Renewed research on Gliricidia sepium to improve soil fertility
22 March 2024
Over eighty-three percent of Africa’s arable land is infertile, which has posed a significant challenge for smallholder farmers as it affects their livelihood. This infertility resulted from applying chemical fertilizers on plants and soils, length of the fallow period, erosion, and burning bushes on the same soil for plantation.
However, the decline in crop yield and soil fertility is attributed to the physical, biological, and chemical qualities, negative nutrient balance, loss of organic matter, nutrient removal, poor nutrient cycling process, and soil acidity.
Studies in the agricultural innovative space reveal that the integration of leguminous trees within alley cropping systems emerges as a promising avenue, showcasing the remarkable potential for both productivity and sustainability in the tropics. These tree species boost soil fertility and increase crop yield, thereby fortifying the resilience of tropical agroecosystems.
Leguminous trees make multiple contributions, including nitrogen fixation, provision of shade, green manuring, and mulch generation. Likewise, nitrogen-fixing leguminous trees and nitrogen mineral fertilizer offer a restorative solution for heavily degraded soils in soil reclamation. Gliricidia sepium (G. sepium) is an example of this beneficial leguminous tree that can serve as a restorative solution for degraded and highly degraded soils
G.sepium, commonly known as ‘walp’ or ‘alfalfa of the tropics,’ is a fast-growing, multi-purpose leguminous agroforestry tree capable of thriving in various soil conditions, including moderately acidic, alkaline, and infertile environments.
Compared to other leguminous trees, G. sepium is a venerable contributor to biomass production, yielding wood and leaves. Thus, G. sepium has long served households by providing essential resources such as firewood, charcoal, and fodder for livestock and poultry.
Beyond G. sepium utilities used in agroforestry, it has therapeutic properties. The leaves contain flavonoids, saponins, and tannins, known for their anti-inflammatory properties, which bolster healing processes. Moreover, the ethanolic leaf extract of G. sepium is efficient against Anopheles stephensi and gastrointestinal nematodes.
IITA–CGIAR Food and Nutrition Scientist Oladeji Alamu lends his voice to the international push to synthesize the knowledge gaps in G. sepium utilization for food crop production regarding improving the nutritional composition of different crops.
A publication titled “Gliricidia sepium (Jacq.) Walp Applications for Enhancing Soil Fertility and Crop Nutritional Qualities: A Review”, published in collaboration with the Norwegian Institute of Bioeconomy Research (NIBIO), established that in different farming systems, the trees and leaves of G. sepium could be used to improve soil fertility indicators such as total soil carbon, nitrogen, phosphorus, available phosphorus, pH, cation exchange capacity, and soil organic matter when it is either intercropped, used as mulch, or biochar—a charcoal-like substance made by burning organic material from agricultural and forestry wastes under a controlled process pyrolysis.
This publication further revealed that the use of G. sepium would be of economic benefit by improving the productivity and profitability of low-income farmers in Africa.
Following the research, Alamu stated, “The integration of G. sepium would reduce the use of mineral fertilizer, resulting in a greener and sustainable environment. He added that applying aged biochar could be a promising tool for agricultural productivity while mitigating climate change.”
Contributed by Anita Akinyomade
