Norman Uphoff is the Senior Advisor for the SRI International Network and Resources Center (SRI-Rice), a program at Cornell University engaged with the System of Rice Intensification (SRI), which is a climate-smart, yield-increasing agriculture methodology that is being utilized by more than 10 million smallholder farms in over 55 countries. Uphoff is working to expand SRI’s international network and strengthen the knowledge base for SRI and its extension to other crops. Here he explains the basic principles of SRI, the implications of the methodology, and the role it can play in agriculture in the future.
System of Rice Intensification (SRI) is best understood as a set of agronomic principles rather than as a typical kind of agricultural technology. SRI effects depend more on ideas than on inputs. Its principles, when put into practice, enable farmers to use their available resources more productively, getting higher-yielding, more robust crops just by changing some of their cultivation practices. These principles and practices are supported by a growing body of scientific research.
Some of the changes are counter-intuitive, like reducing the number of plants grown per square meter to obtain a larger harvest, or transplanting smaller, younger seedlings to get more vigorous plants. The practices, of course, should always be adapted to suit local conditions. We see SRI more as a menu than as a recipe. The principles can be summarized as follows:
- The roots of plants should be given a favorable growing environment, with no trauma or crowding when they are getting started. This principle applies whether the crop is established by transplanting or by direct-seeding. Also, farmers should always start with well-selected, good-quality seeds.
- Plant populations should be optimally sparse rather than being optimally dense. For SRI, seedlings (or seeds) are planted singly rather than in clumps of three to four or more, and in a square grid pattern, not in rows. This gives plants’ roots and canopy more room to grow freely, with unimpeded access to water, nutrients, and sunlight. Lower plant density also eliminates conditions that allow various pests and diseases to proliferate and reduce rice production.
- Sufficient water should be provided, but no excess. Plants should be given just enough water to meet the needs of the plants and the aerobic soil organisms, from earthworms to microbes, that live around, on, and some even inside the plants. A flooded soil environment suffocates plants’ roots and reduces the symbiotic organisms that live with them in the soil, like mycorrhizal fungi.
- Soil should be well supplied with organic matter – both to provide nutrients for the plants and soil organisms, and to improve the structure and functioning of the soil system itself. While some use of inorganic fertilizers can be beneficial, they are not a good substitute for abundant organic material. Instead of feeding the plant, farmers should ‘feed the soil,’ and this will, in turn, feed the plant.
- The soil’s fertility and functioning can be enhanced by active soil aeration to get more oxygen to plant roots and beneficial aerobic soil organisms. The latter make the soil system better able to absorb water and to retain it, thus making more water available to plants.
When these principles are put into practice, the resulting plants can be dramatically different, as seen from the following pictures. By applying SRI principles, farmers can produce better plants, i.e., better phenotypes, from any given variety, i.e., genotype.
Miyatty Jannah in eastern Java, Indonesia, and Edward Sohn in Grand Gedee county of Liberia show us contrasting rice plants that were grown from the same variety in the same soil with the same climate. In each pair, the plants on the right were grown with SRI practices, while the plants on the left were raised with conventional methods. SRI crop yields vary, of course, depending on soil, climate and variety, and on whether all of the SRI methods are used, and used well. But SRI usually increases farmers’ yields by at least 20 to 50 percent, and often by 100 percent or more.
Applying SRI Concepts to Other Crops
The SRI principles reviewed above can be applied to many other crops beyond rice. Finger millet was the first crop to show similar benefits from these ideas and practices, as seen in both India and Ethiopia. Farmers also adapted SRI concepts to wheat and sugarcane; and then to oilseeds, such as mustard, rapeseed, and canola; and various kinds of legumes, including kidney beans, soy beans, and lentils; and even to some vegetables, such as eggplant and tomatoes. This process of innovation is especially effective if promoted through groups, for example, through women’s self-help groups.
System of Crop Intensification
We now talk about and encourage what is being called the System of Crop Intensification. SCI now encompasses a range of crops, adapting SRI ideas and methods quite broadly. Just last month, I received a report from Sierra Leone on how SCI concepts are being applied productively there to growing a green leafy vegetable known locally as krain krain. This crop, which is generally known as mallow and has the scientific name Corchorus olitorius, is an important and nutritious part of many West African diets.
The methodology of System of Crop Intensification varies according to the species. The main variation derives from whether or not the particular crop is irrigated. SRI methods were first developed for irrigated rice production in Madagascar. SRI’s originator, Father Henri Laulanié, found that irrigated rice plants perform better when, in conjunction with using other SRI practices, they are not kept continuously flooded. He advised farmers to provide their rice crops with just a minimum of water, meaning just enough to meet the needs of the plants and the beneficial organisms in the soil. With too much water, these are deprived of oxygen.
When farmers grow their crops under rain-fed conditions, they have to make do with whatever rain falls. With appropriate adaptations, SRI methods can be used under such conditions. Where rainfall is heavy, as with monsoon rains, fields should have some facilities for drainage, so that the soil does not become waterlogged and hypoxic, or lacking in oxygen.
