Author: angharad-johnson

Legumes are valued worldwide as a sustainable and inexpensive food source and are considered second only to cereals for global food security _¹. In addition to their nitrogen-fixing ability, they are nutritionally valuable providing proteins, essential amino acids, complex carbohydrates and dietary fiber, vitamins and minerals _¹, _² . They have also been ascribed cultural and medicinal roles due to their possession of active bio-compounds _¹. For thousands of years this cultural significance has influenced our selective breeding of only the most palatable and fecund legumes _³. It has followed that in modern times the focus of our scientific research has remained limited to this exclusive, select few. Within the field of genomics, this has given rise to a group of ‘model’ legumes from which all of our current genetic understanding is based.

Rapid developments in DNA and RNA sequencing have greatly advanced our genomic knowledge of these model legumes. Their reference genomes have allowed researchers to decipher key genes, pathways, and networks regulating biological mechanisms and important agronomic traits _{^{2, 4}}. This has allowed for more targeted and efficient breeding and cross-breeding of some major economic legumes such as the Peanut _⁵.

While this is undoubtedly crucial knowledge for food security, our genomic maps remain largely limited to sphere of dietary legumes. The rest is uncharted territory. We have little genomic knowledge of forage legumes in comparison, leaving our agricultural systems vulnerable to the effects of climate change. But, thanks to organizations like the International Center for Tropical Agriculture (CIAT), we do now have genomic references for some of the major animal forage and fodder legumes, including Alfalfa, Soybean and Cowpea _⁶.

The Cowpea (Vigna unguiculata) for example is one of the most important forage legumes in tropical and sub-tropical regions with over 14 million hectares of agricultural land planted with it across the globe _⁷. Thanks to CIAT’s Tropical Legumes Projects, we have identified locations within its genomic map that code for important agronomic traits including drought resistance and efficient seed development.

Genetic markers have been used to target these locations and facilitate more efficient and directed breeding depending on what producers need – (I discuss in the previous post how we might better understand ‘what producers need’ through a conceptual approach that incorporates the different ago-ecological dimensions of a farming system).

Despite these major breakthroughs, large gaps remain in the forage legume germplasm collection. It is still a long way from from being representative of the total geographic diversity of tropical legumes _⁸.

Yet, in a round-about way, this is a positive as it can mean only one thing – that there is an unknown quantity of functionally important genes out there in the wilderness, just waiting to be discovered. Within this diversity are almost certainly to be unique sequences not found within our model set that confer novel ways to adapt and survive the growing effects of climate change. Through the continued genomic mapping of these wild and geographically dispersed species, we can begin to chart new territory. We can learn how these genes are linked to others and how they are passed down through generations. From there we can learn how to breed them quickly and efficiently and integrate them into our agricultural systems.

To keep with the vernacular, what Mr. Peanut and his exclusive club of model legumes need are a few wild characters to liven up the party!

_{^{1 -Maphosa, Y., & Jideani, V. A. (2017). The role of legumes in human nutrition. Functional food-improve health through adequate food, 1, 13.}}

_{^{2 – Dai, X., Zhuang, Z., Boschiero, C., Dong, Y., & Zhao, P. X. (2021). LegumeIP V3: from models to crops—an integrative gene discovery platform for translational genomics in legumes. Nucleic Acids Research, 49(D1), D1472-D1479.}}

_{^{3- Liu, J., Yu, X., Qin, Q., Dinkins, R. D., & Zhu, H. (2020). The impacts of domestication and breeding on nitrogen fixation symbiosis in legumes. Frontiers in genetics, 11, 973.}}

_{^{4 – Pandey, M. K., Roorkiwal, M., Singh, V. K., Ramalingam, A., Kudapa, H., Thudi, M., … & Varshney, R. K. (2016). Emerging genomic tools for legume breeding: current status and future prospects. Frontiers in Plant Science, 7, 455.}}

_{^{5 -Vishwakarma, M. K., Nayak, S. N., Guo, B., Wan, L., Liao, B., Varshney, R. K., & Pandey, M. K. (2017). Classical and molecular approaches for mapping of genes and quantitative trait loci in peanut. In The peanut genome (pp. 93-116). Springer, Cham.}}

_{^{6 -Kulkarni, K. P., Tayade, R., Asekova, S., Song, J. T., Shannon, J. G., & Lee, J. D. (2018). Harnessing the potential of forage legumes, alfalfa, soybean, and cowpea for sustainable agriculture and global food security. Frontiers in plant science, 9, 1314.}}

_{^{7-Agbicodo, E. M., Fatokun, C. A., Muranaka, S., & Visser, R. G. (2009). Breeding drought tolerant cowpea: constraints, accomplishments, and future prospects. Euphytica, 167(3), 353-370.}}

_{^{8-Schultze-Kraft, R., Peters, M., & Wenzl, P. (2020). A historical appraisal of the tropical forages collection conserved at CIAT. In Genetic Resources.}}

Mr. Peanut is taking a break this week, after a busy few months (but don’t worry, he’ll be back soon!).

Instead, just for today, I am posting about a news article I read this week regarding the recent wave of Guerilla Gardening. The ‘re-wilding’ of urban landscapes through the somewhat haphazard planting of native wildflower seed bombs.

