Diversity and Diversification: Ecosystem Services Derived From Underutilized Crops and Their Co-benefits for Sustainable Agricultural Landscapes and Resilient Food Systems in Africa

There are growing calls to adopt more sustainable forms of agriculture that balance the need to increase production with environmental, human health, and wellbeing concerns. Part of this conversation has included a debate on promoting and mainstreaming neglected and underutilized crop species (NUS) because they represent a more ecologically friendly type of agriculture. We conducted a systematic review to determine the ecosystem services derived from NUS and assess their potential to promote functional ecological diversity, food and nutritional security, and transition to more equitable, inclusive, sustainable and resilient agricultural landscapes and food systems in Africa. Our literature search yielded 35 articles for further analysis. The review showed that NUS provide various provisioning, regulating, cultural, and supporting ecosystem services and several environmental and health co-benefits, dietary diversity, income, sustainable livelihood outcomes, and economic empowerment, especially for women. Importantly, NUS address the three pillars of sustainable development-ecological, social, and economic. Thus, NUS may provide a sustainable, fit-for-purpose transformative ecosystem-based adaptation solution for Africa to transition to more sustainable, healthy, equitable, and resilient agricultural landscapes and food systems.

Visioning a food system for equitable transition towards sustainable diets

The Global Goals to end hunger requires interpretation of problems, and change across multiple domains. We facilitated a workshop aimed at understanding how stakeholders problematise sustainable diet transition (SDT) among a previously-marginalised social group. Using the systems thinking approach, three sub-systems, access to dietary diversity, sustainable beneficiation of natural capital, and 'food choice for well-being', highlighted the main forces governing the current context, and future interventions. Moreover, when viewed as co-evolving processes within the multi-level perspective, our identified microlevel leverage points - multi-faceted literacy, youth empowerment, deliberative policy-making, promotion of sustainable diet aspirations - can be linked and developed through existing national macrolevel strategies. Thus, by reconsidering knowledge use in the pursuit sustainability, transformational SDT can streamline multiple outcomes to restructure socio-technical sectors, reconnect people to nature-based solutions and, support legitimate aspirations. The approach could be applied in countries having complex socio-political legacy and to bridge the local-global goals coherently.

Towards the Three Dimensions of Sustainability for International Research Team Collaboration: Learnings from the Sustainable and Healthy Food Systems Research Programme

This paper highlights the potential for learning and virtual collaboration in international research teams to contribute towards sustainability goals. Previous research confirmed the environmental benefits of carbon savings from international virtual conferences. This paper adds the social and economic dimensions by using a combination of qualitative and quantitative methods to measure the constraints and benefits for personal development, economic costs, efficiency and team learning of holding international virtual conferences (VCs). Using the Sustainable and Healthy Food Systems (SHEFS) research programme as a case study, we analysed VC participant survey data to identify strengths, weaknesses, opportunities, and threats of VCs. We estimated 'saved' GHG emissions, costs, and time, of using VCs as an alternative for a planned in-person meeting in Chennai, India. Hosting VCs reduced North-South, gender, and researcher inclusivity concerns, financial and travelling time costs, and substantially reduced emissions. For one international meeting with 107 participants, changing to a virtual format reduced the per capita GHG emissions to half the annual global average, and avoided 60% of travel costs. The benefits of VCs outweighed weaknesses. The main strengths were inclusivity and access, with 20% more early/mid-career researchers attending. This study identified opportunities for international research partnerships to mitigate their carbon footprint (environmental benefit) and enhance inclusivity of early/mid-career, women and Global South participants (social benefit), whilst continuing to deliver effective collaborative research meetings (economic benefit). In doing so, we present a holistic view of sustainability opportunities for virtual collaboration.

Urban nexus and transformative pathways towards resilient cities: A case of the Gauteng City-Region, South Africa

Challenges emanating from rapid urbanisation require innovative strategies to transform cities into global climate action and adaptation centres. We provide an analysis of the impacts of rapid urbanisation in the Gauteng City-Region, South Africa, highlighting major challenges related to (i) land use management, (ii) service delivery (water, energy, food, and waste and sanitation), and (iii) social cohesion. Geospatial techniques were used to assess spatio-temporal changes in the urban landscapes, including variations in land surface temperatures. Massive impervious surfaces, rising temperatures, flooding and heatwaves are exacerbating the challenges associated with rapid urbanisation. An outline of the response pathways towards sustainable and resilient cities is given as a lens to formulate informed and coherent adaptation urban planning strategies. The assessment facilitated developing a contextualised conceptual framework, focusing on demographic, climatic, and environmental changes, and the risks associated with rapid urbanisation. If not well managed in an integrated manner, rapid urbanisation poses a huge environmental and human health risk and could retard progress towards sustainable cities by 2030. Nexus planning provides the lens and basis to achieve urban resilience, by integrating complex, but interlinked sectors, by considering both ecological and built infrastructures, in a balanced manner, as key to resilience and adaptation strategies.

