Communicating uncertainties in spatial predictions of grain micronutrient concentration

The concentration of micronutrients in staple crops varies spatially. Quantitative information about this can help in designing efficient interventions to address micronutrient deficiency. Concentration of a micronutrient in a staple crop can be mapped from limited samples, but the resulting statistical predictions are uncertain. Decision makers must understand this uncertainty to make robust use of spatial information, but this is a challenge due to the difficulties in communicating quantitative concepts to a general audience. We proposed strategies to communicate uncertain information and present a systematic evaluation and comparison in the form of maps. We proposed testing five methods to communicate the uncertainty about the conditional mean grain concentration of an essential micronutrient, selenium (Se). Evaluation of the communication methods was done through a questionnaire by eliciting stakeholder opinions about the usefulness of the methods of communicating uncertainty. We found significant differences in how participants responded to the different methods. In particular, there was a preference for methods based on the probability that concentrations are below or above a nutritionally significant threshold compared with general measures of uncertainty such as the prediction interval. There was no evidence that methods which used pictographs or calibrated verbal phrases to support the interpretation of probabilities made a different impression than probability alone, as judged from the responses to interpretative questions, although these approaches were ranked most highly when participants were asked to put the methods in order of preference

Assessing the residual benefit of soil-applied zinc on grain zinc nutritional quality of maize grown under contrasting soil types in Malawi.

A proper understanding of the residual value of zinc (Zn) is necessary for sustainable biofortification of food crops. This study aimed to establish the extent to which application of Zn at the national rate, plus two experimentally elevated rates, in one year provided any benefit to plant yield and nutritional quality in the following growing season. Residual effects of soil-applied Zn on grain Zn concentration and uptake were estimated by an experiment in which maize was grown in successive seasons at two agricultural research stations in Malawi, with Zn applied to the soil in the first season but not the second. At each site two common soil types were used: Lixisols and Vertisols. The study used three Zn fertilizer rates of 1, 30 and 90 kg Zn ha -1 applied to the soil in the previous cropping season, arranged in a randomized complete block design (RCBD) with 10 replications at each experimental site. At harvest, maize grain yield and Zn concentration in grain and stover were measured; Zn uptake by maize grain and stover were determined and Zn harvest index was calculated. Effects on grain yield and Zn uptake by the crop were assessed in relation to residual Zn fertilizer and soil type. Maize grain yield on plots in the second season where 30 kg Zn ha -1 had been applied exceeded that on second season plots where 1 kg Zn ha -1 had been applied by 25%. The grain Zn concentration and Zn uptake in the second season after fertilizer application were larger by 13% and 30% respectively on the plots which had received 30 kg Zn ha -1 than those which had received 1 kg Zn ha -1 . There was no evidence that applying Zn at 90 kg Zn ha -1 resulted in larger crop yield, grain Zn concentration, or Zn uptake the second year after application than was seen in plots the second year after application of 30 kg Zn ha -1 . The magnitude of the benefits attributed to residual effects of soil-applied Zn did not depend on soil type. Conclusively, the residual effects of 30 kg ha -1 of soil-applied Zn in the preceding season benefited the subsequent maize compared to the national recommendation of 1 kg Zn ha -1 . The benefits of larger applications of Zn than the current national recommendations should be considered across at least two seasons and for different crops

Preparing for a community-based agriculture-to-nutrition trial in rural Malawi: formative research to assess feasibility and inform design and implementation decisions.

BACKGROUND: This study reports findings from formative research conducted to assess the feasibility and inform the design and implementation of the Addressing Hidden Hunger with Agronomy (AHHA) trial. The AHHA trial was a randomised, controlled trial conducted in rural Malawi, in which participants were given maize flour biofortified with selenium or control flour not biofortified with selenium for a period of 10 weeks, after which blood samples were taken to measure selenium status. METHODS: Formative research was conducted in villages near to the AHHA trial study site 1 year before the planned intervention. A short questionnaire with adult women (n = 50), focus group discussions with male (n groups = 3) and female (n groups = 3) community members, and in-depth key informant interviews (n = 7) were conducted to understand community practices and perceptions. FINDINGS: Meals were typically cooked and eaten at home in this community, while participants reported that maize flour would be less readily sold than maize grain - important considerations for the design of the trial. Regarding intervention delivery, we identified potential concerns around effects on fertility, links between blood sampling and witchcraft, and the potential for social stigma if community members considered participants lazy for receiving free flour. Participants reported that involvement of the Malawi government partners including health extension workers would increase trust. INTERPRETATION: Following the formative research, the AHHA trial appeared feasible. However, community sensitisation would be essential to address potential fears and concerns; effective sensitisation would support recruitment and treatment adherence, and would protect the safety and wellbeing of participants and researchers. People in positions of authority and trust including village headmen, religious leaders, health and agriculture extension workers, and community care groups should be involved in community sensitisation

