1.Conference AbstractsChallenges and Opportunities forAgricultural Intensification of theHumid Highland Systems of sub- Saharan AfricaFertility Soil Biology banana2008

2. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa 2 3. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan AfricaContentsINTRODUCTORY KEYNOTES 5THEMATIC ORAL SESSIONS 9THEME 1: SYSTEM COMPONENTS 11THEME 2: SYSTEM COMPONENTS 21THEME 3: DRIVERS FOR ADOPTION31THEME 4: COMMUNICATING COMPLEX KNOWLEDGE 41POSTER SESSIONS 51THEME 1: SYSTEM COMPONENTS 53THEME 2: SYSTEM INTEGRATION205THEME 3: DRIVERS FOR ADOPTION 239THEME 4: COMMUNICATING COMPLEX KNOWLEDGE 277AUTHOR INDEX2933 4. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa 4 5. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan AfricaINTRODUCTORYKEYNOTES 5 6. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa 6 7. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa1.Sustainable intensification and the food security challenge Brian Keating1 and Peter Carberry1 Commonwealth Scientific and Industrial Research Organisation(CSIRO), 1 Canberra, Australia.AbstractGlobal food demand is estimated to increase between 50 and 80 percent between2010 and 2050 with the range driven by variation in the key drivers such aspopulation growth, per capita consumption trends, diversion to biofuels and foodwastage rates. Pathways by which this challenge can be met include; reducingthe demand trajectory, filling the production gap and avoiding losses of currentproductive capacity. This paper focuses on the opportunity to expand food supplyto fill this projected increase in demand. Challenges of this scale have been metin the past between 1961 and 2008, agricultural output increased by 179 percentglobally. In many parts of the world, these production increases were achievedby intensification of agricultural practices, in particular via combining inorganicfertiliser and agri-chemical inputs with intensive tillage and improved varieties. Thelonger term sustainability of such intensive systems remains a concern, but thereis little doubt that without the higher yields now being achieved in much of thedeveloping world, the numbers of undernourished would be much higher than thecurrent (still unacceptable) levels. While yields were rising in response to agriculturalintensification in other parts of the world, sub Saharan Africa maintained (just) foodproduction per capita by expanding the land footprint and productivity levels perunit land remain low. While there is still scope for further expansion of agriculturalland, particularly in sub Saharan Africa and in parts of South America, the clearingof forests and woodlands and cultivation of grasslands is going to generate asignificant load of greenhouse gases on an already overloaded atmosphere withconsequences for climate change and potential for negative feedback on agriculturalproductivity. Given the food demand pressures and the environmental constraints(carbon, water, biodiversity), there seems little alternative to an intensificationpathway for agriculture but it needs to be a sustainable one (i.e. eco-efficient) interms of nutrient and water cycles and agro-ecological functions. This conclusionapplies generally, but the potential upside is greatest in Africa where inputs arevery low and productivity is coming off a low baseline. In this paper we argue for astrong evidence base to help guide interventions towards sustainable intensification.We present a diagnostic framework applicable at the field and farm scale, but alsoargue that progress in productivity growth will be slow without concerted effortsto embed agricultural R&D in a wider innovation effort. Such an effort needs tosupport the evolution of a system of enabling institutions (input and output markets,public policy settings, private sector activity, trade and regulation) that are a precondition for any transformation in the African farm sector.7 8. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa2.Paradigm Change for African Agriculture: why and how to make the transition Hans R Herren Millennium Institute, Washington DC, USAAbstractAgriculture needs to transition from being a major problem for climate change, to thesolution, while at the same time it also needs to become the true engine of sustainabledevelopment. The International Assessment of Agricultural Knowledge, Science andTechnology for Development (IAASTD) is a unique and comprehensive assessment ofAgricultural Knowledge, Science and Technology, which outlined the path for such atransition. It started with requests from the private sector and NGOs to the World Bank,to look at new ways for agriculture and food systems to assure sufficient and qualityfood, fiber and feed production for the long term under the challenges of increased andchanging demand, shrinking natural resources and climate change, while also dealingwith the more immediate perennial hunger and poverty nexus. The IAASTD waslaunched by the major UN agencies at the Johannesburg World Summit on SustainableDevelopment in 2002, and subsequently officially endorsed by the OECD and othercountries at a Plenary meeting in Nairobi in 2004. A Bureau made up of representativesfrom government, multilateral agencies and civil society groups, including the privatesector, guided all the steps of the assessment and endorsed over 400 authors, fromdeveloped and developing nations covering agricultural and related disciplines. Ina first step, some 800 stakeholders framed the key questions to be addressed by thereports authors at workshops held in the five regions covered by the assessment (NorthAmerica and Europe, Latin America and the Caribbean, Sub-Saharan Africa, Centraland West Asia and North Africa and South Asia and the Pacific). Of main interestwas how the AKSTs of the past 50 