Knowledge for a sustainable world

BSc (Hons), PGCE, MSc, PhD
Professor Tanya E Stathers
Professor of Sustainable Agri-Food and Postharvest Systems and Practice

Food and Markets Department

Natural Resources Institute, Faculty of Engineering & Science

+44 (0)1634 88 3626

Tanya has worked as an agriculture for development researcher across sub-Saharan Africa and other geographies for > 25 years. Using interdisciplinary and participatory approaches, her work focuses on deepening understanding of and supporting sustainability of various dimensions of smallholder agri-food systems, with a particular interest in postharvest and collective-learning aspects.

Tanya has worked for the Natural Resources Institute (NRI) since 1998, mainly in Tanzania and Kenya (2004-2015). Prior to joining NRI she worked as a researcher at the Cocoa and Coconut Research Institute in Papua New Guinea (1997-98), and on the Cashew Research Programme at Naliendele Agricultural Research Institute in Mtwara, southern Tanzania (1993-95).

Tanya’s research has encompassed an unusually broad range of agricultural development issues including: agricultural adaptation to climate change, urbanising food systems, rural-urban interdependencies, drivers of food choice, reduction and quantification of postharvest food losses, seed systems, use of agricultural innovation systems approach, the role of experiential and multi-stakeholder social-learning processes and tools for increasing sustainability of food systems, poverty impacts of market certification standards, gender and diversity aspects of agri-food systems, as well as field and laboratory research trials into a range of pre and postharvest constraints across a variety of tropical crops. She recently led the Ceres2030 systematic review and evidence synthesis on effective interventions to reduce postharvest losses in 22 different food crops for 57 countries in sub-Saharan Africa and south Asia.

Her interest in the use of creative adult education approaches for strengthening agricultural skills and knowledge has seen her develop several agricultural for development continued professional development training courses. She also delivers seminars on climate change adaptation and postharvest systems and supervises several international postgraduate research students.

She has long-term experience in Tanzania, Kenya and Papua New Guinea, and significant field work experience in Malawi, Zimbabwe, Ethiopia, Rwanda, Uganda, South Africa and Zambia. She speaks Swahili and slightly rusty French.

Every year after harvest, USD$ 4 billion worth of cereal grains alone are lost across Sub-Saharan Africa, this is valuable food that could have fed millions of people and driven economic activity in the region. Much of Tanya’s >25 years of research within agricultural innovation systems across sub-Saharan Africa has focused on the participatory development and promotion of knowledge and effective and acceptable technologies that can help in reducing these postharvest food losses, and particularly those during food storage. She is also involved in quantifying what and why losses are happening at each postharvest stage in different crops, and the financial and nutritional impacts of these losses for countries helping them shape more targeted loss reduction investments.

Realising the importance of experiential learning approaches in building capacity, she has co-developed a number of practical training courses, manuals and other supporting materials for trainers and farmers. Amongst these are the WFP ‘Training Manual for Improving Grain Postharvest Handling and Storage’, the Moyo Nuts/ New Rotations Zambia ‘Improving Groundnut Production and Postharvest Handling and Storage’ and the Reaching Agents of Change ‘Everything you ever wanted to know about sweetpotato’.

Tanya’s main research interests and areas of expertise include:

  • Participatory multi-stakeholder collective-learning around:
    • transforming food systems and urban-rural interdependency
    • reducing food loss and waste
    • agricultural adaptation to climatic and other drivers of change

Tanya has developed and written several research-based training manuals, and created accompanying experiential-learning training courses and appropriate tools including sets of visual flip-charts to facilitate field-based agriculture training and cartoon handouts. These continued-professional development tools combine technical elements of agricultural topics with a hands-on-learning approach. Examples include:

The ‘Everything you ever wanted to know about sweetpotato’ training-of-trainers’ manual and course she developed for the Reaching Agents of Change programme, and updated for use by the Building Nutritious Food Baskets project. The manual has been translated into French, Portuguese, Kiswahili and Amharic and is used in >11 countries, and as a run-for-profit course by training institutes in Ghana, Nigeria, Burkina Faso, Mozambique, and Tanzania.

