Planning Warm Season Planting

Warm-season annual forages are fast-growing, high-quality forages that can supplement production and quality to support animal performance. In the Southeast, they are planted from April through June and can be used under baleage or greenchop production, or grazing management. Most livestock operations in the region are based on perennial grasses, such as tall fescue (Festuca arundinacea), bahiagrass (Paspalum notatum) and bermudagrass (Cynodon dactylon). Summer annuals are a good alternative to complement those operations’ nutritional and yield requirements. For example, they are a good option to support higher nutritional requirements for stockers during the summer months. Also, due to their fast growth and stand establishment, summer annuals can help to fill the gap of forage production in operations.

Warm-season annual forages can be grown either in monoculture or in mixtures. They require proper soil pH and fertility, and adequate land preparation ahead of planting. Among the grasses, the most used ones are crabgrass (Digitaria sanguinalis), pearl millet (Pennisetum glaucum), sorghum (Sorghum bicolor), and sorghum-sudangrass (Sorghum × drummondii). These grasses range around 15% crude protein (CP) and are high yielding. Crabgrass can be managed for reseeding at the end of the season. While, sorghum and sorghum-sudangrass require proper grazing management to avoid issues with prussic acid poisoning or nitrate toxicity, mainly when drought or frost events occur. They may also require sugarcane aphids control in the season to reduce forage yield and quality losses.

With the increasing costs of fertilizer, the incorporation of legumes into grass-based stands is a viable option to add organic nitrogen into the system. Among the warm season annuals, cowpea (Vigna unguiculata), sunn hemp (Crotalaria juncea), and forage soybean (Glycine max. L.) are options to be incorporated into mixtures (Fig. 1). When using forage mixtures, it is necessary to adjust seeding rates and management practices to allow the species to grow and establish well. Forage legumes are higher quality and can tolerate grazing, but the pastures should be managed under rotational management to allow proper resting time for plants to recover. In an ongoing study in Blackville, SC, Dr. Silva is evaluating three warm-season annual diets with 50 lbs N/acre fertilization. In the first year of data collection, forage yield ranged from 5,140 to 6,600 lbs DM/acre among the diets, with CP up to 17%.

Establishment and management tips for summer annuals plantings

  • Prior to select forage species to be planted, it is crucial to determine what are the forage needs (yield and quality), level of investment, management skillset, equipment, type of operation, nutrient management, etc. All these considerations will allow you to make adequate decisions with the help from an Extension agent.
  • Prior to establishing, it is important to conduct a soil test and amend soil pH, as needed. The soil report will also serve as the basis for the P and K fertilizers rate recommendation.
  • Conduct proper weed control and land preparation (disk, harrow, etc). If planting forage legumes in the field, check with your Extension agent which herbicide products you can use due to their soil residual effect.
  • Use certified, high-quality seeds to avoid introducing unwanted plants into your pastures. When using legumes, make sure to purchase inoculated seeds, or to inoculate them prior planting, when necessary.
  • Using proper seeding rate and seed depth is crucial. Calibrate the equipment prior to planting and according to the manual. When using mixtures, calibration adjustments may be required.
  • Plan to split and apply the total fertilizer rate for nitrogen (N) on grass stands only to optimize their use by the plants and decrease nutrient losses. All plantings should be fertilized at planting, but, grass-legume mixtures should not receive N fertilization within the season. When N fertilizer is applied during the season, it may compromise the biological N fixation by forage legumes in the mixture.
  • The use of forage mixtures can extend the forage distribution and grazing season, but, requires adjustments on grazing management. It is important to make sure that stands are not overgrazed as that can compromise the growth and participation of some species in the mixture early in the season.
  • Grazing management will also aid in redistribution of nutrients back into the pastures. Using rotational grazing will allow for proper harvest efficiency of forages, and better distribution of excreta on paddocks.
  • Use proper stubble height recommendations for forages used. Grazing too low will aid in removal of the growing points from individual plants, which compromises their regrowth and can reduce the length of the grazing season.



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