As for the other SRI practices—spacing, organic matter, soil aeration—these are all to be optimized, to provide the best growing conditions for the crop, both above and below ground. These variables apply to any and all cropping. We have colleagues, for example, in the Indian state of Madhya Pradesh and in the U.S. state of Maine who are improving their various crops, even orchard production, by using what they have been learning from their SRI and SCI experience.
Local conditions always vary in terms of soil, climate, and other factors such as labor cost and availability. Based on their experience, farmers work out optimizing practices that best suit their own local circumstances. In any new location, we encourage farmers to do their own experimentation and evaluations to arrive at the best combinations of practices for them. They should start from the base of others’ experience and make adaptations when and as needed.
SRI’s Role in Solving Hunger and Poverty
SRI’s potential to address global issues of hunger and poverty is a complex matter. There are few better ways to combat hunger and extreme poverty than by enabling resource-limited households to get better, more-secure yields from the land, labor, seeds, water, and capital that are already available to them. If they do not have to buy new and expensive inputs, they can avoid going into debt and risking the loss of their land.
The highest SRI yields have come from planting new, ‘improved’ varieties, which is good news for plant breeders; but these seeds can be costly. However, with SRI methods, respectable yields can be obtained from local cultivars such as the traditional Basmati varieties in northern India. With SRI practices, ‘unimproved’ varieties can give yields in the range of five to eight tons per hectare, sometimes even ten tons or more. So, SRI farmers can choose to buy new seeds or to use their familiar ones.
If composted, almost any biomass—straw, weeds, animal manure, cuttings from trees and shrubs, plants collected from uncultivated land—can meet most of the nutrient needs of crops and the soil system. Farmers who have access to enough biomass do not need to purchase much fertilizer, or maybe any.
SRI offers resource-poor farmers an opportunity to reduce their seed rates by 80 to 90 percent. The seeds saved make a direct contribution to households’ food security. Generally, in conventional cultivation, rice farmers sow seed at 50 to 80 kg/hour, whereas with SRI, only five to eight kg are required. With crops like tef and mustard, the seed-saving when transplanting can be 95 percent, with higher yields two or three times higher.
Additionally, under SRI crop management, besides having improved grain nutrition quality, the paddy rice, when milled, gives 10 to 20 percent more edible polished rice because there is less chaff (fewer unfilled grains) and fewer grains break during milling. This higher milling outturn adds more to households’ food security than is indicated just by the increases achieved in harvested yield.
Also, since SRI-grown plants are as a rule less vulnerable to damage by insect pests and diseases, there is less need or even no need for farmers to spend money on pesticides or fungicides. This further reduces their costs of production, and lessens their exposure to health risks.
SRI and Climate Change
Farmers almost everywhere are encountering shifts in their climate, with varying and unpredictable patterns of temperature and rainfall. This makes current technologies, particularly monoculture and agrochemical-dependent production methods, more risky and more costly.
We have found that SRI and SCI crops are generally better able to resist the stresses of drought, of storm damage, of flooding and hot spells and cold snaps, and also of pests and diseases. These hazards all become more serious with climate change. Why the greater resilience? Because the plants develop larger, better-functioning root systems and canopies, and beneficial life in the soil is more abundant and diverse. These effects of wider spacing and more organic matter are crucial for a crop’s success.
Environmental Benefits of SRI
The Green Revolution relied heavily on increasing irrigation. Unfortunately, the availability of water for agriculture is becoming more problematic as the amount and reliability of water are diminishing. Fortunately, SRI methods, and to a lesser extent SCI methods, can lower crop water requirements. There is good evidence that SRI reduces the water footprint of rice production by consuming 30 to 50 percent less irrigation water, and 20 to 25 percent less total water for irrigated production, which includes rainfall. To use a current slogan, SRI helps farmers get more crop per drop.
The natural environment benefits when the rice sector reduces its demand for water while raising crop yields because this diminishes the sector’s competition with natural ecosystems for water. Also, SRI and SCI can counter dynamics and trends that erode biodiversity by lessening the pressures from the agricultural sector to expand into uncropped natural areas.
There is also improved water quality in the runoff of water from irrigated rice fields as well as in percolated groundwater. This is a consideration in countries like Japan, Taiwan, and Korea, where getting higher yields is not a driving concern, but environmental quality is important.
When rice paddies are not kept continuously flooded, as is the case with SRI, the net emission of greenhouse gases is reduced, particularly of methane (CH4). Because the use of nitrogen fertilizer is reduced or eliminated, there are not offsetting increases in the emissions of nitrous oxide (N2O), a more potent greenhouse gas. The emissions of carbon dioxide (CO2) are also reduced when the production, transportation, and use of fertilizers and agrochemicals are decreased.
From a field study in Andhra Pradesh state, Oxford and Indian researchers calculated that with SRI production methods, the net global warming potential of rice cultivation was reduced by 40 percent.
SRI Helping Communities
Crops grown with SRI and SCI methods are not just more productive, but their costs of production are usually lower, which further enhances farmers’ incomes. A large-scale evaluation in India, with over 2,200 farmers sampled across 13 states, showed SRI reducing farmers’ costs of rice production by US$28 per ton, even without full use of SRI methods. When farmers’ costs decline while yields increase, this amplifies the positive impact on households’ and communities’ income.