years influenced where we are today in terms ofagricultural production and food systems and how to reshape these for reducing hungerand poverty; improving rural livelihoods; improving nutrition and human health;and facilitating environmentally, socially, equitable and economically sustainabledevelopment. In the report series Agriculture at a Crossroads, the IAASTD authorsemphasized the need for a new paradigm in AKST that will lead to food systems,that are in harmony with the environment, i.e., agroecology, organic agriculture, thatmitigates rather than contribute to climate change, that has reduced external energyinputs in terms of synthetic fertilizers and pesticides, that is high in genetic and systemdiversity, that targets the small and family farms and one that assures food security andsovereignty at national level. It also emphasized the multi-functionality of agriculture,and in particular its social, environmental and economic aspects, which are all linkedand key in moving to a socially, environmentally and economically sustainable andproductive agriculture in the medium and long term. It suggest among others thatecosystem services be remunerated for all farmers instead of providing market distortingproduction and export support to the industrialized country farmers. The feasibilityof a green agriculture to meet the sustainability and millennium development goalsis presented, based on modeling results from the Millennium Institute, utilizing theoptions for action from the IAASTD report.8 9. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan AfricaTHEMATIC ORAL SESSIONS 9 10. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa10 11. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa THEME 1: SYSTEMCOMPONENTS11 12. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa12 13. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa3.Below- and aboveground organic inputs and the sustainability of agriculture: productivity and supply of ecosystem services Meine van Noordwijk1, Kurniatun Hairiah2, Bernard Vanlauwe3, Sileshi Weldesemayat4, Edmundo Barrios5, Bob Boddey6 and Georg Cadisch7 1Ecosystem Services for Poverty Alleviation (ESPA), Scotland, UK; 2Faculty of Agriculture, University of Brawijaya, Indonesia; 3Tropical Soil and Biology Institute of the International Center for Tropical Agriculture (CIAT-TSBF), Nairobi, Kenya; 4World Agroforestry Centre (ICRAF), Nairobi, Kenya; 5Centre for International Development, Harvard University, Cambridge, USA; 6Embrapa-Agrobiologia, Rio de Janeiro, Brazil; 7University of Hohenheim, Stuttgart, GermanyAbstractOrganic inputs to the soil can derive within the field from aboveground plantresidue left at harvest time, from belowground inputs (roots, rhizosphere foodwebsand mycorrhizal hyphae) and externally, from recycled waste products (includingmanure and compost). Organic inputs serve functions at the surface, includingprotection of the soil from erosion, reduction of soil evaporation and regulation oftopsoil microclimate, as well as after incorporation to the soil, including maintenanceof soil structure, buffering of nutrients and supply of nutrients by mineralization.The tradeoff between these above and belowground functions is modulated bysoil tillage and presence of soil fauna. We review the literature on a number ofhypotheses: I. In the absence of soil tillage or active worm fauna, aboveground littercontributes little to soil organic matter, most of which derives from root turnover,II. Nutrients mineralized from aboveground litter decomposition are available toplants , as superficial roots develop where surface litter is (semi)permanent and/or nutrients leach into the root zone. III. In the presence of permanent surface litter,the dependence of soil function on soil organic matter for soil physical properties isreduced as well as the rate of soil organic matter decomposition, IV. Low-qualitylitter, with e.g. high polyphenol contents, is to be preferred over material with higherrates of decomposition where agricultural sustainability on slopes is an issue. 13 14. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa4.CIALCA interventions for productivity increase of cropping system components in the African Great Lakes zone.P. Pypers1, W. Bimponda2, E. Birachi3, K. Bishikwabo4, G. Blomme5, S. Carpentier6, A.Gahigi7, S. Gaidashova7, J. Jefwa1, S. Kantengwa4, J.P. Kanyaruguru8, P. Lepoint9, J.P.Lodi-Lama4, M. Manzekele2, S. Mapatano10, R. Merckx6, T. Ndabamenye7, T. Ngoga7, J.J.Nitumfuidi2, C. Niyuhire11, J. Ntamwira2, E. Ouma12, J.M. Sanginga4, C. Sivirihauma13,R. Swennen6, P. van Asten14, B. Vanlauwe1, N. Vigheri15, and J.M. Walangululu16 1 TSBF-CIAT (Kenya), 2 INERA (DR Congo), 3 CIAT (DR Congo), 4 TSBF-CIAT (DR Congo), 5 Bioversity (Uganda), 6 KULeuven (Belgium), 7 ISAR (Rwanda), 8 CIALCA (Burundi), 9 Biover- sity (Burundi), 10 DIOBASS (DR Congo), 11 ISABU (Burundi), 12 IITA (Burundi), 13 Bioversity (DR Congo), 14 IITA (Uganda), 15 UCG (DR Congo), 16 UCB (DR Congo).Abstract: In the African Great Lakes zone, farmers are confronted by declining soil fertility, low crop yieldsand food insecurity. The local crop cultivation practice entails the use of local varieties in mixedsystems with often high crop densities, and little or no application of inputs. To improve pro-ductivity, the Consortium for Improving Agricultural Livelihoods in Central Africa (CIALCA)implements a strategy with improved banana and grain legume germplasm as the entry pointand key component of natural resource and disease management options. Successful introductionrequires that new varieties perform superiorly in terms of yield and resistance to biotic and abi-otic stresses in comparison with local varieties, but also match farmer expectations for traits suchas e.g., duration, taste and