Nitrogen Fertility Management For Grain Sorghum In North Carolina.

Grain Sorghum production has increased many folds in the last couple of years in North Carolina. Little research based production information is available for the Mid-Atlantic region of the US, which has a drastically different growing environment compared to the Midwest. Nitrogen is a major, costly input determining yield and profitability. Although sorghum is very efficient in absorbing any residual N from the soil, additional fertilization may result in higher yield and net profit. This study was conducted to determine the optimum rate of Nitrogen fertility, and time of application in North Carolina. Field studies were conducted at Kinston and Rocky Mount, with 60, 90, and 120 lb of N per acre, applied at planting, at side dress, and a split application at planting and at side dress. These treatments were compared with a non-treated control. All treatments resulted in significantly higher yield than control, although decent yields in the range of 70 to 80 bushels/ac were obtained without additional Nitrogen. At the Kinston location, 60 lb/acre pre plant had lower yield while 120 lb/ac at side dress had the highest grain yield, with other treatments exhibiting yield in between these two. At the Rocky Mount location, overall yields were higher compared to Kinston, but the trend was similar. Nitrogen applied at 120 lb/ac at side dress had the highest yield, followed by split application of 120 lb/ac, followed by 120 lb/ac at planting. These results show that Grain Sorghum shows a positive yield response to applied N, however, the best time to apply N is at side dress when it has an established root system to absorb the N. Applying entire N at planting wastes a lot of N due to leaching, thus results in lower yield and profit and causes nitrate pollution of ground water.