Long term effects of Piliostigma reticulatum (DC) Hochst’ densities on carbon and water storage and dynamics of an epipetal Plinthosol in Burkina Faso’s northern Sudanian area

Abstract

Agroforestry remains one of the most accessible soil fertility improvement strategies for farmers in Sahelian countries. The objective of our work was to determine the effects of different planting densities of Piliostigma reticulatum, evolving on two tillages, on the status and dynamics of soil organic carbon and water in Burkina Faso’s northern Sudanian. The experimental design is a two-factor Fisher block design (tillage and shrub density) with eight treatments and four replications. At a depth of 0-10 cm, carbon stock increased by 20.45% and 26.29% respectively for the 1000 and 2000 shrubs / ha compared to 0 shrubs / ha in zaï; and by 38.59% and 57.34% for the 2000 shrubs / ha respectively in cropping system (CS) and in fallow compared to the 500 shrubs / ha density in no-till (NT). Over the same depth, the useful soil water holding capacity was higher with 2000 shrubs / ha (13.05 ± 0.66 mm) in zaï, and with 500 shrubs / ha (11.05 ± 1.13 mm) in NT. The ratio of labile carbon to organic carbon was lower on the 0-10 cm layer (9% to 12%) than on the 20-30 cm layer (49% to 72%) in the presence of shrubs. Infiltration rate increased by 54.20% and 31% respectively for 1000 and 2000 shrubs / ha densities compared to 0 shrubs / ha in zaï; and by 140.32 and 232.23% respectively for 2000 shrubs / ha density under CS and fallow compared to 500 shrubs / ha density in NT. Overall, the densities of 1000 and 2000 shrubs / ha improve the most carbon storage, water storage and soil permeability. Zaï and NT, while having similar effects on the storage of both carbon pools, differ in that zaï seems to improve water storage more while NT improves soil permeability more.