IJAER

International Journal of Agriculture and Environmental Research™

ISSN 2455-6939

Title:
FACTORS MODULATING SOIL NITRATE-N DYNAMICS IN THE WEST AFRICAN SAVANNA ZONE

Authors:
Poulouma Louis Yameogo, Mathias Becker, Zacharie Segda

Abstract:
Soil nitrate-N dynamics during the dry-to-wet transition (DWT) season and its management are key determinants of soil productivity in low-input systems of the dry savanna zone of West Africa. Two field experiments were conducted in 2013 and 2014 with the aim to determine the effect of soil tillage and rainfall intensity on native NO3-N dynamics during DWT. The study on the effects of soil disturbances on N mineralization compared mechanical tillage with a no-till treatment. The effect of rainfall intensity on nitrate dynamics was assessed by comparing natural rainfall with a simulated 30% increase and a 30% reduction. Mechanical soil tillage increased N mineralization in 2013 and during the initial phase of DWT in 2014. Towards the end of DWT, most nitrate from wetland soils adjacent to a tilled upland had disappeared, while N mineralization continued in the lowland below the reduced tillage treatment. Reduced rainfall increased the nitrate accumulation in the soil profile with little apparent nitrate losses. With increased rainfall, on the other hand, most nitrate had disappeared once the volumetric soil moisture exceeded 25%. We conclude that tillage and rainfall differentially affect soil-N dynamics during DWT and, there is a need for site-specifically adapted soil-N-conserving management strategies.

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