tradability. In addition, CIALCA sought to introduce varieties withtraits favourable for soil fertility and human nutrition. Large germplasm evaluation trials wereconducted on-station with research partners in the region, and selected varieties were evaluatedin on-farm demonstration trials to assess genotype x environment interactions and obtain farmerfeedback. Examples are given of the performance of the performance of newly introduced variet-ies. Preferred varieties were then made available to farmers through investments in community-led macropropation of banana germplasm, and legume seed multiplication schemes. Durableproductivity improvements however require further investment. CIALCA is promoting technol-ogy packages that combine improved germplasm with fertilizer use, organic matter managementand/or agronomic measures. Although farmers correctly recognize low soil fertility and droughtas the major abiotic crop constraints, they rarely make use of technologies to overcome these. Fer-tilizer is little used because of its cost and limited availability. The price of fertilizer is characteristi-cally high due to a poorly developed agro-input sector and infrastructural constraints, but pricesof crop produce are likewise high, resulting in favourable benefit-cost ratios. This has been dem-onstrated in all countries, in grain legumes as well as in cassava and maize intercrops, and createdinterest and opportunities for fertilizer use. CIALCA further advocates appropriate organic mat-ter management in conjunction with fertilizer use. Examples are given how quality and methodof application affect fertilizer use efficiency in climbing beans. In banana systems, mulching andzero-tillage have positive effects on moisture retention, nutrient recycling and weed suppression,which results in increased bunch yield even without application of external nutrients. In cassavasystems, combined application of fertilizer and green manure results in greater profitability thanthe sole application of either resource. Agronomic measures can further improve yields. Optimiz-ing the plant density and plantation management can increase banana bunch weights, but mayprolong the cropping cycle and conflict with other farmer objectives. An evaluation of water-harvesting options suggested that benefits can be obtained from tied ridging in drought-proneregions, but poor soil fertility is a more important constraint in maize-based systems. CIALCAhas a substantial evidence base on how the productivity of individual crop components can beimproved, but challenges remain to integrate these at system and farm level, and adjust these tothe diverse agro-ecological and socio-economic conditions of smallholder farmers. Also, the avail-ability and affordability of fertilizer, the economic durability of community-led seed multiplica-tion schemes, as well as the knowledge intensity of technology packages remain limitations forlarge-scale dissemination and adoption. 14 15. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa5.Mitigating the impact of biotic constraints to build resilient banana systems in Central and Eastern Africa Rony Swennen1, Guy Blomme2, Piet van Asten3, Pascale Lepoint4, Eldad Karamura2, Emmanuel Njukwe3 and Jim Lorenzen3 1Katholieke Universiteit Leuven, Leuven, Belgium; 2Bioversity International, Uganda office, Kampala, Uganda; 3International Institute of Tropical Agriculture (IITA), Uganda office, Kampala, Uganda; 4Bioversity International, Bujumbura, BurundiAbstractBanana and plantain are a major food staple and source of income for food-insecuresmallholders across Central and Eastern Africa. Banana diseases and pests continueto threaten the regions banana production. Xanthomonas and Fusarium wilt arewidely spread across the region. Banana bunchy top disease, spread by an aphidvector with a preference for warmer temperatures, is currently mainly presentin the Congo basin and the Rusizi valley. However, the movement of plantingmaterials and climate change may speed up the spread of this disease to highlandbanana producing regions. Black leaf streak, nematodes and weevils, so far onlyimportant in regions below 1,500 masl,could also potentially move to higherelevations with climate change. Population movements during years of war/socialunrest or resettlement of refugees have often been associated with banana plantingmaterial movement and possible disease and pest introduction. A wide range ofintegrated pest and disease management (IPM) technologies has been developedover the past years, including the introduction of resistant Musa germplasm, pesttrapping, male bud removal, disinfection of garden tools and improved canopyand soil management. Significant progress has been achieved through research onpest and disease epidemiology. High yielding exotic and improved varieties wereintroduced via the International Transit Centre (ITC), Leuven, Belgium and the firsthighland banana hybrids originating from IITA/NARO Uganda were tested acrossthe region. These varieties combine higher resistance with higher yields. Rapidand healthy multiplication of banana planting material is key to a vigorous andhealthy banana sector. Farmers mostlyuse suckers, from their own or a neighborsfield, which are often infected by pests and diseases.Technologies for clean seedproduction have been developed and disseminated, including paring of corms,boiling water treatment, the use of macro-propagation units, and to a lesser extenttissue culture plants. Improved linkages between research, extension, the privatesector, and policy makers from farm to regional level is required to improve theproductivity and resilience of banana systems; a critical contribution to sustainablefood systems in the region. 15 16. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa6.Do commercial biological and chemical products increase crop yields and economic returns under smallholder farmer conditions? Jefwa, J.M.1, Asrat, A.2, Hermann, L.1, Jemo, M.3, Kavoo, A.1, Lesueur, D.4, Majengo, C.5, Mucheru, M.6, Mukhongo1, R., Mulet6, F., Munyahali1, W., Mutegi1, E., Mwangi1, E., Ncho3, C., Nwoke, O.C.7, Okalebo, R.5, Pypers, P.1, Were, B.5, and Yusuf, A.8 1 Tropical Soil and Biology Institute of the International Center for Tropical Agriculture (CIAT-TSBF), Nairobi, Kenya; 2Ethiopian Institute of Agricultural Research (EIAR), Ethiopia; 3 International Institute of Tropical Agriculture, Ibadan, Nigeria; 2Ahmadu Bello University, Zaria, Nigeria; 4Agricultural Research for Development (CIRAD), Indonesia; 5Moi University, Eldoret, Kenya; 6Kenyatta University, Nairobi, Kenya; 7Department of Agronomy, Osun State University, Osogbo, Nigeria; 8Ahmadu Bello University, Zaria, NigeriaAbstractSmallholder farmers in sub-Saharan Africa are confronted by low crop yields due to poor soilfertility, and only have a limited capacity to invest in inputs. During recent decennia, newcommercial products have appeared on the market as alternatives to common fertilizers. Whilesome of these products are based on well-established technologies, such as e.g., Rhizobiuminoculation, others have not been subjected to scientific scrutiny. During 3 years, we evaluatedover 80 of these new products, including microbial inoculants and chemical products on majorlegume, cereal and banana crops across diverse agro-ecological conditions in Ethiopia, Nigeriaand Kenya. Amongst the Rhizobium inoculants, several products from different companies werefound very effective, but generally only on soybean. In Ethiopia, for example, over 30% increasein soybean yield was found as a result of increased nodulation and N fixation. In the Nigeriansavannah zone, a similar improvement in productivity was found with three commercial strains,which was relatively independent of soybean variety and soil type, if the soil had a low indigenousRhizobium population. In groundnut, contrarily, the commercial Rhizobium inoculants testedwere not only ineffective but appeared to be inferior to the indigenous soil population, independentof the rate and source of P applied. In Kenya, inoculation increased average soybean grain yieldup to 30%, with a benefit-cost ratio up to 5.0. Responses were largest when control yields rangedbetween 0.5-1.0 t ha-1, and when the soil N content varied between 0.05 and 0.15 % N. The effectof arbuscular mycorrhizal inoculants (AMF) was less evident. No effect was observed in wheatin Ethiopia, or on maize or soybean in Kenya. In tissue culture (TC) banana, in contrast, positivebut soil-dependent effects were found of several AMF inoculants on growth at the plantlets andthe potting stage, a crucial stage in the production process of planting material. Other productscontaining Trichoderma or Bacillus spp. also had positive effects on growth. When transplantedto the field, soil-dependent growth improvements of over 40% were observed, demonstratingthat TC bananas can indeed benefit from commercial biological products. On-going work iselucidating the interactions with pathogenic rhizosphere organisms, particularly Fusarium, onwhich the inoculants have variable and soil-dependent effects. Amongst the chemical productsevaluated, special attention was given to alternative P fertilizers such as leaf sprays, seed coatingsand conditioners with humic acids. The effect on cereals depended on the crop, the soil andaccompanying agronomic measures. In Ethiopia, positive effects in wheat were only found withthe humic acid conditioner. In Nigeria, both humic acid conditioners and leaf sprays increasedmaize grain yield, but the effect of the leaf sprays was highly site-dependent and the cost of thehumic acid conditioner was not compensated by the benefits on yield. In Kenya, positive effectswere found only if products were combined with fertilizer at a sub-optimal rate, and only in themost P-deficient soils. Benefit-cost ratios were only favourable for seed P coating because this is afairly inexpensive treatment (3 USD ha-1). In conclusion, results demonstrate that there is potentialfor biological and chemical commercial products, but there is need for continued evaluation.Smallholders may benefit from some of these products, on the condition that a good-qualityproduct is correctly applied to the appropriate crop with appropriate soil and crop management. 16 17. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa7.Enhanced utilization of biotechnology research and development innovations in eastern and central Africa Masiga, C. W.1, Ketema S.1 and Mugoya C.1 1Associationfor Strengthening Agricultural Research in East and Central Africa (ASARECA), Entebbe, UgandaAbstractThe association for strengthening agricultural research in east and central Africa(ASARECA) through its Agrobiodiversity and biotechnology programme isenhancing utilization of biotechnology research and development innovations inECA. This is achieved through support to national agricultural research systems.The programme supports generation and uptake of biotechnology innovations,capacity strengthening, and availability of information. The successes so far areimpressive. Cassava transformation platforms in Kenya, Uganda and Tanzania havebeen established to Biosafety level II status and have become regional research andtraining epicentres in biotechnology. Low cost tissue culture protocols for cassavaand sweetpotato have been developed for banana, sweetpotatoes and cassava.Virus indexing tools have been developed for screening banana, cassava andsweetpotatoe planting materials against the common diseases and pests. Productionand dissemination of clean banana tissue culture has been strengthened. A