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Agro-ecological intensification of agricultural systems in the African highlands

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Abstract

There is an urgent need to increase agricultural productivity in sub-Saharan Africa in a sustainable and economically-viable manner. Transforming risk-averse smallholders into business-oriented producers that invest in producing surplus food for sale provides a formidable challenge, both from a technological and socio-political perspective. This book addresses the issue of agricultural intensification in the humid highland areas of Africa – regions with relatively good agricultural potential, but where the scarce land resources are increasingly under pressure from the growing population and from climate change. In addition to introductory and synthesis chapters, the book focuses on four themes: system components required for agricultural intensification; the integration of components at the system level; drivers for adoption of technologies towards intensification; and the dissemination of complex knowledge. It provides case studies of improved crop and soil management for staple crops such as cassava and bananas, as well as examples of how the livelihoods of rural people can be improved. The book provides a valuable resource for researchers, development actors, students and policy makers in agricultural systems and economics and in international development. It highlights and addresses key challenges and opportunities that exist for sustainable agricultural intensification in the humid highlands of sub-Saharan Africa.
... The East African highlands can be characterized by relatively good rainfall and bi-modal cropping seasons. Together with the generally deep and well-drained soils, this results in relatively good agronomic potential (Vanlauwe et al., 2013). The population densities in the East African highlands, however, are among the highest in SSA (Vanlauwe et al., 2013), also resulting in average farm sizes that are among the smallest in SSA (Headey and Jayne, 2014a). ...
... Together with the generally deep and well-drained soils, this results in relatively good agronomic potential (Vanlauwe et al., 2013). The population densities in the East African highlands, however, are among the highest in SSA (Vanlauwe et al., 2013), also resulting in average farm sizes that are among the smallest in SSA (Headey and Jayne, 2014a). With growing populations across SSA (UN-DESA, 2019), current population densities, small farm sizes and other agricultural developments in the East African highlands may give an insight in future agricultural developments for other areas in SSA. ...
... Our study was conducted in western Kenya, which is representative of the East African highlands in terms of the bimodal rainfall pattern and deep soils, resulting in a favourable agroecological potential compared with many other regions of SSA (Vanlauwe et al., 2013). Most inputs were relatively easily available and to some extent, farmers were accustomed to applying mineral fertiliser and sowing improved varieties. ...
Thesis
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The UN Sustainable Development Goals of Zero poverty and Zero hunger include leaving no one behind as a key principle. However, many smallholder farmers in sub-Saharan Africa (SSA) are caught in a poverty trap, a vicious cycle of low productivity and limited ability to invest. Moreover, small farm areas may limit the potential benefits that can be accrued at farm level, even if productivity would increase. Sustainable intensification is a key strategy to increase agricultural production for the growing population in SSA, while at the same time avoiding the extension of agricultural land in natural areas. In the first part of the thesis I used an ‘impact-oriented’ perspective to assess, within current farming systems, to what extent integrated co-learning leads to sustainable intensification. In the second part I used a ‘target-oriented’ perspective to explore ‘viable farm sizes’ required to attain a living income (the income required for a decent living including a nutritious diet, clothes, schooling and housing). By situating this study in the East African highlands, characterized by high population density and small farm sizes, I revealed possible pathways towards more sustainable farming systems. We developed the ‘integrated co-learning approach’, which combines input vouchers with iterative learning cycles on sustainable intensification, and tested it in western Kenya from an impact oriented perspective. Farmers participating in co-learning had a more diverse and cohesive knowledge after five seasons compared to farmers who only received the voucher. Irrespectively of the co-learning, the voucher immediately increased farm level maize yield from less than 20% to 40-50% of water-limited yield. This indicates that closing yield gaps is mainly limited by capital constraints and not by technology or knowledge. However, co-learning facilitated the more complex changes in the cropping system that are required for sustain-able