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Effect of Applying Nitrogen with Sorghum Seed (Sorghum bicolor) on Emergence and Final Grain Yield

Eickhoff, Elizabeth Mary
Sorghum (Sorghum bicolor) is becoming an important crop due to its drought tolerance. High production levels of this crop could aid in fulfilling growing food demands. This study was conducted to determine the amount of nitrogen (N) fertilizer that could be applied in furrow with sorghum seed while minimizing decreases in crop emergence and maximizing grain yield. Data was collected in 2017 at two locations and in 2018 at three locations in Oklahoma. Emergence counts were taken frequently to evaluate plant stands and yield was collected at harvest. Urea was used as the N source where four different rates (0, 10, 20, 30 kg N ha-1) were applied at three seeding rates (101,222, 177,700, 216,330 seeds ha-1). Soil moisture levels were monitored at planting due to its influencing effect on the level of salt damage to developing seedlings. In 2017, high rainfall within two days after planting had a prominent impact on the minimal salt injury observed in the emergence values compared to 2018. On average, applying 30 kg N ha-1 with the seed resulted in emergence losses of 51%, where 20 kg N ha-1 and 10 kg N ha-1 resulted in losses of 38% and 29% respectively. The check treatments where 0 kg N ha-1 was applied with the seed resulted in an average 13% loss in emergence. Even though major decreases in emergence were noted, seeding-N-rate did not have a significant effect on yield levels. It is recommended that less than 10 kg N ha-1 be applied with sorghum seed to minimize emergence loss.