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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    Global efforts to foster sustainable soil management
    Kessler, C.A. - \ 2018
    WURcast
    soil management - soil fertility management
    On the role of soil organic matter for crop production in European arable farming
    Hijbeek, Renske - \ 2017
    Wageningen University. Promotor(en): M.K. van Ittersum, co-promotor(en): H.F.M. ten Berge. - Wageningen : Wageningen University - ISBN 9789463436632 - 211
    soil fertility - soil fertility management - soil management - soil conservation - organic matter - soil organic matter - nitrogen - nitrogen fertilizers - green manures - manures - straw - soil carbon sequestration - cover crops - crop yield - yields - meta-analysis - food security - europe - drivers - barriers - bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - bodembeheer - bodembescherming - organische stof - organisch bodemmateriaal - stikstof - stikstofmeststoffen - groenbemesters - mest - stro - koolstofvastlegging in de bodem - dekgewassen - gewasopbrengst - opbrengsten - meta-analyse - voedselzekerheid - europa - chauffeurs - barrières

    The aim of this thesis was to improve understanding of the role of organic inputs and soil organic matter (SOM) for crop production in contemporary arable farming in Europe. For this purpose, long-term experiments were analysed on the additional yield effect of organic inputs and savings in mineral fertiliser. In addition, a farm survey was conducted to find drivers and barriers for the use of organic inputs and to assess if arable farmers in Europe perceive a deficiency of SOM.

    The findings in this thesis suggest that at least on the shorter term, on average, there seems to be no immediate threat from a deficiency of SOM to crop production in arable farming in Europe. The long-term experiments showed that with sufficient use of only mineral fertilisers, on average, similar yields could be attained over multiple years as with the combined use of organic inputs and mineral fertiliser. This was reflected in the farm survey, in which a large majority of farmers indicated not to perceive a deficiency of SOM. Analysis of long-term experiments also showed that more mineral fertiliser N was saved when using farmyard manure at high N rates (with mineral fertiliser application) than at low N rates (without mineral fertiliser application), based on comparisons at equal yield.

    Specific crops and environments did benefit from organic inputs and more SOM in terms of crop production. Long-term experiments showed that organic inputs give benefit to crop production in wet climates and on sandy soils. In addition, farmers perceived a higher deficiency of SOM on steep slopes, sandy soils, wet and very dry climates. The additional yield effect of organic inputs was significant for potatoes. More in general, farmers who cultivated larger shares of their land with specialized crops (including potatoes, sugar beets, onions and other vegetables) than cereals perceived a higher deficiency of SOM. It seems that while the functions of SOM can be replaced with technical means to a large extent (e.g. tillage, use of mineral fertilisers), there are limits to this technical potential when environmental conditions are more extreme and crops are more demanding.

    The farm survey revealed that farmers perceive a trade-off between improved soil quality on the one hand and increased pressures from weeds, pests and diseases and financial consequences on the other hand when using organic inputs. If policies aim to stimulate the maintenance or increase of SOM, more insight is needed into the conditions that regulate the pressures of weeds, pests and diseases in response to organic inputs. Financial consequences (at least on the short term) should also be accounted for. More importantly however, benefits from SOM for crop production cannot be taken for granted. Only in specific situations such benefits will exist. If European policies on SOM aim to include benefits for crop production, focus should be on areas with more extreme environmental conditions (very dry or wet climates, steep slopes, sandy soils), or cropping systems with more specialized or horticultural crops rather than cereals.

    Effecten bodem- en structuurverbeteraars : Onderzoek op klei- en zandgrond 2010-2015 eindrapportage
    Balen, D.J.M. van; Topper, C.G. ; Geel, W.C.A. van; Berg, W. van den; Haas, M.J.G. de; Bussink, Wim ; Schoutsen, M.A. - \ 2016
    Lelystad : Praktijkonderzoek Plant & Omgeving, onderdeel van Wageningen UR, Business Unit Akkerbouw, Groene Ruimte en Vollegrondsgroenten - 121
    bodemkwaliteit - bodemstructuur - fysische bodemeigenschappen - chemische bodemeigenschappen - bodembiologie - bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - zware kleigronden - zandgronden - calciummeststoffen - biochar - soil quality - soil structure - soil physical properties - soil chemical properties - soil biology - soil fertility - soil fertility management - clay soils - sandy soils - calcium fertilizers - biochar
    In de praktijk lopen telers vaak tegen problemen aan van een slechte bodemkwaliteit. Intensieve bouwplannen, steeds zwaardere mechanisatie, uitloging (Ca-uitspoeling), piekneerslagen en de schaalvergroting in de landbouw leiden tot vermindering van de fysische bodemvruchtbaarheid en de structuur van de bodem. Dit veroorzaakt:  toenemende problemen bij de bewerkbaarheid van de bodem;  minder efficiënt gebruik van meststoffen;  verhoogd risico van uit- en afspoeling van nutriënten;  wateroverlast;  verlaging van de opbrengst. Om de bodemstructuur te verbeteren, worden door industrie en handel zogeheten bodemverbeteraars en kalkmeststoffen aangeboden. Er is een grote variatie in type producten, de wijze waarop ze werken en de mate waarin ze een directe dan wel indirecte invloed op de bodemvruchtbaarheid kunnen hebben. Objectieve informatie over het effect van deze producten op de gewasopbrengsten en de fysische, chemische en biologische bodemvruchtbaarheid ontbreekt. Uit eerdere proeven is bekend dat effecten van bodem verbeterende maatregelen vaak pas na enkele jaren zichtbaar worden. Om het effect van verschillende bodemverbeteraars op opbrengst en bodemeigenschappen op de langere termijn te toetsen, zijn proefvelden aangelegd op drie kleilocaties (Kollumerwaard, Lelystad en Westmaas) en twee zandlocaties (Vredepeel, Valthermond). Op deze proefvelden zijn bouwplannen toegepast die gangbaar zijn voor de betreffende regio. Eventuele positieve effecten worden sterker met het verstrijken der jaren. Bovendien zijn deze het duidelijkst te onderscheiden wanneer op alle locaties hetzelfde gewas wordt geteeld. Daarom stonden er in het laatste jaar op alle proefvelden aardappels. In de proef zijn de ontwikkeling van de gewasopbrengst, de gewaskwaliteit en de bodemeigenschappen gevolgd over een periode van zes jaar (2010-2015).
    Tradeoffs around crop residue biomass in smallholder crop-livestock systems - What's next?
    Tittonell, P.A. ; Gérard, B. ; Erenstein, O. - \ 2015
    Agricultural Systems 134 (2015). - ISSN 0308-521X - p. 119 - 128.
    sub-saharan africa - define conservation agriculture - soil fertility management - south-western niger - food-feed crops - ecological intensification - farming systems - impact assessment - appropriate use - 4th principle
    Much has been written on the tradeoffs that smallholder farmers face when having to allocate their biomass resources among competing objectives such as feed, fuel, mulch, compost or the market. This paper summarises yet a new body of evidence from 10 studies on tradeoffs in the allocation of cereal crop residue biomass between soil management and livestock feeding in developing regions, published in the special issue of Agricultural Systems ‘Biomass use tradeoffs in cereal cropping systems: Lessons and implications from the developing world’. The studies cover a diversity of socio-ecological contexts, farming system types and scales of analysis. We reflect on their main findings and methodological progress, and on the new and not-so-new implications of these findings for research and action in the development agenda. We propose stylised graphical models to portray tradeoffs and plausible trajectories towards synergies, in the hope that such generalisations would prevent further efforts to ‘reinvent the wheel’ in the realm of tradeoffs analysis. We advocate an ex-post impact assessment of recent investments in systems research to help focus such research further and clearly define its future role in prioritizing and targeting development interventions.
    Farm diversity, resource use efficiency and sustainable land management in the western highlands of Kenya
    Mutoko, M.C. ; Hein, L.G. ; Shisanya, C.A. - \ 2014
    Journal of Rural Studies 36 (2014). - ISSN 0743-0167 - p. 108 - 120.
    soil fertility management - sub-saharan africa - technical efficiency - rural poverty - degradation - conservation - agriculture - impact - growth - maize
    Sub-Saharan Africa (SSA) faces further population growth in the coming decades and it is essential to increase food production in rural areas. However, development programs to enhance agricultural productivity have achieved mixed results. This study investigates farm household responses to a changing agro-environment in one of the most densely populated rural districts in SSA and examines practical implications for the promotion of sustainable land management (SLM) practices. The specific objective is to analyze farm diversity and resource use efficiency and their implications for promoting SLM in the highlands of Western Kenya. We carried out an elaborate survey of 236 households, and applied multivariate analysis to analyze farm efficiency and livelihood strategies. We found major differences in responses to a changing agro-environment between five farm types in terms of resource endowment, income strategies and farm practices. Across farm types, efficiency was low indicating poor land productivity. Our study shows that there has been a lack of intensification in land use and that households are increasingly depending on off-farm income. Our findings have a number of implications to programs aiming to promote sustainable land management in SSA. We propose that successful implementation of such programs requires targeting areas highly reliant on agriculture and within these areas focus on households mostly dependent on farming to sustain their welfare. (C) 2014 Elsevier Ltd. All rights reserved.
    Fostering technological transition to sustainable land management through stakeholder collaboration in the western highlands of Kenya
    Mutoko, M.C. ; Shisanya, C.A. ; Hein, L.G. - \ 2014
    Land Use Policy 41 (2014). - ISSN 0264-8377 - p. 110 - 120.
    natural-resource management - agricultural input subsidy - soil fertility management - productivity - perceptions - experiences - knowledge
    Application of sustainable land management (SLM) practices is essential to lessen the negative impacts of land degradation on rural welfare in sub-Saharan Africa. Scaling-up of SLM technologies requires collaboration of diverse stakeholders across multiple scales. We follow inter-disciplinary approaches to evaluate prospects for wider promotion of SLM practices in the western highlands of Kenya. Findings from this study reveal that only 10 per cent of farmers are properly implementing the available SLM practices. Agricultural productivity is low and there is high dependence on benefits extracted from the forest resource. A positive correlation (rho = 0.8) was found between stakeholder co-operation and success level of SLM projects. Results clearly show reasonable prospects such as some technology adoption activities and organisation of local actors that are necessary for triggering the transformation process to sustainable state of productivity. Nevertheless, technological transition could likely succeed if facilitated by enhanced stakeholder collaboration, a supportive policy environment and substantial resource mobilisation. We suggest the application of a context-specific transition management approach in this area in order to learn lessons on governance of transformative environmental programmes for similar socio-ecological systems in SSA. (C) 2014 Elsevier Ltd. All rights reserved.
