Impact of long-term tillage, crop rotation and nitrogen fertilization on selected soil properties in Nigerian Savannah <i>Alfisol</i>

Abstract

This study was conducted to evaluate long-term tillage (T) practices, crop rotation (CR) and N-fertilization (NR) on soil chemical properties in savanna Alfisols of Nigeria. The aim of the research was to assess the influence of long-term tillage practices [conventional (CT) and reduced tillage (RT)], cereal/legumes [cowpea-maize (C/M), continuous maize (M/M) and soybean-maize (S/M)] rotation and N-fertilizer [N0 (0 Kg N ha^-1), N1 (90 Kg N ha^-1)] rates on selected soil chemical properties and its interaction on soil fertility status at 0 -15 cm depth. The trial was conducted at the Research Farm of Institute for Agricultural Research (IAR), Samaru-Zaria, Nigeria. Split split-plot experiment design was used with three replications: with tillage as main plot, crop rotation as sub-plot and N-fertilizer rates as sub sub-plot. Selected soil properties were analysed to study the impacts of the treatments on soil chemical properties. Results revealed that tillage practices significantly (P<0.05) affect available P with RT (21.478 mg kg^-1) ranking higher than CT (17.831 mg kg^-1). Crop rotation had significant effect (P<0.05) on available P (S/M ranked highest while the least was M/M rotation). Exchangeable K, Ca, Mg and CEC were highly significantly (P<0.01) influenced by rotations with trend in this order; M/M ˃ S/M ˃ C/M. The interaction of T*CR on exchangeable Ca, Mg and CEC were significant (P<0.05). Effects of interaction of T*CR*NR showed significant (P<0.05) difference on available phosphorus, exchangeable Ca, Mg and CEC. Therefore, RT*M/M*N0 was rated better in improving exchangeable K, Ca, Mg and CEC, while RT*S/M*N0 ranked highest in available P in savanna Alfisols.