Browsing by Subject "Smallholder farmers"

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    Fertility and microbial functioning of soils of smallholder farming systems under contrasting tropical agro-ecologies
    (2021) Balume, Isaac; Rasche, Frank
    Soil fertility in tropical agroecosystems is often subjected to degradation that leads to nutrient depletion with negative effects on land productivity and food security. This challenge is aggravated by the complexity of socio-economic (market distance, farm typology) and biophysical (agro-ecology, site) conditions causing soil fertility variability. Consequently, blanket fertilizer recommendations cannot be applied in areas of high fertility variability. In this PhD study, methods were harmonized to assess drivers of soil fertility status across regions. Despite being pointed as factors contributing to soil fertility variability, market access, farm typology (resource endowment) and agro-ecology have not been subjected to soil fertility assessment. This PhD study aimed mainly at verifying that these factors have to integrated rather than considered in isolation to enable accurate assessments of soil fertility across spatial scales and socio-economic gradients. It was hypothesized that market distance and farm typology is a determinant of agricultural development in Democratic Republic of Congo (DRC). As market distance is increasing, the soil fertility status of smallholder farming systems decreases despite farmers’ wealth. In a parallel study conducted in Ethiopia, it was complementarily hypothesized that the soil fertility status is also influenced by inter-related effects of agro-ecology and farm typology. As nitrogen (N) is known to be limiting in smallholder farms, conservation and sustainable provision of this nutrient will be essential to achieve niche-based integrated soil fertility management (ISFM) strategies. Therefore, understanding of the ecological processes (proteolysis, nitrification) that control soil N availability through organic residue management in varying soil fertility variability conditions will be essential. Low concentrations of lignin (L) and polyphenols (PP) relative to N have been acknowledged to facilitate decomposition, hence, stimulate the abundance of proteolytic and nitrifying soil microbial communities. Therefore, it was hypothesized that high quality (low (L+PP)/N)) residue applied to high pH soils have a positive relationship between the functional potential of proteolytic enzymatic activities and abundance of nitrifying communities. The survey studies in DRC and Ethiopia were guided by the following objectives; 1) To determine the inter-related influence of market distance and farm typology on soil fertility status of smallholder farming systems of South-Kivu, Eastern DRC. 2) To assess the inter-related effects of agro-ecology and farm typology on soil fertility status across crop-livestock systems in Western and Central Ethiopia. Moreover, to better understand the ecological processes (proteolysis, nitrification) that control N through organic residue management in varying soil fertility variability conditions, an incubation study was performed to meet objective 3) To verify that potential proteolytic enzyme activities modulate archaeal and bacterial nitrifier abundance in soils with differing acidity and organic residue treatment. Results from the soil survey study in DRC revealed a decreasing soil fertility with increasing market distance across all farm typologies. A significant influence of farm typology was found for exchangeable calcium and magnesium, while factor site resulted in a significant difference of plant available phosphorus. Furthermore, factor “site” interacted with market distance for soil organic carbon (SOC) quality indexes. In addition, the interaction of market distance and typology became obvious in the medium wealthy and poor farms. Market distance effects were associated with walking distance, while site effects were attributed to factors such as soil type and climatic conditions. In Ethiopia, inter-related effect of agro-ecology and farm typology was found. Higher total carbon and total nitrogen was found in wealthy farmers’ field compared to poor farmers’ field in the highlands. As an indication of soil quality, lowest SOC stability indexes were revealed in soils of wealthy compared to that from poor farm typology. These differences in soil fertility were attributed to farm management practices among typology classes and agro-ecological zone distinctions. The result from the incubation study revealed a significant relationship of proteolytic enzyme activities with the abundance of ammonia oxidizing bacteria and archaea, even though the extent of this relationship was more dependent on soil pH and incubation time, but not residue quality. This suggests that the effect of soil pH is stronger than that of residue quality on enzyme activity and nitrifiers community, reflecting the importance of soil physico-chemical conditions rather than management practices. The incubation study further showed that nitrifying prokaryotes benefitted from the release of N spurred by proteolysis, and indicated a niche specialization between ammonia oxidizing bacteria and archaea depending on soil acidity and resource availability. Overall, this PhD study showed that market access, typology and agro-ecology were important drivers of soil fertility variability in the study regions of DRC and Ethiopia. However, factor site played a significant role in shaping soil fertility variability, implying that site-specific recommendations could be a way forward for designing soil fertility management in smallholder farmers. It was inferred that prospective niche-based ISFM strategies must consider such contrasting but interrelated factors including, but not limited to agro-ecology, farm typology and market access. This would reduce the effect of soil fertility variability across regions. This PhD study only considered land size (DRC, Ethiopia), livestock and mineral fertilizers (Ethiopia) as key features to define the wealth status of targeted farms; future studies should consider a wider range of socio-economic and biophysical factors including labor availability, off-farm household income and soil management history for more accuracy of soil fertility variability. This will strengthen the accuracy of prospective soil fertility assessments across socio-economic gradients and spatial scales. Finally, it is suggested to extend the results from the incubation study to field conditions considering soils with a broader soil acidity range and organic residues with more distinct biochemical quality. This will verify the given assumptions about the functional relationships between proteolytic and nitrifying soil communities. Overall, the presented PhD study has contributed to ongoing research on best-fit soil fertility recommendations and knowledge gaps about soil ecological functioning, by providing an advanced understanding of driving factors of soil fertility variability and soil microbial functioning in smallholder farms in tropical environments.