    Benefits of legume–maize rotations: Assessing the impact of diversity on the productivity of smallholders in Western Kenya
    Ojiem, J.O. ; Franke, A.C. ; Vanlauwe, B. ; Ridder, N. de; Giller, K.E. - \ 2014
    Field Crops Research 168 (2014). - ISSN 0378-4290 - p. 75 - 85.
    soil fertility management - crop-livestock systems - on-farm productivity - soybean glycine-max - cattle manure - sustainable intensification - exploring diversity - semiarid kenya - degraded soils - nitrogen
    Agricultural intensification of farming systems in sub-Saharan Africa is a prerequisite to alleviate rural poverty and improve livelihoods. Legumes have shown great potential to enhance system productivity. On-farm experiments were conducted in different agro-ecological zones (AEZ) in Western Kenya to assess the agronomic and economic benefits of promising legumes. In each zone, trials were established in fields of high, medium and low fertility to assess the effect of soil fertility heterogeneity on legume productivity and subsequent maize yield. Common bean, soybean, groundnut, lima bean, lablab, velvet bean, crotalaria, and jackbean were grown in the short rains season, followed by maize in the long rains season. Alongside, continuous maize treatments fertilised at different rates were established. AEZs and soil fertility gradients within these zones greatly affected crop productivity, returns to land and labour of rotations, as well as the relative performance of rotations. Poorer soil fertility and AEZs with lower rainfall gave smaller legume and maize yields and consequently, smaller returns to land and labour. The cultivation of legumes increased maize yields in the subsequent long rains season compared with continuous maize receiving fertiliser at a similar rate, while the increase of maize after green manure legumes was stronger than that after grain legumes. Maize yield responded strongly to increasing amounts of N applied as legume residues with diminishing returns to legume-N application rates above 100 kg N ha-1. In the low potential zones, factors other than improved N availability likely also stimulated maize yield. Rotations with grain legumes generally provided better returns than those with green manures. Intercropping bean with maize in the long rains season provided an additional bean yield that did not come at the expense of maize yield and improved returns to land and labour, but more so in the high potential zones. The results demonstrate the strong impact of biophysical diversity on the productivity of the legumes and suggest the need for careful targeting of legume technologies to the different biophysical conditions.
    Integrated analysis of land use changes and their impacts on agrarian livelihoods in the western highlands of Kenya
    Mutoko, M.C. ; Hein, L.G. ; Bartholomeus, H. - \ 2014
    Agricultural Systems 128 (2014). - ISSN 0308-521X - p. 1 - 12.
    soil fertility management - proximate causes - cover - deforestation - africa - sustainability - expansion - dynamics - district - growth
    Land degradation is affecting rural livelihoods across sub-Saharan Africa. Promoting sustainable land management requires a thorough understanding of land use change drivers, processes and effects. However, in most African countries reliable data for such investigations are missing. We therefore test an integrated approach to analyse land use dynamics, combining remote sensing images, an in-depth quantitative survey, stakeholder interviews and local statistics. We analyse land dynamics and agricultural production over a 25-year period in Vihiga District, Western Kenya. Specifically, we examine how land use has changed in this period, the main drivers for land use change, and the main effects of these changes on agricultural production. Vihiga District is one of the most densely populated rural areas in Africa. We find that the district has undergone rapid land use change in the past 25 years. In particular, there has been a major conversion of forest and bare land to agricultural land use. Often, it is stated that increasing population pressure triggers agricultural intensification; however, we find little evidence of such a process in Vihiga District. Productivity of tea and, to a lesser extent, vegetables increased but the yields of maize and beans, the most common crops, fluctuated around a ton per hectare. Overall, per capita food crop production dropped by 28% during the past two decades. Our study shows that high and increasing population pressures do not necessarily lead to agricultural intensification, and that there is a need to consider more explicitly off-farm income in development and land management policies and projects.
    Deconstructing and unpacking scientific controversies in intensification and sustainability: why the tensions in concepts and values?
    Struik, P.C. ; Kuyper, T.W. ; Brussaard, L. ; Leeuwis, C. - \ 2014
    Current Opinion in Environmental Sustainability 8 (2014). - ISSN 1877-3435 - p. 80 - 88.
    soil fertility management - resource use efficiency - food security - agricultural sustainability - ecological intensification - sugar-beet - innovation - quality - systems - conservation
    Assuming ‘ceteris paribus’ in terms of the viability of the planet during the coming half-century or so, the rising needs of a burgeoning, but also increasingly rich and demanding world population will drastically change agriculture. Crop yields and animal productivity will have to increase substantially, with the risk of further depleting the resource base and degrading the environment, making food production both the culprit and the victim. Future food security therefore depends on development of technologies that increase the efficiency of resource use and prevent externalization of costs. The current trend is towards intensification, especially more output per production unit so as to increase input efficiency. Whether that trend is sustainable is a matter of strong debate among scientists and policy-makers alike. The big question is how to produce more food with much fewer resources. Sustainable intensification (i.e., increasing agricultural output while keeping the ecological footprint as small as possible) for some is an oxymoron, unless real progress can be made in ecological intensification, that is, increasing agricultural output by capitalizing on ecological processes in agro-ecosystems. Definitions of intensification and sustainability vary greatly. The way these concepts are being used in different disciplines causes tensions and hides trade-offs instead of making them explicit. Inter-disciplinarity and boundary-crossing in terminology and concepts are needed. Implicitly, the operationalization of intensification and sustainability implies appreciation of and choices for values, an issue that is often overlooked and sometimes even denied in the natural sciences. The multidimensional nature of intensification needs to be linked to the various notions of sustainability, acknowledging a hierarchy of considerations underlying decision-making on trade-offs, thus allowing political and moral arguments to play a proper role in the strategy towards sustainable intensification. We make a plea to create clarity in assumptions, norms and values in that decision-making process. Acknowledging that win-win situations are rare and that (some) choices have to be made on non-scientific grounds makes the debate more transparent and its outcome more acceptable both to the scientific community and society at large.
    Bemestingsplan verdient meer aandacht
    Verloop, J. ; Abbink, G. ; Haan, M.H.A. de - \ 2014
    V-focus 11 (2014)4. - ISSN 1574-1575 - p. 32 - 33.
    melkveehouderij - mestbehoeftebepaling - graslandbeheer - zea mays - bodemvruchtbaarheidsbeheer - dairy farming - fertilizer requirement determination - grassland management - zea mays - soil fertility management
    Resultaten van de KringloopWijzer laten grote verschillen zien in stikstof- en fosfaatopbrengsten, die op verschillende bedrijven worden bereikt in maïs- en grasland. Deels wordt dat veroorzaakt door de manier waarop de bemesting wordt uitgevoerd. Met perceelsgericht bemesten kan de potentie van het land meer worden benut.
    The 'One cow per poor family' programme: Current and potential fodder availability within smallholder farming systems in southwest Rwanda
    Klapwijk, C.J. ; Bucagu, C. ; Wijk, M.T. van; Udo, H.M.J. ; Vanlauwe, B. ; Munyanziza, E. ; Giller, K.E. - \ 2014
    Agricultural Systems 131 (2014). - ISSN 0308-521X - p. 11 - 22.
    soil fertility management - exploring diversity - resource-allocation - central highlands - western kenya - napier grass - agroforestry - productivity - variability - growth
    Livestock is an essential component of smallholder farming systems in the East African highlands. The ‘One cow per poor family’ programme was initiated in Rwanda as part of a poverty alleviation strategy, aiming to increase the livestock population. A four month-study was conducted in Umurera village (Simbi sector), southern Rwanda with the objectives to (1) quantify the on-farm fodder availability, (2) quantify the amount and quality of fodder on offer to livestock, (3) analyse potential fodder availability under five future scenarios and (4) evaluate the implications and feasibility of the programme. Farmers’ surveys, measurements of field sizes, together with daily measurements of fodder on offer, milk production and fodder refusals were conducted. Feeds used were diverse, comprising grasses (53%), banana plant parts (25%), residues of several crops (9%) and other plants (10%). Herbs collected from valley-bottoms, uncultivated grasses and crop residues were predominant fodder types on poorer (Resource group 1 – RG1) farms while Pennisetum and Calliandra were predominant fodder types for moderate (RG2) and better resource endowed (RG3) farms. The amount of fodder on offer for cattle ranged from 20 to 179 kg fresh weight animal-1 day-1 (9–47 kg DM). The milk yield ranged between 1.3 and 4.6 L day-1. The amount of Pennisetum and Calliandra fodder available decreased in the dry season with a concomitant increase in reliance on banana leaves and pseudo-stems. The poorest farmers (RG1) were not able to feed a local cow under all scenarios. RG2 farmers can sustain a local cow during both seasons when using all possible fodder resources, but can sustain a European cow under just two scenarios during the rainy season. RG3 farmers can feed a European cow during the rainy season under all scenarios and for four scenarios during the dry season. We conclude that the ‘One cow per poor family’ programme needs to be adjusted to increase its effectiveness. Our main recommendations are to shift to livestock that require less fodder, for example local cattle or small ruminants such as goats.
    Livelihood strategies, resilience and transformability in African agroecosystems
    Tittonell, P.A. - \ 2014
    Agricultural Systems 126 (2014). - ISSN 0308-521X - p. 3 - 14.
    soil fertility management - social-ecological systems - western kenya - exploring diversity - makanya catchment - smallholder farms - poverty traps - heterogeneity - agriculture - tanzania
    Aiming to translate resilience thinking theory into farming systems design practice, this paper examines fundamental properties of complex systems dynamics and their relation with the mechanisms that govern resilience and transformability in African smallholder agriculture. Agroecosystems dynamics emerge from the aggregation of diverse livelihood strategies in response to changes in the agroecosystem context, and are characterised by non-linearity, irreversibility, convergence/divergence and hysteresis. I examine a number of case studies from Africa to verify three guiding hypotheses in connection to the diversity of rural livelihood strategies: (1) diversity as alternative system regimes; (2) diversity as the result of transformability; (3) diversity determined by changing agricultural contexts. The hierarchy of constraints that determine the space for manoeuvring in agroecosystems is described through the analogy of the Matryoshka nesting dolls: each system level confines and is confined by their immediate sub- and supra-systems. Agricultural contexts, as defined by agro-ecological potential, demography and market connectivity are also dynamic and their trajectory can be described as shifts across stability domains. An example from Kenya shows that household diversity can be described as alternative system regimes, through hysteretic rather than continuous, reversible models. In some particular cases diversity emerges from divergent pathways that may have implied radical transformations in the past, as shown here for rural livelihoods in northern Cameroun. A comparative analysis of East African agroecosystems shows that thresholds in specific variables that may point to the existence of possible tipping points are rather elusive and largely site specific, requiring systematic categorisation of agricultural contexts. While agroecology needs to provide the knowledge base for the ecological intensification of smallholder landscapes, policy and market developments are needed to deal with the Matryoshka effect – or with interactions that are presumably panarchical in certain cases. Desirable shifts in farming systems can only be stimulated by working on both ends simultaneously.