The ‘Training Manual and Course on Improving Grain Postharvest Handling and Storage’ she co-developed for the World Food Programme (WFP) with Rick Hodges, is widely-used in >21 countries for training groups of smallholder-farmers to improve the quality of their produce through better postharvest management enabling them to gain access to higher value quality-sensitive markets.

The ‘Improving Groundnut Production and Postharvest Handling and Storage’ manual, course, field charts and farmer handouts developed to assist two private-companies in Malawi and Zambia in building farmers’ capacity to access higher quality aflatoxin-free groundnut markets.

In 2017, as part of a scaling initiative she worked with a CIP team and developed trainers’ guides, farmer handouts and field charts on sweetpotato planting material conservation ‘Triple S (sand, storage, sprouting)’ enabling farmers to produce sweetpotato planting materials prior to the rain season; thus providing food during the hungry season, climate-resilience and extra income. These tools have been used to train service providers in nine African countries, who have used them to train >10,000 farmers.

She also co-supervises postgraduate students registered at the University of Zimbabwe and University of Greenwich. She lectures and provides practical training on Climate Change and Postharvest Systems, and Postharvest Entomology in two MSc programmes. She led the creation and delivery of a short training course on ‘Agricultural adaptation to climate change’ for >40 university lecturers and postgraduate students from Ethiopia and Uganda during the Biofarming initiative. She also acts as a personal tutor to overseas MSc students studying at the University of Greenwich.

She was also involved in developing one of UoG’s earliest e-distance learning MSc programmes on Grain Storage Management in 2000.

Expanding the African Postharvest Losses Information System – APHLIS+

Dates: 2016-2022
Partners: EC Joint Research Council, Agricultural Knowledge Management Services, University of Zimbabwe, network members in 37 Sub-Saharan African countries
Donor: Bill and Melinda Gates Foundation

The 2008 food crisis caused development agencies involved in improving food security across sub-Saharan Africa to realise they needed a more detailed and accurate understanding of the level of postharvest loss of staple food crops occurring

The African Postharvest Losses Information System (APHLIS) was developed and launched in 2009, to bring a rigorous knowledge management approach to cereal postharvest losses (PHL). Tanya leads two work packages: i) development of nutritional and financial dimensions of postharvest loss (PHL) estimates, and ii) expansion of APHLIS to include other key staple food crops (i.e. cowpeas, common beans, groundnuts, cassava), this is being done through combining meta-analysis of loss data from the scientific literature with contextual postharvest data. Since February 2021, she has also become the APHLIS project coordinator.


Ceres2030 Sustainable Solutions to End Hunger

Dates: 2019-2020

As donors mobilise to meet the targets set by Sustainable Development Goal 2, one of the most pervasive challenges they will face involves information: they need to know how much it costs to fix the problem, what interventions are most effective in solving it, and how they affect the rest of the economy. Ceres2030 brought together economic modelling, machine learning, and evidence-based synthesis into one initiative, helping fill a major knowledge gap in the field of agricultural and food policy. Ceres2030 connected this knowledge back to the donor community, making sure decision makers have the cost figures and evidence they need when deciding where and how to make their investments.

Over 70 researchers volunteered to be part of the Ceres2030 team to generate evidence on where to prioritise spending on interventions to achieve Zero Hunger by 2030. Tanya led the Reducing Food Loss team for Ceres2030 systematically reviewing and synthesising the evidence on interventions for reducing postharvest losses in 22 key food crops in smallholder agri-food systems in sub-Saharan Africa and south Asia.


