Micronutrient deficiencies in African soils and the human nutritional nexus: opportunities with staple crops

A synthesis of available agronomic datasets and peer-reviewed scientific literature was conducted to: (1) assess the status of micronutrients in sub-Saharan Africa (SSA) arable soils, (2) improve the understanding of the relations between soil quality/management and crop nutritional quality and (3) evaluate the potential profitability of application of secondary and micronutrients to key food crops in SSA, namely maize (Zea mays L.), beans (Phaseolus spp. and Vicia faba L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.). We found that there is evidence of widespread but varying micronutrient deficiencies in SSA arable soils and that simultaneous deficiencies of multiple elements (co-occurrence) are prevalent. Zinc (Zn) predominates the list of micronutrients that are deficient in SSA arable soils. Boron (B), iron (Fe), molybdenum (Mo) and copper (Cu) deficiencies are also common. Micronutrient fertilization/agronomic biofortification increases micronutrient concentrations in edible plant organs, and it was profitable to apply fertilizers containing micronutrient elements in 60–80% of the cases. However, both the plant nutritional quality and profit had large variations. Possible causes of this variation may be differences in crop species and cultivars, fertilizer type and application methods, climate and initial soil conditions, and soil chemistry effects on nutrient availability for crop uptake. Therefore, micronutrient use efficiency can be improved by adapting the rates and types of fertilizers to site-specific soil and management conditions. To make region-wide nutritional changes using agronomic biofortification, major policy interventions are needed

Soil health and ecosystem services: Lessons from sub-Sahara Africa (SSA)

Management practices to improve soil health influence several ecosystem services including regulation of water flows, changes in soil biodiversity and greenhouse gases that are important at local, regional and global levels. Unfortunately, the primary focus in soil health management over the years has been increasing crop productivity and to some extent the associated economics and use efficiencies of inputs. There are now efforts to study the inter-relationship of associated ecosystem effects of soil health management considering that sustainable intensification cannot occur without conscious recognition of these associated non-provisioning ecosystem services. This review documents the current knowledge of ecosystem services for key management practices based on experiences from agricultural lands in sub-Sahara Africa (SSA). Here, practicing conservation agriculture (CA) and Integrated Soil fertility management (ISFM) have overall positive benefits on increasing infiltration (> 44), reducing runoff (> 30%) and soil erosion (> 33%) and increases soil biodiversity. While ISFM and Agroforestry increase provisioning of fuelwood, fodder and food, the effect of CA on the provisioning of food is unclear. Also, considering long-term perspectives, none of the studied soil health promoting practices are increasing soil organic carbon (SOC). Annual contributions to greenhouse gases are generally low (< 3 kg N2O ha−1) with few exceptions. Nitrogen leaching vary widely, from 0.2 to over 200 kg N ha−1 and are sometimes inconsistent with N inputs. This summary of key considerations for evaluating practices from multiple perspectives including provisioning, regulating, supporting and cultural ecosystem services is important to inform future soil health policy and research initiatives in SSA

Soil fertility management in Babati: A practical guide on good agricultural management practices in smallholder farming systems

Working with farmers and extension staff within the Ministry of Agriculture and interactions with broad range of researchers across national research and CGIAR Centers operating in Northern Tanzania resulted in a wealth of experience and knowledge that we bring forward in this guide. We have observed wide yield gaps across farms and experienced first-hand key challenges faced by farmers as we worked in their fields, interacted in field days, participatory technology evaluations, exchange visits and brainstorming meetings with farmers. High attainable yields observed by some individual farmers and researchers in experimental and demonstration trials clearly demonstrate potential of applying simple agronomic and other supporting practices to change fortunes of farmers. This is what inspired this guide. Although expressed through simple illustrations and language, most of the data and information are generated through rigorous scientific and data analysis approaches to ensure accuracy of the information. The guide, a knowledge intensive resource, brings together key messages from 6 years of International Center for Tropical Agriculture’s (CIAT) operations in Babati and is a valuable management tool for farmers. It is also an essential reference tool for local agricultural extension and other stakeholders involved in the field of agriculture. The agricultural extension staff reviewed this guide during a workshop held on 17 June 2019 in Babati. These staff included: Jetrida Kyekaka, the District Agriculture, Irrigation and Cooperative Officer (DAICO); Rose Pallangjo, Jonus Masamu and Paulo Tarmo, the District Extension Officers; and Adelta Macha, an extension officer in Gallapo village

