IMPACT DE LA FERTILISATION PAR MICRODOSE DE NPK SUR LES PROPRIETES CHIMIQUES ET BIOLOGIQUES DUN SOL SABLEUX SOUS CULTURE DE SESAME (SESAMUM INDICUM L.) AU NIGER

Improving the productivity of sesame (Sesamum indicumL.) on the sandy soils of Niger often poor in essential nutrients is a major challenge for food security. The microdosing technology, designed to optimize productivity while minimizing fertilizer investment and natural resource degradation, was evaluated for its effects on soil properties. A field trial was conducted in 2012 in N Dounga, in the Kollo department of Niger, comparing different NPK rates (0 g, 0.5 g, 1 g, and 1.5 g per hill) on two sesame varieties. This study focuses on the analysis of soil chemical and biological parameters before and after cultivation. The results showed a contrasting effect of microdosing: it significantly improved the chemical properties of the soil (increases in N, C, and K) but was associated with a decrease in pH, available phosphorus, and microbial biomass.This confirms that while microdosing enhances short-term nutrient availability, its exclusive use could, in the long term, lead to biological and chemical degradation of the soil. These findings highlight the importance of combining mineral fertilizers with organic amendments to ensure the long-term sustainability of soil fertility in the sandy soils of Niger.