Nitrogen topdressing with subsurface drip facility improves growth and yield in maize ( <i>Zea mays</i> L.)

Maize requires nitrogen for optimal growth, but the efficacy of nitrogen topdressing via subsurface fertigation remain unclear. This study used a subsurface drip system buried 40 cm deep to examine growth and yield of maize with a nitrogen topdressing. Nitrogen fertilizer was applied at rates of 0, 60, 80, and 100 kg ha−1 at the V6 (jointing) and R1 (silking) stages. Approximately 243 mm ha−1 of water was needed to saturate the soil to a depth of 10 cm. The fertilizer solution, applied with water, moved upward through capillary action in the soil profile and was subsequently absorbed by the roots, adsorbed by the soil, or leached. Maximum nitrogen uptake occurred at 80 kg ha−1. Higher levels did not increase uptake but increased nitrogen levels in soil water. About 50.9% of applied nitrogen remained below the drip line. Growth and yield were optimal at 80 kg ha−1, but more nitrogen stayed in the soil than was absorbed by the plants. The results of this study suggest that a subsurface fertigation strategy at the V6 or R1 stages, targeting saturation to a depth of 10 cm, using a drip system buried 30–40 cm deep, is optimal.