    Regenwormen op het melkveebedrijf : handreiking voor herkennen, benutten en managen
    Eekeren, N.J.M. van; Bokhorst, J. ; Deru, J. ; Wit, J. de - \ 2014
    Driebergen : Louis Bolk Instituut (Rapport / Louis Bolk Instituut 2014-004 LbD) - 37 p.
    aardwormen - bodemkwaliteit - bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - melkveehouderij - bodembiologie - graslanden - bouwland - graslandbeheer - earthworms - soil quality - soil fertility - soil fertility management - dairy farming - soil biology - grasslands - arable land - grassland management
    In deze brochure worden handreikingen gegeven voor de praktijk, waarbij zowel strooiselbewonende, bodembewonende en pendelende regenwormen aan bod komen.
    BioESoil
    Elferink, E. ; Alterra - Centrum Landschap, - \ 2014
    CLM
    bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - bodemkwaliteit - bio-energie - voedingsstoffen - mineralenboekhouding - biobased economy - soil fertility - soil fertility management - soil quality - bioenergy - nutrients - nutrient accounting system - biobased economy
    In opdracht van Rijksdienst voor Ondernemend Nederland hebben Alterra en CLM de meetlat BioESoil ontwikkeld. BioESoil geeft inzicht in: verliezen van nutriënten tijdens de productie van bioenergie, de potentiele terugvoer van nutriënten middels residuen en het effect op de bodem organische stof. De meetlat is zo ontworpen dat deze gebruiksvriendelijk is van opzet. BioESoil is wereldwijd toepasbaar en geschikt voor grootschalige en kleinschalige bio-energie producenten en gebruikers.
    Agriculture and nature: Trouble and strife?
    Baudron, F. ; Giller, K.E. - \ 2014
    Biological Conservation 170 (2014). - ISSN 0006-3207 - p. 232 - 245.
    soil fertility management - agri-environment schemes - land-use change - biodiversity conservation - habitat fragmentation - food-production - tropical conservation - farmland biodiversity - protect biodiversity - organic agriculture
    Global demand for agricultural products is expected to double in the next decades, putting tremendous pressure on agriculture to produce more. The bulk of this increase will come from developing countries, which host most biodiversity-rich areas of the planet. Whilst most biodiversity is found in production landscapes shared with people, where agriculture represents an increasing threat, international conservation organisations continue to focus on the maintenance and expansion of the network of protected areas. When conservation organisations partner with agricultural programmes, they promote low input, extensive agriculture. Combined with the focus on protected areas, this may exacerbate rather than mitigate conflicts between biodiversity conservation and agricultural production. Two models have been proposed to increase agricultural production whilst minimising the negative consequences for biodiversity: ‘land sparing’ and ‘land sharing’. Although often polarized in debates, both are realistic solutions, depending on the local circumstances. We propose a number of criteria that could guide the choice towards one or the other. We conclude that general principles to be considered in both land sparing and land sharing are: managing spillover effects, maintaining resilience and ecosystem services, accounting for landscape structure, reducing losses and wastes, improving access to agricultural products in developing countries and changing consumption patterns in developed countries, and developing supportive markets and policies.
    Whole-farm nitrogen cycling and intensification of crop-livestock systems in the highlands of Madagascar: An application of network analysis
    Alvarez, S. ; Rufino, M.C. ; Vayssières, J. ; Salgado, P. ; Tittonell, P.A. ; Tillard, E. ; Bocquier, F. - \ 2014
    Agricultural Systems 126 (2014). - ISSN 0308-521X - p. 25 - 37.
    soil fertility management - nutrient balances - exploring diversity - efficiencies - resource - manure - flows - kenya - conservation - agriculture
    Food insecurity, soil fertility depletion and strong competition for biomass are commonly observed in smallholder crop-livestock systems. The objective of this study was to explore options to improve farm-level nitrogen cycling, productivity and economic performance through the analysis of N flows within four contrasting crop-livestock farm systems of Madagascar highlands. Farms were conceptualized as networks where the compartments were the household and their farming activities, all connected by N flows. Indicators assessing network size and cycling, and the organization and diversity of the N flows, were compared with system productivity, food self-sufficiency, and gross margins for the current situation and under four scenarios of intensification (i) dairy production increased by increasing N inputs as supplementary feed; (ii) crop production increased by increasing N inputs as mineral fertilizer; (iii) manure management improved to increase N conservation during storage and application to soils; (iv) a combination of the two most economically attractive scenarios (i and iii). The four case study farms represent local diversity differing widely in terms of network size, with total annual system N throughput ranging from 113 to 1037kgN per capita, and in terms of N cycling, from 3 to 41kgN per capita per year. They differed less in terms of external dependence, from 0.26 to 0.41kgN kgN-1. Improving N conservation through improved manure management (scenario iii) had a positive impact on gross margin, and this in combination with increased concentrate supply (scenario iv) led to increases in whole-farm N use efficiencies from 2% to 50%, in N cycling from 9% to 68% and in food self-sufficiency from 12% to 37% across farm types. Gross margin was the most sensitive indicator to changes in management. Intensification through scenario iv had the highest impact on farm productivity, gross margin, food self-sufficiency, and environment sustainability (N use efficiency, capacity of the soil to stock N)
    Farmers' Perceptions of Land Degradation and their Investments in Land Management: a Case Study in the Cental Rift Valley of Ethiopia
    Adimassu, Zenebe ; Kessler, A. ; Yirga, C. - \ 2013
    Environmental Management 51 (2013)5. - ISSN 0364-152X - p. 989 - 998.
    soil fertility management - conservation practices - nutrient balances - tenure security - south wello - highlands - adoption - smallholders - erosion - area
    To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers’ perceptions of land degradation and their investments in land management, and to what extent the latter are influenced by these perceptions. Water erosion and fertility depletion are taken as main indicators of land degradation, and the results show that farmers perceive an increase in both indicators over the last decade. They are aware of it and consider it as a problem. Nevertheless, farmers’ investments to control water erosion and soil fertility depletion are very limited in the CRV. Results also show that farmers’ awareness of both water erosion and soil fertility decline as a problem is not significantly associated with their investments in land management. Hence, even farmers who perceive land degradation on their fields and are concerned about its increase over the last decade do not significantly invest more in water erosion and soil fertility control measures than farmers who do not perceive these phenomena. Further research is needed to assess which other factors might influence farmers’ investments in land management, especially factors related to socioeconomic characteristics of farm households and plot characteristics which were not addressed by this study.
    Maismoeheid bestrijden met vruchtwisseling
    Groten, Jos - \ 2013
    zea mays - dairy farming - arable farming - soil fertility management - soil fertility - cropping systems - rotations - soil quality - green manures
    Can we define the term 'farming systems'? A question of scale : Guest Editorial
    Giller, K.E. - \ 2013
    Outlook on Agriculture 42 (2013)3. - ISSN 0030-7270 - p. 149 - 153.
    soil fertility management - smallholder farms - exploring diversity - resource-allocation - western kenya - land-use - variability - methodology - space
    Participatory trials and farmers' social realities: understanding the adoption of legume technologies in a Malawian farmer community
    Pircher, T. ; Almekinders, C.J.M. ; Kamanga, B.C.G. - \ 2013
    International Journal of Agricultural Sustainability 11 (2013)3. - ISSN 1473-5903 - p. 252 - 263.
    soil fertility management - africa - poverty - improvement - lessons - crop
    This article presents results from a study exploring the reasons for low adoption of legume technologies to improve soil fertility by farmers from a community in central Malawi who took part in participatory trials. This study explores the influence of gender roles in agriculture and land ownership and socio-economic differentiation in the community. Because most women do not own land and are traditionally responsible for legume crops, they have little interest in managing soil fertility for maize crops. Men are not interested in using legumes in maize-cropping systems. Some are too poor: this group needs to complement their subsistence maize production with paid labour on the farms of better-off farmers; restricting the labour availability for their own farming activities. Wealthier farmers have access to, and prefer to use chemical fertilizer and cattle manure. Take-up rates among the middle group of farmers were also low. This study discusses how these (and other) factors influence the (non-)adoption of maize-legume technologies in Malawi and the effectiveness of participatory research. It emphasizes how differentiated farmer-realities affect the uptake of technologies identified as promising in participatory field evaluations.
    When yield gaps are poverty traps: The paradigm of ecological intensification in African smallholder agriculture
    Tittonell, P.A. ; Giller, K.E. - \ 2013
    Field Crops Research 143 (2013). - ISSN 0378-4290 - p. 76 - 90.
    soil fertility management - nutrient use efficiencies - resource use efficiency - western kenya - conservation agriculture - exploring diversity - semiarid tropics - different scales - farming systems - field-scale
    Yield gaps are pervasive in African smallholder agriculture, and are large for almost all crops in all regions. There is consensus that poor soil fertility and nutrient availability are the major biophysical limitations to agricultural production in the continent. We identify two major yield gaps: (1) the gap between actual yields (YA) and the water-limited yield potential (Yw), which is the maximum yield achievable under rainfed conditions without irrigation if soil water capture and storage is optimal and nutrient constraints are released, and (2) The gap between YA, and a locally attainable yield (YL) which corresponds to the water and nutrient-limited yields that can be measured in the most productive fields of resource endowed farmers in a community. Estimates of these two yield gaps are given for major crops, together with a framework for how yield gaps can be estimated in a pragmatic way for different farming systems. The paradigm of ecological intensification which focuses on yield potential, soil quality and precision agriculture is explored for the African context. Our analysis suggests that smallholder farmers are unable to benefit from the current yield gains offered by plant genetic improvement. In particular, continued cropping without sufficient inputs of nutrients and organic matter leads to localised but extensive soil degradation and renders many soils in a non-responsive state. The lack of immediate response to increased inputs of fertiliser and labour in such soils constitutes a chronic poverty trap for many smallholder farmers in Africa. This necessitates a rethink for development policy aimed to improve productivity and address problems of food insecurity.
