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Approximately one-third of the global population suffering from chronic hunger are in sub-Saharan Africa (SSA). In addition to high prevalence of chronic hunger, millions of people suffer from micronutrient deficiencies. Meanwhile, there is growing consensus across scientific disciplines concurring that fish plays a crucial role in improving food and nutrition security. Therefore, the present review aims to demonstrate the role of fish and the whole fisheries sector towards securing food and nutrition security in SSA by summarizing the existing literature. Fish is a treasure store of animal protein and essential micronutrients such as zinc, iodine, calcium, and vitamins, which are essential in human nutrition and have proven to help reduce the risks of both malnutrition and non-communicable diseases. Policymakers, development agencies, and society should recognize the role that the fisheries sector can play in combatting hunger and undernutrition, especially for the poor and marginalized people in SSA. [ABSTRACT FROM AUTHOR]

Abstract: Rotation of nitrogen-fixing woody legumes with maize has been widely promoted to reduce the loss of soil organic matter and decline in soil biological fertility in maize cropping systems in Africa. The objective of this study was to determine the effect of maize-fallow rotations with pure stands, two-species legume mixtures and mixed vegetation fallows on the richness and abundance of soil macrofauna and mineral nitrogen (N) dynamics. Pure stands of sesbania (Sesbania sesban), pigeon pea (Cajanus cajan), tephrosia (Tephrosia vogelii), 1:1 mixtures of sesbania+pigeon pea and sesbania+tephrosia, and a mixed vegetation fallow were compared with a continuously cropped monoculture maize receiving the recommended fertilizer rate, which was used as the control. The legume mixtures did not differ from the respective pure stands in leaf, litter and recycled biomass, soil Ca, Mg and K. Sesbania+pigeon pea mixtures consistently increased richness in soil macrofauna, and abundance of earthworms and millipedes compared with the maize monoculture (control). The nitrate-N, ammonium-N and total mineral N concentration of the till layer soil (upper 20cm) of pure stands and mixed-species legume plots were comparable with the control plots. Sesbania+pigeon pea mixtures also gave higher maize grain yield compared with the pure stands of legume species and mixed vegetation fallows. It is concluded that maize-legume rotations increase soil macrofaunal richness and abundance compared with continuously cropped maize, and that further research is needed to better understand the interaction effect of macrofauna and mixtures of organic resources from legumes on soil microbial communities and nutrient fluxes in such agro-ecosystems. [Copyright &y& Elsevier]

Inputs of organic materials play a central role in the productivity of many tropical farming systems by providing nutrients through decomposition and substrate for synthesis of soil organic matter (SOM). The organic inputs in many tropical farming systems such as crop residues, manures, and natural fallows are currently of low quality and insufficient quantity to maintain soil fertility hence there is need to find alternative or supplementary sources of nutrients. Knowledge gained over the past decade on the role of organic resource quality in influencing soil nutrient availability patterns (Synchrony Principle) and SOM maintenance (SOM Principle) provides a strong scientific basis on which to develop management tools. This scientific information must be linked with farmer knowledge and circumstances to provide a realistic approach to soil fertility and SOM management in the tropics. A decision tree has been developed for testing hypotheses about the resource quality parameters that affect nitrogen release patterns and rates. The decision tree is linked to an Organic Resource Database (ORD) with detailed information on the resource quality of agroforestry trees and leguminous cover crops providing a systematic means of selecting organic resources for soil fertility management. The decision tree has also been translated into a practical field guide for use with farmers in evaluating organic materials. The longer-term effects of organic inputs on SOM might also be addressed through the decision tree and database. It is generally believed that materials good for short-term soil fertility will not build or maintain SOM; if true then it is difficult to imagine practical means of maintaining SOM in the African context where short-term fertility issues will take precedence over longer-term maintenance of SOM. [ABSTRACT FROM AUTHOR]

Frequent droughts have threatened the crop yields and livelihoods of many smallholder farmers in South Africa. Pigeonpea can be grown by farmers to mitigate the impacts of droughts caused by climate change. An experiment was conducted at Fountainhill Farm from January 2016 to December 2017. The trial examined grain yield in addition to water use efficiency (WUE) of pigeonpea intercropped with maize versus sole pigeonpea and maize. A randomized complete block design, replicated three times, was used. Soil water tension was measured at 20, 50, and 120 cm within plots. The highest and lowest soil water tension was recorded at 20 m and 120 m respectively. Combined biomass and grain yield were significantly different: pigeonpea + maize (5513 kg ha−1) > pigeonpea (3368 kg ha−1) > maize (2425 kg ha−1). A similar trend was observed for WUE and land equivalent ratio (LER), where pigeonpea + maize outperformed all sole cropping systems. The inclusion of pigeonpea in a traditional mono-cropping system is recommended for smallholder farmers due to greater WUE, LER and other associated benefits such as food, feed and soil fertility amelioration, and it can reduce the effects of droughts induced by climate change. [ABSTRACT FROM AUTHOR]

