By Ayman Mostafa and Mike Ottman, University of Arizona
Forage sorghums are warm-season, annual grasses that have the potential to produce large amounts of nutritious forage during summer months, especially in lower-elevation deserts, like central Arizona. If managed properly, sorghum can be used as supplemental feed during times of inadequate forage production or can be used as an emergency, late-planted crop to replace a primary crop that has been damaged by wind, hail or drought early in the growing season. The nutritional value of forage sorghum can becomparable to silage corn, however sorghum uses less water. Forage sorghum meets the proper characteristics for a crop to be ensiled; it has high levels of water-soluble carbohydrates, low crude protein content, and low buffering capacity.
One of the greatest advantages of forage sorghums is the diversity of management options that the grower has to choose from in order to match his production needs. Depending on which species and variety selected, sorghums may be used for grazing pasture, hay production, and silage and green-chop. Forage sorghums are usually grown for single-cut silage or green-chop operations. The one-time harvest gives higher yield and optimum forage quality. The crop can be directly chopped without wilting when harvested near soft-dough stage. It is reported that the main issue with ensiling forage sorghum is the great variability that exists among cultivars and the high moisture content at the time of ensiling, which makes ensilability of forage sorghum more challenging than other crops. Many of the sorghum silage acresin central Arizona are close to harvest these days.In forage sorghum trials conducted at Maricopa with a late season hybrid, the crop was harvested at soft dough, which occurred about 3 weeks after bloom, and the crop was at about 72% moisture at this time.
The Western Forage Production Guide of United Sorghum Checkoff Program discuss, among other useful topics, the harvest of silage sorghum with focus on maturity at harvest, silage management, and the use of additives.