    Conservation Agriculture in mixed crop–livestock systems: Scoping crop residue trade-offs in Sub-Saharan Africa and South Asia
    Valbuena, D.F. ; Erenstein, O. ; Homann-Kee Tui, S. ; Abdoulaye, T. ; Claessens, L.F.G. ; Duncan, A.J. ; Gerard, B. ; Rufino, M. ; Teufel, N. ; Wijk, M.T. van - \ 2012
    Field Crops Research 132 (2012). - ISSN 0378-4290 - p. 175 - 184.
    smallholder farming systems - soil fertility management - pressure - food - productivity - strategies - community - dynamics - patterns - zimbabwe
    Conservation Agriculture (CA) is being advocated to enhance soil health and sustain long term crop productivity in the developing world. One of CA's key principles is the maintenance of soil cover often by retaining a proportion of crop residues on the field as mulch. Yet smallholder crop–livestock systems across Africa and Asia face trade-offs among various options for crop residue use. Knowledge of the potential trade-offs of leaving more residues as mulch is only partial and the objective of this research is to address some of these knowledge gaps by assessing the trade-offs in contrasting settings with mixed crop–livestock systems. The paper draws from village surveys in 12 sites in 9 different countries across Sub-Sahara Africa and South Asia. Sites were clustered into 3 groups along the combined population and livestock density gradients to assess current crop residue management practices and explore potential challenges to adopting mulching practices in different circumstances. Results show that although high-density sites face higher potential pressure on resources on an area basis, biomass production tends to be more substantial in these sites covering demands for livestock feed and allowing part of the residues to be used as mulch. In medium-density sites, although population and livestock densities are relatively lower, biomass is scarce and pressure on land and feed are high, increasing the pressure on crop residues and their opportunity cost as mulch. In low-density areas, population and livestock densities are relatively low and communal feed and fuel resources exist, resulting in lower potential pressure on residues on an area basis. Yet, biomass production is low and farmers largely rely on crop residues to feed livestock during the long dry season, implying substantial opportunity costs to their use as mulch. Despite its potential benefit for smallholder farmers across the density gradient, the introduction of CA-based mulching practices appears potentially easier in sites where biomass production is high enough to fulfil existing demands for feed and fuel. In sites with relatively high feed and fuel pressure, the eventual introduction of CA needs complementary research and development efforts to increase biomass production and/or develop alternative sources to alleviate the opportunity costs of leaving some crop residues as mulch.
    The political ecology of land management in the oil palm based cropping system on the Adja Plateau in Benin. NJAS - Wageningen
    Yemadje, H.R.M. ; Crane, T.A. ; Vissoh, V.P. ; Mongbo, R.L. ; Richards, P. ; Kossou, D.K. ; Kuyper, T.W. - \ 2012
    NJAS Wageningen Journal of Life Sciences 60-63 (2012). - ISSN 1573-5214 - p. 91 - 99.
    soil fertility management - tenure - ghana - farmers - gender - wenchi
    The Adja plateau (Benin) is densely populated by tenant and landowner farmers engaged in oil palm based cropping. Landowners use oil palm sap for the production of sodabi (a local spirit), and an oil palm fallow (if no crops are grown beneath the palms) to restore soil fertility. In this area, growing oil palm for its oil is uncommon. Tenants access the land under specific contracts but are not allowed to plant oil palm. They grow food crops beneath the oil palm and extend the cropping period by severely pruning the palms because their right to grow food crops terminates when the palms reach a height of 2 m. The competing claims between landowners and tenants and between oil palm and annual food crops result in conflicts over practices that either degrade or restore soil fertility. Using a political ecology perspective, we examined how two overlapping institutions shape access to and management of the land: the customary tenure system and the legal system that was introduced to regulate titling and contracting. These institutions have divergent implications for tenants and landowners, in terms of both social equity and land management practices. The implications of this institutional patchwork (bricolage) for joint learning to achieve sustainable agriculture are discussed.
    Liever zorgen vóór dan óver organische stof : beheer van organische stof op het melkveebedrijf
    Verloop, J. ; Oenema, J. - \ 2012
    V-focus 9 (2012)5. - ISSN 1574-1575 - p. 34 - 36.
    melkveehouderij - melkveebedrijven - bodemvruchtbaarheidsbeheer - organische stof - dierlijke meststoffen - dairy farming - dairy farms - soil fertility management - organic matter - animal manures
    Sinds 2006 gelden gebruiksnormen voor stikstof en fosfaat, die grenzen stellen aan de aanwending van organische mest op de bodem. Deze regels hebben indirect gevolgen voor de aanvoer van organische stof met dierlijke mest naar de bodem. Dit leidt soms tot zorg over de bodemvruchtbaarheid op lange termijn. Blijft het organische stofgehalte in de bodem wel op een goed niveau? Koeien & Kansen-deelnemers lopen voor op de bestaande regelgeving om problemen in een vroeg stadium te onderkennen. In dit artikel schetsen we de ontwikkelingen en gaan we in op het beheer, in het bijzonder voor bedrijven op droge zandgrond.
    30 vragen en antwoorden over bodemvruchtbaarheid
    Schils, R.L.M. - \ 2012
    Wageningen : Alterra, Wageningen-UR - 143
    bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - organische stof - bodembiologie - bemesting - voedingsstoffen - overheidsbeleid - mestbeleid - voedselproductie - biomassa productie - akkerbouw - melkveehouderij - biobased economy - biologische landbouw - grondbewerking - soil fertility - soil fertility management - organic matter - soil biology - fertilizer application - nutrients - government policy - manure policy - food production - biomass production - arable farming - dairy farming - biobased economy - organic farming - tillage
    Bodemvruchtbaarheid staat steeds nadrukkelijker op de agenda van politiek, overheid, bedrijfsleven en maatschappelijke organisaties. Deze publicatie is vooral geschreven voor medewerkers van deze organisaties, van rijksoverheid tot waterschap, en van productschap tot mestverwerker. Uiteindelijk draait het om de boeren die het land bewerken. Ook zij vinden in deze publicatie achtergronden over alle belangrijke aspecten van bodemvruchtbaarheid. De dertig vragen en antwoorden zijn grofweg in drie groepen ingedeeld. Eerst komen de klassiekers aan bod waarin de basiskennis wordt uitgelegd. De volgende groep vragen behandelt de actuele thema's zoals mestbeleid, energieproductie en klimaatverandering. Tot slot komen in de laatste vragen de kennisagenda en nieuwe ontwikkelingen aan bod.
    Poor people and poor fields? : integrating legumes for smallholder soil fertility management in Chisepo, central Malawi
    Kamanga, B. - \ 2011
    Wageningen University. Promotor(en): Ken Giller, co-promotor(en): Conny Almekinders; S.R. Waddington. - [s.l.] : S.n. - ISBN 9789461730046 - 168
    gewassen - bodemvruchtbaarheidsbeheer - maïs - peulgewassen - kunstmeststoffen - zelfvoorzieningslandbouw - kleine landbouwbedrijven - voedselzekerheid - landbouwhuishoudens - malawi - armoede - crops - soil fertility management - maize - legumes - fertilizers - subsistence farming - small farms - food security - agricultural households - malawi - poverty

    Soil infertility undermines the agriculture-based livelihoods in Malawi, where it is blamed for poor crop yields and the creation of cycles of poverty. Although technologies and management strategies have been developed to reverse the decline in soil fertility, they are under-used by smallholder farmers. This study was conducted to assess with farmers the performance of a range of maize-legume technologies and their benefits on soil fertility management in central Malawi. Farmer participatory experimentation was a focus of the study. The aim was to facilitate learning and the interpretation of experiences, improve the communication of information about the concepts and technologies to farmers, and provide insights for researchers.

    Using a combination of survey and participatory methods, 136 smallholder farmers from Chisepo were grouped into four resource groups, comprising of better-resourced (RG 1 with 6 farmers), medium resourced (RG 2, 14 farmers), less well-resourced (RG 3, 64 farmers) and least-resourced groups (RG 4, 52 farmers). Analysing their livelihoods for their effects on soil fertility revealed that soil fertility management is a complex activity which is influenced by ownership of assets. Farmers from RG 1 and RG 2 owned more resources including cattle, had larger fields, hired-in labour for timely farm operations, earned more income and invested far more in soil fertility improvement. Farmers from RG 3 and 4 (who are in the large majority) were resource constrained and did not invest adequately in improving soil fertility. They had large food deficits due to poor crop yields. Ganyu labour (casual work done for other farmers for food or cash) was their main strategy to reduce food deficits. Farmers from all the four RGs were interested in working with research to explore strategies to improve soil fertility. They tested various grain- and green-manure-legumes, and mineral N and P fertiliser on maize and the legumes for effects on crop productivity and soil fertility. Associated production risk and interest in technology adoption were assessed.

    On-farm evaluation was done on maize (cv. MH18) in rotation with pigeonpea cv. ICP 9145,intercropped with groundnut (cv. CG 7), (Mz/Pp+Gn); intercropped with tephrosia (Mz+Tv); intercropped with pigeonpea (Mz+Pp) and in rotation with mucuna (Mz/Mp). These technologies were compared with sole crop maize without fertiliser (Mz−Ft) or with 35 kg N ha-1(Mz+Ft) in experiments with 32 farmers from the four RGs over four years. Economic and risk assessments were made. Maize grain yields (accumulated over the four years) were greater for farmers from RG 1 and 2 than RGs 3 and 4. Mz+Pp and Mz+Tv gave greater cumulative yields than Mz/Pp+Gn and Mz/Mp. The legumes improved maize grain yields by between 0.2 and 4 t ha-1(P < 0.001) over Mz-Ft and additionally they gave legume grain to the household.Mz+Pp was less risky to all RGs, and applying 35 kg N ha-1to the legumes resulted in Mz+Tv, Mz/Pp+Gn and Mz/Mp being least risky to RG 1, RG2 and RG 3. Farmers in RG 1 had the highest returns to labour (USconv2.info.8 day-1with Mz-Ft and US.1 day-1with Mz+Pp) and these increased to 1.9 and 1.7 respectively with 35 kg N ha-1. Mz+Pp intercrop gave consistent positive returns across the RGs and was the only technology to provide positive returns to labour in RG 4. Use of pigeonpea was overall the least risky option, and was especially suited to least-resourced farmers.

    Application of phosphorus fertiliser (0, 20 kg P ha-1) to legumes significantly (P = 0.05) increased grain and biomass yields for mucuna, groundnut, soyabean, Bambara groundnut and cowpea by 1.0, 0.8, 0.5, 1.0 and 0.3 t ha-1compared with unfertilised plots. Cowpea and fertilised groundnut had larger yields in the home fields than middle fields, but other legumes performed better (P = 0.05) in the middle fields.

    Maize responses to small amounts of fertiliser (0, 15, and 30 kg N ha-1and 0, 20 kg P ha-1) in two weeding regimes showed that weeding twice significantly (P < 0.001) raised maize yields by 0.4 t ha-1over weeding once (0.9 t ha-1). Stover yields (significant at P < 0.001) were 2.3 and 1.6 t ha-1respectively. Mean grain N kg ha-1was 17.1 and 9.8 for plots weeded twice and once respectively while that of stover were 10.1 and 5.6 kg N ha-1. Applying N at 15 kg N ha-1increased maize yields, but the 30 kg N ha-1increased yield only on more clay soils due to the effects of mid-season dry spells on sandy soils. Except for the physiological efficiency of N (PEN), all agronomic indices of N use showed significant differences due to weeding (agronomic efficiency of applied fertiliser N (AEN) at P < 0.001, recovery efficiency of applied N (REN) and partial factor productivity for N (PFPN) at P < 0.01). The average PENof 40.7and PFPNof 78.8 in plots weeded twice were within the ranges of 40–60 kg grain kg-1N and 40–80 kg grain kg-1N applied respectively. AENand REN values of 38.7 and 0.9 respectively were above the common range of 10-30 kg grain kg-1 N applied and 0.3-0.5 or 0.5–0.8 kg N kg-1. Mean indices from plots weeded just once were all within the ranges stated above but lower than indices from plots weeded twice; suggesting the unsustainability of the use of fertiliser without means to raise its efficiency through better management or combination with organic resources. Weeding twice gave higher returns to labour (USconv2.info.30 day-1) than weeding once (USconv2.info.05 day-1) and gross margins of US5.00 and US.00 with labour taken into account respectively.Farmers need to ensure timely weeding to get decent efficiencies and returns from the fertiliser, especially in drier cropping seasons.