intensification, such as the incorporation of legumes. Although yields improved after the introduction of the voucher, the value of produce from crops was still below the living income benchmark for most households due to their small farm areas. Increasing yield alone was thus not enough to attain a living income from arable farming. Also for other indicators of sustainable intensification the desired outcomes were often not achieved. For instance, nitrogen (N) use efficiency remained too high, indicating the risk of soil N mining. Maize area and farm area also increased, all pointing towards the pathway of extensification instead of desired intensification. This implies the need for policies that favour increased input use and policies that limit area expansion. Building on the finding that farm size strongly limited farmer income, we explored viable farm sizes for contrasting future scenarios in three sites in the East African highlands. This target-oriented perspective revealed that in the current baseline scenario, cultivated areas per farm would have to increase by 4.5, 1.3 and 2.5 times in Nyando (Kenya), Rakai (Uganda) and Lushoto (Tanzania) respectively, to make a living income. However, if crop yields increased to 50% of the water-limited yields, current cultivated areas of most households (>70%) would be large enough to make a living income in Rakai and Lushoto. In Nyando additional sources of income, such as income from livestock, were required to make a living income. Comparing the outcomes of the two different perspectives indicates that increasing yields of staple crops, e.g. through input subsidies, is not enough for all farmers to make a living income from current farm sizes. Larger changes are required, both within the farming system, e.g. increasing farm areas and/or cultivating more profitable crops, as well as outside the farming system, e.g. alternative employment options outside agriculture. The integrated co-learning approach can be deployed to explore incentives for smallholder farmers to sustainably intensify. Further research is required on how to scale the approach and integrate it into extension systems while keeping the valuable farm-researcher feedback. The viable farm size as a benchmark is a useful method for assessing how to leave no one behind while moving towards more sustainable farming systems.
... Introduction East African Highland Banana (Musa acuminata genome group AAA-EA; hereafter referred to as banana) provides food and income for over 30 million inhabitants of the African Great Lakes Region [1]. The plant's asynchronous fruiting habit allows farmers to harvest throughout the year [2], providing a continuous supply of food in contrast with seasonal crops. ...
Article
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East African highland banana ( Musa acuminata genome group AAA-EA; hereafter referred to as banana) is critical for Uganda’s food supply, hence our aim to map current distribution and to understand changes in banana production areas over the past five decades. We collected banana presence/absence data through an online survey based on high-resolution satellite images and coupled this data with independent covariates as inputs for ensemble machine learning prediction of current banana distribution. We assessed geographic shifts of production areas using spatially explicit differences between the 1958 and 2016 banana distribution maps. The biophysical factors associated with banana spatial distribution and geographic shift were determined using a logistic regression model and classification and regression tree, respectively. Ensemble models were superior (AUC = 0.895; 0.907) compared to their constituent algorithms trained with 12 and 17 covariates, respectively: random forests (AUC = 0.883; 0.901), gradient boosting machines (AUC = 0.878; 0.903), and neural networks (AUC = 0.870; 0.890). The logistic regression model (AUC = 0.879) performance was similar to that for the ensemble model and its constituent algorithms. In 2016, banana cultivation was concentrated in the western (44%) and central (36%) regions, while only a small proportion was in the eastern (18%) and northern (2%) regions. About 60% of increased cultivation since 1958 was in the western region; 50% of decreased cultivation in the eastern region; and 44% of continued cultivation in the central region. Soil organic carbon, soil pH, annual precipitation, slope gradient, bulk density and blue reflectance were associated with increased banana cultivation while precipitation seasonality and mean annual temperature were associated with decreased banana cultivation over the past 50 years. The maps of spatial distribution and geographic shift of banana can support targeting of context-specific intensification options and policy advocacy to avert agriculture driven environmental degradation.
... Other important crops are maize, beans and Irish potato (Lyamchai et al., 2011). Population densities in the three sites ( Table 1) are typical for the areas where the largest part of the population of the East African highlands lives (Vanlauwe et al., 2013). ...