Rangeland Degradation: Causes, Consequences, Monitoring Techniques and Remedies

Rangelands occupy 25% of the total land surface globally. In Africa, rangelands are estimated to cover 66% of the land surface, although there are variations from country to country. In Eastern Africa, for example, land surface coverage of rangeland areas varies from 44% in Uganda and 65% in Ethiopia to 74% in Tanzania and over 80% in Kenya. Rangelands have environmental, social and economic benefits, including support to national economies through tourism and employment. In Kenya, tourism, much of which is attributed to rangelands, accounts for 13% of the gross domestic product. In Tanzania, tourism contributed 9.0% of the total GDP, supporting 26% of total exports, 8.2% of the total employment, and 8.7% of total investment in the year 2017. Despite their benefits, rangelands are under threat of continued degradation driven by anthropogenic and natural causes. Natural causes of rangeland degradation include climate change and variabilities, aridity and desertification, drought, as well as alien species invasion. Anthropogenic rangeland degradation can manifest through agricultural activities and associated developmental practices, overstocking and overgrazing, as well as breakdown of social structures and government policies/by-laws. Continuous overgrazing and overstocking not only affect soil physical (compaction, breakdown of aggregates) but also chemical (soil pH and salinization, nutrient leaching, diminishing organic matter content), and biological properties. These decrease rangeland production potentials. However, numerous strategies to arrest and remedy rangeland degradation, such as rangeland re-vegetation, water harvesting, soil surface scarification, and livestock grazing management are available. This report addresses rangeland degradation and potential control measures with a strong focus on soil aspects

Sudden flamingo deaths in Kenyan rift valley lakes.

The East African Rift Valley Lakes Bogoria and Nakuru sometimes host around 75% of the world population of lesser flamingos Phoeniconaias minor. In this area, mysterious flamingo die-offs have occupied researchers for four decades. Recently, cyanobacterial toxins came into the fore as a possible explanation for mass mortalities because the main food source of lesser flamingos is the cyanobacterium Arthrospira fusiformis. We took weekly samples from July 2008 to November 2009 from Lakes Nakuru and Bogoria and analyzed them by high performance liquid chromatography for microcystins. Monthly, samples were cross-checked using protein phosphatase inhibition assays with lower detection limits and additionally screened for polar toxins. During our study period, three flamingo die-offs occurred at L. Bogoria and we were able to analyze tissues of 20 carcasses collected at the shoreline. No cyanotoxins were detected either in plankton samples or in flamingo tissues. Accordingly, other reasons such as food composition or bird diseases played a key role in the observed flamingo die-offs

Continent-Wide Survey Reveals Massive Decline in African Savannah Elephants

African elephants (Loxodonta africana) are imperiled by poaching and habitat loss. Despite global attention to the plight of elephants, their population sizes and trends are uncertain or unknown over much of Africa. To conserve this iconic species, conservationists need timely, accurate data on elephant populations. Here, we report the results of the Great Elephant Census (GEC), the first continent-wide, standardized survey of African savannah elephants. We also provide the first quantitative model of elephant population trends across Africa. We estimated a population of 352,271 savannah elephants on study sites in 18 countries, representing approximately 93% of all savannah elephants in those countries. Elephant populations in survey areas with historical data decreased by an estimated 144,000 from 2007 to 2014, and populations are currently shrinking by 8% per year continent-wide, primarily due to poaching. Though 84% of elephants occurred in protected areas, many protected areas had carcass ratios that indicated high levels of elephant mortality. Results of the GEC show the necessity of action to end the African elephants’ downward trajectory by preventing poaching and protecting habitat

Detection of banana plants and their major diseases through aerial images and machine learning methods: A case study in DR Congo and Republic of Benin

Front-line remote sensing tools, coupled with machine learning (ML), have a significant role in crop monitoring and disease surveillance. Crop type classification and a disease early warning system are some of these remote sensing applications that provide precise, timely, and cost-effective information at different spatial, temporal, and spectral resolutions. To our knowledge, most disease surveillance systems focus on a single-sensor based solutions and lagging the integration of multiple information sources. Moreover, monitoring larger landscapes using unmanned aerial vehicles (UAV) are challenging, and, therefore combining high resolution satellite imagery data with advanced machine learning (ML) models through the use of mobile apps could help detect and classify banana plants and provide more information on its overall health status. In this study, we classified banana under mixed-complex African landscapes through pixel-based classifications and ML models derived from multi-level satellite images (Sentinel 2, PlanetScope and WorldView-2) and UAV (MicaSense RedEdge) platforms. Our pixel-based classification from random forest (RF) model using combined features of vegetation indices (VIs) and principal component analysis (PCA) showed up to 97% overall accuracy (OA) with less than 10% omission and commission errors (OE and CE) and Kappa coefficient of 0.96 in high resolution multispectral images. We used UAV-RGB aerial images from DR Congo and Republic of Benin fields to develop a mixed-model system combining object detection model (RetinaNet) and a custom classifier for simultaneous banana localization and disease classification. Their accuracies were tested using different performance metrics. Our UAV-RGB mixed-model revealed that the developed object detection and classification model successfully classified healthy and diseased plants with 99.4%, 92.8%, 93.3% and 90.8% accuracy for the four classes: banana bunchy top disease (BBTD), Xanthomonas Wilt of Banana (BXW), healthy banana cluster and individual banana plants, respectively. These approaches of aerial image-based ML models have high potential to provide a decision support system for major banana diseases in Afric

Human Salmonella and Concurrent Decreased Susceptibility to Quinolones and Extended-Spectrum Cephalosporins

For complicated infections, decreased susceptibility could compromise treatment with drugs from either antimicrobial class