Influence of Re-Greening on the Infiltrability of Soils in South-Central Niger

Abstract

In the Sahel, the climate and the agricultural practices are the main factors used to observe regreening process. But the extension of this re-greening is not uniform in the fields, so we can assume that there are other factors contributing to the greening of some areas and not others. The infiltrability of soils is considered as an important factor for these changes in the last decades. The influence of re-greening on the infiltrability of soils in the southern strip of Niger was studied through a comparison of zones according to the type of sandy soils (Jigawa/Rerey), silty-clay (Guiéza), silty-sandy (Hako) and clay-silty-sandy (Laka). The evaluated parameters are the texture, the infiltrability and the ecological characteristics (specific index of regeneration "SIR" and the Importance Value Index "IVI"). The main conclusions were: the soils of Niger South-Central are characterized by a sandy texture for more than 80%. The soils which are very sandy ("Jigawa", "Rerey" and "Guieza") are more permeable and have more trees contrary to the soil Hako and Laka. Their encrusting has the tendency to reduce the vegetation cover on the soil. The infiltration measurements indicated that the rate of initial and stationary infiltration diminishes while going down towards the South. In fact, it has been recorded a rate of 123 mm/min of initial infiltration and 87 mm/min stationary in Dan Saga on the sandy soils against 76 mm/min and 65 mm/min in Daré respectively for the initial and stationary rate. Therefore, the infiltration seems to influence the density, the SIR and the IVI of the trees from the North towards the South. Some additional work is necessary in order to determine the contribution of Farmer Managed Natural Regeneration (FMNR) in the improvement of the quality of soils and the movement of water in the superficial zones of the soil.

Farmers’ perspectives and context are key for the success and sustainability of farmer-managed natural regeneration (FMNR) in northeastern Ghana

“…Fire is cited as a key obstacle (Chomba et al, 2020), along with traditional land management practices in agropastoral systems, which, due to free range livestock grazing, lead to browsing pressures that inhibit the natural regeneration of woody vegetation (Lohbeck et al, 2020;Sida, Baudron, Deme, Tolera, & Giller, 2018). One study reports that pastoralists inhibit assisted natural regeneration, although it is unclear from the publication whether they interviewed pastoralists or observed their livestock damaging shrubs or trees (Moustapha, Baggnian, Yahaya, & Adam, 2014). While unaddressed in the Chomba et al (2020) review, certain gaps in knowledge such as why and how farmers might practice FMNR and how context influences FMNR decision-making, reflects the lack of in-depth qualitative case studies.…”

Opportunities and Constraints for Using Farmer Managed Natural Regeneration for Land Restoration in Sub-Saharan Africa

“…Sida et al (2018) also characterize the soils under FMNR in central rift valley of Ethiopia as andosols, which are highly porous dark-colored soils of volcanic origin. This indicates that FMNR is mainly practiced in areas with low soil fertility which are sandy textured with a partially formed surface horizon, high permeability and low top-soil organic carbon and other nutrient contents (Larwanou et al, 2010;Haglund et al, 2011;Sendzimir et al, 2011;Moustapha et al, 2014). Agricultural use of these soils requires careful management (FAO, 2001).…”

“…Bayala et al (2019) reported an increase in total SOC in the top 0-10 cm soil, with SOC being more under trees than away from the tree and larger effects in sandy soils. Trees have also been reported to have a positive effect on infiltration due to the formation of root channels as well as macro and micro pores (Moustapha et al, 2014). Increase in SOC is caused by accumulated biomass from leaf litter and root turnover and the cooler and moister microclimate under shade, that reduces CO 2 efflux, so that the difference between under and away from trees is associated with the balance between inputs of organic matter and outputs as soil respiration (Bayala et al, 2019).…”