Addressing postharvest bottlenecks: what role for solar powered storage of fresh sweetpotato roots in sub-Saharan Africa? – an integral part of the Sweetpotato Action for Security and Health in Africa (SASHA II) project

Dates: 2015-2019
Partners: International Potato Centre (CIP), Organi Ltd.
Donor: Bill and Melinda Gates Foundation

Africa is rapidly urbanising. Fresh sweetpotato roots are already an important part of urban diets in many countries. Exciting new initiatives include the use of orange-fleshed sweetpotato (OFSP) puree in bread recipes by major supermarket chains in Kenya, helping to provide vital Vitamin A in the diets of the rapidly growing urban population. However, a year-round supply of fresh sweetpotato roots and sweetpotato products is required to meet these urban consumers’ demands; this can be achieved either through constant year-round production and supply of fresh roots or through a combination of staggered production and the storage of fresh OFSP roots to cover periods of low supply.

One of the objectives of the Sweetpotato Action for Security and Health in Africa (SASHA II) project is to investigate whether commercial-scale storage of fresh OFSP roots is feasible.

To better understand whether fresh root storage might offer opportunities within this OFSP supply chain, in 2015 Tanya undertook a detailed value chain study involving 59 stakeholder and focus group interviews across eight focal counties in Kenya to understand existing sweetpotato value chains, their seasonality, farmers’ production trends and constraints, traders’ root sourcing and trading patterns, price dynamics, retailing behaviours, and consumers’ preferences. This found that large quantities of yellow-fleshed sweetpotato roots are traded from Kabondo and Migori to the large urban markets in Kisumu, Nakuru and Nairobi, with traders sequentially purchasing roots from different areas during the year in order to smooth the supply. Prices vary between the peak and low supply seasons by up to 70%, suggesting that storage has the potential to reduce cost to the consumer. Only very limited amounts of OFSP are currently grown in these counties. The findings of this study were combined with different OFSP puree and fresh root requirement scenarios to calculate the storage capacity needed for a puree processor to hold at least one month’s stock of OFSP roots to control and smooth their supply chain, and reduce the impact of price rises during the low season. Based on this, a medium scale (10 - 30 tonnes) fresh root storage facility was constructed at the processor’s site in Homa Bay (see summary brief).

Tanya has then designed and together with the Organi Ltd and CIP team run a series of fresh OFSP root storage trials in three different storage facilities (2016-2019) at the Organi Ltd in western Kenya. These trials have compared the storage characteristics of different OFSP varieties, and different pre-postharvest handling and curing practices on stored root quality during 4 months storage (see summary briefs 20162017, 2018).

To better understand demand for OFSP fresh roots amongst urban consumers, Tanya has worked with the CIP team in designing and leading a study of consumer awareness of, demand for and packaging of vitamin A rich OFSP roots in informal markets and high-end grocery stores in Nairobi (2018).


Supporting smallholder farmers in southern Africa to better manage climate-related risks to crop production and postharvest handling

Dates: 2013-2016
Partners: University of Zimbabwe, Chitedze Agricultural Research Services Malawi, Food and Agriculture Organisation, University of Pretoria, FANRPAN, SOFESCA, University of Wageningen
Donor: European Union

Southern Africa is prone to extreme weather events, such as drought, floods and tropical cyclones, which have devastating impacts on human health, agriculture, infrastructure and other key socio-economic sectors. These climate-related shocks severely affect the livelihoods of the region’s population; 75% of who depend on predominantly rain-fed agriculture. Climate change, with projected increases in the incidence and intensity of extreme climatic events, is likely to exacerbate existing vulnerabilities.

This project aimed to i) develop and promote innovative techniques, methods and approaches for smallholder farmers to manage risks to crop production and postharvest handling associated with drought, floods and cyclones, and ii) strengthen regional knowledge and institutional arrangements on risk management for crop production and postharvest handling in areas prone to climatic hazards.

Tanya was involved in the design and implementation of community-profiling surveys in southern Malawi and Hwedza and Mbire districts of Zimbabwe in 2013 and 2014, which sought to understand farmers and key stakeholders’ experiences and perspectives on the impacts of and coping strategies for climate-related risks and longer-term adaptation options.