I have always viewed this as a positive thing, for both native pollinators and biodiversity in general and I am well and truly on the bandwagon! This is made evident by the web page I have dedicated to updating anyone who will listen on the progress of my Beebomb garden.

That was until I came across a recent article in The Irish Times; an Expose’ on the so called “Trinity Debate” by Michael Viney. Apparently, some botanists from Dublin’s Naturalists’ Field Club (DNFC) are not wild about Trinity College’s newly planted wildflower meadow….

Their argument raises some valid points including the displacement of native species and the potentially unnatural composition of species that grow from a typical wildflower mix.

The article states-

“To the DNFC ,“simply introducing colourful flowers … at best provides a short-term food supply for some common insects that are not threatened.

The typical mix of plant species contained in “wildflower” seed packets “is never found growing together in the wild”. Natural habitats, formed by local conditions, grow the plants adapted to them and these colonise the ground by natural means. Conserving natural habitats should be the priority. And even mowing old lawns less often can allow native species already in the soil bank to flower and set seed.“

Given I recently wrote about the importance of ecological context in crop breeding and commercial seed production, in an effort to be slightly less hypocritical I thought it important to give some air time to the lesser known, CON side of the current ‘Re-Wilding’ argument.

So please, have a read of the Irish Times article and feel free to tell me your thoughts on the Trinity Debate in the comment section below!

So far, my blog posts have (I hope) given some insight into why Tropical Forage Legumes are a vital tool in helping us lessen the contribution of agriculture to climate change. They can also help us adapt our agricultural systems to cope with its effects. I have touched on the role of ‘Adaptive Traits’ in both of these endeavors. Today, I hope to delve a little deeper into this with an important case study that aided the development of my conceptual approach to successful trait selection towards the main objective of ‘Climate Proof’ forage legumes.

Adaptive Traits are those that confer some sort of advantage in a given context. In a drought prone area this could be deep roots that can access the below ground water table. Or, as a previous post discussed, in areas where fire is a significant risk , it could be ‘fire-proof’ seed-pods that can withstand extreme heat of wildfire and go on to germinate.

In the context of livestock production there are other factors to consider and a specific set of adaptive traits needed. A recent Review of Tropical Forage Legumes in Brazil highlighted the importance of context and management via a failed attempt to introduce legumes into a livestock grazing system.

A few years ago in Brazil, in an attempt to improve soil health, cattle farmers introduced a native Stylosanthes legume species into their predominantly Brachiaria grass pastures _¹. But far from delivering on the promise of improved productivity, these legumes failed to thrive _¹ . After only a few years they had died out and disappeared from the pasture biome altogether – an expensive and worrying problem for the farmers. An investigation found the ‘Crown-Forming’ structure of these Stylosanthes legumes had unforeseen consequences.

If we look at the diagram above, we see that crown-forming legumes like Alfalfa, Sainfoin (and indeed many Stylosanthes species) display a tall, elongated primary axis _^2. When planted in the pasture, these legumes grew taller than their neighboring grasses and were left exposed above the pasture canopy. As a result, they disproportionately suffered defoliation by livestock _¹. In layman’s terms they were more easily and more often eaten by the cattle until they were ‘grazed-out’ all together. This phenomenon was consistently observed in cattle farms across Brazil and for several years caused significant worry for livestock farmers.

Because legumes play a vital role in soil health and fertility, these Stylosanthes/Brachiaria pastures became degraded and less fertile over time as they reverted back to solely Brachiaria. This resulted in lower quality grazing and lower quality cattle _¹ . This had knock on effects for the economic security of the farmers who are paid in weight per carcass _^3. It also lead to lower systematic efficiency across the board – a big problem for global Food Security and Climate Change.

Unlike these tall, crown-wearing legumes, other legume crops such as many of the Clover cultivars (Trifolium spp.) exhibit shorter axes which spread outwards instead of upwards and keep below the pasture canopy _². They are therefore likely to suffer less defoliation stress and may persist in the pasture biome for longer. Had farmers perhaps used a well matched Trifolium spp. instead of a Stylosanthes spp., this costly problem could have been avoided.

This case study highlights why commercial legume cultivars must be matched not only with the climate, but also with the specific agricultural context. I discuss this in my literature review and have developed a preliminary, conceptual approach to trait selection in legumes for downstream commercial breeding pipelines. I identify three major dimensions that I consider critical for trait selection and breeding of superior cultivars – Climate Change, External Inputs and Natural Endowments. Some of my previous posts have already discussed climate change. Lets now explore the other dimensions…..

External Inputs

The ‘External Inputs’ dimension could be broadly considered as everything farmers can control and manage _^4,5. It includes factors like the irrigation system in place, animal density per hectare and the relative pasture biome. Defoliation stress by over-grazing for example is related to both herd density and pasture biome and falls within this dimension.

In smaller, lower-input farms with fewer animals, the problem of over-grazing and defoliation might not be such a problem. However, in a larger more industrial scale context, where herds are bigger and grazing is more intense, this should be a major concern. For developing countries in the tropical zone undergoing major livestock intensification, this example is particularly relevant.

Irrigation also has a major contextual impact. A farm that has an irrigation system in place will have a less urgent need for drought resistance legumes compared to a ‘rain-fed’ farm wholly dependent on the weather. This farm will be far more vulnerable to the effects of drought and will need legumes selected or designed to withstand periods of high stress.

