Using mucuna and P fertilizer to increase maize grain yield and N fertilizer use efficiency in the Coastal savanna of Togo
Van Reuler, H.
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To reduce severe soil degradation associated with agriculture, intensified land-use system is being promoted in West African countries. Most soils of the West African savanna zones are so poor that the efficiency of mineral fertilizers, if applied is very low. Many small-scale farmers are therefore reluctant to apply fertilizer also because of their high cost and unavailability. This work investigates a fertilizer management strategy using integrated soil fertility management with a leguminous cover crop (mucuna) so as to improve the soil fertility and increase the use efficiency of fertilizer. The experiment was conducted in the coastal savanna of Togo at Djaka Kopé. The aim was to evaluate the effectiveness of mucuna short fallow (MSF) in increasing maize grain yield through an improved use efficiency of mineral fertilizer. A 2-year maize-mucuna relay intercropping system was compared with continuous sole maize cropping. Fertilizer treatments were factorial combinations of 0, 50 and 100 kg nitrogen (N) ha^-1 and 0, 20 and 40 kg phosphorus (P) ha^-1. While maize grain yield was significantly increased by N fertilization, P did not show any important effect on grain yield. With no N and P applied, grain yield after MSF was on average 40 % (572 kg ha-1) higher than without. The response to N was much greater than the response to MSF, indicating that N was undoubtedly the key element for maize yield building. P fertilization and MSF together influenced positively the apparent N recovery fraction (NRF). N uptake alone did not reflect on its own the yield obtained, and the relationship between grain yield and N uptake is shifted by MSF with the grain yield increase per unit of N uptake being higher with than without MSF. Combining MSF and P fertilization may therefore lead to improved N use efficiency, making the application of fertilizer N (lower rates) more attractive to small-scale farmers.