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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    Towards actionable farm typologies : Scaling adoption of agricultural inputs in Rwanda
    Hammond, Jim ; Rosenblum, Nathaniel ; Breseman, Dana ; Gorman, Léo ; Manners, Rhys ; Wijk, Mark T. van; Sibomana, Milindi ; Remans, Roseline ; Vanlauwe, Bernard ; Schut, Marc - \ 2020
    Agricultural Systems 183 (2020). - ISSN 0308-521X
    Adoption of agricultural innovations - Intensification - Rural development - Scaling - Smallholders - Typologies

    Rollout of development interventions using a one-size-fits-all model can achieve economies of scale but neglects to account for variability in farm and farmer characteristics. A data-driven approach to incorporate farmer diversity in scaling strategies may help to achieve greater development impact. However, interpreting the multiplicity of smallholder characteristics is complex, time-consuming, and the ways in which the insights gained can be implemented is poorly understood. Navigating these tensions, we present a farm typology study carried out in collaboration with a large development organisation (the “scaling partner”) promoting agricultural inputs in Rwanda. This study was conducted late in the scaling pathway, in order to finesse the scaling strategy, rather than to target intervention selection. Drawing on nearly 3000 interviews from 17 districts of the Western, Southern, and Eastern Provinces of Rwanda, the typology differentiates households along two axes: 1. prosperity (a cornerstone of conventional typologies), and 2. adoption of inputs (fertilisers and improved crop varieties). We used an efficient household survey tool, a minimum-variable approach, and concepts from the study of adoption of agricultural innovations. Through an action-research collaboration with the scaling organisation we adapted the methods and the findings to be “actionable. Approximately two-thirds of the study population were using fertilisers and improved seed to some extent. Along each prosperity stratum, however, there were multiple degrees of adoption, demonstrating the value of including adoption information in typology constructions. Ten farm types were identified, where the key differences along the prosperity axis were land area cultivated and livestock owned, and the key differences along the adoption axis were perceptions of input efficacy, access to training, and education level. We also present a simple decision tree model to assign new households to a farm type. The findings were used in three ways by the scaling organisation: (i) characterisation of the population into discrete groups; (ii) prioritisation, of farm types for engagement, and geographical locations for further investment; and (iii) design of decision support tools or re-design of packages to support technology adoption for specific farm types. The need for field-level validation of the typologies was also stressed by the scaling organisation.

    Review of solar dryers for agricultural products in Asia and Africa : An innovation landscape approach
    Udomkun, Patchimaporn ; Romuli, Sebastian ; Schock, Steffen ; Mahayothee, Busarakorn ; Sartas, Murat ; Wossen, Tesfamicheal ; Njukwe, Emmanuel ; Vanlauwe, Bernard ; Müller, Joachim - \ 2020
    Journal of Environmental Management 268 (2020). - ISSN 0301-4797
    Active dryer - Hybrid dryer - Passive dryer - Renewable energy - Solar drying application - Technology adoption

    Solar drying is one of the most efficient and cost-effective, renewable, and sustainable technologies to conserve agricultural products in Asian and sub-Saharan African (SSA) countries. This review paper presents the different types of solar dryers that are widely used in Africa and Asia. In addition, the pre-eminent effects of their use on product quality, as well as their economic, environmental, and social impacts, are highlighted. Since financial, external, and structural factors play a key role in the adoption and scaling of solar dryers, this paper also discusses the impact of these factors on the effectiveness of solar drying technologies in selected Asian and SSA countries.

    The Rural Household Multiple Indicator Survey, data from 13,310 farm households in 21 countries
    Wijk, Mark van; Hammond, James ; Gorman, Leo ; Adams, Sam ; Ayantunde, Augustine ; Baines, David ; Bolliger, Adrian ; Bosire, Caroline ; Carpena, Pietro ; Chesterman, Sabrina ; Chinyophiro, Amon ; Daudi, Happy ; Dontsop, Paul ; Douxchamps, Sabine ; Emera, Willy Desire ; Fraval, Simon ; Fonte, Steven ; Hok, Lyda ; Kiara, Henry ; Kihoro, Esther ; Korir, Luke ; Lamanna, Christine ; Long, Chau T.M. ; Manyawu, Godfrey ; Mehrabi, Zia ; Mengistu, Dejene K. ; Mercado, Leida ; Meza, Katherin ; Mora, Vesalio ; Mutemi, Jacob ; Ng’endo, Mary ; Njingulula, Paulin ; Okafor, Chris ; Pagella, Tim ; Phengsavanh, Phonepaseuth ; Rao, James ; Ritzema, Randall ; Rosenstock, Todd S. ; Skirrow, Tom ; Steinke, Jonathan ; Stirling, Clare ; Gabriel Suchini, Jose ; Teufel, Nils ; Thorne, Peter ; Vanek, Steven ; Etten, Jacob van; Vanlauwe, Bernard ; Wichern, Jannike ; Yameogo, Viviane - \ 2020
    Scientific Data 7 (2020)1. - ISSN 2052-4463