Natural Endowments

This dimension broadly encompasses everything that cannot be controlled to any major degree. Depending on the context or discipline, it may be considered as ‘Natural Assets’, ‘Natural Capital’ or ‘Ecosystem Services’ _⁶. It can include elements of the natural landscape such as proximity to natural water bodies, elevation and slope and soil type (i.e. predominantly clay or sand) _^4,5.

These dimensions interact with each in a multitude of ways; the number of computations across the many variables is vast. A farm located on a steep hill with sandy soil for example will experience higher rates of erosion and poor soil quality than one located at the bottom of a valley in predominately clay soil (particularly if located in a region experiencing higher rainfall as a result of climate change). Each context will require different legumes and solutions…..

Trade-Offs

There are also trade-offs involved between agricultural yield and environmental considerations. To strike the right balance between food security and climate change outcomes, genomic approaches to crop breeding should aim to match different cultivars with particular farming systems, ecological contexts and local climates.

As the field of legume genomics advances and commercial breeding strategies improve, we may begin to more accurately target commercial cultivars to suit a specific set of needs. In the meantime, by taking these other dimensions into consideration, we are more likely to prevent costly and largely avoidable mistakes as that experienced in Brazil.

Direction over Perfection

However, as the Sixth IPCC report makes strikingly clear, we are running out of time to meet climate targets _⁷. We cannot wait for the ‘perfect crop’ before we take action. In this (and all) sustainable agricultural endeavors, we should aim for ‘Direction over Perfection’.

By using this contextually based directional approach to trait selection in legumes and other important crops, we are more likely to be successful in developing superior and successful cultivars for climate change action without sacrificing food security.

_{^{1 – Boddey, Robert M, Daniel Rume Casagrande, Bruno GC Homem, and Bruno JR Alves. 2020. ‘Forage legumes in grass pastures in tropical Brazil and likely impacts on greenhouse gas emissions: A review’, Grass and Forage Science, 75: 357-71}}

_{^{2 – Faverjon, L., Escobar-Gutiérrez, A. J., Litrico, I., & Louarn, G. (2017). A conserved potential development framework applies to shoots of legume species with contrasting morphogenetic strategies. Frontiers in Plant Science, 8, 405.}}

_{^{3- Ritchie, Hannah, and Max Roser. 2017. ‘Meat and dairy production’, Our World in Data}}

_{^{4 – Mendelsohn, Robert, and Jinxia Wang. 2017. ‘The impact of climate on farm inputs in developing countries agriculture’, Atmósfera, 30: 77-86.}}

_{^{5 -Pandey, CB, RC Srivastava, and RK Singh. 2009. ‘Soil nitrogen mineralization and microbial biomass relation, and nitrogen conservation in humid‐tropics’, Soil Science Society of America Journal, 73: 1142-49}}

_{^{6 -Martinez-Harms, M. J., Gelcich, S., Krug, R. M., Maseyk, F. J., Moersberger, H., Rastogi, A., … & Pascual, U. (2018). Framing natural assets for advancing sustainability research: translating different perspectives into actions. Sustainability science, 13(6), 1519-1531.}}

_{^{7 -IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press.}}

Ahead of the COP26 in Glasgow, the IPCC this week released their sixth assessment report on climate change. The landmark report “is a code red for humanity”, says the UN chief. The focus of today’s blog post relates directly to the question of ‘Fire Weather’- One of the report’s key Five Future Impacts.

Throughout my research on Tropical Forage Legumes and Agriculture, I have found the theme of fire to be alarmingly sparse in the current literature. This is made even more apparent against the backdrop of wildfires currently burning in Europe, Africa and America. Moreover, the world recently witnessed unprecedented wildfires in Australia that devastated rural and agricultural communities and wiped out many native and endemic species found nowhere else on earth and never to be recovered. The threat of climate change and fire weather is already having a monumental impact on food security and biodiversity.

In relation to food security, my previous posts have explored how legumes can help improve both agricultural efficiency and resilience against climate change. A key question for both is how (and where) to build fire recovery mechanisms into our agricultural systems?

Historical records and soil profiles tell us that wildfire in the tropical zone has previously occurred in intervals of hundreds to thousands of years _¹. Perhaps unsurprisingly then, the consideration of fire is not a priority for farmers and researchers in tropical regions. However, as the planet warms and historical weather systems begin to change, wildfire will increase in frequency and intensity.

Changes to inter-annual variability of climactic phenomena such as the El Niño Southern Oscillation will cause big decreases in rainfall across the tropics _². This will ‘dry out’ biomass fuels, making them more combustible, increasing both the frequency and intensity of wildfire _². Historically humid topical regions in West Africa, southeast Asia and Latin America for example have experienced an increasing frequency and severity of wildfires in recent decades _¹.

One solution to this problem might lie in places like the Mediterranean, Australia, South Africa, and America. Regions where the native flora have evolved to not only survive wildfires but depend on them for their reproduction. The restoration and management of farming systems against wildfire may be improved by increased knowledge of fire-related germination responses for functionally important groups of plant species – Those such as Tropical Forage Legumes _³.