    Using surveys, focus group discussions and the analytical hierarchy process (AHP), adoption of the ten legumes introduced to farmers in Chisepo was assessed among 136 farmers in 2004 and 84 farmers in 2007. Thirty-five percent of the farmers in 2004 and 22% in 2007 had adopted at least one of the legumes, with food grain legumes predominantly soyabean, groundnut, pigeonpea and to a lesser extent Bambara groundnut and cowpea being most adopted. Mucuna and tephrosia were adopted by few farmers while sunnhemp and grahamiana were not adopted at all. Farmers from RGs 1 and 2 adopted more of the legumes than those from RG 3 and 4. Lack of consistent markets, a lack of seed for planting, as well as land and labour shortages were cited for weak adoption.

    Soil fertility management by smallholder farmers is influenced by ownership of assets and the majority poorer farmers fail to invest adequately in improving soil fertility. In the absence of such resources, grain legumes will play an important role as a source of both food and organic matter to improve soil fertility. The participatory methods used in the study helped farmers better understand some of the soil fertility concepts and options, including the legumes. There is need to focus on how to assist farmers with practical knowledge to help them best combine organic and mineral fertiliser resources for improving soil fertility, and to develop and promote new dual-purpose legume options that feed humans and the soil.

    Key words: Adoption, analytical hierarchy process, crop yield, financial returns, food security, household assets, legume integration, livelihoods, NP fertiliser, nitrogen use efficiency, production risk, resource groups, smallholder, soil fertility, weeding.

    Competing use of organic resources, village-level interactions between farm types and climate variability in a communal area of NE Zimbabwe
    Rufino, M.C. ; Dury, J. ; Tittonell, P.A. ; Wijk, M.T. van; Herrero, M. ; Zingore, S. ; Mapfumo, P. ; Giller, K.E. - \ 2011
    Agricultural Systems 104 (2011)2. - ISSN 0308-521X - p. 175 - 190.
    soil fertility management - african smallholder farms - southern africa - systems - productivity - manure - strategies - efficiencies - nutrition - gradients
    In communal areas of NE Zimbabwe, feed resources are collectively managed, with herds grazing on grasslands during the rainy season and mainly on crop residues during the dry season, which creates interactions between farmers and competition for organic resources. Addition of crop residues or animal manure is needed to sustain agricultural production on inherently poor soils. Objectives of this study were to assess the effect of village-level interactions on carbon and nutrient flows, and to explore their impact on the long-term productivity of different farm types under climate variability. Crop and cattle management data collected in Murewa Communal area, NE Zimbabwe was used together with a dynamic farm-scale simulation model (NUANCES-FARMSIM) to simulate village-level interactions. Simulations showed that grasslands support most cattle feed intake (c. 75%), and that crop residues produced by non-cattle farmers sustain about 30% of the dry season feed intake. Removal of crop residues (0.3–0.4 t C ha-1 yr-1) from fields of non-cattle farmers resulted in a long-term decrease in crop yields. No-access to crop residues of non-cattle farmers increased soil C modestly and improved yields in the long-term, but not enough to meet household energy requirements. Harvest of grain and removal of most crop residues by grazing cattle caused a long-term decline in soil C stocks for all farm types. The smallest decrease (-0.5 t C ha-1) was observed for most fertile fields of cattle farmers, who manure their fields. Cattle farmers needed to access 4–10 ha of grassland to apply 3 t of manure ha-1 yr-1. Rainfall variability intensifies crop–livestock interactions increasing competition for biomass to feed livestock (short-term effect) or to rehabilitate soils (long-term effect). Prolonged dry seasons and low availability of crop residues may lead to cattle losses, with negative impact in turn on availability of draught power, affecting area under cultivation in consecutive seasons until farmers re-stock. Increasing mineral fertiliser use concurrently with keeping crop residues in fertile fields and allocating manure to poor fields appears to be a promising strategy to boost crop and cattle productivity at village level. The likelihood of this scenario being implemented depends on availability of fertilisers and decision of farmers to invest in rehabilitating soils to obtain benefits in the long-term. Adaptation options cannot be blind to what occurs beyond field and farm level, because otherwise recommendations from research and development do not fit the local conditions and farmers tend to ignore them.
    Drivers of land use change and household determinants of sustainability in smallholder farming systems of Eastern Uganda
    Ebanyat, P. ; Ridder, N. de; Jager, A. de; Delve, R.J. ; Bekunda, M. ; Giller, K.E. - \ 2010
    Population and Environment 31 (2010)6. - ISSN 0199-0039 - p. 474 - 506.
    soil fertility management - sub-saharan africa - cover change - nutrient balances - brazilian amazon - level evidence - southern mali - use patterns - dynamics - agriculture
    Smallholder farming systems in sub-Saharan Africa have undergone changes in land use, productivity and sustainability. Understanding of the drivers that have led to changes in land use in these systems and factors that influence the systems’ sustainability is useful to guide appropriate targeting of intervention strategies for improvement. We studied low input Teso farming systems in eastern Uganda from 1960 to 2001 in a place-based analysis combined with a comparative analysis of similar low input systems in southern Mali. This study showed that policy-institutional factors next to population growth have driven land use changes in the Teso systems, and that nutrient balances of farm households are useful indicators to identify their sustainability. During the period of analysis, the fraction of land under cultivation increased from 46 to 78%, and communal grazing lands nearly completely disappeared. Cropping diversified over time; cassava overtook cotton and millet in importance, and rice emerged as an alternative cash crop. Impacts of political instability, such as the collapse of cotton marketing and land management institutions, of communal labour arrangements and aggravation of cattle rustling were linked to the changes. Crop productivity in the farming systems is poor and nutrient balances differed between farm types. Balances of N, P and K were all positive for larger farms (LF) that had more cattle and derived a larger proportion of their income from off-farm activities, whereas on the medium farms (MF), small farms with cattle (SF1) and without cattle (SF2) balances were mostly negative. Sustainability of the farming system is driven by livestock, crop production, labour and access to off-farm income. Building private public partnerships around market-oriented crops can be an entry point for encouraging investment in use of external nutrient inputs to boost productivity in such African farming systems. However, intervention strategies should recognise the diversity and heterogeneity between farms to ensure efficient use of these external inputs.
    Striga infestation in northern Cameroon: Magnitude, dynamics and implications for managament
    Ayongwa, G.C. ; Stomph, T.J. ; Hoevers, R. ; Ngoumou, T.N. ; Kuyper, T.W. - \ 2010
    NJAS Wageningen Journal of Life Sciences 57 (2010)2. - ISSN 1573-5214 - p. 159 - 165.
    soil fertility management - sub-saharan africa - hermonthica control - savanna zone - nigeria - land - sahel - productivity - cultivation - challenges
    Surveys of Striga (S. hermonthica (Del.) Benth.) infestation in northern Cameroon over the period 1987–2005 assessed Striga dynamics and evaluated its control strategies. In that period the percentage of Striga-infested fields increased in North and Far-North Provinces. Striga incidence increased more in maize fields than in the already heavily infested sorghum fields, where it remained almost constant. During the study period increased land pressure led to a reduction in the use of fallow and a higher frequency of cereal (mono-) cropping. Yields from farmers’ fields did not correlate with Striga incidence, confirming farmers’ prioritization of soil fertility, weeds, and labour for weeding as production constraints, rather than Striga. We discuss how conceptualization of Striga as a weed in the research arena may have led to a misunderstanding of farmers’ constraints. The decline of the cotton industry reduced farmers’ access to fertilizers, while access to organic manure remained limited, increasing the soil fertility constraint. We conclude that two decades of emphasis on Striga were unsuccessful. Enhanced crop yield through soil fertility management should be the entry point to tackle low yields and further worsening of the Striga situation
    Het belang van groencompost
    Haan, J.J. de - \ 2010
    Nieuwe oogst / Magazine gewas 6 (2010)7. - ISSN 1871-093X - p. 18 - 19.
    proeven op proefstations - prestatie-onderzoek - tests - groenbemesters - bodemvruchtbaarheid - gewassen - mest - dekgewassen - bodemvruchtbaarheidsbeheer - station tests - performance testing - tests - green manures - soil fertility - crops - manures - cover crops - soil fertility management
    Groencompost wordt een aantal belangrijke positieve effecten toegedicht, maar onderzoek laat zien dat het gaat om investeren voor de lange termijn. Praktijkonderzoek Plant en Omgeving heeft samen met de Branche Vereniging Reststoffen (BVOR) en vijf agrarische ondernemers in diverse sectoren gekeken naar de effecten van de toediening van groencompost.
    Hulpmeststoffen : eigenschappen en innovaties
    Anonymous, ; Cuijpers, W.J.M. - \ 2010
    manures - innovations - soil fertility - fertilizer application - soil fertility management - overijssel
    Hulpmeststoffen: eigenschappen en innovaties
    Anonymous, ; Cuijpers, W.J.M. - \ 2010
    manures - innovations - soil fertility - compound fertilizers - use value - fertilizer application - soil fertility management - noord-limburg
    Do mixed-species legume fallows provide long-term maize yield benefit compared with monoculture legume fallows?