    The Rural Household Multiple Indicator Survey (RHoMIS) is a standardized farm household survey approach which collects information on 758 variables covering household demographics, farm area, crops grown and their production, livestock holdings and their production, agricultural product use and variables underlying standard socio-economic and food security indicators such as the Probability of Poverty Index, the Household Food Insecurity Access Scale, and household dietary diversity. These variables are used to quantify more than 40 different indicators on farm and household characteristics, welfare, productivity, and economic performance. Between 2015 and the beginning of 2018, the survey instrument was applied in 21 countries in Central America, sub-Saharan Africa and Asia. The data presented here include the raw survey response data, the indicator calculation code, and the resulting indicator values. These data can be used to quantify on- and off-farm pathways to food security, diverse diets, and changes in poverty for rural smallholder farm households.

    The story of N2Africa: Putting nitrogen fixation to work for smallholder farmers in Africa : A flavour of the excitement and the richness of learning from N2Africa
    Giller, K.E. ; Vanlauwe, Bernard ; Kanamplu, Fred - \ 2020
    N2Africa
    Science-based decision support for formulating crop fertilizer recommendations in sub-Saharan Africa
    Rurinda, Jairos ; Zingore, Shamie ; Jibrin, Jibrin M. ; Balemi, Tesfaye ; Masuki, Kenneth ; Andersson, Jens A. ; Pampolino, Mirasol F. ; Mohammed, Ibrahim ; Mutegi, James ; Kamara, Alpha Y. ; Vanlauwe, Bernard ; Craufurd, Peter Q. - \ 2020
    Agricultural Systems 180 (2020). - ISSN 0308-521X
    Fertilizer recommendations - Maize intensification - Nutrient use efficiency - Smallholder farming systems - Soil fertility management - Yield response

    In sub-Saharan Africa, there is considerable spatial and temporal variability in relations between nutrient application and crop yield, due to varying inherent soil nutrients supply, soil moisture, crop management and germplasm. This variability affects fertilizer use efficiency and crop productivity. Therefore, development of decision systems that support formulation and delivery of site-specific fertilizer recommendations is important for increased crop yield and environmental protection. Nutrient Expert (NE) is a computer-based decision support system, which enables extension advisers to generate field- or area-specific fertilizer recommendations based on yield response to fertilizer and nutrient use efficiency. We calibrated NE for major maize agroecological zones in Nigeria, Ethiopia and Tanzania, with data generated from 735 on-farm nutrient omission trials conducted between 2015 and 2017. Between 2016 and 2018, 368 NE performance trials were conducted across the three countries in which recommendations generated with NE were evaluated relative to soil-test based recommendations, the current blanket fertilizer recommendations and a control with no fertilizer applied. Although maize yield response to fertilizer differed with geographic location; on average, maize yield response to nitrogen (N), phosphorus (P) and potassium (K) were respectively 2.4, 1.6 and 0.2 t ha−1 in Nigeria, 2.3, 0.9 and 0.2 t ha−1 in Ethiopia, and 1.5, 0.8 and 0.2 t ha−1 in Tanzania. Secondary and micronutrients increased maize yield only in specific areas in each country. Agronomic use efficiencies of N were 18, 22 and 13 kg grain kg−1 N, on average, in Nigeria, Ethiopia and Tanzania, respectively. In Nigeria, NE recommended lower amounts of P by 9 and 11 kg ha−1 and K by 24 and 38 kg ha−1 than soil-test based and regional fertilizer recommendations, respectively. Yet maize yield (4 t ha−1) was similar among the three methods. Agronomic use efficiencies of P and K (300 and 250 kg kg−1, respectively) were higher with NE than with the blanket recommendation (150 and 70 kg kg−1). In Ethiopia, NE and soil-test based respectively recommended lower amounts of P by 8 and 19 kg ha−1 than the blanket recommendations, but maize yield (6 t ha−1) was similar among the three methods. Overall, fertilizer recommendations generated with NE maintained high maize yield, but at a lower fertilizer input cost than conventional methods. NE was effective as a simple and cost-effective decision support tool for fine-tuning fertilizer recommendations to farm-specific conditions and offers an alternative to soil testing, which is hardly available to most smallholder farmers.

    Micro-livestock in smallholder farming systems: the role, challenges and opportunities for cavies in South Kivu, eastern DR Congo
    Klapwijk, Charlotte J. ; Schut, Marc ; Asten, Piet J.A. van; Vanlauwe, Bernard ; Giller, Ken E. ; Descheemaeker, Katrien - \ 2020
    Tropical Animal Health and Production 52 (2020). - ISSN 0049-4747 - p. 1167 - 1177.
    Cavia porcellus - DR Congo - Micro-livestock - Smallholder livelihoods