Article
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Smallholder farming in sub-Saharan Africa keeps many rural households trapped in a cycle of poor productivity and low incomes. Two options to reach a decent income include intensification of production and expansion of farm areas per household. In this study, we explore what is a “viable farm size,” i.e., the farm area that is required to attain a “living income,” which sustains a nutritious diet, housing, education and health care. We used survey data from three contrasting sites in the East African highlands—Nyando (Kenya), Rakai (Uganda), and Lushoto (Tanzania) to explore viable farm sizes in six scenarios. Starting from the baseline cropping system, we built scenarios by incrementally including intensified and re-configured cropping systems, income from livestock and off-farm sources. In the most conservative scenario (baseline cropping patterns and yields, minus basic input costs), viable farm areas were 3.6, 2.4, and 2.1 ha, for Nyando, Rakai, and Lushoto, respectively—whereas current median farm areas were just 0.8, 1.8, and 0.8 ha. Given the skewed distribution of current farm areas, only few of the households in the study sites (0, 27, and 4% for Nyando, Rakai, and Lushoto, respectively) were able to attain a living income. Raising baseline yields to 50% of the water-limited yields strongly reduced the land area needed to achieve a viable farm size, and thereby enabled 92% of the households in Rakai and 70% of the households in Lushoto to attain a living income on their existing farm areas. By contrast, intensification of crop production alone was insufficient in Nyando, although including income from livestock enabled the majority of households (73%) to attain a living income with current farm areas. These scenarios show that increasing farm area and/or intensifying production is required for smallholder farmers to attain a living income from farming. Obviously such changes would require considerable capital and labor investment, as well as land reform and alternative off-farm employment options for those who exit farming.
... Sound information of ecological interactions optimizes the management of service-providing organisms that contribute to increase productivity (Kremen 2005;Bianchi et al. 2006;Kremen et al. 2007;Bommarco et al. 2013;Gaba et al. 2014;Goedhart et al. 2018). Natural pest control is one of the main ecosystem services (Naylor and Ehrlich 1997;Chaplin-Kramer et al. 2011;Thies et al. 2011;Crowder and Jabbour 2013;Vanlauwe et al. 2014) and can be incorporated to agroecosystem management by increasing predatory species richness and abundance (Landis et al. 2000;Greenop et al. 2018). The present article studies a novel way to control acorn pests in oak agroforestry systems based on promoting intraguild predation on insects by livestock. ...
Article
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Iberian oak savannahs are traditional silvopastoral systems in which acorns constitute a key food source for livestock. Acorn feeding insects provoke significant economic losses; however, the high natural value of Iberian oak savannahs precludes any chemical treatment. This paper shows a novel way of biological pest control based on promoting livestock predation on these insects. Female Curculio elephas (Coleoptera: Curculionidae) oviposit into developing acorns, which are prematurely abscised before reaching their potential size. Larvae still spend 20 days feeding on the cotyledons after acorn drop, being during this period very vulnerable to predation by livestock. We experimentally assessed that cows, pigs and sheep ate sound and infested acorns in the same proportion, so that infestation rates were lower in those Iberian oak savannahs in which livestock density was higher. An effective biological control of Curculio elephas weevils should involve an early predation of infested acorns by livestock, preferentially within 10 days after falling. Doing this, most larvae will be predated before completing their development and, in addition, the nutritional value of infested acorns will still be high (cotyledons not yet depleted by weevils). We encourage landowners to increase livestock densities during September–October, when the infested acorn dropping peaks. These increased densities should rotate over the farm and be maintained at the same plot for a maximum of 3 years in a row. Otherwise, a prolonged and concentrated livestock predation on sound acorns and seedlings would hamper long-term oak regeneration.
... Besides increasing production and minimizing environmental impact, elements such as social and cultural perspectives are also included. Practices like mulching, intercropping, crop rotations, integrated soil-and nutrient management, soil-and water conservation, integrated pest management and biological control strategies and a balanced and more efficient use of fertilizers are mentioned as possible AEI strategies by different authors (Gliessman, 2000;Côte et al., 2010;Karamura et al., 2013;Vanlauwe et al., 2013;Wezel et al., 2015). 1 http://www.fao.org/faostat/en/#data/CC Several studies report the application of AEI practices on banana-based farms in Uganda and the Great Lakes region (Katungi et al., 2006;Jassogne et al., 2013;Mpiira et al., 2013;Ocimati et al., 2013;Ssebulime et al., 2017). ...