    Ndufa, J.K. ; Gathumbi, S.M. ; Kamiri, H.W. ; Giller, K.E. ; Cadisch, G. - \ 2009
    Agronomy Journal 101 (2009)6. - ISSN 0002-1962 - p. 1352 - 1362.
    soil fertility management - western kenya - tree prunings - nitrogen release - planted fallows - organic-matter - quality - rotation - mineralization - agroforestry
    The deliberate planting of fast-growing N2-fixing legume monoculture species in rotation with cereal crops can be an important source of N for soil fertility replenishment. We hypothesized that mixed-species fallows have a higher potential of giving long-term residual benefits in terms of biomass, nutrients, and quality of residuals leading to long-term nutrient supply to postfallow maize (Zea mays L.) crops. To test these hypotheses, two experiments were established in farmers' fields on very fine Kandiudalfic Eutrudox soils with monoculture and mixed-species fallows. Treatments included: sesbania [Sesbania sesban (L.) Merr.], crotalaria (Crotalaria grahamiana Wight and Arn.), pigeonpea [Cajanus cajan (L.) Millsp.], siratro [Macroptilium atropurpureum (DC.) Urb.], and calliandra (Calliandra calothyrsus Meissn.) as monoculture-species fallow and mixture fallows of sesbania + crotalaria, sesbania + pigeonpea, sesbania + siratro, or sesbania + calliandra compared with continuous maize cropping with or without N fertilizer, and natural weed fallow. Total aboveground biomass ranged from 4.1 to 20.5 Mg ha-1 for monoculture and 7.8 to 23.3 Mg ha-1 for mixed-species fallows. Recyclable fallow biomass N ranged from 70 to 313 kg ha-1 and there was a positive interaction in some mixtures leading to increased N accumulation. Postfallow maize yields for fallows over five cropping seasons were 161-272% or 61-103% higher when compared with continuous maize without or with N fertilizer, respectively. Long-term postfallow effects on maize yield were linearly related to the amount of recycled fallow N yield. Thus, choice of fallow species to mix should be primarily driven by a better risk management strategy and an increased basket of multiple products and services
    Linking participatory and GIS-based land use planning methods; A case study from Burkina Faso
    Hessel, R. ; Berg, J. van den; Kabore, O. ; Kekem, A.J. van; Verzandvoort, S.J.E. - \ 2009
    Land Use Policy 26 (2009)4. - ISSN 0264-8377 - p. 1162 - 1172.
    soil fertility management - sub-saharan africa - desertification debate - degradation - views - sahel
    Sustainable land use planning is crucial for realizing the aim of food security and for combating land degradation in the Sahel. A participatory land use planning workshop was organised in a village in the eastern region of Burkina Faso to investigate land use problems, their causes, effects and possible solutions. Participatory research tools and GIS were combined to get insight into possible conflicts or synergies between different land use options as mapped by different ethnic groups. Pictograms were used to locate alternative land use options on the map, after which they were digitised for analysis with GIS. The workshop confirms the importance of integrating scientific and local knowledge to develop concrete options for sustainable land use that fit to local realities and aspirations. Local people are knowledgeable about the driving forces behind land degradation, they take actions to combat the effects of degradation, and they have concrete ideas about alternative land use options. The use of GIS proved its added value in the participatory process of integrated land use planning. The maps that were produced also facilitate discussions between community members, researchers and government representatives at the regional level, both regarding current land use problems and regarding alternative options as perceived by the local population.
    Beyond resource constraints - Exploring the biophysical feasibility of options for the intensification of smallholder crop-livestock systems in Vihiga district, Kenya
    Tittonell, P.A. ; Wijk, M.T. van; Herrero, M. ; Rufino, M.C. ; Ridder, N. de; Giller, K.E. - \ 2009
    Agricultural Systems 101 (2009)1-2. - ISSN 0308-521X - p. 1 - 19.
    soil fertility management - western kenya - farm-scale - simulation-models - dynamics - efficiencies - strategies - gradients - impact - manure
    During participatory prototyping activities in Vihiga, western Kenya, farmers designed what they considered to be the ideal farm [Waithaka, M.M., Thornton, P.K., Herrero, M., Shepherd, K.D., 2006. Bio-economic evaluation of farmers¿ perceptions of viable farms in western Kenya. Agric. Syst. 90, 243-271]: one in which high productivity is achieved through optimising crop-livestock interactions. We selected four case study crop-livestock farms of different resource endowment (Type 1-4-excluding the poorest farmers, Type 5, who do not own livestock) and quantified all relevant physical flows through and within them. With this information we parameterised a dynamic, farm-scale simulation model to investigate (i) current differences in resource use efficiencies and degree of crop-livestock interactions across farm types; and (ii) the impact of different interventions in farm Types 3 and 4 on producing the desired shifts in productivity towards the ideal farm. Assuming no resource constraints, changes in the current farm systems were introduced stepwise, as both intensification of external input use (fertilisers and fodder) and qualitative changes in the configuration of the farms (i.e. changing land use towards fodder production, improving manure handling and/or changing cattle breeds). In 10-year simulations of the baseline, current scenario using historical weather data the wealthiest farms Type 2 achieved food self-sufficiency (FSS) in 20% of the seasons due to rainfall variability, whereas the poorer Type 4 only achieved FSS in 0 to 30% of the seasons; soil organic C decreased during the simulations at annual rates of ¿0.54, ¿0.73, ¿0.85 and -0.84 t C ha¿1 on farms of Type 1-4, respectively; large differences in productivity and recycling efficiency between farm types indicated that there is ample room to improve the physical performance of the poorer farms (e.g. light and water use efficiency was 2-3 times larger on wealthier farms). Simulating different intensification scenarios indicated that household FSS can be achieved in all farm types through input intensification, e.g. using P fertilisers at rates as small as 15 kg farm¿1 season¿1 (i.e. from 7 to 28 kg ha¿1). Increasing the area under Napier grass from c. 20 to 40% and reducing the area of maize, beans and sweet potato in farms of Type 3 and 4 increased their primary productivity by c. 1 t ha¿1 season¿1, their milk production by 156 and 45 L season¿1, respectively, but decreased the production of edible energy (by 2000 and 250 MJ ha¿1 season¿1) and protein (by 20 and 3 kg ha¿1 season¿1). By bringing in a more productive cow the primary productivity increased even further in Farm Type 3 (up to 5 t ha¿1 season¿1), as did milk production (up to c. 1000 L season¿1), edible energy (up to c. 10,000 MJ ha¿1 season¿1) and protein (up to c. 100 kg ha¿1 season¿1). The impact of livestock management on the recycling of nutrients and on the efficiency of nutrient use at farm scale can be large, provided that enough nutrients are present in or enter the system to be redistributed. An increase in N cycling efficiency through improved manure handling from 25 to 50% would increase the amount of N cycled in the case study farms of Type 1 and 2 by only ca. 10 kg season¿1, and only 1-2 kg season¿1 in Type 3 and 4. The various alternatives simulated when disregarding resource constraints contributed to narrow the productivity and efficiency gaps between poorer and wealthier farms. However, the feasibility of implementing such interventions on a large number of farms is questionable. Implications for system (re-)design and intensification strategies are discussed
    Identifying key entry-points for strategic management of smallholder farming systems in sub-Saharan Africa using the dynamic farm-scale simulation model NUANCES-FARMSIM
    Wijk, M.T. van; Tittonell, P.A. ; Rufino, M.C. ; Herrero, M. ; Pacini, C. ; Ridder, N. de; Giller, K.E. - \ 2009
    Agricultural Systems 102 (2009)1-3. - ISSN 0308-521X - p. 89 - 101.
    soil fertility management - term crop response - western kenya - exploring diversity - resource-allocation - use efficiencies - field-scale - productivity - nitrogen - integration
    African smallholder farming systems are complex, dynamic systems with many interacting biophysical subcomponents. In these systems the major inputs and outputs are managed by human agency ¿ the farmers. To analyse potential developmental pathways of smallholder farming systems in sub-Saharan Africa (SSA), we recognised the need for a tool that can capture the effects and consequences of decision-making on the use of resources. Here we describe and apply such a new modelling tool, developed within the NUANCES framework (Nutrient Use in ANimal and Cropping systems: Efficiencies and Scales), called NUANCES-FARMSIM (FARM SIMulator), an integrated crop ¿ livestock model developed to analyse African smallholder farm systems. NUANCES-FARMSIM was used to analyse a representative case study farm in the highlands of Western Kenya, a site for which each of the components of FARMSIM has been thoroughly tested. We present the results of a sensitivity analysis which showed the model to be sufficiently robust to identify key management options that explain most of the variability in farm productivity, and the long-term consequences of these options for the case study farm. The analyses showed clearly that the most important decisions are those related to the interactions between the different components of the farm and therefore justify the need of integrating crop and livestock components within one modelling tool. The allocation of limited resources across the farm, and the way organic matter is recycled or redistributed within the farm determines the long-term production capacity of the system. The results of the sensitivity analyses further showed that for the case study farm in Western Kenya a strong focus on improving the reliability of the subsystem level or process descriptions will only result in minor improvement in simulating productivity at farm level
    Biodiversity, carbon stocks and sequestration potential in aboveground biomass in smallholder farming systems of western Kenya
    Henry, M. ; Tittonell, P.A. ; Manlay, R.J. ; Bernoux, M. ; Albrecht, A. ; Vanlauwe, B. - \ 2009
    Agriculture, Ecosystems and Environment 129 (2009)1-3. - ISSN 0167-8809 - p. 238 - 252.
    soil fertility management - agroforestry systems - allocation - productivity - environment - forests
    While Carbon (C) sequestration on farmlands may contribute to mitigate CO2 concentrations in the atmosphere, greater agro-biodiversity may ensure longer term stability of C storage in fluctuating environments. This study was conducted in the highlands of western Kenya, a region with high potential for agroforestry, with the objectives of assessing current biodiversity and aboveground C stocks in perennial vegetation growing on farmland, and estimating C sequestration potential in aboveground C pools. Allometric models were developed to estimate aboveground biomass of trees and hedgerows, and an inventory of perennial vegetation was conducted in 35 farms in Vihiga and Siaya districts. Values of the Shannon index (H), used to evaluate biodiversity, ranged from 0.01 in woodlots through 0.4¿0.6 in food crop plots, to 1.3¿1.6 in homegardens. Eucalyptus saligna was the most frequent tree species found as individual trees (20%), in windrows (47%), and in woodlots (99%) in Vihiga and the most frequent in woodlots (96%) in Siaya. Trees represented the most important C pool in aboveground biomass of perennial plants growing on-farm, contributing to 81 and 55% of total aboveground farm C in Vihiga and Siaya, respectively, followed by hedgerows (13 and 39%, respectively) and permanent crop stands (5 and 6%, respectively). Most of the tree C was located in woodlots in Vihiga (61%) and in individual trees growing in or around food crop plots in Siaya (57%). The homegardens represented the second C pool in importance, with 25 and 33% of C stocks in Vihiga and Siaya, respectively. Considering the mean total aboveground C stocks observed, and taking the average farm sizes of Vihiga (0.6 ha) and Siaya (1.4 ha), an average farm would store 6.5 ± 0.1 Mg C farm¿1 in Vihiga and 12.4 ± 0.1 Mg C farm¿1 in Siaya. At both sites, the C sequestration potential in perennial aboveground biomass was estimated at ca. 16 Mg C ha¿1. With the current market price for carbon, the implementation of Clean Development Mechanism Afforestation/Reforestation (CDM A/R) projects seems unfeasible, due to the large number of small farms (between 140 and 300) necessary to achieve a critical land area able to compensate the concomitant minimum transaction costs. Higher financial compensation for C sequestration projects that encourage biodiversity would allow clearer win¿win scenarios for smallholder farmers. Thus, a better valuation of ecosystem services should encourage C sequestration together with on-farm biodiversity when promoting CDM A/R projects.