    Livestock play multiple roles for smallholder farmers in sub-Saharan Africa. Mixed crop-livestock systems are common in South Kivu, eastern DR Congo, but herd sizes are small and numbers of large livestock (i.e. cattle) have declined, due to high population density, recent conflicts and extreme poverty. Over half of the farmers keep cavies, a type of micro-livestock fitting the circumstances of smallholders and a valuable asset especially for the poorest households. To characterize cavy husbandry practices, detailed monthly on-farm data on cavy numbers, weights, herd dynamics and feeding practices were collected over 15 months and from households in two contrasting sites in South Kivu. Cavy herds contained on average 10 animals and strongly varied in size over time and between households. The main reasons for keeping cavies were meat consumption, especially for children, and the opportunity to generate petty cash. A large difference was observed in adult cavy live weights between the sites (an average of 0.6 and 1.0 kg per animal in Kabamba and Lurhala, respectively) and attributed to differences in cavy husbandry and genetics. In both sites, quantities of fresh fodder on offer were larger than fodder demand by 50–100%, but no correlation was found between amount of fodder on offer and cavy weight. Farmers faced several constraints to cavy production, including substantial declines in cavy herd size due to predation or theft and a lack of knowledge regarding breeding and feeding. Hence, the introduction of cages to limit mortality and fodder cultivation to improve feed quality were opportunities for improving cavy production. Overall, micro-livestock present a promising entry-point for development initiatives, also outside DR Congo, because of their potential to decrease poverty and improve human nutrition.

    Food Access Deficiencies in Sub-saharan Africa: Prevalence and Implications for Agricultural Interventions
    Fraval, Simon ; Hammond, James ; Bogard, Jessica R. ; Ng'endo, Mary ; Etten, Jacob van; Herrero, Mario ; Oosting, Simon J. ; Boer, Imke J.M. de; Lannerstad, Mats ; Teufel, Nils ; Lamanna, Christine ; Rosenstock, Todd S. ; Pagella, Tim ; Vanlauwe, Bernard ; Dontsop-Nguezet, Paul M. ; Baines, David ; Carpena, Pietro ; Njingulula, Paulin ; Okafor, Christopher ; Wichern, Jannike ; Ayantunde, Augustine ; Bosire, Caroline ; Chesterman, Sabrina ; Kihoro, Esther ; Rao, Elizaphan J.O. ; Skirrow, Tom ; Steinke, Jonathan ; Stirling, Clare M. ; Yameogo, Viviane ; Wijk, Mark T. van - \ 2019
    Frontiers in Sustainable Food Systems 3 (2019). - ISSN 2571-581X
    Bayesian - crops - diet diversity - farm systems - livestock - nutrition-sensitive - rural development

    Our understanding of food security in sub-Saharan Africa (SSA) has been hampered by limitations in the temporal and spatial representativeness of data. Food balance sheets provide scalable estimates of per capita food availability, but fail to represent food access, stability and their causal linkages. In contrast, rural household surveys represent detailed conditions for one or multiple points in time, but are influenced by survey timing and are often limited in geographical coverage. This study draws on a large sample of rural land-holding households in SSA (n = 6,353) to identify household level food access deficiencies and to understand the associations with rural livelihoods and food sourcing behavior throughout the year. Food access deficiencies were identified using food security of access and diet diversity indicators. Dietary diversity and channel of access (farm or purchased) were enumerated for the “flush” and “lean” periods and food security of access was enumerated for the lean period only - making the results of this study independent of survey timing. As many as 39% of households were classified as severely food insecure (in terms of food access) and as many as 49% of households were likely to be deficient in micronutrients in the lean period. Vulnerability to food insecurity and micronutrient deficiencies differed by household composition, agricultural livelihood characteristics and agro-ecological zone. Dairy, fruit and vitamin A-rich produce were predominantly accessed through the farm channel. Households with a livestock component to their farm had a lower prevalence of severe food insecurity and higher diet diversity scores. These findings have implications for the development of nutrition-sensitive and nutrition-specific interventions. Interventions need to be tailored to agro-ecological zone, household composition, scale of operation and production mix. Increasing income will not necessarily result in improved diet diversity or healthy dietary choices. Interventions focused on income generation should monitor and promote crop and livestock production diversity and provide nutrition education.

    Integrating legumes while increasing maize yields – five seasons of co-learning in western Kenya
    Marinus, Wytze ; Descheemaeker, K.K.E. ; Ven, G.W.J. van de; Vanlauwe, Bernard ; Giller, K.E. - \ 2019
    Sustainable intensification of smallholder agriculture in sub-Saharan Africa (SSA) is a key pathway to provide food for the growing population (e.g. SDSN 2013; Vanlauwe et al. 2014). Grain legumes are seen as a central option for sustainable intensification as they fix nitrogen (N) from the air (reducing the need for mineral N fertiliser), are nutritious food and can be more profitable than staple crops such as maize (Giller et al. 2013). Yet adoption of options for sustainable intensification is often limited by knowledge and resource constraints, due to the poverty trap within which smallholder farmers operate (Tittonell and Giller 2013). The objective of this study was to assess the outcomes of a trajectory of five seasons of co-learning, when resource constraints are partly alleviated. This paper focuses on the adoption process oflegumes as part of the intensified maize-legume cropping system, which together comprise the main crop component of the farming systems.
    Enhancing biological nitrogen fixation and yield of soybean and common bean in smallholder farming systems of Rwanda
    Rurangwa, Edouard - \ 2019
    Wageningen University. Promotor(en): K.E. Giller, co-promotor(en): B. Vanlauwe. - Wageningen : Wageningen University - ISBN 9789463951784 - 148

    Legumes play a key role in soil fertility replenishment, yet the yields achieved are far below their potential due to poor management practices. The main objective of this thesis was to increase soybean and common bean productivity in the smallholder farming systems of Rwanda. Inputs of manure at different rates, mineral fertilizers and rhizobial inoculants were used.