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    Integrated rural and urban agricultural systems for the sustainability transition towards the bioeconomy
    (2021) Winkler, Bastian; Lewandowski, Iris
    The goal of the bioeconomy is a fundamental transition of both the economy and society towards sustainability. Replacing fossil resources by biomass for the provision of food, feed, fibre and fuel/energy (the 4F’s) will result in a substantial increase in demand for agricultural products. The consequent intensification of agricultural production, however, needs to be achieved while alleviating the societal challenges of the 21st century. The bioeconomy provides a knowledge-based, cross-sectoral and systemic pathway to increase agricultural production that involves all relevant stakeholders in the sustainability transition. This interdisciplinary thesis investigated the contribution that three selected bioeconomic approaches can make to the sustainable intensification of agricultural production, encompassing the growing urban population on the demand side and the numerous smallholder family farmers in countries of the global South on the supply side. The first study develops the ‘Integrated Renewable Energy Potential Assessment’ (IREPA) approach that involves smallholder farmers in planning and selection of renewable energy (RE) technologies for implementation into their agricultural systems. The bottom-up potential assessment, participatory learning and action research and multi-criteria decision analysis supported the smallholders in two case studies in rural South Africa and India in the identification of locally appropriate RE technologies. The second study uses IREPA to explore smallholders’ perception of agricultural RE production. Social, environmental, technical, institutional and economic factors are analysed to identify drivers of and barriers to RE implementation into smallholder agricultural systems. Mainly environmental factors, in particular climate change impacts, motivate smallholders to produce RE, while social factors (social cohesion, gender aspects, well-being, food and water security) determine the actual change. The barrier of high upfront investment costs can be eliminated by falling RET prices, the development of novel rural RE business models and institutional support. In addition, growing smartphone penetration rates in rural areas and open-access online information enables do-it-yourself RET operation and maintenance. Integrated approaches and such insights are crucial for the targeted formulation of agricultural development policies and stakeholder involvement in the sustainability transition towards a bioeconomy. The third study investigates the characteristics of urban gardening in Germany and its potential to encourage sustainable consumer behaviour, based on a review of 657 urban gardening project websites and an online survey involving 380 project participants. The results reveal multiple social, environmental and economic benefits of urban gardens for sustainable city development. The diverse gardener communities actively promote sustainable consumer behaviour by (unintentionally) applying several methods known to encourage pro-environmental behaviour. Hence, urban gardens are transformative spaces that involve the growing urban population in the societal transition towards a bioeconomy. In the context of sustainable intensification of biomass production in rural areas, the fourth study investigates the contribution of environmental service assessment and monetization in agricultural systems, using the example of the perennial biomass crop miscanthus for biofuel production. The valorisation makes environmental services - such as soil fertility improvement, carbon sequestration, water and air purification – tangible. This can incentivise payments to farmers for the provision of these public goods. Enhancing and utilising environmental services through nature-based solutions is a promising pathway to sustainable intensification, providing a shift from input-based towards process-based agricultural production. Finally, it can be concluded that integrated approaches which connect different production systems, disciplines and stakeholders are central for the development of the bioeconomy: - The integration of sustainable technologies, such as RE, into agricultural systems requires case-based research and participation of local stakeholders in project planning, decision making and targeted policy formulation. - The integration of the growing urban population in the sustainability transition can be supported by urban gardening because it promotes sustainable consumer behaviour. - The integration of nature-based solutions into agricultural systems enhances environmental service provision and supports the shift from input-based towards process-based agricultural systems. The approaches discussed in this thesis can support the sustainable intensification of agriculture, serve to re-connect the perspectives of rural producers and urban consumers, and enable the involvement of large portions of society in the sustainability transition towards the bioeconomy.