Renewed interest in the nexus between sustainability and food security has led to growing discussions on the use of food sovereignty principles in agricultural practice. As a result of the transfiguration of the urban and socioeconomic landscape in the global South, urban and peri-urban agriculture has been touted as a potential response to increasing food insecurity in cities. Yet, both urban and peri-urban agriculture and food sovereignty have attracted cursory scholarship and programming in Zimbabwe due to fixation on more dominant rural and conventional agriculture. Beyond the rudimentary idea that the urban landscape is unfit for food production, literature has demonstrated that urban households have ingrained urban and peri-urban agriculture into their livelihoods. Regardless, institutional arrangements governing the practice remain ambivalent towards the practice, bringing to question the ability of households to fully exploit the benefits of the practice. This review underscores that failure to involve of all stakeholders undermines urban and peri-urban agriculture, consequently leading to heightened food insecurity and use of unsustainable practices. By delving into the political economy of food, we hope to stimulate discussion centered on food sovereignty within and urban spaces and beyond. [ABSTRACT FROM AUTHOR]

Sub-Saharan Africa is faced with the challenge of improving current food security on highly degraded land. At the same time, the region has to develop strategies to ensure future food security for the increasing population under worsening climate change. Conventional tillage (CT) has for many years resulted in the deterioration of soil quality through depletion of soil organic matter. This review of literature provides an overview of the impact of conservation agriculture (CA) on soil quality with particular emphasis on key soil physical, chemical and biological properties. This paper also discusses impact of CA on yield, highlighting South African research gaps since the adoption is still very low in the country. The review of numerous studies indicated that soil quality and yield improvements are possible in CA although some negative results have also been reported under contrasting environments. Yield under CA were recognised to be resilient to seasonal rainfall variability compared with CT because of its ability to conserve water. CA is particularly relevant to the South African maize production given high levels of soil degradation, water scarcity and low soil fertility status. This review of literature demonstrated that CA can have substantial positive environmental, financial, social and health benefits for South Africa and the world. However, more research on CA is required from different agroecological zones and socio-economic contexts since maize is the biggest produced crop in South Africa. [ABSTRACT FROM AUTHOR]

• The majority of KwaZulu-Natal's SOC stocks were found to be distributed between 60–200 cm. • Forested areas in KwaZulu-Natal had the greatest SOC concentration per unit Area. • Rainfall, clay content, temperature, elevation, and RVI were found to be key determinants of SOC prediction at different depths. • DNN model performed well in topsoil (0–30 cm), but less accurate with deeper depth. The preservation and augmentation of soil organic carbon (SOC) stocks is critical to designing climate change mitigation strategies and alleviating global warming. However, due to the susceptibility of SOC stocks to environmental and topo-climatic variability and changes, it is essential to obtain a comprehensive understanding of the state of current SOC stocks both spatially and vertically. Consequently, to effectively assess SOC storage and sequestration capacity, precise evaluations at multiple soil depths are required. Hence, this study implemented an advanced Deep Neural Network (DNN) model incorporating Sentinel-1 Synthetic Aperture Radar (SAR) data, topo-climatic features, and soil physical properties to predict SOC stocks at multiple depths (0–30 cm, 30–60 cm, 60–100 cm, and 100–200 cm) across diverse land-use categories in the KwaZulu-Natal province, South Africa. There was a general decline in the accuracy of the DNN model's prediction with increasing soil depth, with the root mean square error (RMSE) ranging from 8.34 t/h to 11.97 t/h for the four depths. These findings imply that the link between environmental covariates and SOC stocks weakens with soil depth. Additionally, distinct factors driving SOC stocks were discovered in both topsoil and deep-soil, with vegetation having the strongest effect in topsoil, and topo-climate factors and soil physical properties becoming more important as depth increases. This underscores the importance of incorporating depth-related soil properties in SOC modelling. Grasslands had the largest SOC stocks, while commercial forests have the highest SOC sequestration rates per unit area. This study offers valuable insights to policymakers and provides a basis for devising regional management strategies that can be used to effectively mitigate climate change. [ABSTRACT FROM AUTHOR]