    Field trials evaluating the response of common bean and soybean to inoculation, P and manure (0, 5 and 10 t ha-1) in three agro-ecological zones of Rwanda showed greater grain yield, biomass and stover yields when inputs were combined. The %Ndfa, amount of N2-fixed, N and P uptake were larger in treated plots compared to control plots. Large variability in the data following inputs application was observed, but there was no clear relationship between the response to inputs and soil parameters. Inputs applied to the legumes lead to substantial increase in the yield of a subsequent maize crop. However, maize grown after soybean failed to yield in Bugesera due to the long maturity of the soybean variety used which resulted in late planting of the maize.

    The role of manure on the survival of rhizobia in the soil was explored. The population of rhizobia in the soil was higher in plots that had received manure two seasons earlier compared with plots that had been inoculated or plots that had received P fertilizer only. The number of rhizobia in manured plots was still higher eighteen months from the first sampling. In the dry season rhizobial numbers decreased and increased again soon after during the rainy season.

    The Northern Province of Rwanda is the best region for climbing bean. However, yields achieved are very poor. Trials evaluating the response of climbing bean to manure (0, 2 and 5 t ha-1) and mineral fertilizers (N, P, K and their combination) were established in Kinoni and Muko villages with seven fields in each village. Results showed consistent yield increase when inputs were used together. Greater yields were achieved when manure was combined with NPK. In all cases larger responses were observed with the higher rate of manure. Similarly, inputs application increased the amount of N2-fixed, N and P uptake.

    Determination of limiting nutrients to climbing bean was performed using the Compositional Nutrient Diagnosis (CND) and the Diagnosis and Recommendation Integrated System (DRIS). The two approaches were useful in identifying nutrient limitations to climbing bean in Northern Rwanda. We observed deficiencies of Zn, N, K and P in Kinoni, and Zn, Mg, Ca, P and N in the Muko site.

    The role of nitrogen fixation in African smallholder agriculture
    Giller, K.E. ; Kanampiu, Fred ; Hungria, Mariangela ; Vanlauwe, Bernard - \ 2019
    Agriculture, Ecosystems and Environment 285 (2019). - ISSN 0167-8809
    African smallholders face a conundrum! They spend their whole life surrounded by air which is 79% nitrogen gas and yet their crops are yellow and starved of nitrogen. The biological fixation of nitrogen by legumes offers a pathway for smallholders to access this infinite source of nitrogen. Yet current input of nitrogen fixation in African smallholder systems is very limited – often much less than 10 kg N ha−1 when calculated across the whole farm.

    Legumes are a key component of pathways to the Sustainable Intensification of agriculture: they provide food, fodder other products such as fuelwood and stakes and improve soil fertility (Vanlauwe et al., 2014). Further, legumes offer the opportunity to diversify monotonous diets, as protein and micronutrient dense food and to diversify cropping systems often built on monocultures of cereals or root and tuber crops. In Africa, rates of nitrogen fixation by grain legumes as high as 250 kg N ha−1 have been measured in experimental fields, demonstrating their huge potential. Lastly, the sale of legume grains contributes substantially to household income in major legume production areas.

    Against a backdrop of a rapidly growing population and decreasing farm size, a large pan-African collaborative project was initiated in 2009. The project entitled: Putting nitrogen fixation to work for smallholder farmers in Africa: N2Africa works across a wide range of agroecological conditions across 11 countries of sub-Saharan Africa. N2Africa is conceived as a “development-to-research” project in which grain legume technologies emerging from research are disseminated and tested at scale with many thousands of farmers (Giller et al., 2013). Through a structured and targeted approach N2Africa seeks to understand where, when, why and for whom approaches to the intensification and diversification of farming using different grain legume technologies work best. A key concept is the socio-ecological niche – recognizing the rich diversity of agroecologies, societies and cultures to enable the matching of technologies to farming systems, farms and fields (Ojiem et al., 2006).

