with membership to farmers’ groups, household size, sex of the household head, and number of months of food shortage. Farmer group membership enhanced adaptation at intermediate (50% quantile) level whereas access to credit increased adaptation at high (75% quantile) level. Food insecurity, however, correlated negatively with the likelihood to choose individual adaptation strategies suggesting that although households adapted to improve food security status of their households, hunger was a barrier to adaptation. Our findings suggest that providing climate information to inform timely planting, promoting crop diversification, and encouraging adoption of adapted varieties of crops might be successful to enhancing resilience of farming systems in the short-term. In the long-term, increased investment in reducing hunger, encouraging groups formation, and easing liquidity constraints will be required to promote adaptation through implementation of soil, water, and land management strategies.

Indicator microorganisms in fresh vegetables from “farm to fork” in Rwanda
Ssemanda, James Noah ; Reij, Martine ; Muvunyi, Claude Mambo ; Joosten, Han ; Zwietering, Marcel H. - \ 2017
Food Control 75 (2017). - ISSN 0956-7135 - p. 126 - 133.
Developing countries - East Africa - Hygiene indicators - Microbial safety - Produce - Ready-to-eat vegetables - Salad
Microbial safety of ready-to-eat vegetables is currently a global concern. We studied indicator microorganisms in fresh vegetables from “farm to fork” in Rwanda, to identify possible trends in microbial counts along the supply chain in a developing country. A total of 453 samples were taken across the vegetable supply chain (farm, market and food service establishment level) and analyzed for indicator microorganisms; Enterobacteriaceae, Listeria spp., aerobic plate count and coagulase - positive staphylococci. The sampling at farm and market covered 11 types of vegetables commonly eaten raw in salads. Results show that the mean count of Enterobacteriaceae and Listeria spp. in vegetables were respectively 5.8 and 4.6 log cfu/g at farm, 6.3 and 4.9 log cfu/g at market, 6.0 and 5.1 log cfu/g upon arrival at food service establishments, and finally 3.3 and 2.9 log cfu/g in ready-to-eat salads. Aerobic plate count and coagulase-positive Staphylococci were on average 6.8 and 4.6 respectively at start of salad preparation and 4.9 and 3.0 in the final product. Unit operations like washing with or without sanitizers, trimming and peeling significantly reduced indicator counts by on average 2.1 log cfu/g from start to end of salad preparation. Results also show that 91% (51/56) and 22% (12/56) of ready-to-eat salads prepared by food service establishments met the guidelines for coagulase - positive staphylococci (104 cfu/g) and presumptive Listeria spp. (102 cfu/g). The high counts of these indicator microorganisms along the vegetable supply chain, raises concern about the potential presence of foodborne pathogens. This study calls for improved adherence to GAPs and GHPs in the fresh vegetable supply chain so as to minimize the potential risk from foodborne pathogens.
Skill of ECMWF system-4 ensemble seasonal climate forecasts for East Africa
Ogutu, Geoffrey E.O. ; Franssen, Wietse H.P. ; Supit, Iwan ; Omondi, P. ; Hutjes, Ronald W.A. - \ 2017
International Journal of Climatology 37 (2017)5. - ISSN 0899-8418 - p. 2734 - 2756.
Bias correction - East Africa - Ensemble prediction - Probabilistic verification - Seasonal climate forecasts

This study evaluates the potential use of the ECMWF System-4 seasonal forecasts (S4) for impact analysis over East Africa. For use, these forecasts should have skill and small biases. We used the 15-member ensemble of 7-month forecasts initiated every month, and tested forecast skill of precipitation (tp), near-surface air temperature (tas) and surface downwelling shortwave radiation (rsds). We validated the 30-year (1981-2010) hindcast version of S4 against the WFDEI reanalysis (WATCH Forcing Data ERA-Interim) and to independent relevant observational data sets. Probabilistic skill is assessed using anomaly correlation, ranked probability skill score (RPSS) and the relative operating curve skill score (ROCSS) at both grid cell and over six distinct homogeneous rainfall regions for the three growing seasons of East Africa (i.e. MAM, JJA and OND). S4 exhibits a wet bias in OND, a dry bias in MAM and a mix of both in JJA. Temperature biases are similar in all seasons, constant with lead-time and correlate with elevation. Biases in rsds correlate with cloud/rain patterns. Bias correction clears biases but does not affect probabilistic skills. Predictability of the three variables varies with season, location and lead-time. The choice of validating dataset plays little role in the regional patterns and magnitudes of probabilistic skill scores. The OND tp forecasts show skill over a larger area up to 3 months lead-time compared to MAM and JJA. Upper- and lower-tercile tp forecasts are 20-80% better than climatology. Temperature forecasts are skillful for at least 3months lead-time and they are 40-100% better than climatology. The rsds is less skillful than tp and tas in all seasons when verified against WFDEI but higher in all lead months against the alternative datasets. The forecast system captures El-Niño Southern Oscillation (ENSO)-related anomalous years with region-dependent skill.

Impact of farmer field schools on sustainable tea production in Kenya
Hiller, S.R.C.H. ; Jager, A. de - \ 2010
Wageningen : Wageningen UR (Market, chains and sustainable development strategy &amp; policy paper 20) - ISBN 9789461734730 - 8
agrarisch onderwijs - onderwijs - thee - theeoogstmachines - thee-industrie - duurzaamheid (sustainability) - kenya - afrika - oost-afrika - ontwikkelingslanden - farmer field schools - agricultural education - education - tea - tea harvesters - tea industry - sustainability - africa - East Africa - developing countries
Het Britse aardnotenplan
Anonymous, - \ 1966
Wageningen : [s.n.] (Literatuurlijst / Centrum voor landbouwpublikaties en landbouwdocumentatie no. 2676)
Arachis hypogaea - bibliografieën - Oost-Afrika - Groot-Brittannië - aardnoten - bibliographies - East Africa - Great Britain - groundnuts
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