Breeders face serious challenges in breeding early-maturing maize hybrids which are required by farmers in marginal environments. The objectives of the study were to determine the genetic gain for breeding for high yield, and investigate levels of genetic variation, heritability and associations between grain yield and secondary traits in early-maturing hybrids. Fifty maize hybrids were evaluated at three sites in KwaZulu-Natal, South Africa in a 5 × 10 α-lattice design with two replications. Genetic gain for grain yield of 18 % was reflected by the top five experimental hybrids over the population mean, indicating a significant improvement. One of the top five hybrids 14XH293 was early-maturing and non-significantly different from other three top yielding intermediate to late hybrids but was as early as the early commercial checks. Significant genetic variation for grain yield, plant and ear height, grain moisture, days to anthesis and silking, ear position, ear prolificacy, number of ears and anthesis-silking interval was observed, indicating opportunities for further improvement of the hybrids. Grain yield was highly heritable (75 %) but heritability ranged from low (3 %) to high (79 %) for secondary traits. Both correlation (P ≤ 0.001) and regression (P ≤ 0.001) indicated that ear prolificacy is the highest contributor to grain yield improvement. Furthermore, ear prolificacy displayed the major direct effects on yield that was greater than its correlation with yield, indicating that selection for this trait would indirectly improve grain yield of early-maturing maize hybrids. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) stocks are critical for land management strategies and climate change mitigation. However, understanding SOC distribution in South Africa's arid and semi-arid regions remains a challenge due to data limitations, and the complex spatial and sub-surface variability in SOC stocks driven by desertification and land degradation. Thus, to support soil and land-use management practices as well as advance climate change mitigation efforts, there is an urgent need to provide more precise SOC stock estimates within South Africa's arid and semi-arid regions. Hence, this study adopted remote-sensing approaches to determine the spatial sub-surface distribution of SOC stocks and the influence of environmental co-variates at four soil depths (i.e., 0-30 cm, 30-60 cm, 60-100 cm, and 100-200 cm). Using two regression-based algorithms, i.e., Extreme Gradient Boosting (XGBoost) and Random Forest (RF), the study found the former (RMSE values ranging from 7.12 t/ha to 29.55 t/ha) to be a superior predictor of SOC in comparison to the latter (RMSE values ranging from 7.36 t/ha to 31.10 t/ha). Nonetheless, both models achieved satisfactory accuracy (R 2 ≥ 0.52) for regional-scale SOC predictions at the studied soil depths. Thereafter, using a variable importance analysis, the study demonstrated the influence of climatic variables like rainfall and temperature on SOC stocks at different depths. Furthermore, the study revealed significant spatial variability in SOC stocks, and an increase in SOC stocks with soil depth. Overall, these findings enhance the understanding of SOC dynamics in South Africa's arid and semi-arid landscapes and emphasizes the importance of considering site specific topo-climatic characteristics for sustainable land management and climate change mitigation. Furthermore, the study offers valuable insights into sub-surface SOC distribution, crucial for informing carbon sequestration strategies, guiding land management practices, and informing environmental policies within arid and semi-arid environments., Competing Interests: Competing interests The authors declare no conflict of interest.

The provision of resilience and adaptation to climate change to smallholder irrigation communities is a critical component in implementing common pool resource management. Institutions in many smallholder irrigation schemes in developing countries are diverse and have potential to contribute to building climate resilience and improving livelihoods of smallholder irrigator. Human behaviour, institutional capacity and culture play important roles in shaping adaptive capacity of communities to climate change. Although much is known about how these contribute to this adaptive capacity, research focusing on their interaction is limited. In order to close this the gap, this study seeks to explore how socio-demographic, governance and institutional factors influence adaptive capacity in Exchange, Insukamini and Ruchanyu irrigation schemes. Questionnaire-based interviews, group discussions and key informant interviews were used for data collection. Adaptive capacity calculated using the livelihood vulnerability model was used as the dependent variable for this study. Ordinary least square regression was used to assess socio-demographic, institutional and governance factors influencing adaptive capacity in the smallholder irrigation scheme. The study reveals that adaptive capacity is influenced by age, gender, education, land tenure security, irrigation committee satisfaction, cooperatives, and interaction of factors. The link between age and gender were negatively moderated by awareness of irrigation policies, access to credit and land tenure security. Assessing factors influencing adaptive capacity help to improve the livelihoods of scheme farmers in the face of climate change., Competing Interests: The authors have declared that no competing interests exist.