Besides vegetative sprouting, post-fire seed germination maintains fire affected ecosystems and is an adaptive trait of many legumes species ^₄. Some of the Fabaccae family for example produce a hard seed coating that requires the extreme temperature of fire to germinate ^₄. The hard coat also prevents water absorption and decay in the soil during prolonged inter-fire periods ^₅. Integrating such adaptive mechanisms into commercial legume breeding could be a key strategy for fire-proofing agricultural ecosystems.

As I mentioned in my previous post, by exploring the untapped potential of wild, uncultivated legumes, we will likely find many species that produce these hard, fire-loving seeds. However, in another post we see how integrating uncultivated species into an agricultural setting is fraught with difficulties. It is a delicate balancing act to develop commercial cultivars that can compete with other agricultural crops. Legumes that lie dormant in the soil for years, even decades, before they germinate are likely to be both functionally and economically unhelpful for farmers. Particularly small-scale operations for whom the cost of new and improved cultivar seeds is proportionally large. Moreover, other concurrent morphological characteristics found in these ‘fire-loving’ legumes may be incompatible with certain agricultural systems.

We do not yet have all the answers to such problems and the challenge to incorporate more functionally diverse legumes into agricultural systems remains significant. The solution to this particular problem may lie in developing a seed mixture of functionally complementary legume cultivars – some that can germinate and grow quickly and others that can lie dormant for decades until they are needed for fire recovery. Such an endeavor will take time. Time we can ill-afford as the Sixth IPCC report highlights.

Nevertheless, the need to design tropical agricultural systems with some degree of post-fire recovery potential (and the need to adjust crop genomic and breeding research objectives to match) is a key take-away message of my CCAFS research project.

_{1 -Cochrane, M. A. (2003). Fire science for rainforests. Nature, 421(6926), 913-919.}

_{2 –Herawati, H., & Santoso, H. (2011). Tropical forest susceptibility to and risk of fire under changing climate: A review of fire nature, policy and institutions in Indonesia. Forest Policy and Economics, 13(4), 227-233.}

_{3 -Wiggers, M. S. (2011). Some like it hot: fire and legume germination in the longleaf pine ecosystem (Doctoral dissertation).}

_{4 -Doussi, M. A., & Thanos, C. A. (1994, November). Post-fire regeneration of hardseeded plants: ecophysiology of seed germination. In Proceedings of the 2nd International Conference on Forest Fire Research (Vol. 2, pp. 1035-1044). Coimbra.}

_{5-SOUZA, F. H., & MARCOS-FILHO, J. Ú. L. I. O. (2001). The seed coat as a modulator of seed-environment relationships in Fabaceae. Brazilian Journal of Botany, 24, 365-375.}

Next month the UN Secretary-General António Guterres will convene a Food Systems Summit as part of the Decade of Action to achieve the Sustainable Development Goals (SDGs) by 2030. The Summit will launch bold new actions to deliver progress on all 17 SDGs, each of which relies to some degree on healthier, more sustainable and equitable food systems.

As world leaders prepare, and as the Pre-Summit meeting concluded in Rome this week, I took some time to revisit and reflect on the last year’s IFIAD conference – Covid-19 & Sustainable Food Systems – Transforming food systems in times of crises. Through it, we sought to learn from the Covid-19 crisis by examining the weaknesses (and strengths) it exposed in our food networks.

And as the world also moves towards the COP26 in Glasgow this November, contemplating the lessons we pulled from the depths of the Covid-19 crisis and applying them to Climate Change – arguably one of the biggest crises humanity will ever face – seemed pertinent and necessary.

My own MSc CCAFS research project is centered in buttressing our agricultural systems against the onslaught of climate change by ‘Climate Proofing’ our crops. My focus has been Tropical Forage Legumes which are critical for agricultural efficiency and resilience, particularly for small scale producers in developing countries.

Below is an excerpt of my thoughts from last year after the MSc CCAFS cohort attended the online IFIAD conference. I found much of what was relevant then remains entirely relevant to my own research goals now, particularly as my project and Masters course nears its completion.

‘Covid-19 highlighted the connectivity between sectors. A health crisis which demanded a political response whose affects cascaded down the economic and social building blocks of modern society, simultaneously exposing the fundamental inequalities and inherent strengths in each. We should expect the resilience of global food systems, when faced with the many challenges of climate change, to depend on a similarly multi-sectorial response. In this context, Covid-19 provided a unique opportunity to “Build-Back Better”.

Global food systems are underpinned by agriculture and trade. Agricultural resilience, particularly for developing nations, will require greater recognition, protection and empowerment of small-scale producers. This in turn will require systematic policy changes in land tenure, gender equality and the recognition of indigenous people. In terms of trade, the EU/Africa partnership was examined as a model of successful international trade. It particularly illustrates the importance of private enterprise (which showed enormous innovation in the face of Covid-19) in domestic productivity. Digital communication was central to this and we should aim to expand its role in future networking.

However, just as in agriculture, the recognition and protection of human rights is paramount. This will require systematic changes in data protection policies. Within the public sector, we should seek to align local and national governance towards common objectives. At the local level, a greater recognition of the value of civil society is needed. At the national level, the expansion of social and income protection, in all its forms, will be central to maintaining the equality at the heart of any resilient society.‘

The previous post explored how tropical legumes can contribute to greater agricultural efficiency. Today we will discuss how they can contribute to greater resilience.

