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-RiceThe System of Rice IntensificationThe 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 AfricaWest 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.

SuitabilityofSRIforWestAfricanSoils

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.

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Principles of SRI1. Careful plant establishment

3. Improved soil health

2. Reduced plant competition

4. Water management

Selected References

Photos by Devon Jenkins & Hillary MaraBabalola, 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

ConclusionsImproved 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 glaberrimais 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 glaberrimaproductivity. 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.

DriversofSoilDegradation,Lal

SRI plots in Dubreka,Republic of Guinea demonstrate impressivetillering and strong root growth