This shaped the development of the activities for building postharvest capacity of key agricultural service providers and actors; and learning alliances for community testing of different stored grain (sorghum, maize, cowpeas) treatment options which Tanya has been involved in.


Exploring rural-urban interdependence and the impact of climate change on interdependent food and agricultural systems in Tanzania and Malawi

Dates: 2009-2012
Partners: Institute of Resource Assessment University of Dar es Salaam, Chancellor College University of Malawi, ARI Hombolo Tanzania, ARI Uyole Tanzania, INADES Formation Tanzania, Bvumbwe ARI Malawi
Donor: FCDO (previously DFID) and IDRC

Background: Africa is rapidly urbanizing. By 2030 there are projected to be over 759 million African urban dwellers. This poses major challenges for the further provision of infrastructure and services. Alongside this, Africa is particularly vulnerable to climate change and climate variability (CC&CV). As urbanisation and inequality increase, more sophisticated analyses of the linkages and interdependencies between rural and urban areas are emerging. Flows of products, people, knowledge and information, natural resources and money provide strong and dynamic linkages.

Objectives: This research project funded by IDRC and FCDO aimed to strengthen the capacity of individuals, organizations and systems within the agriculture and food innovation systems connecting rural and urban communities in Tanzania and Malawi to adapt to the challenges and opportunities arising from CC&CV.

Results: The project used a multi-stakeholder participatory action research process to explore Rural-Urban interdependencies and climate change (CC). This helped raise awareness amongst local government and other stakeholders regarding urban-rural linkages, urban food systems and their vulnerability to climate change, highlighting important knowledge gaps surrounding urban food security. An experiential learning approach supported peri-urban horticultural producers to work together with other key agricultural stakeholders (e.g. researchers, extension, micro-credit, stockists, and NGOs) and develop horticultural learning plots on which they experimented with soil water conservation techniques (including admixture of manure, reduced width and levelling of seed beds), new varieties, tower gardening techniques (important for situations where land and water are scarce, and for women and disabled persons), different pesticide application methods and crop diversification opportunities (such as sunflower production fields). The process strengthened farmers’ ability to analyse and test ways of improving their situation, to link with other stakeholders and led to a fast uptake of sustainable technologies. The participating farmers managed to significantly increase their profits from horticultural production through increased yields and quality (and therefore prices) and reduced water and land requirements. Neighbouring farmers requested training from the learning group members and copied new practices. In Malawi, urban agriculture was incorporated into national and local government policy and will build on the project’s activities recognising that horticultural systems can be adapted to both improve capacity of vulnerable people and strengthen resilience of food systems.

NRI’s Dr Tanya Stathers and Richard Lamboll participated in the project design, urban food systems situation analysis, and the multi-stakeholder learning processes.


Development of a post-harvest handling and storage handbook and training approach for the World Food Programme’s (WFP), Purchase for Progress (P4P) programme

Dates: 2011-2013
Donor: Bill and Melinda Gates Foundation

Background: WFP aims to purchase food from areas close to where relief food is needed. Over 950 Farmers’ Organisations (FOs) in 20 developing countries are registered to supply grain to WFP through the P4P programme for local food aid procurement. Many of these FOs struggle to supply WFP with cereals and beans that meet quality and safety standards. To help them meet quality standards, FOs are trained in postharvest handling and storage (PHHS).

Objectives: To develop a comprehensive set of Postharvest Handling and Storage training materials and to help ensure a common basis based on best practice for PHHS training efforts within WFP’s Purchase for Progress (P4P) programme. This will enable FOs to collect, store and supply better quality grain to WFP.