regionalgenebank utilizing conservation biotechnology for conservation of cassava andsweetpotatoes is being rehabilitated and refurbished at the National Gene bankof Kenya. A parallel research activity involving development of a genetic linkagemap to map the location of the genes that confer resistance to cassava brown streakdisease (CBSD) is underway. Drought tolerant transgenic maize has been developedfor seven farmer preferred maize lines for Kenya, Sudan, Tanzania and Ethiopia.Marker assisted selection has been used to generate 51 sorghum lines resistant tostriga. Fine mapping of sorghum for striga resistance is almost completed. A pen-side diagnostic kit for detection of Taenia solium cysticercosis has been developedin ECA and the vaccine is under going trial. A number of post graduate trainingshave been supported. Information on these technological breakthroughs is beingdeveloped and will be published through books, journals and workshops. 17 18. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa8.Production of virus free sweetpotato planting materials using horticultural fleece Schulte-Geldermann, E. 1, Omuse, O.P.2, Agili, S. 1 and Low, J.1 International Potato Center (CIP), Nairobi, Kenya; 2Moi University, School of 1 Agricultural sciences, Eldoret, KenyaAbstractSweetpotato (Ipomea batatas) is one of the most important staple crops in denselypopulated parts of Eastern Africa and is quickly becoming an importantsupplementary staple in the southern part of the continent. It is vital to small scalefarmers with limited land, labor and capital. One of the major yield limiting factorsin sweetpotato production are lack of clean planting material owing to infection ofSweetpotato virus diseases (SPVD). Therefore there is a need to provide farmerswith better technologies for rapidly multiplying clean planting materials andmaintaining a clean stock for a long period on-farm without compromising on thequality. An experiment was set at Kakamega agriculture research station, in Kenyafrom June 2009 to March 2011. Three varieties of sweet potato free from virus butsusceptible to SPVD have been evaluated in three methods of vine multiplication a)control -exposed, b) Fleece-cover and c) Fleece-tunnel. In an interval of 5 monthscuttings have been taken and tested for virus incidence. Furthermore, cuttings werereplanted to measure the effect on field performance. Results indicate significantreduction in aphid, white fly population and virus levels, and a significant higherproduction of vine cuttings from the second cutting onwards. However, direct fleececover led to heat damage on vines which couldnt be observed in the tunnel. Yieldsfrom vines obtained from both covering treatments have been significantly higherthan from vines out of the exposed treatment with all varieties. Preliminary datareveal that the use of horticulture fleece could act as a cheap measure to maintainvirus free foundation seed. 18 19. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa9.Lessons from Upstream Soil Conservation Measures to Mitigate Soil Erosion and Improve Land Productivity in the Humid Highlands of Northwestern Ethiopia Mengesha, Y.G.S.1 and Tadele, A.2 Department of Natural Resources Management, College of Agriculture and Environ- 1 mental Science Bahir Dar University, Bahir Dar, Ethiopia; 2 Department of Natural Resources Management, College of Agriculture and Natural Resources, Debremarkos University, Debremarkos, EthiopiaAbstractA study was conducted in Absela site, Banja Shikudad district, Awi administrativeZone of the Amhara National Regional State (ANRS), Northwestern Ethiopia locatedin the Blue Nile Basin to evaluate the effects of soil bunds stabilized with vetiver grass(V. zizanioides) and tree lucerne (C. palmensis) on selected soil physical and chemicalproperties, bund height, inter-terrace slope and barley (Hordeum vulgare L.) yield. Theexperiment had five treatments that included non-conserved land (control), a 9-yearold soil bund stabilized with tree lucerne, a 9-year old soil bund stabilized with vetivergrass, a 9-year old sole soil bund, and a 6-year old soil bund stabilized with tree lucerne.Data were analyzed using one-way analysis of variance (ANOVA) and mean valuesfor the treatments were separated using Duncan Multiple Range Test. Results of theexperiment indicated that OC, total N, bulk density, infiltration rate, bund height, andinter-terrace slope are significantly (p0.05) affected by soil conservation measures.The non-conserved fields had significantly lower OC, total N, infiltration rate; whereashigher bulk density as compared to the conserved fields with different conservationmeasures. However, no significant differences in bulk density were observed among theconservation methods. The field treated with 9-year old soil bund stabilized with treelucerne or sole soil bund had significantly higher OC content than all other treatments.Fields having 6-year old soil bunds had lower OM and total N when compared to fieldshaving 9-year old soil bunds irrespective of their method of stabilization. Fields with soilbunds stabilized with vetiver grass had the highest bund height and the lowest inter-terrace slope than fields with the remaining conservation measures. Barley grain andstraw yields were significantly (PP>K except in more acidic soils (KontelaMali for example) where P was more limiting than N. Nutrient omission resulted insignificant yield reductions of 30% for N and 20% for P on average, relative to fullNPK while K showed no effect in most sites. For maize growing sites, applicationof lime (500 kg/ha) increased grain yield by up to 500 kg/ha in acidic sites whilemanure resulted in even higher increases (600 kg/ha) in comparison to the full NPKtreatment. The effect of multi-nutrients was low and insignificant in most cases.In each site, amendment treatments (lime, manure and multi-nutrients) that hadat least 300 kg/ha more grain than in NPK treatments constituted 40 to 75% of allcases indicating wide existence of non-responsive soils that can be improved withsimple management. Similarly to other mapped soil constraints, the magnitude ofthe yield differences between control and NPK was high in high erosion risk areasas compared to lower erosion risk ones. These results are compared with data fromsimilar trials conducted beyond AfSIS sentinel sites, such as those from CIALCAproject. Suggestions for minimum treatments needed to diagnose soil constraints,and analysis framework for such trials are made. 92 93. