Assisted Natural Regeneration (RNA) is one of practices that small farmers adopted to restore vegetation cover and improve land productivity in cultivated areas in Niger. The present study, conducted in the main cultivation areas in Niger, aims to assess the effects of RNA trees on soil physicochemical characteristics of cultivated tropical ferruginous soil in order to assess their fertility. Composite soil samples were collected at 0-20 cm deep under and outside trees crowns of Piliostigma reticulatum, Combretum glutinosum and Sclerocarya birrea respectvily to determine physicochemical characteristics i.e soil particle size composition, pH, CEC, organic matter contents, assimilable phosphorus. The results showed that trees have no influence on particle size composition because there are no significant differences between area under crown and area outside crown on granulometric composition under all species. However, the presence of these trees (Piliostigma reticulatum, Combretum glutinosum and Sclerocarya birrea) significantly improves chemical soil fertility. Indeed, organic matter content was 26, 3.8 and 4.2 times higher respectively under crown of P. reticulatum, C. glutinosum and S. birrea than that outside crown of these species. Moreover, available phosphorus content, often very low in cultivated tropical ferruginous soils in Niger, was 2.5, 1.2 and 2.1 times higher in soil under crown than soil outside without crown of P. reticulatum, C. glutinosum and S. birrea respectively. Thus, RNA practice improves soil chemical fertility of cultivated tropical ferriginous soils through input organic matter and nutrients by biomass plant. However, further studies can be performed to determine effects of RNA ligneous plants on soil hydrostructural properties.

The use of organic manure is very old and practiced both in rainfed cultivation and in horticulture. In Niger it has been reported the presence of another source of organic manure called bat guano which is unknown to the population of the said country. The objective of this study is to describe the sector of guano exploitation in Niger. A series of questionnaires was formulated to describe the system of exploitation and use of bat guano. In addition to the agriculture and environment departments, three groups of stakeholders in the sector, including extractors and sellers, the trader (s) and users of guano were interviewed. The results of the investigations showed that to date, the only production and exploitation site of guano identified is that of Magarawa located in the department of Gouré in the Region of Zinder (Niger). The extraction is done using rudimentary tools (pick, knife, plastic) then bagged 40 and 85 kg. The quantity extracted per year is 332 tons. Marketing is mainly carried out by a single individual and the selling price is 4000 to 5000 FCFA per 85 kg bag of bat guano. The buyers are located in the vicinity of Gouré and the Diffa region, there is also a clientele coming from Nigeria. The users of guano are mainly horticulturalist in oasis basins. One of the biggest buyers is the commune of Guidimouni located in the southwest, 100km from Gouré. We conclude that this exploitation of bald guano is an income-generating activity and requires good organization.