Browsing by Author "Carsky, R. J."

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    Integrated soil management for the savanna zone of W. Africa: legume rotation and fertilizer N
    Carsky, R. J.; Oyewole, B.; Tian, G. (Springer Science+Business Media B.V., Formerly Kluwer Academic Publishers B.V., 1999)
    Integrated soil management with leguminous cover crops was studied at two sites in the northern Guinea savanna zone of northern Nigeria, Kaduna (190 day growing season) and Bauchi (150 days). One-year planted fallows of mucuna, lablab, and crotalaria were compared with natural grass fallow and cowpea controls. All treatments were followed by a maize test crop in the second year with 0, 30, or 60 kg N/ha as urea. Above ground legume residues were not incorporated into the soil and most residues were burned early in the dry season at the Kaduna site. Legume rotation increased soil total N, maize growth in greenhouse pots, and dry matter and N accumulation of maize. Response of maize grain yield to 30 kg N ha1 as urea was highly significant at both sites and much greater than the response to legume rotation. The mean N fertilizer replacement value from legume rotation was 14 kg N/ha at Kaduna and 6 kg N/ha at Bauchi. W ith no N applied to the maize test crop, maize grain yield following legume fallow was 365 kg/ha higher than natural fallow at Bauchi and 235 kg/ha higher at Kaduna. The benefit of specific legume fallows to subsequent maize was mostly related to above ground N of the previous legume at Bauchi, where residues were protected from fire and grazing. At Kaduna, where fallow vegetation was burned, maize yield was related to estimated below ground N. The results show that legume rotation alone results in small maize yield increases in the dry savanna zone.
  • Using mucuna and P fertilizer to increase maize grain yield and N fertilizer use efficiency in the Coastal savanna of Togo
    Fofana, B.; Breman, H.; Carsky, R. J.; Van Reuler, H.; Tamelokpo, A.; Gnakpenou, K. (Kluwer Academic Publishers, 2004)
    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.