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa69. Determination of appropriate rate and mode of applying lime to acid soils of western kenya targeting small scale farmers Kiplagat J.1, Okalebo J.R.2, Serrem C.K.2, Mbakaya D.S.3 and Jama B.4 1Moi University, Eldoret, Kenya; 2Department of Soil Science, School of Agriculture and Biotechnology, Chepkoilel University College, Eldoret, Kenya; 3Kenya Agricultural Research Institute (KARI), Kakamega, Kenya; 4Alliance for a Green Revolution in Af- rica, Nairobi, KenyaAbstractWestern Kenya is experiencing declining food production as a result of increased Soilacidity in smallholder farms. To counteract this, KARI Kakamega and MoiUniversityhave demonstrated the potential of using agricultural lime, inorganic fertilizers andMinjingu rock phosphates to address the food security problem. Despite this, the use oflime is still low due to: unawareness on lime effectiveness, and importance and modeof application by small holder farmers. The study aimed at comparing three possiblemethods of applying lime (spot, band and broadcast methods) to acid soils at 4 differentrates of application (0, 2, 4 and 6 t/ha) in terms of maize performance in the twotarget districts of Western Kenya. On farm experiment was conducted in two sites inSiaya district and two sites in North Kakamega district, laid out in a 3x4 factorial inRCBD with 4 replications. Lime was applied but with phosphorus as (TSP) and nitrogenas (CAN) applied as blankets at the rate of 26kg/ha P and 75kg/ha N. Highest grainyield increased on average from 1.67 t/ha in control to 4.37 t/ha from application of6 t/ha lime by broadcast method in Siaya district for two seasons (2010 long rains andshort rains). While in Kakamega north district it increased from 1.49 t/ha to 3.14 t/ha with 6 t/ha lime applied by band methodThe labour costs per hectare required forthe application of lime differed with method, the broadcast method was costly becausea farmer has to incorporate lime in the entire plot, while for the other methods, onlythe applied areas i.e. band rows and hills are tilth. Therefore, with the current resultsit can be inferred that the methods of applying lime for the two districts vary due todifferences in soil type and climatic conditions. 93 94. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa70. Dissemination and use of Cassava Chippers in Cameroon Kirscht Holger1 and Njukwe Emmanuel2 1International Institute of Tropical Agriculture (IITA), Cameroon; 2International Insti- tute of Tropical Agriculture (IITA), Uganda office, Kampala, UgandaAbstractIn 2007 the International Institute of Tropical Agriculture (IITA-Cameroon) andthe IFAD funded Roots and Tuber Program of Cameroon (Programme Nationalde Dveloppement des Racineset Tubercules - PNDRT) started to promote anddisseminate cassava chipping machines in the main cassava production zones ofCameroon. Beneficiaries of the programme were rural agricultural associations towhom the machines were assigned. They are supposed to store and maintain thechipper and they control the access of their members to the machines. In the regionsof action, women account for about two thirds of all members rural agriculturalassociations. Women are the main cassava producers and transformers in Cameroonand are playing important roles as ordinary members or part of the board. Togetherwith or preceding the dissemination of the chipping machines, improved cassavavarieties, which carry certain resistance against pests and diseases, and thereforeallow higher yields, were introduced by IITA and its partners. It was one of theprograms targets to especially facilitate the transformation of this improved cassavavarieties. It was aimed at producing storable and marketable products with agood price to weight ratio, thus increasing the storage options and reducing costsfor transport to the local and regional markets. It was assumed, that particularlywomen would like to benefit from the chipping machines because of the relativelylow labourinput necessary for the processing and the small operational costs.Nevertheless, the survey revealed, that men show a considerable interest in themachines, which was reflected in the high number of male beneficiaries in the survey.In 2010 the distribution of the chipping machines was completed and 25 villagesreceived about 100 manual machines, developed by IITA and produced by localfabricators. In addition motor driven machines were delivered to selected villages.This poster presents results of a socio-economic survey about the acceptance ofthe cassava chipping machines by the local population and the benefits they havebrought to the participating village communities. 94 95. