Effect of Application Rate and Timing of Meat and Bone Meal As an Organic Fertilizer on Growth and Yield of Sweet Corn

Meat and Bone Meal (MBM) or tankage is a high-nitrogen (N~ 10%) solid by-product of animal rendering that is locally-produced/available for use as a fertilizer. Local inputs, such as MBM, are key components of sustainable agricultural systems in Hawai‘i and must be properly applied to achieve crop yields and to limit adverse environmental impacts. The objectives of this study were to examine sweet corn growth and yield response to MBM (1) application rate and (2) application timing. Field trials were conducted in Waimanalo, HI arranged in a Split-Plot RCBD with 4 replicates. Each plot was planted with Supersweet #10 corn (Zea mays L.). Treatments included 5 rates of N (0, 112, 224, 336, and 448) kg ha^-1 and 2 timings of application, before planting (Preplant) or half preplant and the remainder one month later (Split). Suction cup lysimeters were installed at 30 and 60 cm depth (within and below the root zone, respectively) to collect soil water. Weekly, leaf chlorophyll was measured with a SPAD meter and soil water samples were collected and analyzed for nitrate (NO₃-N) and ammonium (NH₄-N). Rate of MBM, but not timing, had a significant effect on yield, shoot and root biomass, and leaf area. While timing was not significant, nitrates in soil concentrations below the root zone were decreased by nearly 20% for split application compared to preplant application. In conclusion, as expected yield increased with increasing application rate but more importantly, split application reduced potential for ground water pollution without decreasing yield. These findings will help local farmers work towards precision agriculture by improving their nutrient management when using this local resource.