1.
Improved Soil Health through Climate-smart Rice Cultivation Increases
Productivity and Promotes Biodiversity in West Africa
Hillary Mara, MPA ‘17 Cornell Institute for Public Affairs/ SRI-Rice
The System of Rice Intensification
The System of Rice Intensification (SRI) is an agroecological and knowledge-based methodology
for increasing the productivity of rice by modifying the management of plants, soil, water and
nutrients while reducing dependency on external inputs. A climate-smart methodology that uses
less water, seed, and agrochemicals, SRI helps farmers adapt to and mitigate climate change.
SRI has been adopted in 60 countries around the world by millions of farmers.
Rice production in West Africa
West Africa produces 65% of the rice grown in Sub-Saharan Africa: more than 6 million MT
in 2016. Yields tend to be far lower than other places in the world that use more intensive
farming systems: farmers achieve an average of less than 2 tons/ hectare in the region as
compared to over 6 tons/ hectare in China, leading to a consumption deficit. Rice is grown
in ecosystems including mangrove, deepwater swamp, irrigated lowland, rainfed lowland,
and rainfed upland.
Suitability of SRI for West African Soils
The principle of biologically active soil in SRI can specifically correct constraints that are
typical of poor soils in the region: minimal amounts of SOM, low CEC, and low base
saturation. The application of organic fertilizers such as compost—unlike chemical
fertilizer—can facilitate soil restoration by building up SOM, which can permanently alter the
productivity of soil over time. This occurs thanks to improved physical conditions as well as
an increase in soil biota, and therefore, the amount of nutrients available in the soil.
Practices such as decreased tillage and cover cropping, also recommended in SRI, also
facilitate biological activity. Water management methods give roots access to O and N, the
and the AWD method increases the populations of beneficial microbiota (bacteria and fungi)
as well as the activity of these populations. Mycorrhizal fungi serve the function of
translocating to rice plants N, P, K, as well as a number of other beneficial elements.
.
Principles of SRI
1. Careful plant establishment
3. Improved soil health
2. Reduced plant competition
4. Water management
Selected References
Photos by Devon Jenkins & Hillary Mara
Babalola, O., and O. A. Opara-Nadi. "Tillage systems and soil properties in West Africa." Soil and
tillage research 27, no. 1 (1993).
Lal, Rattan. "Restoring soil quality to mitigate soil degradation." Sustainability 7, no. 5 (2015).
Ruskin, F. R., ed. Lost Crops of Africa: Grains. DIANE Publishing, 1999.
SRI-Rice SRI International Network and Resource Center sririce.org
Subardja, V. O., I. Anas, and R. Widyastuti. "Utilization of organic fertilizer to increase paddy
growth and productivity using System of Rice Intensification (SRI) method in saline soil." Journal
of Degraded and Mining Lands Management 3, no. 2 (2016).
Sylla, Fana. USDA Foreign Agricultural Service. 2016 Update West Africa Rice Annual.
Styger E and Jenkins D (2014). Technical Manual for SRI in West Africa; Improving and Scaling
up of the System of Rice Intensification in West Africa; Version 2, Cornell University, Ithaca New
York.
Styger, E and G Traoré. “Improving and Scaling up SRI in West Africa: a Success Story.” (2015).
Van Wambeke, Armand. “Soils of the Tropics: Properties and Appraisal." McGraw-Hill, Inc, 1992.
Oryza glaberrima
Conclusions
Improved soil health is essential for increased productivity of West Africa’s staple crop. SRI can
contribute to improved soil health in the region through management practices that increase
beneficial soil biological processes and improve soil in the long term. Increased yields through
SRI can permit farmers to achieve food security, improve commercialization, and adapt to climate
change. By applying SRI methods to production of native African rice O. glaberrima, important for
its climate adaptability, cultural importance, and biodiversity, farmers can improve yields of this
disappearing crop, rendering it useful for future generations and protecting the diverse agricultural
heritage of the region.
O. glaberrima, native African rice, was domesticated in
Mali around 1500 BC. This native species is still
cultivated in pockets around the region today, though
virtually all rice grown is the more common Asian
species O. sativa, this despite the fact that glaberrima
is hardier and more adapted to the unique resource
constraints of the region. It has been noted that,
“compared to its Asian cousin, African rice is better at
tolerating fluctuating water depths, excessive iron, low
levels of management, infertile soils, harsh climates,
and late planting.” With rising pressure to increase
yields to feed growing populations, glaberrima risks
being lost entirely; however, SRI methodologies can
allow farmers to dramatically increase glaberrima
productivity. Initial results and previous research
suggests that offering glaberrima farmers the
knowledge and resources needed to apply SRI can
improve rice yields, increasing potential for wider
cultivation and commercialization.
Oryza sativa and Oryza glaberrima
Farmer
holding
glaberrima
plants,
Timbuktu,
Mali. Photo
by Erika
Styger
Special thanks to Dr. Norman Uphoff, Dr. Jonathan Russell-Anneli, Dr. Erika Styger, Lucy Fisher, and Devon Jenkins
Most soils in the region are classified as Oxisols and
Ultisols. These highly degraded soils have low cation
exchange capacity (CEC), low-activity clays, are deficient
in major nutrients, and can contain toxic levels of
aluminum and manganese. Alfisols, also dominant, contain
low-activity clays, but have high base saturation. Soil is
also threatened by anthropological factors. Farmers have
increasingly adopted intensification, mechanization, and
application of chemical fertilizer. Furthermore, climate
change is giving rise to shorter, more erratic rainy seasons
and higher temperatures, threatening agriculture in the
region. These factors, including the soil’s innate lack of
beneficial elements, minimal presence of soil organic
matter (SOM), and poor management, result in a poor
growing environment and limited productivity of rice.
Drivers of Soil
Degradation,
Lal
SRI plots in Dubreka,
Republic of Guinea
demonstrate impressive
tillering and strong root
growth