Effect of Crotalaria Species on the Dynamics of Soil Biological Activity in the Northern Sudanian Zone of Burkina Faso

Abstract

Declining soil biological activity threatens the sustainability of agricultural production in the Sudanian zone of Burkina Faso. Split-plot experiments conducted in 2023 and 2024 at Yarci, Arbollé, evaluated the effects of Crotalaria mucronata and Crotalaria retusa combined with four amendment treatments: an unamended control (T0), organic matter (OM), Burkina phosphate (BP), and OM+BP. Daily CO2 emissions, microbial biomass carbon (MBC), microbial yield (MY), overall mineralization rate (OMR), and metabolic quotient (qCO2) were assessed. Results showed that both Crotalaria species produced similar effects. Cumulative CO2 emissions increased between 2023 and 2024, reaching maximum values of 320.90 and 298.98 mg 100 g-1 soil under C. retusa and C. mucronata, respectively. For both species, OM+BP generally produced the highest CO2 emissions and improved most soil biological indicators, followed by OM alone. MY was stable at approximately 48-51%, whereas qCO2 and OMR remained below 2 mg CO2-C g-1 MBC day-1 and 2%, respectively, suggesting relatively low microbial metabolic stress and moderate organic matter mineralization. These findings indicate that combining Crotalaria-based improved fallows with organic matter and Burkina phosphate can enhance soil biological functioning and represent a promising agroecological strategy for restoring degraded soils in Burkina Faso.