    This Special Issue brings together a series of papers based on recent research on N2-fixation by grain legumes and its wider benefits across sub-Saharan Africa. The final chapter (Vanlauwe et al., 2014) reflects on the contributions and highlights issues requiring the attention of research in future.
    N2Africa Annual Report 2019
    Dontsop-Nguezet, Paul M. ; Ampadu-Boakye, Theresa ; Ronner, E. ; Baars, Edward ; Kanampiu, Fred ; Giller, K.E. ; Vanlauwe, B. ; Adjei-nsiah, Samuel ; Wolde-Meskel, E. ; Ebanyat, Peter ; Baijukya, Frederick ; Dianda, M. ; Sanginga, Jean-Marie ; Woomer, P.L. ; Chikowo, Regis ; Phiphira, Lloyd ; Kantengwa, Speciose ; Leonardo, W. ; Kamai, Nkeki ; Thuijsman, E.C. ; Schilt-van Ettekoven, C. - \ 2019
    Wageningen : N2Africa (N2Africa project report 120) - 78 p.
    Annual report, Key milestones, objectives, progress, biological nitrogen fixation, grain legumes, Nigeria, Borno State, Ghana, Tanzania, Ethiopia, Uganda, DR Congo, Rwanda, Kenya, Malawi, Zimbabwe, Mozambique
    Banana leaf pruning to facilitate annual legume intercropping as an intensification strategy in the East African highlands
    Ocimati, W. ; Ntamwira, J. ; Groot, J.C.J. ; Taulya, G. ; Tittonell, P. ; Dhed'a, B. ; Asten, P. van; Vanlauwe, B. ; Ruhigwa, B. ; Blomme, G. - \ 2019
    European Journal of Agronomy 110 (2019). - ISSN 1161-0301
    Banana - Intercrop - Leaf pruning - Legume - LER - Revenue

    Banana leaf pruning is a common practice to facilitate intercropping with legumes on farmers’ fields. It is however not clear if this practice improves farmers land-use and economic efficiency, especially after full canopy formation. To analyze pruning effects, three legumes viz. bush bean (Phaseolus vulgaris L), climbing bean (Phaseolus vulgaris L) and soybean (Glycine max), were planted under three banana leaf pruning levels in which four, seven and all fully grown leaves were retained. Sole banana or legume plots served as controls. Each treatment combination was replicated three times. Banana growth and yield attributes were measured for the plant and first ratoon crops while legume biomass and yields determined over five consecutive cropping seasons. Significant (P < 0.001) reductions in banana growth and yield were associated with leaf pruning. Banana yield reductions of 31% and 10% for the four- and seven-leaf retention treatments, respectively occurred. The vigorous intercrops (climbing beans and soybeans) more often depressed the growth and yield of banana. Legume grain and biomass yields increased with leaf pruning levels. Weed biomass and associated management costs increased with decline in shade intensity. The land-use efficiency measured using the land equivalence ratio (LER) was far lower in the treatment with four-leaves (1.10) compared to when all leaves were retained (1.4) but higher (1.54) for the seven-leaf treatment. Severe banana leaf pruning could thus be detrimental to banana performance and inefficient. Moderate banana leaf pruning could however be promoted were land is limiting and farmers want to maximize diversity/nutrition. However, the highest values for gross revenue and benefit-cost ratio were realized for sole banana-all-leaf retention treatment due to a higher labor productivity and lower input costs attributed to the perennial nature of banana. The higher economic efficiency in sole banana plots suggests that reliance on LER only may be insufficient for guiding intercropping decisions.

    The role of legumes in the sustainable intensification of African smallholder agriculture : Lessons learnt and challenges for the future
    Vanlauwe, B. ; Hungria, M. ; Kanampiu, F. ; Giller, K.E. - \ 2019
    Agriculture, Ecosystems and Environment 284 (2019). - ISSN 0167-8809
    Best-fit technologies - Biological N fixation - Legume agronomy - Legume-rhizobium symbiosis - Rhizobium inoculants - Rotational benefits

