The System of Rice Intensification (SRI) is an agroecological approach to growing rice that achieves greater yields from reduced inputs, while simultaneously minimising GHG emissions, particularly methane. Simply put, SRI has the ability to positively influence food security, climate change all while supporting economic, social and environmental development.
Take a look at rice in numbers on the global scale:
Rice production needs to grow by 25% over the next 25 years to meet future projected demands. In order to sustainably meet this demand and support food security, the way rice is cultivated must be adapted to lessen pressure on our climate and water resources.
SRI provides an answer to support food security and the environment together without trade-offs for social and economic development.
The System of Rice Intensification (SRI) follows four key principles. When practiced together SRI principles produce greater and more nutritious yields and reduce the environmental impacts of rice cultivation.
The four main principles are:
SRI methods start with selecting only robust healthy seeds. These can be directly seeded or carefully transplanted before the 4th phyllochron (8-12 days old). By focusing on healthy plants from the start, this conserves each rice plant's innate potential to develop larger tillers and roots.
By not overcrowding the rice plants are better able to fully express their genetic potential by producing more tillers and larger panicles, supported by larger root systems. The spacing will be optimised according to the rice variety and soil fertility so that sunlight and soil nutrients are better absorbed and utilised by plants. This provides the best conditions for each plant's growth.
Fertile soil stimulates the growth of healthy plants and allows the agricultural system to be more sustainable and resilient to stresses in the long term.
Although rice plants can survive in standing water, they are not aquatic plants and do not perform best under flooded conditions. Anaerobic soil (flooded soil) actually suffocates the plant roots and the beneficial soil organisms that boost plant health and growth. SRI encourages aerobic conditions which is better for plant growth and significantly cuts the methane emissions produced in traditional flooded rice cultivation.
On average SRI increases yields by 25-50% with many examples of over 50% and even up to 200%
Increased and more reliable rice yields contribute to food security and allow small-scale farmers to diversify their crop system. SRI rice panicles have fewer unfilled or broken grains which increases the amount of milled rice from harvested paddy by up to 15%. SRI methods also increase the micronutrient uptake by the plant, resulting in improved nutritional qualities in the grain. Beneficial nutrients such as Iron, Zinc, Copper and Manganese are all found to increase in SRI rice when compared with traditionally cultivated rice and levels of heavy metals, such as arsenic and lead, are shown to decrease.
SRI reduces methane emissions by up to 70% due to aerobic soil condition achieved by using Alternate Wetting and Drying (AWD) water management instead of the traditional continuous flooding. SRI also enhances carbon sequestration. SRI reduces net GHG emissions per hectare on average by 20-40%, even shown up to 73%. Because of the increased yields, net GHG emissions per kilogram of rice are reduced by an average of 60%
Yield increases are achieved with less inputs: seeds are reduced by up to 90%; dependence on synthetic fertilizers and pesticides is lessened and instead a more integrated approach based on healthy soil and optimised environments for rice plants is followed. This allows farmers to use already accessible resources more productively, save costs, and increase their return.
SRI improves total water use efficiency by 52% and irrigation water use efficiency by 78%. SRI reduces irrigation water application by 3.9 million litres per hectare.
SRI presents many benefits for women who provide up to 80% of rice cultivation labour. SRI reduces the burden of labour with smaller nurseries and fewer plants to manage. Women's health is also improved under SRI practices. In traditional cultivation, women are often expected to perform the weeding which involves being continually bent over for many hours in muddy, unsanitary, flooded paddy fields. By not flooding the fields, and using a mechanical weeder instead, SRI reduces the health risks and negative impact traditional cultivation practices cause on women's bodies.
No! SRI methods can be merged with other agroecological practices such as agroforestry, conservation agriculture and organic farming to name a few. There are a range of benefits that can be achieved by combining diverse agroecological approaches. For example, SRI has been successfully combined with Conservation Agriculture (CA) resulting in higher rice yields and reduced labour and water requirements. SRI is always adapted to the local context and environment in which it is practiced, and by merging SRI with other agroecological methods, the sustainability and the resilience of the entire farming system can be enhanced. Read more on 'SRI +' here!
SRI practices are currently adopted on 6.7 out of the 167 million hectares under rice cultivation. By upscaling SRI to 50 million hectares, it would achieve 1 billion tons extra rice produced, 8.5Gt CO2e emissions avoided and $1.6 trillion in net farmer profits by 2050.
SRI has mostly spread through farmer-to-farmer networks and grassroots movements. Stronger institutional support can provide the foundation to scale SRI rapidly.
Ways to support SRI uptake include:
SRI-2030's goal is to increase SRI coverage globally from the currently estimated 6.7 million hectares to 50 million hectares by 2030. In doing so this means by 2050 we will:
produce an extra 1 billion tons rice
avoid 8.5Gt CO2e emissions
create $1.6 trillion net farmer profits
SRI is validated in over 60 countries; and used in 11 different country's NDCs for climate action.
SRI awaits coordinated institutional support to upscale at the rapid pact necessary to generate these multiple positive impacts.