State-of-the art climate models have established that (because of anthropogenic emissions) global land and sea temperatures will continue to warm for at least the next two decades regardless of what intervention we collectively take _¹. We must therefore tailor our crops to withstand the very high certainty of continued global warming. The tropical zone is particularly vulnerable, where extreme temperatures are already common and the risk of high magnitude events such as tropical storms is high ^₁.

Since the mid-1970s, the tropics have warmed at an average rate of 0.2°C per decade ^₂. On this trajectory, we are looking at a total baseline shift of ~1.5°C by 2030 ^₃. As this unfolds, the number of extreme (and potentially dangerous) hot days are expected to increase ^₁. And as the air temperature rises, the water holding capacity rises with it ^₄. Intense precipitation events are thus expected to occur more frequently, increasing the risk of flooding, even in places where total precipitation is decreasing ^₄. Already more than half of the tropical zone is heavily influenced by drought ^₅ but the continued disruption of global cycles such as the El Niño–Southern Oscillation is driving up their frequency and severity ^₆.

In terms of food security, adverse impacts are likely to be greatest in regions where both current need and future growth for nutritional demand is greatest _⁷. Countries with large populations and fast-growing economies – China, India, Indonesia, and Brazil for example – are undergoing periods of major agricultural intensification and moving towards more intense livestock production _⁸. Protection against the onslaught of climate change in these regions is vital for global food security.

For the major food crops like Wheat, Rice and Maize, substantial progress has been made in breeding climate resilient cultivars. Yet, despite their multitude of environmental and commercial benefits (particularly for livestock) far less attention has been paid to legumes. If we are to buttress our tropical farming systems against climate change, we must rectify this immediately. A first step is finding genes that confer adaptability and resilience.

The problem is that the process of domestication, by design, breeds out genetic variation _⁹. We select the traits we need and discard those we don’t. As far back as the Neolithic age we have bred crops to be big and fruitful. Over thousands of generations we have selected only the best performing individuals, culminating in our modern day, monoculture crops that produce high yields. The trade off is that they require highly favorable and regulated farming conditions. Thus, of the relatively few domesticated legumes we do have, it is likely they have lost many potentially resilient genes in favor of those that confer a higher yield _⁹.

In comparison, preserved within wild and uncultivated legumes species (of which there are literally hundreds!) is likely to be a treasure trove of genetic variation. Having not been pushed through the bottleneck of domestication, this wild gene pool will be more diverse _³. Moreover, having adapted to fend for themselves under harsh, unregulated conditions, wild species are expected to display morphology or behavior that confers hardiness and self-sufficiency.

To breed self-sustaining and resilient farming crops, we should exploit self-sustaining and resilient genes _³. This process is far from easy or straightforwards but there are many national and international organizations currently working to do just that. Scientific Institutions like CGIAR, CIAT and ICARDA. In the next installment, I aim to provide a more detailed exploration of their work – past, present and future – towards ‘Climate Proof’ legumes.

Without this vital research in his corner, Mr. Peanut faces a devastating ‘KO’ in the ring….

_{1 -Hoegh-Guldberg, Ove, Daniela Jacob, M Bindi, S Brown, I Camilloni, A Diedhiou, R Djalante, K Ebi, F Engelbrecht, and J Guiot. 2018. ‘Impacts of 1.5 C global warming on natural and human systems’, Global warming of 1.5 C. An IPCC Special Report.}

_{2 -Malhi, Yadvinder, and James Wright. 2004. ‘Spatial patterns and recent trends in the climate of tropical rainforest regions’, Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 359: 311-29.}

_{3- Mitchell, ML, HC Norman, and RDB Whalley. 2015. ‘Use of functional traits to identify Australian forage grasses, legumes and shrubs for domestication and use in pastoral areas under a changing climate’, Crop and Pasture Science, 66: 71-89.}

_{4 -Trenberth, Kevin E. 2006. ‘The impact of climate change and variability on heavy precipitation, floods, and droughts’, Encyclopedia of hydrological sciences.}

_{5 –Lal, R. 2018. ‘Erosion impact on soil quality in the tropics.’ in, Soil quality and soil erosion (CRC Press).}

_{6 -Moon, J, WK Lee, C Song, SG Lee, SB Heo, A Shvidenko, F Kraxner, M Lamchin, EJ Lee, and Y Zhu. 2017. ‘An introduction to Mid-Latitude ecotone: Sustainability and environmental challenges’, Siberian Journal of Forest Science, 6: 41-51.}

_{7 -Henry, BK, RJ Eckard, and KA Beauchemin. 2018. ‘Adaptation of ruminant livestock production systems to climate changes’, Animal, 12: s445-s56.}

_{8 -Delgado, Christopher L, Mark W Rosegrant, and Siet Meijer. 2001. “Livestock to 2020: The revolution continues.” In}

_{9- Abberton, Michael, Jacqueline Batley, Alison Bentley, John Bryant, Hongwei Cai, James Cockram, Antonio Costa de Oliveira, Leland J Cseke, Hannes Dempewolf, and Ciro De Pace. 2016. ‘Global agricultural intensification during climate change: a role for genomics’, Plant biotechnology journal, 14: 1095-98.}

I last left you with the story of Mr. Peanut and his quest to restore balance to the Earth’s nitrogen cycle. Today, we will explore this a little further in the context of tropical livestock production and highlight why we need more aggressive legumes.