    Talking soil science with farmers
    Tittonell, P.A. ; Misiko, M. ; Ekise, I.E. - \ 2008
    LEISA : ILEIA newsletter for low-external-input and sustainable agriculture 24 (2008)2. - ISSN 1569-8424 - p. 9 - 11.
    bodemvruchtbaarheid - kenya - oost-afrika - bodemvruchtbaarheidsbeheer - kennis van boeren - soil fertility - kenya - east africa - soil fertility management - farmers' knowledge
    When agricultural researchers visit farms in order to gather information for their research programmes, farmers rarely get proper feedback. Research information on scientific concepts such as soil fertility and nutrient balances is often considered too abstract for them. Researchers in Kenya returned to farmers to discuss their results in the context of Farmer Field Schools. Through the workshops that ensued, they managed to find a common language to bridge the communication gap.
    Ex ante assessment of dual-purpose sweet potato in the crop-livestock system of western Kenya: a minimum-data approach
    Claessens, L. ; Stoorvogel, J.J. ; Antle, J.M. - \ 2008
    Agricultural Systems 99 (2008)1. - ISSN 0308-521X - p. 13 - 22.
    soil fertility management - agricultural production systems - semi-humid tropics - dairy-cows - pennisetum-purpureum - nutrient balances - economic-analysis - farming systems - maize stover - feed
    Mixed crop¿livestock systems have a crucial role to play in meeting the agricultural production challenges of smallholder farmers in sub-Saharan Africa. Sweet potato is seen as a potential remedial crop for these farmers because of its high productivity and low input requirements, while its usefulness for both food and feed (dual-purpose) make it attractive in areas where land availability is declining. In this paper, we develop and apply a `minimum-data¿ methodology to assess ex ante the economic viability of adopting dual-purpose sweet potato in Vihiga district, western Kenya. The methodology uses and integrates available socio-economic and bio-physical data on farmers¿ land use allocation, production, and input and output use. Spatially heterogeneous characteristics of the current system regarding resources and productivity are analyzed to assess the profitability of substituting dual-purpose sweet potato for other crops currently grown for food and feed. Results indicate that a substantial number of farmers in the study area could benefit economically from adopting dual-purpose sweet potato. Depending on assumptions made, the adoption rate, expressed as the percentage of the total land under adopting farms, is between 55% and 80%. The analysis shows that the adoption rate is likely to vary positively with the average total yield of dual-purpose sweet potato, the harvest index (the ratio between tuber and fodder yields), the price of milk, and the nutritional value of available fodder. This study demonstrates the usefulness of the minimum-data methodology and provides evidence to support the hypothesis that dissemination of the dual-purpose sweet potato could help improve the livelihoods of smallholder farmers operating in mixed crop¿livestock systems in east Africa.
    Increasing land pressure in East Africa: The changing role of cassava and consequences for sustainability of farming systems
    Fermont, A.M. van; Asten, P.J.A. van; Giller, K.E. - \ 2008
    Agriculture, Ecosystems and Environment 128 (2008)4. - ISSN 0167-8809 - p. 239 - 250.
    soil fertility management - western kenya - gradients - farmers - maize - crops
    Increasing land pressure during the past three to four decades has transformed farming systems in the mid-altitude zone of East Africa. Traditional millet-, cotton-, sugarcane- and/or banana-based farming systems with an important fallow and/or grazing component have evolved into continuously cultivated cassava or cassava/maize-based systems. Within three to four decades, cassava cultivation increased from 1¿11 to 16¿55% of cropped fields in our six study sites. Declining soil fertility, and not labour or food shortage, was apparently the primary trigger for this transformation. The land use changes have increased nutrient offtakes and reduced nutrient recycling rates. Cassava and maize now account for 50¿90% of nutrient removal. Whereas single-season fallows were the most important source of nutrient recycling on cropped fields in the past, currently cassava litterfall and maize stover contribute roughly 70% of nutrient recycling, with 50¿70% of N, P and K recycled in cassava litterfall. This may explain why many farmers reason that cassava `rests¿ the soil. With increasing land use pressure farmers progressively use cassava as an `imitation fallow¿ throughout their farm. Farmers increasingly target cassava to poor fertility fields characterized by low pH and available P. High cassava intensities are nonetheless maintained on more fertile fields, probably to guarantee regeneration of soil fertility on all fields. Once cassava is targeted to poor fertility soils, farmers have run out of low-input management options and need to intensify management to maintain system productivity. As cassava is now used by more farmers and on a larger acreage than fallowing in the studied farming systems, cassava cropping could perhaps serve as an excellent entry point to strengthen system sustainability.
    Stikstofbemesting in spruitkool na 15 september
    Geel, W.C.A. van; Dekker, P.H.M. ; Vlaswinkel, M.E.T. - \ 2008
    Lelystad : PPO AGV (Rapport / PPO-AGV ) - 27
    brassica oleracea var. gemmifera - spruitjes - mestbehoeftebepaling - plantenvoeding - nederland - bemesting - bodemvruchtbaarheidsbeheer - brassica oleracea var. gemmifera - brussels sprouts - fertilizer requirement determination - plant nutrition - netherlands - fertilizer application - soil fertility management
    In dit rapport zijn de beschikbare resultaten van Nederlands onderzoek in spruitkool met betrekking tot landbouwkundige en milieukundige gevolgen van bemesting met kunstmeststikstof in de winterperiode op een rij gezet
    Improving local technologies to manage speargrass (Imperata cylindrica) in southern Benin
    Vissoh, P.V. ; Kuyper, T.W. ; Gbehounou, G. ; Hounkonnou, D. ; Ahanchede, A. ; Röling, N.G. - \ 2008
    International Journal of Pest Management 54 (2008)1. - ISSN 0967-0874 - p. 21 - 29.
    soil fertility management - cover crops - l. raeuschel - west-africa - grain-yield - maize - systems - cassava - perceptions - farmers
    Speargrass (Imperata cylindrica) is difficult to control in the tropics. Farmers allocate most of their time and labour to weeding speargrass. We investigated in a joint experiment concluded with farmers, how effectively grain legumes suppress speargrass, and the relationships between speargrass suppression, legume grain yield, and subsequent maize yield. Without management, speargrass shoots and rhizomes increased with 31 and 17% per month, respectively. The integration of deep ridging, deep hoe weeding and shading suppressed speargrass more effectively than farmers' practices. Creeping varieties of cowpea that produced most biomass were most successful in suppressing speargrass and in enhancing subsequent maize yields, but erect cowpea cultivars produced more grain. Farmers traded off cowpea yield against speargrass suppression to bridge the hungry gap. They preferred the erect cowpea cultivar wan. The need to forego a harvest and the fact that pigeonpea is not consumed in the area makes pigeonpea presently unsuitable for integration into the cropping system.
    Msimu wa Kupanda : targeting resources within diverse, heterogenous and dynamic farming systemes of East Africa
    Tittonell, P.A. - \ 2008
    Wageningen University. Promotor(en): Ken Giller, co-promotor(en): B. Vanlauwe; Mark van Wijk. - [S.l.] : s.n. - ISBN 9789085048077 - 320
    bedrijfssystemen - bodemvruchtbaarheid - middelentoewijzing - systeemanalyse - simulatiemodellen - kringlopen - voedingsstoffen - stikstofkringloop - organisch bodemmateriaal - kenya - uganda - afrika ten zuiden van de sahara - bodemvruchtbaarheidsbeheer - farming systems - soil fertility - resource allocation - systems analysis - simulation models - cycling - nutrients - nitrogen cycle - soil organic matter - kenya - uganda - africa south of sahara - soil fertility management - cum laude
    cum laude graduation (with distinction)
    A journey without maps: towards sustainable subsistence agriculture in South Africa
    Adey, S. - \ 2007
    Wageningen University. Promotor(en): Han Wiskerke, co-promotor(en): F.H.J. Rijkenberg. - [S.l.] : S.n. - 242
    ontwikkeling - sociologie - participatie - technische vooruitgang - zelfvoorzieningslandbouw - duurzaamheid (sustainability) - plattelandsontwikkeling - bodemvruchtbaarheid - economische ontwikkeling - sociale ontwikkeling - instellingen - kunstnijverheid - natuurlijke hulpbronnen - hulpbronnenbeheer - gezinstuinen - voeren van een landbouwhuishouding - zuid-afrika - strategieën voor levensonderhoud - bodemvruchtbaarheidsbeheer - development - sociology - participation - technical progress - subsistence farming - sustainability - rural development - soil fertility - economic development - social development - institutions - crafts - natural resources - resource management - home gardens - homesteading - south africa - livelihood strategies - soil fertility management
    Participatory technology development within the subsistence-farming sector in South Africa is receiving increasing attention. Linked to this is an interest in sustainable development, particularly for agricultural interventions. Ecological approaches to agriculture have largely been considered unable to provide a route for income generation. However, some promising examples of sustainable small-scale farming systems can be found in South Africa. The main aim of this thesis was to identify factors within these development programmes that led to sustainable technology development in the context of subsistence farmers’ livelihoods. This objective was achieved through exploring practically, the concepts derived from the sustainability paradigm. To be sustainable, a farming system should be biologically, technically and socially feasible and viable at farm level, within a positive and enhancing external environment. Sustainability ultimately concerns the relationships between all elements of the farming system and for this reason researching sustainability in agriculture requires a multi-level, multi-aspect and multi-actor approach. Sustainability was explored in three case studies in this thesis and at a number of levels: field level; farm and district level, including organizational interaction. Different aspects were researched that included agricultural technologies, household livelihoods and organizational development. The various actors involved in the technology-development process examined in the three case studies included farmers, change-agents, researchers and local traditional authorities. Interactions at all three levels influenced and contributed to the overall sustainability of the development intervention and this research supports the widely demonstrated conclusion that the challenges faced by agriculture will not readily be solved by technological interventions at the field level alone. The factors at each of the levels that contributed to the sustainability of the develop projects are presented and the lessons learned from the three case studies are also given.