    Grain legumes play a key role in smallholder farming systems in sub-Saharan Africa (SSA), in relation to food and nutrition security and income generation. Moreover, because of their N2-fixation capacity, such legumes can also have a positive influence on soil fertility. Notwithstanding many decades of research on the agronomy of grain legumes, their N2-fixation capacity, and their contribution to overall system productivity, several issues remain to be resolved to realize fully the benefits of grain legumes. In this paper we highlight major lessons learnt and expose key knowledge gaps in relation to grain legumes and their contributions to farming system productivity. The symbiosis between legumes and rhizobia forms the basis for its benefits and biological N2-fixation (BNF) relies as much on the legume genotype as on the rhizobial strains. As such, breeding grain legumes for BNF deserves considerably more attention. Even promiscuous varieties usually respond to inoculation, and as African soils contain a huge pool of unexploited biodiversity with potential to contribute elite rhizobial strains, strain selection should go hand-in-hand with legume breeding for N2-fixation. Although inoculated strains can outcompete indigenous strains, our understanding of what constitutes a good competitor is rudimentary, as well as which factors affect the persistence of inoculated rhizobia, which in its turn determines whether a farmer needs to re-inoculate each and every season. Although it is commonly assumed that indigenous rhizobia are better adapted to local conditions than elite strains used in inoculants, there is little evidence that this is the case. The problems of delivering inoculants to smallholders through poorly-developed supply chains in Africa necessitates inoculants based on sterile carriers with long shelf life. Other factors critical for a well-functioning symbiosis are also central to the overall productivity of grain legumes. Good agronomic practices, including the use of phosphorus (P)-containing fertilizer, improve legume yields though responses to inputs are usually very variable. In some situations, a considerable proportion of soils show no response of legumes to applied inputs, often referred to as non-responsive soils. Understanding the causes underlying this phenomenon is limited and hinders the uptake of legume agronomy practices. Grain legumes also contribute to the productivity of farming systems, although such effects are commonly greater in rotational than in intercropping systems. While most cropping systems allow for the integration of legumes, intercropped legumes provide only marginal benefits to associated crops. Important rotational benefits have been shown for most grain legumes though those with the highest N accumulation and lowest N harvest index appear to demonstrate higher residual benefits. N balance estimates often results in contradictory observations, mostly caused by the lack of understanding of belowground contributions of legumes to the N balance. Lastly, the ultimate condition for increased uptake of grain legumes by smallholder farmers lies in the understanding of how legume technologies and management practices can be tailored to the enormous diversity of agroecologies, farming systems, and smallholder farms in SSA. In conclusion, while research on grain legumes has revealed a number of important insights that will guide realization of the full potential of such legumes to the sustainable intensification of smallholder farming systems in SSA, many research challenges remain to be addressed to realize the full potential of BNF in these systems.

    N2Africa Annual Report 2018
    Ampadu-Boakye, Theresa ; Ronner, E. ; Kanampiu, Fred ; Giller, K.E. ; Baars, Edward ; Vanlauwe, B. ; Adjei-nsiah, Samuel ; Wolde-Meskel, E. ; Ebanyat, Peter ; Baijukya, Frederick ; Sanginga, Jean-Marie ; Woomer, P.L. ; Chikowo, Regis ; Phiphira, Lloyd ; Kantengwa, Speciose ; Leonardo, W. ; Kamai, Nkeki ; Thuijsman, E.C. ; Schilt-van Ettekoven, C. - \ 2019
    Wageningen : N2Africa (N2Africa project report 111) - 77 p.
    Annual report, Key milestones, objectives, progress, biological nitrogen fixation, grain legumes, Nigeria, Borno State, Ghana, Tanzania, Ethiopia, Uganda, DR Congo, Rwanda, Kenya, Malawi, Zimbabwe, Mozambique
    From best fit technologies to best fit scaling: incorporating and evaluating factors affecting the adoption of grain legumes in Sub-Saharan Africa
    Farrow, Andrew ; Ronner, Esther ; Brand, Greta J. Van Den; Boahen, Stephen K. ; Leonardo, Wilson ; Wolde-Meskel, Endalkachew ; Adjei-Nsiah, Samuel ; Chikowo, Regis ; Baijukya, Fredrick ; Ebanyat, Peter ; Sangodele, Emmanuel A. ; Sanginga, Jean-Marie ; Kantengwa, Speciose ; Phiphira, Lloyd ; Woomer, Paul ; Ampadu-Boakye, Theresa ; Baars, Edward ; Kanampiu, Fred ; Vanlauwe, Bernard ; Giller, Kenneth E. - \ 2019
    Experimental Agriculture 55 (2019)S1. - ISSN 0014-4797 - p. 226 - 251.
    The success of scaling out depends on a clear understanding of the factors that affect adoption of grain legumes and account for the dynamism of those factors across heterogeneous contexts of sub-Saharan Africa. We reviewed literature on adoption of grain legumes and other technologies in sub-Saharan Africa and other developing countries. Our review enabled us to define broad factors affecting different components of the scaling out programme of N2Africa and the scales at which those factors were important. We identified three strategies for managing those factors in the N2Africa scaling out programme: (i) testing different technologies and practices; (ii) evaluating the performance of different technologies in different contexts; and (iii) monitoring factors that are difficult to predict. We incorporated the review lessons in a design to appropriately target and evaluate technologies in multiple contexts across scales from that of the farm to whole countries. Our implementation of this design has only been partially successful because of competing reasons for selecting activity sites. Nevertheless, we observe that grain legume species have been successfully targeted for multiple biophysical environments across sub-Saharan Africa, and to social and economic contexts within countries. Rhizobium inoculant and legume specific fertiliser blends have also been targeted to specific contexts, although not in all countries. Relatively fewer input and output marketing models have been tested due to public–private partnerships, which are a key mechanism for dissemination in the N2Africa project.
    Poor farmers - poor yields: Socio-economic soil fertility and crop management indicators affecting climbing bean productivity in Northern Rwanda
    Franke, A.C. ; Baijukya, F. ; Kantengwa, S. ; Reckling, M. ; Vanlauwe, B. ; Giller, K.E. - \ 2019
    Experimental Agriculture 55 (2019)S1. - ISSN 0014-4797 - p. 14 - 34.
    Climbing bean is the key staple legume crop in the highlands of East and Central Africa. We assessed the impact of interactions between soil fertility characteristics, crop management and socio-economic factors, such as household resource endowment and gender of the farmer, on climbing bean productivity and yield responses to basal P fertiliser in northern Rwanda. Through a combination of detailed characterisations of 12 farms and on-farm demonstration trials at 110 sites, we evaluated variability in grain yields and
    responses to fertiliser. Grain yields varied between 0.14 and 6.9 t ha−1 with an overall average of 1.69 t ha−1. Household resource endowment and gender of the farmer was strongly associated with Climbing bean yield, even though these were partly confounded with Sector. Poorer households and women farmers
    achieved lower yields than wealthier households and male farmers. Household resource endowment and gender were likely to act as proxies for a range of agronomic and crop management factors that determine crop productivity, such as soil fertility, current and past access to organic manure and mineral fertiliser,
    access to sufficient quality staking material, ability to conduct crop management operation on time, but we found evidence for only some of these relationships. Poorer households and female farmers grew beans on soils with poorer soil fertility. Moreover, poorer households had a lower density of stakes, while stake density was strongly correlated with yield. Diammonium phosphate (DAP) fertiliser application led to a substantial increase in the average grain yield (0.66 t ha−1), but a large variability in responses implied that its use
    would be economically worthwhile for roughly half of the farmers. For the sake of targeting Agricultural innovations to those households that are most likely to adopt, the Ubudehe household typology – a Rwandan government system of wealth categorisation – could be a useful and easily available tool to
    structure rural households within regions of Rwanda that are relatively uniform in agro-ecology.
    Impact of arbuscular mycorrhizal fungi and earthworms on soil aggregate stability, glomalin, and performance of pigeonpea, Cajanus cajan
    Muchane, Mary N. ; Pulleman, Mirjam M. ; Vanlauwe, Bernard ; Jefwa, Joyce ; Kuyper, Thomas W. - \ 2018
    Soil Research 57 (2018)1. - ISSN 1838-675X - p. 53 - 65.
    endogeic - epigeic - integrated soil fertility management (ISFM) - soil biota - soil fertility - soil structure