Lets quickly recap…

In my previous post we looked at how, in the technological boom of the post-war era, we were able to dramatically intensify crop production with the invention of synthetic nitrogen-based fertilisers ^₁. This hailed in the ‘Green Revolution’, one of the most significant events in our agricultural history since our hunter-gatherer ancestors first started farming. But fast forward a few decades and our increasing reliance on synthetic fertliser is driving an increase in nitrous oxide emissions, a potent greenhouse gas with a “severe global warming potential” ^₂.

“A failure to adapt to the tropical context of Asia and Latin America brought with it a new set of problems.”

The rapid income growth and urbanisation of the post-revolution era meant price was not the constraint on food it had once been. Many more people were able to access more expensive, animal derived products like meat, milk and eggs ^₃. This trend has been labelled by many as the ‘Livestock Revolution’ ^₄. In recent decades, it has been particularly apparent in places like China, India, Indonesia, and Brazil – developing countries with large populations and growing economies ^₄. At the turn of the century, the average meat and dairy consumption in these regions had almost doubled from what it had been ^₄. To keep up with such demand, and with a seemingly inexhaustible source of synthetic fertiliser to hand for feed crop production, farmers turned to more intensive methods of raising livestock ^₄. But a failure to adapt the conventional, post-war regime to the tropical context of Asia and Latin America brought with it a new set of problems.

“Scientists, accustomed to housing stock in European and North American winters and the need to conserve forage for the winter, assumed that the dry season shortfall in feed supply in tropical regions might be overcome by hay conservation.”

The highly weathered, acidic soils of the tropical zone rapidly saw the efficacy of fertiliser diminish. And in the extreme dichotomy of the wet and dry seasons, poor feed quality quickly became a problem – particularly in periods of drought _⁵. This risked locking farmers into a downward spiral of low productivity and inefficiency. But, by including legumes into the feed, pasture or forage mix, farmers found a high-quality, protein-rich feed source _⁵. Their presence in the biome also improved soil structure, health and fertility, thus facilitating greater systematic efficiency across the board _{^{6, 7.}} .

“Commercialising legumes selected for their aggressive seedling establishment”

But life is tough in the tropics. To cope with the boom/bust cycle of the seasons, you have to be tough, hardy and quick to take advantage of the good times. Legume seedlings, unlike many of their tropical grass counterparts, establish relatively slowly and are quickly out-competed for space and resources before they can mature _⁸. This must change if successful grass-legume mixtures are to flourish and see farmers and their charges through the hard times. Commercialising legumes selected for their aggressive establishment will go a long way to resolving this particular issue _⁸.

The problem is, where breeding of grasses and cereal crops is highly advanced, for legumes it remains in its infancy. We know relatively little about tropical legumes and how best to breed superior strains. But we are gaining ground; Scientific Institutions like CGIAR, the International Center for Tropical Agriculture (CIAT) and International Center for Agricultural Research in the Dry Areas (ICARDA) have spearheaded the Tropical Legumes Projects I, II and III to develop better legume varieties _⁹.

Most critically, not only must these varieties be more aggressive, they must also be matched with the myriad of ago-ecological conditions throughout the tropical zone ^₁₀. A major challenge for the future is tailoring them to an environment that is becoming increasingly unpredictable under climate change ^₁₁, ^₁₂. This brings us to the next phase in the Tropical Legume Project.

We will explore this issue in the next post where I will ask – how might we ‘Climate Proof’ Mr. Peanut?

_{1- Moreau, Delphine, Richard D Bardgett, Roger D Finlay, David L Jones, and Laurent Philippot. 2019. ‘A plant perspective on nitrogen cycling in the rhizosphere’, Functional Ecology, 33: 540-52.}

_{2- Beeckman, Fabian, Hans Motte, and Tom Beeckman. 2018. ‘Nitrification in agricultural soils: impact, actors and mitigation’, Current opinion in biotechnology, 50: 166-73.}

_{3- Hall, Nicolette G, and Hettie C Schönfeldt. 2013. ‘Total nitrogen vs. amino-acid profile as indicator of protein content of beef’, Food Chemistry, 140: 608-12.}

_{4 – Pica-Ciamarra, U, and J Otte. 2009. “The ‘Livestock Revolution’: Rhetoric and Reality, Pro-Poor Livestock Policy Initiative, A Living from Livestock.” In.: RPPLPI Research Report RR.}

_{5 – Humphreys, L. R. (2005). Tropical pasture utilisation. Cambridge university press.}

_{6 – Schultze-Kraft, Rainer, Michael Peters, and Peter Wenzl. 2020. “A historical appraisal of the tropical forages collection conserved at CIAT.” In Genetic Resources.}

_{7- Hassen, Abubeker. 2017. ‘Potential use of forage-legume intercropping technologies to adapt to climate-change impacts on mixed croplivestock systems in Africa: A review’, Regional Environmental Change, 17: 1713-24}

_{8 – Muir, JP, JCB Dubeux Jr, and LO Tedeschi. 2018. “New perspectives on forage legumes in mixed pastures.” In Proceedings of the CONFOR II International Conference on Forages. University of Lavras & Suprema Grafica e Editora, Lavras, MG, Brazil, 147-58}