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa71. Maize Yield and Striga Emergence Response to Varying Desmodium Trimming Regime in the Push- Pull Intercropping System in Western Kenya Koech-Njeri, M.1, J.R. Okalebo1, C.O. Othieno1, P. Pypers2, B.Vanlauwe2, Z. Khan3 and J.A. Pickett4 1Moi University, Eldoret, Kenya; 2Tropical Soil and Biology Institute of the Interna- tional Center for Tropical Agriculture (CIAT-TSBF), Nairobi, Kenya; 3International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya; 4Rothamsted Re- search, Harpenden, Hertfordshire, United KingdomAbstractLow soil fertility, cereal stem borers and Striga weeds are the major constraints tothe production of maize which is the major staple food in western Kenya. Push-pull technology (PPT) defined as maize intercropped with a stem borer moth repellent legume, Desmodium, and surrounded with an attractant host plant, Napiergrass planted as a trap plant for stem borers has been described as an appropriateinnovative technology capable of addressing maize yield losses caused by theabove constraints in this region. This study tested the hypothesis that inclusion ofDesmodium spp into maize cropping system and varying its trimming regime mayprovide a substitute for inorganic nitrogen fertilizers and control striga whichwould result to enhanced crop growth and yield. The tested technologies includedtwo Desmodium spp [Desmodium uncinatum Jacq and Desmodium intortum Urb.)intercropped with maize, mono maize with urea (90 kg N /ha), mono maize withouturea and three Desmodium trimming regimes (9, 12 and 18 weeks after planting maize(WAPM) in two sites in western Kenya with contrasting soil fertility levels during4 consecutive seasons. Maize grain yields obtained from three consecutive seasonswere independent of Desmodium trimming regimes. Desmodium spp increased maizegrain yield above mono maize without urea from the second and third season in theless (Busia) and more fertile (Siaya) sites respectively. Desmodium uncinatum resultedto higher maize grain yields compared to Desmodium intortum but both Desmodiumspp reduced striga emergence from the second season in both sites. 95 96. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa72. Irrigation Livelihoods Heterogeneity and Water Management in Bua Watershed, Central Malawi: Policy Implications for Irrigation Development Kopa-Kamanga Tawina Jane1 and Jose Kjosavik Darley2Research & Development Section; Department of Irrigation, Mzuzu, Malawi;1 Noragric-Department of International Environment and Development Studies 2 Norwegian University of Life Sciences, NorwayAbstract:A study was conducted in Nkhotakota, Malawi, among Bua watershed irrigationhouseholds to determine the economic importance of irrigation in relation to otherlivelihood activities, and examine institutional arrangements for irrigation and watermanagement. The study also explored the determinants of household livelihooddiversity and factors that affected performance of single production or livelihoodcomponents. A livelihoods approach was adopted for the study. The results indicate that`irrigation livelihoods are heterogeneous in that some are more irrigation based thanothers, as reflected in varying benefits accrued from irrigation as a single productioncomponent. They further show that most irrigation households venture into diverselivelihood activities, notably, livestock production, rain-fed crop production, sellingdried fish. The study suggests that some livelihood components are water dependentunlike others, e.g. livestock production is water dependent while selling of groceriesis not. Thus water was noted to be a major constraint to production of the livelihoodcomponents, among other constraints such as access to credit, land, labour and capital.Therefore, dichotomising these livelihood activities between water-dependency andnon-water dependency provides a useful framework for analysing inter- and intra-household competing water uses. The study reveals that irrigation, like most water-dependent activities, is less profitable to non-water dependent households contributingonly 24 % to their livelihoods than it is to water-dependent households with 62 %contribution. The study further suggests that as households make decisions on resourceallocation, rationally more resources are allocated to more profitable activities. It alsoshows that water-dependent households have more diversified income sources andrelatively less income than non-water dependent households who are better off by 29%. Furthermore, irrigation seems to play a role in reducing income inequalities amongthe water-dependent households but it has no significant effect among non-waterdependent households. The results of this study argue against the common view thatirrigation households are dependent on irrigation-based livelihoods. It shows that thisview overshadows the water-dependency dichotomy of livelihood activities whichhas implications for water management. The study concludes that integrated waterresource management starts at household level as households efficiently allocatewater to diverse uses. Therefore, placing irrigation within the livelihood frameworkwill promote the integrated approach as well as ensure effective and result-orientedpolicies. Additionally, a household approach would yield positive results in improvingrural livelihoods and presumably performance of each single production component.However, as this is piloted in some sites within my research area, it would be prematureto propose and let alone evaluate interventions that would improve the efficiency,profitability, quality and productivity of the production components. 96 97. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa73. Impact of agroforestry and other land uses on microbial communities and functional capacity of soil bacteria in Kenyan highland soils Lagerlf Jan1, Lena Adolfsson1, Gunnar Brjesson2, Knut Ehlers3, Glria Pallars Vinyoles1 and Ingvar Sundh1 1 Swedish University of Agricultural Sciences, Sweden; 2Department of Water and En- vironmental Studies, Linkping University, Linkping, Sweden; 3Institute of Plant Sci- ences, Swiss Federal Institute of Technology (ETH), Zrich, SwitzerlandAbstractThe objective of this study was to compare the microbial community and potentialfunctional capacity of soils under different land uses and to correlate this to otherchemical and biological soil properties. The hypotheses were: 1) Microbial biomassand diversity as well as the functional capacity of the soil decreases with intensifiedcultivation. 