    Earthworms and arbuscular mycorrhizal fungi (AMF) modify soil physical and chemical properties. However, little is known about how their interactions affect water-stable aggregation, glomalin and crop performance. A greenhouse experiment was run for 9 months to test the effects of earthworms (endogeic, Pontoscolex corethrurus and epigeic, Dichogaster bolaui) and AMF (none, Glomus etunicatum and Scutellospora verrucosa) on water-stable aggregation, glomalin levels in aggregate size classes and crop performance. The test crop was pigeonpea (Cajanus cajan (L.) Millsp.). The soil material used for the experiment was a humic nitisol from central Kenya mixed with sand (ratio 1: 1). Grass residue (equivalent to 20 t ha-1) was placed on top. The AMF root colonisation and external hyphal length, water-stable macroaggregates and microaggregates, total and easily-extractable glomalin in aggregate size classes, plant biomass and plant N and P uptake were measured. Earthworms were a major source of variation for soil aggregation, glomalin content and crop performance. The epigeic earthworms (D. bolaui) increased the amount of water-stable macroaggregates (by 10%) and glomalin in microaggregates and improved crop (growth and biomass) performance. The endogeic earthworms (P. corethrurus) reduced external hyphal length, root colonisation and crop performance but had no effect on water-stable aggregates and glomalin levels in in aggregate size classes. A significant AMF × earthworm interaction was observed for plant biomass and concentrations of nitrogen (N) and phosphorus (P). The AMF species together with epigeic earthworms increased plant biomass and N and P concentrations. Our results contribute to the understanding of interactions between AMF and earthworms in relation to soil aggregation, plant productivity and nutrient uptake.