    Niche-based assessment of contributions of legumes to the nitrogen economy of Western Kenya smallholder farms
    Ojiem, J.O. ; Vanlauwe, B. ; Ridder, N. de; Giller, K.E. - \ 2007
    Plant and Soil 292 (2007)1-2. - ISSN 0032-079X - p. 119 - 135.
    soil fertility management - n-15 natural-abundance - exploring diversity - improved fallows - africa - n-2-fixation - fixation - adoption - systems
    Nitrogen (N) deficiency is a major constraint to the productivity of the African smallholder farming systems. Grain, green manure and forage legumes have the potential to improve the soil N fertility of smallholder farming systems through biological N-2-fixation. The N-2-fixation of bean (Phaseolus vulgaris), soyabean (Glycine max), groundnut (Arachis hypogaea), Lima bean (Phaseolus lunatus), lablab (Lablab purpureus), velvet bean (Mucuna pruriens), crotalaria (Crotalaria ochroleuca), jackbean (Canavalia ensiformis), desmodium (Desmodium uncinatum), stylo (Stylosanthes guianensis) and siratro (Macroptilium atropurpureum) was assessed using the N-15 natural abundance method. The experiments were conducted at three sites in western Kenya, selected on an agro-ecological zone (AEZ) gradient defined by rainfall. On a relative scale, Museno represents high potential AEZ 1, Majengo medium potential AEZ 2 and Ndori low potential AEZ 3. Rainfall in the year of experimentation was highest in AEZ 2, followed by AEZ 1 and AEZ 3. Experimental fields were classified into high, medium and low fertility classes, to assess the influence of soil fertility on N-2-fixation performance. The legumes were planted with triple super phosphate (TSP) at 30 kg P ha(-1) stop, with an extra soyabean plot planted without TSP (soyabean-P), to assess response to P, and no artificial inoculation was done. Legume grain yield, shoot N accumulation, %N derived from N-2-fixation, N-2-fixation and net N inputs differed significantly (P <0.01) with rainfall and soil fertility. Mean grain yield ranged from 0.86 Mg ha(-1), in AEZ 2, to 0.30 Mg ha(-1), in AEZ 3, and from 0.78 Mg ha(-1), in the high fertility field, to 0.48 Mg ha(-1) stop, in the low fertility field. Shoot N accumulation ranged from a maximum of 486 kg N ha(-1) in AEZ 2, to a minimum of 10 kg N ha(-1) in AEZ 3. Based on shoot biomass estimates, the species fixed 25-90% of their N requirements in AEZ 2, 23-90% in AEZ 1, and 7-77% in AEZ 3. Mean N-2-fixation by green manure legumes ranged from 319 kg ha(-1)(velvet bean) in AEZ 2 to 29 kg ha(-1) (jackbean) in AEZ 3. For the forage legumes, mean N-2-fixation ranged from 97 kg N ha(-1) for desmodium in AEZ 2 to 39 kg N ha(-1) for siratro in AEZ 3, while for the grain legumes, the range was from 172 kg N ha(-1) for lablab in AEZ 1 to 3 kg N ha(-1) for soyabean-P in AEZ 3. Lablab and groundnut showed consistently greater N-2-fixation and net N inputs across agro-ecological and soil fertility gradients. The use of maize as reference crop resulted in lower N-2-fixation values than when broad-leaved weed plants were used. The results demonstrate differential contributions of the green manure, forage and grain legume species to soil fertility improvement in different biophysical niches in smallholder farming systems and suggest that appropriate selection is needed to match species with the niches and farmers' needs.
    Raising the productivity of smallholder farms under semi-arid conditions by use of small doses of manure and nitrogen: a case of participatory research
    Ncube, B. ; Dimes, J.P. ; Twomlow, S.J. ; Mupangwa, W. ; Giller, K.E. - \ 2007
    Nutrient Cycling in Agroecosystems 77 (2007)1. - ISSN 1385-1314 - p. 53 - 67.
    soil fertility management - africa - dynamics - systems
    Participatory on-form trials were conducted for three seasons to assess the benefits of small rates of manure and nitrogen fertilizer on maize grain yield in semi-arid Tsholotsho, Zimbabwe. Two farmer resource groups conducted trials based on available amounts of manure, 3 t ha(-1) (low resource group) and 6 t ha(-1) ( high resource group). Maize yields varied between 0.15 t ha(-1) and 4.28 t ha(-1) and both absolute yields and response to manure were strongly related to rainfall received across seasons (P <0.001). The first two seasons were dry while the third season received above average rainfall. Maize yields within the seasons were strongly related to N applied (R-2 = 0.77 in season 1, and R-2 = 0.88 and 0.83 in season 3) and other beneficial effects of manure, possibly availability of cations and P. In the 2001 - 2002 season (total rainfall 478 mm), application of 3 and 6 t ha(-1) of manure in combination with N fertilizer increased grain yield by about 0.14 and 0.18 t ha(-1), respectively. The trend was similar for the high resource group in 2002 - 2003 although the season was very dry ( 334 mm). In 2003 - 2004, with good rainfall ( 672 mm), grain yields were high even for the control plots (average 1.2 and 2.7 t ha(-1)). Maize yields due to manure applications at 3 and 6 t ha(-1) were 1.96 and 3.44 t ha(-1), respectively. Application of 8.5 kg N ha(-1) increased yields to 2.5 t ha(-1) with 3 t ha(-1) of manure, and to 4.28 t ha(-1) with 6 t ha(-1) of manure. In this area farmers do not traditionally use either manure or fertilizer on their crops, but they actively participated in this research during three consecutive seasons and were positive about using the outcomes of the research in future. The results showed that there is potential to improve livelihoods of smallholder farmers through the use of small rates of manure and N under semi-arid conditions.
    Zorg voor een gezonde bodem
    Os, G.J. van - \ 2006
    bodembiologie - bodemtextuur - bodemfauna - bodemvruchtbaarheid - bodembiodiversiteit - bodemvruchtbaarheidsbeheer - soil biology - soil texture - soil fauna - soil fertility - soil biodiversity - soil fertility management
    Een rijk bodemleven is de basis voor een gezonde teelt, omdat het bodemleven zorgt voor een betere bodemvruchtbaarheid, betere bodemstructuur en zorgt voor onderdrukking van ziekteverwekkers. Er worden tips gegeven hoe voor een rijk bodemleven gezorgd kan worden.
    Integrating legumes to improve N cycling on smallholder farms in sub-humid Zimbabwe: resource quality, biophysical and environmental limitations
    Chikowo, R. ; Mapfumo, P. ; Leffelaar, P.A. ; Giller, K.E. - \ 2006
    Nutrient Cycling in Agroecosystems 76 (2006)2-3. - ISSN 1385-1314 - p. 219 - 231.
    soil fertility management - nitrogen mineralization - organic-matter - maize - dynamics - leaves - productivity - emissions - residues - release
    The release of mineral-N in soil from plant residues is regulated by their `quality¿ or chemical composition. Legume materials used by farmers in southern Africa are often in the form of litter with N concentration 5 Mg ha¿1) and improved N cycling significantly (>150 kg N ha¿1) on the clay loam soil, but adapted poorly on the sandier soil. There was a rapid N accumulation in the topsoil at the beginning of the rains in plots where large amounts of Sesbania or Acacia biomass had been incorporated. Despite the wide differences in resource quality between these two, there was virtually no difference in N availability in the field as this was, among other factors, confounded by the quantity of N added. A substantial amount of the nitrate was leached to greater than 0.4 m depth within a three-week period. Also, the incidence of pests in the first season, and drought in the second season resulted in poor nitrogen use efficiency. Our measurements of gaseous N losses in the field confirmed that N2O emissions were
    Nitrogen cycling efficiencies through resource-poor African crop-livestock systems
    Rufino, M.C. ; Rowe, E.C. ; Delve, R.J. ; Giller, K.E. - \ 2006
    Agriculture, Ecosystems and Environment 112 (2006)4. - ISSN 0167-8809 - p. 261 - 282.
    soil fertility management - quality native hay - farming systems - cattle manure - organic-matter - dairy-cows - ammonia emissions - sesbania-sesban - milk-production - nutrient-uptake
    Success in long-term agricultural production in resource-poor farming systems relies on the efficiency with which nutrients are conserved and recycled. Each transfer of nutrients across the farming system provides a risk of inefficiency, and how much is lost at each step depends on the type of farming system, its management practices and site conditions. The aim of this review was to identify critical steps where efficiency of nitrogen (N) cycling through livestock in smallholder crop-livestock farming systems could be increased, with special emphasis on Africa. Farming systems were conceptualised in four sub-systems through which nutrient transfer takes place: (1) livestock: animals partition dietary intake into growth and milk production, faeces and urine; (2) manure collection and handling: housing and management determine what proportion of the animal excreta may be collected; (3) manure storage: manure can be composted with or without addition of plant materials and (4) soil and crop conversion: a proportion of the N in organic materials applied to soil becomes available, part of which is taken up by plants, of which a further proportion is partitioned into grain N. An exhaustive literature review showed that partial efficiencies have been much more commonly calculated for the first and last steps than for manure handling and storage. Partial N cycling efficiencies were calculated for every sub-system as the ratio of nutrient output to nutrient input. Estimates of partial N cycling efficiency (NCE) for each sub-system ranged from 46 to 121% (livestock), 6 to 99% (manure handling), 30 to 87% (manure storage) and 3 to 76% (soil and crop conversion). Overall N cycling efficiency is the product of the partial efficiencies at each of the steps through which N passes. Direct application of plant materials to soil results in more efficient cycling of N, with fewer losses than from materials fed to livestock. However, livestock provide many other benefits highly valued by farmers, and animal manures can contain large amounts of available N, which increases the immediate crop response. Manures also can contribute to increase (or at least maintain) the soil organic C pool but more quantitative information is needed to assess the actual benefits. Making most efficient use of animal manures depends critically on improving manure handling and storage, and on synchrony of mineralisation with crop uptake. Measures to improve manure handling and storage are generally easier to design and implement than measures to improve crop recovery of N, and should receive much greater attention if overall system NCE is to be improved.
    Resource use dynamics and interactions in the tropics: Scaling up in space and time
    Giller, K.E. ; Rowe, E.C. ; Ridder, N. de; Keulen, H. van - \ 2006
    Agricultural Systems 88 (2006)1. - ISSN 0308-521X - p. 8 - 27.
    soil fertility management - farming systems - organic-matter - livestock - crops - rainfall - legumes - africa - mucuna - rice
    We discuss the temporal and spatial dynamics of nutrient resources and water within cropping and livestock systems, their interactions and those with other resources such as labour. Short-term dynamics (within season) revolve around nutrient availability and losses as a function of soil moisture dynamics. Longer-term effects (multiple seasons and years) are related to residual effects of crop management in successive seasons and to changes in soil organic matter contents. Spatial patterns of resource use are consistent across different tropical farming systems. Farmers preferentially allocate manure, mineral fertilizers and labour to fields close to the homestead, resulting in strong negative soil fertility gradients away from the homestead. Livestock are the central means of concentration of nutrients within farming systems, resulting in their inequitable redistribution from common lands and poorer households to richer households. Productivity gains achieved by concentration on home plots are at the expense of long-term declining productivity on remote fields. Restricted availability of inputs leads to a form of self-organization resulting in repeating patterns of farm organization that are recognisable across sub-Saharan Africa. Principles for enhancing allocation efficiency of scarce resources are required that address the dynamics of interacting temporal and spatial scales. Managed variability that creates gradients of soil fertility can have major effects on resource use efficiency of both nutrients and water, necessitating analysis of trade-offs at farm scale. Investment decisions of farming families are shaped through complex interactions among competing demands for investment of cash and labour within and beyond farm boundaries. Combinations of socio-economic and agro-ecological conditions can provide windows of opportunity in both time and space that favour investment in particular forms of management. Past research provides a vast array of technologies to improve agricultural production, and understanding of the underlying processes. A research framework is proposed representing farm systems as sets of interacting components. This framework can be used ex-ante, to assist in targeting technologies to specific types of farmers, and for identification of more appropriate technologies. It can be used to explore short and long-term trade-offs of management strategies and to evaluate effects of policy on farms varying in resource endowment.
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