2) Microbial biomass, diversity and functional capacity can be restoredby active soil and land management in agroforestry practices. Replicated samplesfrom undisturbed natural forest, forest plantations, agroforestry fields, agriculturalfields and eroded soil were taken from farms on the slopes of Mount Elgon inwestern Kenya. Agroforestry fields had earlier been agricultural fields without trees.Agroforestry practise was introduced during the latest 20 years with support from theSwedish NGO Vi Agroforestry Programme. Functional capacity of soil bacteria wasmeasured as potential substrate utilization studied by Biolog Ecoplates, where theutilisation of 31 different substrates is measured. Microorganism communities werecharacterised by PLFA analysis and by determination of microbial C and N. Othersoil properties measured were soil texture, moisture, pH, total N and C, extractableP and nitrate.The results followed a pattern with eroded and agricultural land onthe low end of the scale and agroforestry and planted and natural forest on thehigh end concerning bacterial substrate utilisation capacity measured by EcoPlate.All 31 substrates were metabolised in all treatments, i.e. functional diversity didnot differ among treatments but so did substrate utilisation rate. Soil pH and Nand C contents, as well as microbial C and N and total PFLA had similar patternamong treatments; the values increased with decreasing disturbance and increasedsoil organic matter content. A PCA analysis showed a significant difference betweennatural forest and the other land uses for chemical and microbial properties, whileagroforestry overlapped with both agriculture and forest plantation but wasdifferent from eroded land. These results indicate that the substrate utilisationcapacity of soil bacteria was similar in land with similar vegetation and thus thatthe functional capacity of the soil can be restored by active soil management, suchas agroforestry practices. The advantages and limitations of the methods used andmicrobial community composition are discussed. 97 98. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa74. La qualit de la chaux, le chaulage une ncessit pour lintensification agricole en sols acides des RGLACs. Lindiro Revelien1, Breman Henk1, Nzohabonayo Zacharie1 and Hatangimana Thomas1 1International Fertilizer Development Centre (IFDC), CATALIST project, BurundiAbstractLe projet CATALIST est excut au Rwanda, au Burundi et la RD Congo (Provincesde Kivu). Lapproche de la Gestion Intgr de la Fertilit des Sols (GIFS) quutiliseCATALIST pour dclencher lintensification agricole dans la RGLAC, fait entreautres attention aux sols acides. Le problme le plus srieux de ces sols acidesconcerne la toxicit aluminique, o la prsence des (hydr)oxydes dAl et de Fe faitque la structure physique du sol acide est bonne. La bonne gestion des sols acidesdans les tropiques, fait appel au chaulage, aux engrais non acidifiant et au respectdes principes et technologies de la GIFS pour un systme de production durable. Nostudes et nos expriences nous ont convaincu quil suffit de corriger le pH un niveaude 5.2. Des tests participatifs de contrle dacidit ont t conduits par CATALISTavec des organisations de dveloppement et de producteurs. Les rsultats montrentune augmentation des rendements de 5 12 % avec lutilisation saisonnire de CAN(Carbonate Ammonium Nitrate) au lieu dure dans des formules dengrais, parrapport aux mmes formules ayant ure comme composant. Laugmentation grceaux derniers engrais est de 15 23 % avec une dose unique de chaux pour unepriode de 3 4 ans. Ainsi, lefficacit agronomique (EA) et la Ration Valeur Cot(RVC) des engrais samliorent. Un problme srieux est le manque des normesstandard de la chaux et un manque de liaison entre prix et qualit. La correctiondune acidit donne visant ramener le pH du sol 5.2 demande des quantits trsdiffrentes de chaux en dpendance des sources, et le prix de chaulage peut devenirexorbitant. Les rsultats avec la meilleure chaux obtenue est bien suprieure auxvaleurs moyennes : une augmentation de 30% pour le rendement, 72% pour lEA et60% pour la RCV des engrais. 98 99. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of sub-Saharan Africa75. Evaluation of pre-screened sweet potato germplasm for biomass production under different cropping regimes and their potential as dual-purpose varieties in Kenya Lukuyu B.1, J. Kinyua2, S. Agili3, C.K. Gachuiri4 and J. Low3 1International Livestock Research Institute (ILRI), Nairobi, Kenya; 2School of Informa- tion Communication Technology, Central University of Technology, Free State, South Africa; 3International Potato Center (CIP), Nairobi, Kenya; 4University of Nairobi, Nairobi, KenyaAbstractSix cultivars of sweet potato were grown on farms in five sites located in central,south and north rift valley regions of Kenya under rain fed conditions. Two siteseach were located in the high and medium altitude areas while one was located inthe low altitude area. All sites have warm climates except one in the high altitude thatexperiences cold climate. The cultivars included 103001, Gweri, Kemb 23, Kemb 36,Naspot 1 and Wagabolige. The vines of each variety were harvested at two differentstages (75 and 150 days) post planting. The 75-day treatment was ratooned again at150 day post planting. Agronomical observations were carried during the long rainsseason 2010. Harvesting vines twice significantly (P