Sorghum Fertility: More Yield, Less Guesswork

Forage sorghum can be a practical summer hay option in Oklahoma, but producers still have to manage the line between more tonnage and safe feed. In this episode of Red Dirt and Round Bales, Dave Deken visits the question of nitrogen timing in forage sorghum with insight from Steve Phillips Ph.D. of Oklahoma State University. Phillips shares field research from Stillwater and Perkins looking at nitrogen rates, split applications, hay yield, protein, TDN, and nitrate levels. The results point to strong forage production potential, but also remind producers that nitrate risk is driven heavily by plant stress, erratic rainfall, and growing conditions. Key takeaways: Forage sorghum can make hay, silage, or grain and fits Oklahoma’s weather and livestock systems. OSU research showed yield increases up to 200 pounds of nitrogen per acre in the trials discussed. Split nitrogen applications may improve efficiency compared with older nitrogen-per-ton assumptions. Hay quality held around 7–8% protein and about 60% TDN in the research. Nitrate levels did not exceed 3,000 parts per million in the trial, but drought stress and erratic rainfall can change nitrate risk quickly. Detailed timestamped rundown 00:00–00:10 — Opening from Oklahoma Dave Deken introduces the episode as a look at agriculture and rural life across Oklahoma.00:13–01:35 — Why sorghum fits Oklahoma The episode frames sorghum as a crop that does not need perfect weather or the richest ground. Dave explains that sorghum can produce grain, silage, and forage, making it especially useful for livestock producers trying to make hay during tough summer conditions.01:35–01:59 — The producer question Dave introduces the central management question: how much nitrogen does forage sorghum need, when should it be applied, and can producers push yield without creating nitrate problems in the hay?01:59–03:47 — Steve Phillips on nitrogen research Steve Phillips Ph.D. explains OSU research on nitrogen rates and timing for forage sorghum hay. Trials near Stillwater and Perkins showed forage yield increases up to 200 pounds of nitrogen per acre. Phillips notes that yields ranged from about 9 tons at 100 pounds of nitrogen to about 13 tons at 200 pounds, suggesting split applications may offer a more efficient path than older recommendations.03:47–04:09 — Yield is only part of the story Dave shifts the focus from tonnage to feed value. Hay must be safe and useful for cattle, so quality and nitrate levels matter as much as yield.04:09–04:59 — Protein, TDN, and nitrate results Phillips says nitrogen rate did not create major differences in protein in this trial. Hay tested around 7–8% protein and about 60% TDN. Nitrate levels stayed below 3,000 parts per million, even at 200 pounds of nitrogen, which was below the level of concern discussed in the episode.04:59–05:41 — Weather still drives risk Dave closes by emphasizing the value of field research and the reality of Oklahoma weather. Phillips explains that nitrate toxicity is environmentally dependent, with plant stress, growth surges, and erratic rainfall playing a major role in nitrate accumulation. Red Dirt And Round Bales website