_{9-Ojiewo, Chris, Emmanuel Monyo, Haile Desmae, Ousmane Boukar, Clare Mukankusi‐Mugisha, Mahendar Thudi, Manish K Pandey, Rachit K Saxena, Pooran M Gaur, and Sushil K Chaturvedi. 2019. ‘Genomics, genetics and breeding of tropical legumes for better livelihoods of smallholder farmers’, Plant Breeding, 138: 487-99}

_{10 -Rusdy, M. 2021. ‘Grass-legume intercropping for sustainability animal production in the tropics’, CAB Reviews, 16: 1-9}

_{11 – Lal, Rattan. 2009. ‘Soil degradation as a reason for inadequate human nutrition’, Food Security, 1: 45-57.}

_{12- Rockström, Johan, Will Steffen, Kevin Noone, Åsa Persson, F Stuart Chapin III, Eric Lambin, Timothy M Lenton, Marten Scheffer, Carl Folke, and Hans Joachim Schellnhuber. 2009. ‘Planetary boundaries: exploring the safe operating space for humanity’, Ecology and society, 14.}

I went looking for inspiration for my first MScCCAFS research project blog post. I found an article in the BBC’s Future Planet series titled The World’s Forgotten Greenhouse Gas. It explored some of the emerging technological strategies to mitigate nitrous oxide (N₂O) emissions from agricultural production. Ironically though, in an article about a forgotten greenhouse gas, it also highlighted a forgotten mitigation strategy – Legumes. A major player in agriculture and the topic of my research project. By including their benefits in the narrative, I was able to better understand my own research objective.

“Humanity has tipped the Earth’s nitrogen cycle out of balance.”

As the article highlights, N₂O molecules are both long lived and about 300 times as potent as CO₂. Yet in the carbon-centric political mindscape, as a dangerous greenhouse gas, nitrous oxide is often invisible, overlooked and forgotten. All the while it is expelled in vast quantities from agricultural production, wreaking havoc with the Earth’s nitrogen cycle and contributing significantly to climate change.

“Synthetic nitrogen fertiliser is the culprit”

Nitrogen (N) is the limiting element in agriculture and with population growth, farmers have had to turn to synthetic fertiliser to boost crop yields. Between 1960 and 2000, global agricultural productivity increased substantially because of the use of fertilisers _¹. However, the numbers reveal that over time this strategy gives diminishing returns and is now beyond the point of profitability or sustainability _¹. Currently, for every 100 kg of N applied to the soil, about 1 kg is lost to the atmosphere as N₂O _². In addition, the fossil fuels used for the chemical synthesis of nitrogen fertilisers contribute 10% of agricultural emissions and 1% of all anthropogenic greenhouse gas emissions _¹.

“Can we cut emissions from its greatest source?”

The technological innovations to improve efficiency include remote sensing technology to determine when, where and how much fertiliser to add to land, and harnessing beneficial soil microbes to directly supply biological nitrogen to crops through fixation of atmospheric nitrogen. Legumes however, beating us to the punch by only a few thousand millennia, have already harnessed these microbes within their root system and sustainably generate their own reactive nitrogen (Nr). Consequentially they occupy a critical niche in agriculture. Forage peanut cultivars for example, of the genus Arachis, when mixed with grasses, provide a low-cost supply of Nr not only for themselves but for the crops around them ^₃. This reduces the need for synthetic fertilizers, lowering waste in the form of N₂O ^₃. In addition, the extra Nr now available in the soil contributes to improved health across the board and reduces the need for tillage, further decreasing soil based greenhouse gas emissions ^₂.

Why then do legumes not feature in the BBC’s Future Planet story…..?

In a future themed article, perhaps they didn’t fit the technological angle. Legumes are not a new discovery. They appear as “A thread of archeological and written record since the emergence of evidence for the management of plants and animals for food” ^₄ . But their omission is perhaps more indicative of how far they now lag behind the major cereal crops in terms of management, breeding strategies and indeed technology _⁵.

With a few exceptions, they have failed to deliver improvements in agricultural productivity, particularly in the tropics _³. Unsuccessful experiences in establishing and maintaining productive and persistent grass-legumes mixtures generated a lack of credibility among farmers and researchers _³. They have also been pitched against the increasing availability of cheap fossil fuels for the chemical synthesis of fertiliser, until now masking a lack of action on sustainable alternatives _{², ⁶} . As a result, they remain a largely misunderstood and underutilised resource in Climate Smart Agriculture.

In response, The United Nation’s Sustainable Development Goals now seek a greater contribution of legumes to Food Security and Climate Action targets ^₅ . And progress is being made. Those same forage peanuts for example are now being successfully adopted in Nepal, Australia, Brazil, Colombia and the southern United States ^₃. The challenge lies in ensuring knowledge gains, policy developments and technological innovations continue on equal footing with cereal crops. Exploring new breeding technologies is, in a (pea)nutshell, the objective of my research project. It is my intention over the coming weeks, as I progress through the literature, to provide further insight into what some of these technologies are and how we can utilize them in the best possible way.

In the fight against climate change, the personal story of Mr. Peanut has only just begun…

“Fixing food is a unique and powerful opportunity to achieve the Sustainable Development Goals by 2030”^₁. The humble school lunch and kitchen garden are a hugely undervalued and underutilised resource in this endeavor; not only in the food provided but (and perhaps more importantly) in the lessons learnt.