Can selenium deficiency in Malawi be alleviated through consumption of agro-biofortified maize flour? Study protocol for a randomised, double-blind, controlled trial

Micronutrient deficiencies including selenium (Se) are widespread in Malawi and potentially underlie a substantial disease burden, particularly among poorer and marginalised populations. Concentrations of Se in staple cereal crops can be increased through application of Se fertilisers – a process known as agronomic biofortification (agro-biofortification) – and this may contribute to alleviating deficiencies. The Addressing Hidden Hunger with Agronomy (AHHA) trial aims to establish the efficacy of this approach for improving Se status in rural Malawi

Stakeholder interpretation of probabilistic representations of uncertainty in spatial information: an example on the nutritional quality of staple crops

Spatial information, inferred from samples, is needed for decision-making, but is uncertain. One way to convey uncertain information is with probabilities (e.g. that a value falls below a critical threshold). We examined how different professional groups (agricultural scientists or health and nutrition experts) interpret information, presented this way, when making a decision about interventions to address human selenium (Se) deficiency. The information provided was a map, either of the probability that Se concentration in local staple grain falls below a nutritionally-significant threshold (negative framing) or of the probability that grain Se concentration is above the threshold (positive framing). There was evidence for an effect of professional group and of framing on the decision process. Negative framing led to more conservative decisions; intervention was recommended at a smaller probability that the grain Se is inadequate than if the question were framed positively, and the decisions were more comparable between professional groups under negative framing. Our results show the importance of framing in probabilistic presentations of uncertainty, and of the background of the interpreter. Our experimental approach could be used to elicit threshold probabilities which represent the preferences of stakeholder communities to support them in the interpretation of uncertain information

Letter to the Editor: response to global soil science research collaboration in the 21st century: time to end helicopter research by Minasny et al

Budiman Minasny and colleagues (Minasny et al., 2020) are to be congratulated for their incisive article about helicopter research in soil science, as are the editors of Geoderma for their new policy such that papers reporting research with primary data collection should include authors from the countries concerned. On the basis of our shared experience, as collaborating investigators working on soil science research in sub-Saharan Africa, we recognize the importance of this issue and its wider implications for sustainability of both research collaboration and development partnerships. We are collaborators on the CEPHaS project, a project funded by the UK Government’s Global Challenges Research Fund, which addresses the development of capacity in soil physics, geophysics, hydrogeology and statistics to study conservation agriculture, a suite of interventions aimed at improving resilience of soils and crops under climate change. CEPHaS involves researchers from Zambia, Zimbabwe, Malawi and the United Kingdom – soil scientists, agronomists, agricultural economists, social scientists, geophysicists, hydrogeologists and statisticians. We have been collaborating on the project since October 2017, and many of us have been working together for longer than that. In this letter we share some aspects of our experience, practices and policies which we think go some way towards facilitating more equitable partnership in research. In summary, we think that the problem of helicopter research can be tackled only through the development of genuine partnerships, in which the global asymmetries of power and wealth between north and south are not allowed to distort the research agenda or to prevent equitable collaboration in which the interests, opportunities and contribution of all parties are respected. This requires a commitment to capacity strengthening and long-term engagement on the part of researchers, their institutions and the funders of research

