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.