Rice is one of the main crops of irrigated perimeters of the Niger River Valley. Reasoned fertilization on rice diocers is very important in improving yields, decreasing nutrient losses but also conservation of soil. The objective of this study is to characterize the physico-chemical solutions of soils to evaluate the effects of several fertilization formulas on the production of three varieties of rice at the irrigated niamey and Tillabéry perimeters. The study is carried out in two stages first one on the soil analyzes and the other on agricultural tests. Solutions of solutions were conducted at the Liborated sites, Saadia Amount and N’Dounga 1 during the year 2023. All ten samples taken were studied at the Social Science Laboratory of the Faculty of Agronomy and the LANB laboratory to know the physicochemical characteristics of the soil of the sites. Study of the study sites. For testing, kogoni91-1 (rifles), Orylux and IR15 rice varieties were used in a 2123 winter season and dry season 2023. The experimental device is the blocking block (3x5) with two factors: the 1st factor as variety with three varieties (Gambiaka; Orylux and IR15) and the 2nd factor fertilizer factor feature with five treatments: T0 = N122P30K30 (peasant practice); T1 = N138P90K60; T2 = N175P112 K60; T3 = N100P120K 50S20ZN2; T4 = N122P30K30S20ZN2. The soil analysis of the three sites have shown that soils have lemon-sandbrandex textures (Liborated and N’Dounga 1) and limited texture to Saadia upstream. The soils of the three sites are low in chemical and poor elements in exchangeable bases. The rates of organic matter and total nitrogen decrease with the depth at all the sites studied. The performance of genotypes are influenced by the imposed treatments or the environment in which the culture has been installed. During the dry season, the best combinations and also the most stable in the three sites are the variety 2 with T4 treatment and variety 1 with T4. During the rainy season, the variety combination 2 and T4 treatment has a high and stable yield to Liborated and Ndounga1 while the variety combination 3 with T4 treatment is the best performance in Saadia AMONT. The comparison of the averages shows that the highest average yield was obtained with the T4 formula combined with the varieties that are V1, V2 and V3 for the dry season and the wintering season.

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.