Prevalence of plastic and hardware foreign bodies among goats at Malawi markets

Smallholder goat production plays a major role in rural livelihoods and food security in Malawi, but suffers from drastic and unpredictable production losses. While goat production is closely linked to small-scale local markets for slaughter and butchering, the perspectives of butchers and their potential as a source of animal health information are largely untapped. Butchers can provide insights into goat health status at slaughter as well as issues that go unseen before slaughter, such as the presence of indigestible foreign bodies (IFBs). IFBs include solid materials such as plastics and hardware (metals, stones, and other hard objects) that cause foreign body syndrome and can lead to impaction, oedema, malnutrition, and death. To estimate the presence of IFBs, 150 market stand butchers were surveyed across five districts in Malawi, focusing on a distinction between hardware and single-use plastics, which are still widely present in Malawi despite bans on production. Most butchers found plastic IFBs (80.7%), with over half (56.7%) reporting plastic IFBs recently among the past five slaughters. Hardware IFBs were less common, reported by 45.3% of butchers. While some butchers commented on the impact of IFBs on meat quality metrics ex-post, the majority observed no differences. While butchers unanimously considered health to be an important characteristic when sourcing goats, 70.7% consider injury status to be less important or not important. Overall, this study highlights the issue of anthropogenic waste pollution on goat production in Malawi and demonstrates the potential for the surveillance of goat health at market.<br/

Goat health and management for improved smallholders’ livelihoods in central Malawi – a socioeconomic analysis of rural households

The true value of goats, their management systems, and the limitations of smallholdings have not been fully explored in the context of sustainable livelihoods among rural smallholders in central Malawi. However, goats are an essential part of rural livelihoods as transferable assets and sources of household nutrition, especially at times of food insecurity aligned to an ever more variable climate. To study the impact and limitations of goat ownership in Malawi’s Lilongwe district, surveys were performed across four villages covering 148 households from October-November 2019. Surveys were designed to identify linkages between household demographics, livelihoods, goat ownership, and management practices. Findings revealed goats are highly valued compared to other livestock. However, herds were small (median = 3) with only 62% reported kidding in the last year, while 50% reported deaths due to diseases, predation (such as by hyenas), and dog bites. Odds-ratio analyses identified farmers (as a primary occupation) were more likely to successfully breed goats to increase their herd size. Larger herds were associated with those who could accumulate wealth and utilise goats for ceremonies. However, diseases were a major contributor to losses and increased the risk of household food insecurity. Limiting disease impacts through anthelmintics and supplementation were correlated to an increased likelihood of sustainable offtake from smallholdings and improved livelihoods. With limited access to veterinary services, smallholders utilise a diversity of medicinal plants and ash to treat diarrhoea in their herd. The results highlight that goat security and health is fundamental to realising smallholding livelihood gains. Future efforts should aim to empower smallholders through providing tools to monitor goat health and to assess the effects of local practices, including the use of medicinal plants, for goat health.<br/

Increasing zinc concentration in maize grown under contrasting soil types in Malawi through agronomic biofortification: trial protocol for a field experiment to detect small effect sizes

The prevalence of micronutrient deficiencies including zinc (Zn) is widespread in Malawi, especially among poor and marginalized rural populations. This is due to low concentrations of Zn in most staple cereal crops and limited consumption of animal source foods. The Zn concentration of cereal grain can be increased through application of Zn‐enriched fertilizers; a process termed agronomic biofortification or agro‐fortification. This trial protocol describes a field experiment which aims to assess the potential of agronomic biofortification to improve the grain Zn concentration of maize, the predominant staple crop of Malawi. The hypotheses of the study are that application of Zn‐enriched fertilizers will create a relatively small increase in the concentration of Zn in maize grains that will be sufficient to benefit dietary supplies of Zn, and that the effectiveness of agronomic biofortification will differ between soil types. The study will be conducted at three sites, Chitedze, Chitala, and Ngabu Agricultural Research Stations, in Lilongwe, Salima, and Chikwawa Districts respectively. These three sites represent locations in the Central and Southern Regions of Malawi. At each site, two different sub‐sites will be used, each corresponding to one of two agriculturally important soil types of Malawi, Lixisols, and Vertisols. Within each sub‐site, three Zn fertilizer rates (1, 30, and 90 kg/ha) will be applied to experimental plots using standard soil application methods, in a randomized complete block design. The number of replicates at plot level has been informed by a power analysis from pilot study data, assuming that a minimum 10% increase in Zn concentration of grain at 90 kg/ha relative to the concentration at 1 kg/ha is of interest. Grain mass (yield), stover mass, and both stover and grain Zn concentrations will be measured at harvest. A second year of cropping will be used to establish whether there are any residual benefits to grain Zn concentration. The potential for Zn agronomic biofortification will be communicated to relevant academic and government stakeholders through a peer review journal article and a briefing paper