INTERACTIVE EFFECTS OF NITROGEN, PHOSPHORUS AND CROPPING SYSTEM ON THE GROWTH PERFORMANCE OF POPCORN (Zea mays L. Everta) AND LABLAB (Lablab purpureus L. Rongai) INTERCROPPING

Abstract

The study evaluated the interactive effects of nitrogen, phosphorus, and cropping systems on the growth performance of popcorn (Zea mays var. everta) and lablab (Lablab purpureus) during the 2020–2022 wet seasons at Bayero University, Kano, Nigeria. Treatments consisted of five nitrogen levels (0, 30, 60, 90, and 120 kg N ha⁻¹), three phosphorus levels (0, 30, and 60 kg P₂O₅ ha⁻¹), and three cropping systems (alternate stand, alternate row, and alternate strip). The factors were factorially combined and arranged in a split–split plot design with three replications, where nitrogen was assigned to the main plots, cropping system to the subplots, and phosphorus to the sub-subplots. Nitrogen and phosphorus application significantly (p < 0.05) improved plant height, number of leaves, stem girth, and biomass of both crops. The highest values were obtained with 120 kg N ha⁻¹ and 60 kg P₂O₅ ha⁻¹, indicating optimal nutrient availability without diminishing returns. Among the cropping systems, the alternate strip arrangement consistently produced superior growth and biomass accumulation, owing to better light interception, root complementarity, and efficient nutrient utilization. Significant N × P and N × cropping system interactions revealed synergistic effects between nutrient supply and spatial configuration. Integrating 120 kg N ha⁻¹ and 60 kg P₂O₅ ha⁻¹ with alternate strip intercropping optimized growth and resource-use efficiency, demonstrating a practical and sustainable approach for enhancing cereal–legume productivity and soil fertility restoration in the fragile sandy loam soils of the Sudan Savanna.