Later this year, the UN Secretary-General will convene a Food Systems Summit to launch bold new actions to transform the way the world produces and consumes food. To deliver progress on all 17 of the Sustainable Development Goals (SDGs), preparations across 5 Action Tracks are being made. The focus of Action Track 2 (AT2) is ‘Shifting to Sustainable and Healthy Consumption Patterns’. As part of its preparation, the AT2 Public Forum Discussion was held in December 2020. A common thread among its speakers was the role of social norms in our food systems and how, in changing these norms, we can begin to break down the barriers to progress such as meeting the SDGs.

Within this discussion, Dr. Gunhild Stordalen, Founder and Executive Chair of EAT, highlighted how with growing urbanisation, people have shifted away from their traditional practices and diets. Within the urban landscape, ultra-processed foods and beverages are replacing healthy and nutritious wholefoods. Consequently food has now become the biggest killer of all, for both people and the planet. We are witnessing rising obesity and cardiovascular disease together with escalating land degradation and biodiversity loss. However, Dr. Stordalen also argued “Food can be the most powerful medicine for both people and planet”.

So far, in a typically western style, we have taken a limited view on such an idea and sought to alleviate the symptoms and ignore the disease. Tax schemes for fat, sugar and meat have been implemented but to limited success. Not only do these schemes hit hardest those with the least capacity for choice, they ignore the social norms and foundations of our food systems. As AT2 keynote speaker and chef Sam Kass stated, “When we talk about changing the system, we run directly into people’s identity”. Early exposure to cultural norms shape the way we as children form our self- identity, including what we eat. So, if we are to change our relationship with food, what better place to start than in the playground.

The scientific data tells us that the introduction of food based school gardens, as a component of early education, increases knowledge of fruits and vegetables and creates skills and attitudes conducive to enhancing their consumption ^{_{2, 3, 4}}. Critically, the data also shows this behavior continues into adolescence ^₄. As discussed in the AT2 forum, not only must we adopt healthy eating habits, we must maintain them throughout our lifetimes. So while school gardens are not a novel concept, innovation is needed in the scale at which they must be implemented and the landscapes in which they are most needed.

Almost 20 years ago, the Food and Agriculture Organization (FAO) released the ‘School Gardens Concept Note’ _⁵ which outlined the strategic elements necessary for a national School Garden Program. It showed how previous attempts at similar programs had failed because of a lack of attention to the institutional framework. It highlighted the need for political commitment and national policies. We must demand then of our governments (quite literally as a matter of life and death) the national institutional frameworks needed to ensure long term success of educational gardening programs.

For me, the only point of contention in the Concept Note was one of geography. It had at the time identified rural areas as most in need of intervention, but by 2050 by nearly 10 billion people will be living in cities (according the United Nations). A recent UNICEF Report focused on the food challenges faced by children in urban settings; where fast food and packaged snacks are readily available and where outdoor spaces to gather and play are limited. It stated in no uncertain terms, “The need to transform the food environment in cities is clear and urgent” ^₆.

To meet the food challenge in the urban landscape, we must be extra innovative and inventive. We must incorporate into the institutional frameworks, new stakeholders and new knowledge. Experts in small space gardening, architecture and urban planning. Those whose’ knowledge of big cities and small spaces can be used to create a new city dwelling identity. Such an identity, a new collective attitude and relationship to healthy food, will help us go beyond the single issue of poor diets towards the collective goal of the SDGs.

By ensuring these programs and innovations are implemented in the most inner city schools, we can create ‘Sustainable Cities and Communities’. By having students eat what they grow, we can begin to address ‘Zero Hunger’ and ‘Good Health and Well-being’. By teaching new skills in horticulture and food science, city students may access employment opportunities and ‘Economic Growth’ otherwise excluded to them. By ensuring such programs are integrated into the earliest of learning, regardless of race, gender or background, we can contribute to ‘Quality Education’, ‘Gender Equality’ and ‘Reduced Inequalities’.

To create a new cultural identity and turn our food into medicine, we must literally plant the appetite for change.

_{1 – United Nations Action Track Discussion Starter. Action Track 2 – Shift to healthy and sustainable consumption patterns. www.un.org/sites/un2.un.org/files/unfss-at2-discussion_starter-dec2020.pdf}

_{2- Somerset, S., & Markwell, K. (2009). Impact of a school-based food garden on attitudes and identification skills regarding vegetables and fruit: a 12-month intervention trial. Public Health Nutrition, 12(2), 214-221}

_{3- Parmer, S. M., Salisbury-Glennon, J., Shannon, D., & Struempler, B. (2009). School gardens: an experiential learning approach for a nutrition education program to increase fruit and vegetable knowledge, preference, and consumption among second-grade students. Journal of nutrition education and behavior, 41(3), 212-217}

_{4- McAleese, J. D., & Rankin, L. L. (2007). Garden-based nutrition education affects fruit and vegetable consumption in sixth-grade adolescents. Journal of the American Dietetic Association, 107(4), 662-665}

_{5- FAO (2002), SCHOOL GARDENS CONCEPT NOTE Improving Child Nutrition and Education through the Promotion of School Garden Programmes. Rome. www.fao.org/3/af080e/af080e00.pdf}

_{6- United Nations Children’s Fund, The State of the World’s Children 2019: Children, food and nutrition – Growing well in a changing world, UNICEF, New York.}