    Xanthomonas Wilt of Banana (BXW) in Central Africa : Opportunities, challenges, and pathways for citizen science and ICT-based control and prevention strategies
    McCampbell, Mariette ; Schut, Marc ; Bergh, Inge Van den; Schagen, Boudy van; Vanlauwe, Bernard ; Blomme, Guy ; Gaidashova, Svetlana ; Njukwe, Emmanuel ; Leeuwis, Cees - \ 2018
    NJAS Wageningen Journal of Life Sciences 86-87 (2018). - ISSN 1573-5214 - p. 89 - 100.
    Agricultural transformation - Banana wilt disease - Digital innovation - Environmental monitoring - ICT4Ag - Systems analysis
    Xanthomonas Wilt of Banana (BXW) is a complex problem in the African Great Lakes Region that is affecting the livelihoods of millions of smallholder farmers. Since the first disease reports from Uganda and the Democratic Republic of Congo in 2001, BXW has been studied widely. The majority of these studies focus on the technological or biophysical dimensions, while aspects and influence of socio-cultural, economic and institutional dimensions only recently started to gain attention. This paper provides an in-depth analysis of the broader BXW problem using a systems perspective, with the aim to add to the understanding about reasons for poor uptake of appropriate disease management practices, and limited ability to prevent rather than control BXW in the region. We comprehensively describe and analyse the various problem dimensions, and determine relations with data, information, knowledge, and connectivity. Building on this, the paper explores and discusses entry-points for the use of Information and Communication Technologies (ICT) and citizen science tools to better address BXW in banana production systems.
    Soyabean response to rhizobium inoculation across sub-Saharan Africa : Patterns of variation and the role of promiscuity
    Heerwaarden, Joost van; Baijukya, Frederick ; Kyei-Boahen, Stephen ; Adjei-nsiah, Samuel ; Ebanyat, Peter ; Kamai, Nkeki ; Wolde-Meskel, Endalkachew ; Kanampiu, Fred ; Vanlauwe, Bernard ; Giller, Ken - \ 2018
    Agriculture, Ecosystems and Environment 261 (2018). - ISSN 0167-8809 - p. 211 - 218.
    Bradyrhizobium - Promiscuous varieties - Response variability - Smallholder farmers - Soyabean - Sub saharan Africa - Sustainable intensification
    Improving bacterial nitrogen fixation in grain legumes is central to sustainable intensification of agriculture in sub-Saharan Africa. In the case of soyabean, two main approaches have been pursued: first, promiscuous varieties were developed to form effective symbiosis with locally abundant nitrogen fixing bacteria. Second, inoculation with elite bacterial strains is being promoted. Analyses of the success of these approaches in tropical smallholder systems are scarce. It is unclear how current promiscuous and non-promiscuous soyabean varieties perform in inoculated and uninoculated fields, and the extent of variation in inoculation response across regions and environmental conditions remains to be determined.We present an analysis of on-farm yields and inoculation responses across ten countries in Sub Saharan Africa, including both promiscuous and non-promiscuous varieties. By combining data from a core set of replicated on-farm trials with that from a large number of farmer-managed try-outs, we study the potential for inoculation to increase yields in both variety types and evaluate the magnitude and variability of response.Average yields were estimated to be 1343 and 1227. kg/ha with and without inoculation respectively. Inoculation response varied widely between trials and locations, with no clear spatial patterns at larger scales and without evidence that this variation could be explained by yield constraints or environmental conditions. On average, specific varieties had similar uninoculated yields, while responding more strongly to inoculation. Side-by side comparisons revealed that stronger responses were observed at sites where promiscuous varieties had superior uninoculated yields, suggesting the availability of compatible, effective bacteria as a yield limiting factor and as a determinant of the magnitude of inoculation response.
    Sustainable intensification through rotations with grain legumes in Sub-Saharan Africa : A review
    Franke, A.C. ; Brand, G.J. van den; Vanlauwe, B. ; Giller, K.E. - \ 2018
    Agriculture, Ecosystems and Environment 261 (2018). - ISSN 0167-8809 - p. 172 - 185.
    Biotic factors - Cereals - Nitrogen fixation - Phosphorus - Residual benefits - Smallholder farmers

    We conducted a systematic review of literature on the residual effects of grain legumes in cereal-based systems of sub-Saharan Africa (SSA) to quantify the magnitude and variability of rotational effects, to explore the importance of environmental and management factors in determining variability and to evaluate the evidence of the different mechanisms that explain rotational effects. We retrieved 44 unique publications providing 199 observations comparing continuous cereal performance with that of a grain legume-cereal rotation. The overall mean yield increase of 0.49t grainha-1, equal to an increase of 41% of the continuous cereal yield, is highly significant, but the variability in residual effects is large. Effects were more pronounced in southern Africa, the highlands of East Africa and the Guinea savannah, and less in the humid forest/derived savannah of West Africa and the Sudano-Sahelian zone. Maize showed stronger yield responses after a legume than millet and sorghum. Agro-ecological zone and cereal type were however confounded. All grain legume types significantly improved cereal yields, with stronger residual effects observed after soybean and groundnut than after cowpea. Fertiliser N application to cereals reduces the residual effects of legumes, but the response at 60-120kgNha-1 still equalled 0.32tha-1 or 59% of the response when no N is applied. The sustained benefits with large N applications indicate the importance of non-N effects. While mechanisms for improved soil P availability after grain legumes have been studied in some detail, it remains uncertain how important these are in farmers' fields. Grain legumes are unlikely to have a major influence on the availability of nutrients other than N and P, or on soil pH. Beneficial impacts of grain legumes on soil organic matter content can occur if legumes contribute to a greater overall cropping productivity, but studies generally report no such impacts. Evidence of impacts of grain legumes on weeds is limited to striga. Studies on the impacts on nematode pressure in cereals are inconclusive, probably because legumes act as a host for some of the key nematode genera that harm maize. The impact on the pressure of other pests and diseases in cereals is probably important, but evidence on this from SSA is lacking. Future research on N2-fixation by grain legumes and residual N benefits should focus on explaining the wide variability observed among sites. There is a clear need for more detailed mechanistic studies to assess the occurrence and relevance of non-N effects of grain legumes, particularly in relation to common pests and diseases in cereals.

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