Results: The ‘Training Manual for Improving Grain Postharvest Handling and Storage’ can be viewed online. 4,000 copies have been printed in English for distribution to the trainers in the Anglophone P4P focal countries, and 2,000 copies in French. The manual includes technical PHHS information for improving household, primary aggregation point and warehouse level PHHS, it includes ~200 cartoons and 6 posters for farmer training which are designed so the text can be added in the relevant vernacular language, it also includes a detailed section on ‘How to deliver training on PHHS’ using an experiential learning approach.

NRI’s Dr Stathers and Prof Hodges analysed the existing training materials, conducted a detailed needs assessment with key players in 3 focal P4P countries, designed, wrote and developed the manual and approach. They along with colleagues also created the text underlying the World Bank’s 2011 ‘Missing Food’ report which proposes an approach to reducing cereal postharvest losses in Sub-Saharan Africa – this builds on their long and detailed field experiences of smallholder postharvest systems.


Assessing the poverty impact of social and environmental voluntary standard systems in the Kenyan tea sector

Dates: 2010-2013
Partners: Matrix Kenya
Donor: FCDO (previously DFID)

Background: Social and environmental voluntary standards, such as Fairtrade and Rainforest Alliance certification, are becoming increasingly common in global value chains. However, there is limited systematic evidence available on the impact and development potential of such standards. Donors, the media, NGOs, academics and development practitioners, as well as the voluntary standard bodies themselves are all keen to understand better what difference these standards make to disadvantaged workers and smallholders.

Objective: to systematically examine the impact of voluntary social and environmental standards on poverty and livelihoods, particularly for the most disadvantaged workers and producers in developing countries.

Results: The impact of social and environmental voluntary standards systems was studied in tea (in Kenya and India) and cocoa (in Ghana and Ecuador) amongst smallholder, outgrowers and estate producers. The study used large scale quantitative surveys and numerous sequential qualitative interviews with various stakeholders (e.g. producer organisation managers, smallholder and outgrowers famers (men and women), estate workers (men and women), key informants (e.g. local leaders, academics, trade unions), standard bodies).

Amongst smallholder growers tea farming is their main source of income. The strict quality criteria, increased plucking frequency and crop husbandry trainings associated with the Fairtrade and Rainforest Alliance certifications have led to improved green leaf quality and higher yields which translates to higher tea incomes particularly when the tea prices are high. They have been able to invest more in their children’s education, and the Fairtrade premium has been used for a wide range of community investments. These farmers incur long-term and short-term costs associated with being certified but generally feel the benefits outweigh the costs. The detailed findings of certification impacts for smallholders, outgrowers and estate workers are presented in the final report (Stathers, Gathuthi et al., 2013. Poverty impact of social and environmental voluntary systems in Kenyan tea).

NRI’s Dr Stathers led the Kenyan study involving design and implementation of the field work, and analysis and reporting of all the information collected.

  • Daniel Mbogo – Reducing acrylamide risk in processed sweetpotato
  • Shaw MlamboGrain postharvest pest management in maize smallholder systems in a changing climate – University of Zimbabwe
  • Macdonald MubayiwaSmallholder postharvest technologies to manage climate-related risks in selected sorghum production systems - University of Zimbabwe
  • Charles SinganoInvestigation of grain postharvest technologies and systems for managing climate-related risks in smallholder farms of Shire Valley, southern Malawi – University of Zimbabwe
  • Tinashe NyabakoDevelopment of a smart-phone based decision-support system for grain postharvest management in Zimbabwe – University of Zimbabwe
  • Onika StellingburgAn investigation into the factors that influence food choice among Gillingham North Residents – University of Greenwich
  • Technical committee member of the International Working Conference on Store Product Protection (IWCSPP)
  • Technical committee member of the All Africa Postharvest Congress and Exhibition
  • Reviewer for various research journals including Food Policy, Food Security, Global Food Security, Journal of Stored Products Research, Crop Protection, Scientific Reports, Agricultural Education and Extension amongst others
  • Proposal reviewer for various donors and organisations
  • Award: De Montfort prize as one of Britain’s Top Younger Researchers at the House of Commons in March 2001
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