There is some evidence coming in that SRI rice-growing practices reduce the uptake of arsenic in rice grains, a current consumer concern, and further that these practices enhance the uptake and concentration of various micronutrients—iron, zinc, copper, magnesium—in the grain. So, with SRI practices, more nutritious grain can be grown without having to breed new varieties.
Implementing SRI Internationally
There are a few obstacles in implementing SRI around the world. Early on, SRI got tagged with the label of being too labor-intensive. This label is correct in that SRI is certainly more labor-intensive than capital-intensive. But it is misleading and often incorrect. For farmers, what is important is whether their own labor inputs will increase if they take up SRI. Usually, with SRI, labor requirements do not increase or even decrease.
In Madagascar, where SRI was developed and first evaluated, traditional rice cultivation is definitely labor-extensive. Any improvement in rice production there will require more labor. But the question is: what happens to labor productivity? Does SRI increase or decrease the amount of rice that is produced per day or per hour of labor invested? No evaluation that I know of has ever found that labor productivity is less with SRI. Initially, more labor is required until the methods are mastered. But the amount of labor that farmers need declines as they move up the learning curve. Even in Madagascar, we know that SRI becomes labor-saving within a few years once farmers have gained experience with its techniques.
In most of Asia, where 90 percent of the world’s rice is produced, rice cultivation is already relatively labor-intensive. Most evaluations in Asia have shown SRI methods to be labor-neutral, or even labor-saving, right from the start. However, the characterization of SRI as labor-intensive has been a real deterrent to its spread.
Another impediment to the expansion of SRI use is the limited availability of appropriate implements and equipment, particularly weeders for controlling weeds and aerating the soil at the same time. Such tools are usually simple and not very expensive, paying for themselves several times over in a single season. But they need to be available, well-designed, durable, and reasonably priced. This is one of the bottlenecks that SRI-Rice is working on.
At the farm level, a frequent impediment is lack of water control. Both plant roots and aerobic soil organisms suffer when there is too much water (and too little air) in the soil. Both need enough water for their functioning, but not continuous flooding or complete saturation. Water control need not be perfect, although the best yields come when farmers can strike a good balance in the amounts of water and air in the soil, applying just small amounts of water regularly or alternatively flooding the field and then drying it out.
To some extent, skepticism and resistance from various sources internationally has held back the spread of SRI. However, between 10 and 20 million farmers around the world, in more than 50 countries, are already benefiting from their use of SRI ideas and methods to grow more productive and more robust rice crops from their preferred varieties, either old or new. We are starting to see SCI methods spread, particularly for wheat and sugarcane. International acceptance is growing as well.
The Future for SRI-Rice
Much has been accomplished over the last 10 to 15 years, mostly with the personal efforts and resources of a small number of colleagues at Cornell University who have encouraged, informed, backstopped, and at the same time learned from the initiatives, implementation, and further innovation of dozens, then hundreds, and now thousands, of civil-society colleagues, researchers, practitioners, and farmers in dozens of countries around the world.
So far, the only significant support for SRI-Rice’s catalytic work has come from Jim Carrey’s Better U Foundation which made a gift to Cornell in 2010 to establish SRI-Rice. However, we do not know how much longer we can continue to operate without more support. This means that SRI-Rice’s current time horizon is, unfortunately, more a matter of months than of years.
Initiatives that we have gotten started with a lot of input and positive response from colleagues in various countries, and which we seek to develop further, include the following:
- Researchers in many countries have been building up a significant body of SRI knowledge for practical application. SRI-Rice has put together a worldwide network of researchers across many disciplines to share and expand the SRI knowledge base.
- We have set up a network of NGOs, researchers, and practitioners who are trying to improve the equipment available for SRI, as noted above.
- Women probably benefit from SRI more than do men, which is a good kind of gender-bias. We want to get more work done that evaluates and highlights SRI’s gender impacts. We have started working on this subject together with colleagues in Great Britain.
- More effort and resources should be devoted to extending and adapting SRI ideas and methods for better production of other crops, so that these can be produced with fewer inputs, less cost, and fewer adverse impacts on the environment.
- We will continue working with colleagues on conservation agriculture, the contemporary version of ‘no-till’ cultivation systems, for the sake of soil health and conservation and for more sustainable agriculture.
This is a large agenda—more than SRI-Rice can accomplish by itself—but we are linked, thanks to the internet and email, to a remarkably talented and energized community of SRI colleagues in more than 50 countries around the world. What unifies this community is a commitment to farmers’ well-being, to consumers’ health, to sustainability, and to a healthier environment.
The ideas and practices that constituted our modern agriculture in the latter half of the 20th century will not, I am afraid, serve us equally well in this 21st century, which has very different and changing economic, social, institutional and environmental conditions. I see SRI and SCI as pointing the way to what could be characterized as a ‘post-modern agriculture,’ which is a needed advance beyond our present knowledge and practices. These ideas and methods are still evolving, but innovation is no longer coming just from scientific institutions and universities, but also from civil society and farmers themselves. This is both an exciting and a necessary shift in strategy.