Article
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Agroecological intensification (AEI) practices relying on on-farm diversity tend to close nutrient cycles and reduce dependency on external inputs in agricultural systems. These practices improve the productivity of banana-based systems in Uganda, but their extent of implementation differs between and within regions. However, the impact of AEI practices on a broader range of objectives including environmental and nutritional objectives, is hardly quantified. Additionally, recommendations to improve the farm performance, given these options, are lacking. We, therefore, analyzed the current farm performance for these broad range of objectives and explored optimal farm reconfigurations in two Ugandan districts, one in Central Uganda and one in Southwestern (SW) Uganda. Given the heterogeneity of smallholder farms, a farm typology based on the applied AEI practices was developed. It classified the subsistence farms in Central Uganda into two extreme groups with an average of 11.0 and 16.4 AEI practices applied per farm. Farms in SW Uganda were moderately intensified (i.e., 13.0 practices). The FarmDESIGN model revealed a higher species diversity, relatively higher profitability (2,039 – 3,270 $/ha/year) and nutritional yield on farms in Central Uganda. However, relatively high soil erosion levels (0.243 – 0.240) and negative nitrogen (N) balances (−72 to −50 kg N/ha/year) were indicative of unsustainable practices. In contrast, farms in SW Uganda were less diverse and more market oriented. Their commercial orientation allowed investments in soil fertility management, resulting in more sustainable [low soil erosion level (0.172) and positive N balance (5 kg/ha/year)], but less profitable (506 $/ha/year) systems. To improve farm performance, bananas and other perennials played a key role. Explorations with Calliandra calothyrsus (Calliandra) hedgerow or Mucuna pruriens (Mucuna) cover crop increased on-farm mulch production, improved sustainability indicators and profitability. We conclude that AEI practices can improve farm performance, and a more intensive use would be beneficial. In addition, the FarmDESIGN model provides a useful tool for redesigning these farms, proposing different redesigns depending on farmers' objectives (profitability, productivity or sustainability), and for evaluating ex ante the impact of new agricultural measures on farm performance.
... Slope stabilization by low-cost gunny bags/ katta-crate structure should be used for sloppy areas. First-order gullies/ channels receiving small quantity of runoff should be stabilized either by brushwood check dams or loose stone masonry check dams (Angima et al., 2003;Barungi and Maonga, 2011;Mishra and Rai, 2013;Vanlauwe et al., 2013). Similarly, for larger gullies, masonry check dams are provided with aprons on lower side and their wing wall should be properly embedded in the Nala sites. ...
... This calls for sustainable intensification whose potential can be harnessed through application of ISFM. Vanlauwe et al. (2013) argue that the use of inorganic fertilizer to improve soil organic matter (SOM) increases fertilizer use efficiency thus minimizing nutrient losses to the environment. ISFM also envisages recycling of organic inputs, which builds the SOM pool over time resulting in healthy soils capable of delivering vital provisioning (e.g. ...
Article
Integrated soil fertility management (ISFM) has been widely promoted by research and philanthropic organizations as well as governments to increase crop yields and improve livelihoods of smallholder farmers in Africa. Therefore, it is surprising that there is still scant information on its impact on crop yields and household income. This paper uses a counterfactual model to assess ISFM impact on yields and total household incomes using farm household data from Tamale (Northern Ghana) and Kakamega (Western Kenya). The analyses reveal that ISFM adoption leads to an increase in maize yields by up to 27% in Tamale and 16% in Kakamega. Increasing the number of ISFM components, however, does not improve yields. Despite the effect on yields, adoption of ISFM does not increase total household incomes at both locations. Some implications for future research are discussed.
