A Paradigm Shift for Agriculture: The Case for SRI
July 5, 2013 By canwefeedtheworld
Perhaps the greatest change in mindset in human history was from the belief in a Ptolemaic or geocentric view of the universe (Earth at the orbital centre of all celestial bodies) to a Copernican or heliocentric (the sun at the centre).
Today the world is facing many threats not least the need to feed an ever increasing population amid severe resource constraints. World food production per capita peaked in 1984 and if we are to achieve global food security we require, according to Norman Uphoff, political scientist at [Cornell University 2 and lead of the SRI-Rice group, a similar paradigm shift.
Presenting his case for the use and adoption of Systems of Rice Intensification at the International Institute for Environment and Development on 4th July, Uphoff explained the dire need for a change in mindset in agriculture: from an egocentric view, placing humans as the producers of food and manipulators of nature, to a heliocentric, whereby humans capitalise on the power and resources of natural systems while accepting their role within the system rather than outside. So often we view food production systems as closed, whereby inputs and outputs are measurable, linear and proportional but in doing so we neglect the biology of these systems. We fail to understand the myriad of ecological relationships that combine to create the food on our plate.
For decades the Green Revolution has allowed food production to keep pace with population growth, based on two pillars:
1) The improvement of genetic potentials of crop and animal genotypes; and
2) Greater application of external inputs.
But today we are seeing declining returns to this form of farming. In China where the application of 1kg of nitrogen fertiliser to crops would result in a 20kg increase in rice yields we are now seeing an increase of only 1 to 5kg. Despite this failing to maintain the momentum of past productivity trajectories, Uphoff explains that many agronomists are still arguing for current farming methods, only slightly improved. He believes we need a greater focus on the ecological sciences. In particular the contributions of plant roots and soil biota to crop health, and research into how to get more productive phenotypes from existing genotypes through making beneficial changes in crop environments. And SRI does just that. What’s proven to be a rather controversial method of farming rice and other crops, and seemingly dismissed by many research institutions, has yielded impressive results.
Originating in Madagascar, SRI is “a climate-smart, agroecological methodology for increasing the productivity of rice…. by changing the management of plants, soil, water and nutrients ” More recently it has been applied to other crops such as wheat, sugarcane, finger millet and tef (Systems of Crop Intensification). SRI is based on four main principles allowing for farmers to adapt the methodology to their own environments:
Early, quick and healthy plant establishment, transplanting seedlings between 8 and 12 days old;
Reduced plant density, one plant per hill in a 25x25cm square pattern;
Improved soil conditions through enrichment with organic matter, weeding and aeration of the soil;
Reduced and controlled water application using intermittent irrigation.
Using these principles SRI has yielded significant increases in crop yields, reductions in water use, more resilient food production and increases to household incomes. Overall the benefits of SRI have included yield increases of 50%-100% or more, a 90% reduction in required seed, and up to 50% water savings. Results are being seen in 52 countries around the world. Even under conditions of stress SRI can outperform conventionally bred rice: in Bihar in 2010 during drought rice yields under SRI were 3.22t/ha compared to 1.66t/ha for conventional. These benefits are being seen using the same genotypes with no need to move away from traditional varieties and with little or no need for chemicals such as pesticides and fertilisers.
SRI also has environmental benefits, reducing the need for land expansion, lowering greenhouse gas emissions and pollution by agrochemicals. The key to its success is thought to lie in its yielding of larger root systems and of soil biota, which support root and shoot systems.
SRI is an example of sustainable intensification, of producing more from less. It is not an intensification in the classic sense of greater use of inputs but rather of knowledge, skills and management. And because it is knowledge, intensive it doesn’t work everywhere. Farmers must have access to water that can be easily controlled and adopting SRI can be labour intensive as weeding is done by hand. Although as time goes on the need to weed reduces as soils become healthier (as is also true of conservation farming).
But SRI is not completely understood. Why do these methods in certain cases result in such significant increases in yield? Uphoff believes things are happening in the root zone that we do not yet fully understand. For example one study by Andriankaja in 2002 found the use of NPK fertilisers to significantly reduce Azospirillum (a free-living nitrogen-fixing bacterium) in plant roots in comparison to the use of compost. Another study by Feng Chi et al in 2005 and more recently in2010 evidenced the ability of soil organisms to migrate through the plant and impact how the plant’s genotype is expressed. All these and other questions require research.
But this research is not happening at geographic or time scales to have significant impact and SRI is not supported by the CGIAR, the largest grouping of agricultural research institutions in the world. Indeed in the academic community SRI appears to have been shunned. But why?
Uphoff believes SRI has been overlooked for several reasons. Inertia being one. Are we invested in one model and loath to change? Or could it be because SRI is just so different? It requires us to think outside the box so to speak. It is a break from the norm. Uphoff admits himself that it took three years of seeing SRI in practice for him to accept it. Far worse could it be that big business (e.g. seed, fertiliser and tractor manufacturers) has little to gain from SRI? As Uphoff explains SRI is not inherently against the use of inorganic inputs or of making genetic improvements to crop varieties but through SRI we can make serious gains in crop production right now, and at a low cost and with side benefits for the environment.
Many have dismissed SRI as too good to be true. Uphoff states perhaps it is because he is a political scientist rather than an agronomist. Whatever the reason, Uphoff believes investigation and research into SRI, along with the de-industrialisation and re-biologisation of agriculture, is warranted and long overdue.