A systems analysis and conceptual system dynamics model of the livestock-derived food system in South Africa: A tool for policy guidance

Global food production systems are currently under scrutiny, in particular the health, nutrition, and environmental impacts of livestock-derived food (LDF). Despite South Africa's recent socio-economic transformation and increased per-capita LDF consumption, the triple burden of malnutrition persists. Policy responses to such complex problems often fail because of linear thinking with short-term goals. However, a systems approach helps identify root causes, feedback mechanisms, potential unintended consequences, and opportunities for integrated, durable solutions. Participation in the systems-thinking process improves stakeholder understanding and buy-in. Our participatory workshop facilitated the development of a systems map for South African LDF, identifying key system elements, linkages, and nexus points. The latter included climate change, land access and management, livestock management and productivity, farming systems, food safety, policy articulation, agricultural knowledge, and income. Based on these findings, and an overview of related literature, we produced a conceptual system dynamics model of the LDF system. We identified key vari-ables and causal relationships, vicious and virtuous loops, system archetypes, conceptual stock and flows, and links to Sustainable Development Goals. The LDF system is complex and dynamic, with a dominance of commercial enterprises across agriculture and food retail, presenting barriers for small and medium-scale individuals. Other key elements relate to population growth and urbanization, land access, deregulation of international trade, climate change vulnerability, feed production limitations, and food safety. Our work provides a unique reference for policymakers, identifying the need for deep structural change, highlighting the possible unintended consequences, and thereby mitigating the risk of system destabilization.

Mainstreaming Underutilized Indigenous and Traditional Crops into Food Systems: A South African Perspective

Business as usual or transformative change? While the global agro-industrial food system is credited with increasing food production, availability and accessibility, it is also credited with giving birth to 'new' challenges such as malnutrition, biodiversity loss, and environmental degradation. We reviewed the potential of underutilized indigenous and traditional crops to bring about a transformative change to South Africa's food system. South Africa has a dichotomous food system, characterized by a distinct, dominant agro-industrial, and, alternative, informal food system. This dichotomous food system has inadvertently undermined the development of smallholder producers. While the dominant agro-industrial food system has led to improvements in food supply, it has also resulted in significant trade-offs with agro-biodiversity, dietary diversity, environmental sustainability, and socio-economic stability, especially amongst the rural poor. This challenges South Africa's ability to deliver on sustainable and healthy food systems under environmental change. The review proposes a transdisciplinary approach to mainstreaming underutilized indigenous and traditional crops into the food system, which offers real opportunities for developing a sustainable and healthy food system, while, at the same time, achieving societal goals such as employment creation, wellbeing, and environmental sustainability. This process can be initiated by researchers translating existing evidence for informing policy-makers. Similarly, policy-makers need to acknowledge the divergence in the existing policies, and bring about policy convergence in pursuit of a food system which includes smallholder famers, and where underutilized indigenous and traditional crops are mainstreamed into the South African food system.

Modelling of Changes in Postharvest Quality Parameters of Stored Carrots Subjected to Pre- and Postharvest Treatments

The aim of this study was to develop qualitative models that enable prediction of quality of carrots. A full factorial experiment including preharvest biocatalyst application, dipping treatments and storage temperatures was employed. Eleven different biochemical and microbiological quality parameters of carrot (Daucus carota L.) were investigated. The effects of treatments on the shelf-life were investigated using discriminant analysis (DA). The lower storage temperatures (1°C) maintained the superior quality. Kinetic functions were applied to each parameter using the Levenberg–Marquardt algorithm to characterize the rate of change of quality. DAs significantly (P < 0.001) differentiated between the combined effects of the preharvest biocatalyst treatment and storage temperatures. Four discriminant functions factored the differentiation of the quality attributes based on storage time. The models fit well to the experimental data for storage at 1°C. The second-order reaction equations allowed for prediction of ascorbic acid, sucrose and sugar–hexose ratio. First-order reaction equations that allow estimation of fructose, sucrose equivalent, total coliform and total fungi and O2 were developed. The empirical evidence suggests that freshness was maintained in the carrots until day 14 (P < 0.001). Ascorbic acid, sucrose and sugar–hexose ratio were the most relevant parameters to rapidly detect the postharvest changes following the second-order decay rate.

