Nitrogen is the most limiting plant nutrient in Vertisols in Kenya. Soilproperties, climatic conditions and management factors as well as fertilizercharacteristics can influence fertilizer nitrogen (N) use efficiency by crops.Vertisols, characterized by low-basic water infiltration rate, are prone towaterlogging under sub-humid and humid conditions. We determined effects ofdrainage, N source and time of application on yields, nutrient uptake andutilization efficiencies by maize grown on Vertisols in sub-humid environments.Treatments comprised two furrows (40 cm and 60 cmdeep) and a check (i.e., no furrow), calcium nitrate to furnishNO3-N, ammonium sulphate to supply NH4-N at 100 kgNha–1, a control (i.e., no fertilizer N), and fertilizerN application at sowing, 40 days after sowing, and split (i.e., half the rateatsowing and half 40 days after sowing). A split-plot design was used in whichdrainage formed the main plots and N source x time of N applicationformedthe sub-plots. Higher grain and total dry matter yields, harvest index, leaf Ncontent, uptake of N, P and K, as well as N agronomic (NAE) and recovery (NRE)efficiencies were obtained from drained compared to undrained plots. The increase ingrain yields as a result of drainage varied from 31 to 45␏or control,35 to 43␏or NO3-N, and 16 to 21␏orNH4-Ntreatments. Drainage resulted in total N uptake increases from 50 to 80kgN ha–1 in control plots, 80 to 130 kg Nha–1 in NO3-N treated plots, and 90 to 130kg N ha–1 in NH4-N treated plots.Ammonium-N source was superior to NO3-N source in terms of higheryields, NAE, and NRE in undrained plots, but the two N sources behavedsimilarlyin drained plots. Delayed or split NO3-N application gave higheryields, NAE and NRE than when all N was applied at sowing in undrained plots.There was no difference between 40 cm and 60 cm deepfurrows in terms of crop yields and nutrient use efficiencies. Thus, drainingexcess water with furrows at least 40 cm deep is essential forsuccessful crop production in these Vertisols under sub-humid conditions.