Journal of Experimental Agriculture International

Sowing quality is essential for uniform crop establishment and satisfactory maize yield. However, the combined effects of sowing speed and seed-placement depth on sowing uniformity, seedling emergence, and grain yield require further evaluation under field conditions. This study evaluated the effects of sowing speed and sowing depth on sowing uniformity, seedling emergence, and grain yield of maize (Zea mays L.). A randomised complete block design was used in a 4 × 3 factorial arrangement with three replications. The treatments comprised four sowing speeds (2.1, 3.7, 5.9, and 7.8 km h⁻¹) and three sowing depths (2.5, 5.0, and 8.0 cm). Seed-placement depth, seed spacing, and plant spacing were assessed through coefficients of variation and the proportions of acceptable, double, and missed spacings. The onset and completion of seedling emergence, emergence speed index, and grain yield were also evaluated. Increasing sowing speed raised the variability of seed-placement depth and seed spacing and reduced the proportion of acceptable seed and plant spacings, indicating poorer longitudinal distribution. Sowing depth had a stronger influence on crop development than sowing speed. The shallowest depth, 2.5 cm, delayed the onset and completion of emergence, reduced the emergence speed index, and produced the lowest grain yield. Across the evaluated speeds, the highest grain yields were obtained at a depth of 5.0 cm, whereas sowing speed did not significantly affect grain yield within each depth. These findings show that lower operating speeds favour sowing uniformity, while appropriate seed placement depth is important for timely emergence and yield under the field conditions evaluated.