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Objective: To improve soil chemical properties and crops productivity, this study was conducted from 2008 to 2015, on lixisoil in a research station, using reduced soil tillage and leguminous plant cover.
Methodology and Results: Three soil tillage practices in main plot (T1 = no tillage with direct sowing, T2 = minimum tillage by soil scarifying with IR12 tool and T3 = conventional tillage with animals drawn plough) were compared and combined to four crops rotation systems, in a split-plot experimental design. Soil chemical characteristics and crops yields were evaluated. The results showed that tillage practices did not influence significantly the soil chemical properties, but soil organic matter contents, nitrogen, phosphorus and potassium were lower in conventional tillage plots (T3) compared to minimum tillage (T2) and no tillage (direct sowing). Rotations did not significantly influence nitrogen and soil organic matter contents, even the leguminous mucuna insertion in the rotation during three years. After 8 years, crops rotations improved significantly cotton (Gossypium hirsutum L.) and maize (Zea mays L.) yields. The yield increases were respectively +7, +23 and +43%, with one, two and three years of mucuna insertion into rotations. No tillage (direct sowing) and minimum tillage (scarifying with IR12) were as efficacy as conventional tillage on Mucuna and maize yields whereas cotton yield, with minimum tillage (T2) was significantly higher than no tillage (T1).
Conclusion and application of results: The study showed that conventional tillage with mouldboard plough, appear to be the soil tillage practice, which led to soil properties degradation. Crops rotations with the use of leguminous mucuna allowed reducing soil N contents decreases. No tillage (direct sowing) and minimum tillage (scarifying with IR12) showed same efficacy with conventional tillage on cotton, maize and mucuna yields, which were improved after mucuna insertion into crops rotations. Therefore, tillage suppression or its reduction combined to one year leguminous cover plant insertion in rotation (mucuna-cotton-maize) could be used for crops diversification and sustainable productivity in cotton and cereals based production systems.
Keywords: Tillage practices, crops rotations, plant cover, soil fertility, yields, Burkina Faso