Evaluation of Chemical, Biochemical and Microbiological Quality in Tomato Using Multivariate Analysis

Tomato quality is determined by metabolite content which is governed by post-harvest physiological changes. A 30-day full factorial experiment investigated pre-packaging, disinfection and storage temperatures on 18 different biochemical, microbiological, enzymatic and subjective quality attributes of tomato quality. Principal component analysis revealed associations among the variables such as PC1 (28.85%): coliform/enzymatic softening; PC2 (21.52%): free sugars/sweetness; and PC3 (18.20%): sucrose hydrolysis/microbial spoilage/defense metabolites. Discriminant analysis showed that some specific parameters were highly significant (P<0.001) in determining quality changes in relation to the washing procedures and storage temperature. The prominence of ascorbic acid was observed in the equations which discriminate mostly on the basis of microbial deterioration. Further works in this respect entail fine-tuning through model verification of the equations. Multivariate analysis techniques are, therefore, recommended in studies whereby understanding of the phenomenon driving the post-harvest system’s dynamics has to be understood through diverse interrelated metabolic parameters.

Quantitative exposure of root crops to indicator enterobacteria from composted spent broiler litter under sub-tropical environment

The study aimed to quantify and compare the incremental exposure of root crops, at point of harvest, to enteric pathogens from untreated vs. composted spent broiler litter (SBL)/bagasse mix in field-crop application. An exposure assessment based on the Source-Pathway-Receptor approach was developed for bacterial indicator species, total coliforms, faecal coliforms, Escherichia coli and faecal enterococci. Event trees were constructed to model the pathways leading to the partitioning of pathogens present in the SBL blend during composting and after land application. The main barriers are induction of composting, high-rate thermophilic phase, maturation phase, and, decay and dilution of the indicator pathogens in the soil. The computed exposures have been expressed in terms of the arithmetic mean. TC, FC, E. coli and FE levels on root crops were reduced to very remote fractions of 0.01826, 0.00046, 0.000132 and 0.000013 kg(-1), respectively. The degree of by-pass (pi) of the treatment at operational scale showed that less than 1-log reduction has been by-passed during each turning event, revealing the effectiveness of turning for process control. The predicted E. coli counts on root crops at point of harvest provided a basis for estimating the exposure potential by the beta-Poisson model. Probability of exposure was 0.782 for raw SBL mix compared to 1.40x10(-11) with composting. It can be concluded that there is a definite advantage in optimally composting SBL mix before land application. The exposure assessment may essentially require modification and fine tuning as and when further data become available.

Transformation of spent broiler litter from exogenous matter to compost in a sub-tropical context

Composting, an environmentally-sound treatment option for confined animal feeding operations (CAFO)-derived wastes, provides opportunities for stabilisation and hygienisation. A 110-day systematic composting study investigated Salmonella presence and survival of total coliforms, faecal coliforms, Escherichia coli and faecal enterococci in three experimental windrows consisting of SBL/bagasse mixture in a close-sided roofed facility. Salmonella was absent throughout the experiment. Log(10) reductions of -6.98, -8.03, -8.18 and -5.96 occurred in TC, FC, E. coli and FE concentrations respectively. As expected, FE exhibited resistance to high temperature compared to E. coli especially for the first 21 days. Temperature histories revealed hygienisation attainment. Differences in mean, representing benchmark stages of composting, were highly significant (P<0.05) for all pathogen indicators. VSRed (%) proved effective in depicting system progress. Final respiration rate of 0.000206 mg CO(2)g(-1) organic-C day(-1) with no phytotoxicity showed the stability achieved. Besides stabilisation, quantitative analysis of the sanitisation potential of composting is elemental for hygienic compliance.

Survival kinetics of faecal bacterial indicators in spent broiler litter composting

AIMS

The objective of this study was to deduce and analyse equations that best describe the behaviour of faecal bacterial indicators and two decomposition parameters during broiler litter composting. Mathematical models were fitted and the order of rate equations were identified.

METHODS AND RESULTS

The Levenburg-Marquardt algorithm was used to fit nonlinear mathematical models to total coliforms (TC), faecal coliforms (FC), Escherichia coli (EC), faecal enterococci (FE), organic-C and volatile solids reduction, VS Red, by the least squares procedure. The rate equations showed that TC, FC and EC reductions were expressed by second-order decay kinetics. FE reduction followed first-order decay. Temperature dependency of decomposition rate was effectively verified by applying empirically derived rate equations.

CONCLUSIONS

The governing mathematical models critically compare the inactivation kinetics of faecal indicators. TC, FC and EC were rapidly destroyed while FE was more resistant. Temperature elevation, organic-C and VS Red dynamics provide an accurate understanding of composting-induced decomposition of the broiler litter.

SIGNIFICANCE AND IMPACT OF THE STUDY

The conservative performance of FE with respect to the other indicators has been established. Hence, FE presents better opportunities to encompass the totality of the composting process in terms of attainment of hygiene efficacy compared with EC.