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Background: Heterobeltiosis is the phenomenon when the hybrid’s performance is superior to its best performing parent. Banana ( Musa spp. AAA) breeding is a tedious, time-consuming process, taking up to two decades to develop a consumer acceptable hybrid. Exploiting heterobeltiosis in banana breeding will help to select breeding material with high complementarity, thus increasing banana breeding efficiency. The aim of this study was therefore to determine and document the level of heterobeltiosis of bunch weight and plant stature in the East African highland bananas, in order to identify potential parents that can be used to produce offspring with desired bunch weight and stature after a few crosses. Results: This research found significant progressive heterobeltiosis in cross-bred ‘Matooke’ (highland cooking) banana hybrids, also known as NARITAs, when grown together across years with their parents and grandparents in Uganda. Most (all except 4) NARITAs exhibited positive heterobeltiosis for bunch weight, whereas slightly more than half of them had negative heterobeltiosis for stature. The secondary triploid NARITA 17 had the highest heterobeltiosis for bunch weight: 249% versus its matooke grandparent and 136% against its primary tetraploid parent. Broad sense heritability (across three cropping cycles) for yield potential and bunch weight were high (0.84 and 0.76 respectively), while that of plant stature was very low (0.0035). There was a positive significant correlation ( P < 0.05) between grandparent heterobeltiosis for bunch weight and genetic distance between parents (r = 0.39, P = 0.036), bunch weight (r = 0.7, P < 0.001), plant stature (r = 0.38, P = 0.033) and yield potential (r = 0.59, P < 0.001). Grandparent heterobeltiosis for plant stature was significantly, but negatively, correlated to the genetic distance between parents (r = -0.6, P < 0.001). Conclusions: Such significant heterobeltiosis exhibited for bunch weight is to our knowledge the largest among main food crops. Since bananas are vegetatively propagated, the effect of heterobeltiosis is easily fixed in the hybrids and will not be lost over time after the release and further commercialization of these hybrids.
Conference Paper
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This paper reviews the role of post-harvest mechanization and the attempts made in the Ethiopian post-harvest mechanization research. Quality and safe produce is very important to consumers and retailers. To satisfy the demands and prepare the market for foreign countries, post-harvest mechanization technologies are very important for Ethiopia. Research results show that post-harvest mechanization technologies can contribute to the food security of a country. According to different literatures, it is difficult to get the exact information on post-harvest losses of food grains in Ethiopia but the frequently used figure ranges from 20-30 percent. The figure increases up to 50 percent for perishable crops. Therefore, reducing the post-harvest loss is as equal as increasing crop productivity. This paper focuses on post-harvest-loss interventions through mechanization and the way forward to address the challenges.
Article
Poor yields of East African highland bananas (Musa spp., AAA-EAHB) on smallholder farms have often been attributed to problems of poor soil fertility. We measured the effects of mineral fertilizers on crop performance at two sites over two to three crop cycles; Kawanda in central Uganda and Ntungamo in southwest Uganda. Fertilizers were applied at rates of 0N–50P–600K, 150N–50P–600K, 400N–0P–600K, 400N–50P–0K, 400N–50P–250K and 400N–50P–600K kg ha−1 yr−1. In addition 60Mg–6Zn–0.5Mo–1B kg ha−1 yr−1 was applied to all treatments, with the exception of the control plots which received no fertilizer. Fresh bunch mass and yield increased with successive cycles. Yield increases above the control ranged from 3.1 to 6.2 kg bunch−1 (average bunch weight for all treatments 11.5 kg bunch−1) and 2.2–11.2 Mg ha−1 yr−1 (average yield for all treatments 15.8 Mg ha−1 yr−1) at Kawanda, compared with 12.4–16.0 kg bunch−1 (average bunch weight for all treatments 14.7 kg bunch−1) and 7.0–29.5 Mg ha−1 yr−1 (average yield for all treatments 17.9 Mg ha−1 yr−1) at Ntungamo. The limiting nutrients at both sites were in the order K > P > N. Potassium, N and P foliar nutrient mass fractions were below previously established Diagnosis and Recommendation Integrated System (DRIS) norms, with the smallest K mass fractions observed in the best yielding plots at Ntungamo. Total nutrient uptakes (K > N > P) were higher at Ntungamo as compared with Kawanda, probably due to better soil moisture availability and root exploration of the soil. Average N, P and K conversion efficiencies for two crop cycles at both sites amounted to 49.2 kg finger DM kg−1 N, 587 kg finger DM kg−1 P and 10.8 kg finger DM kg−1 K. Calibration results of the model QUEFTS using data from Ntungamo were reasonable (R2 = 0.57, RMSE = 648 kg ha−1). Using the measured soil chemical properties and yield data from an experiment at Mbarara in southwest Uganda, the calibrated QUEFTS model predicted yields well (R2 = 0.68, RMSE = 562 kg ha−1). We conclude that banana yields can be increased by use of mineral fertilizers, but fertilizer recovery efficiencies need to improve substantially before promoting wide-scale adoption.