Establishing Warm Season Annuals in Pastures
Imagine this, when our established cool season pastures slow during mid-summer (as seen below) we can have our warm season annuals there just in time to provide grazing for livestock in our rotation. A combination of warm season grasses, legumes, and broadleaves emerge perfectly. Livestock are happy to graze the high quality, highly digestible forage all summer. Fall comes and the cool season pastures pick back up while the warm seasons slow and stop growing. *rewinding sound* There are a few hurdles we have to face to get close to achieving this goal and making it at all comparable to planting to warm season annual in its own paddock.
As you can see above, cool season pastures will slow, but not go completely dormant during summer months. They will still be competing for sunlight, water and soil minerals (Gerrish, 4). This is where adequate fertility is important, especially when putting a grass (warm season) into a grass (cool season). There are a lot of nitrogen needs there. Also, the existing pasture already has an established root system that is a pro at grabbing all of the nutrients, and not to mention moisture, that it can. These new seedings of sorghum, sudangrass, millet, etc. may be fast to establish, but can have trouble competing with the root systems already in place. Shattering the soil and breaking up those root systems around where that seed will go in the ground is key to give it a less competitive area when establishing. This is where a very effective no-till drill is important, as well as the next guidelines mentioned.
Establishment Challenges –
We have seen many producers try to establish warm season in pasture stands and meet some challenges. Sometimes the larger seeds were not put deep enough to produce a healthy root system, or smaller seeded species were sunk too deep to establish. Another issue we have seen is conditions that are too wet when the warm season are planted. This leads to sidewall compaction that does not let the root system get established or the planting slot stays open and the seed to soil contact is not adequate. What is the answer to all of this? Be very mindful of seeding depth and soil conditions when planting (and remember to use an effective no-till drill). Giving the warm season plants a fair chance to germinate and establish a strong root system is a vital step.
In late spring, soil temperatures have to be 65 degrees and rising before planting any warm season annuals. Before that, they will not have proper temperatures to germinate or form a healthy root system. This stunting only allows the existing pasture to get further ahead. Timing of grazing is key to make sure you do not damage your perennial pasture. A successful, thriving establishment of these warm season needs to be rotationally grazed in a timely manner as to not shade out your pasture. If your warm seasons take off and get ahead of livestock in a rotation, this is where you could chop or make baleage from these species. So versatile!
Planting warm season forages alone will always be the most reliable way to have a successful establishment anf forage yield, but this can be an option if it matches your goals better. Overall, the key guidelines for establishing warm season into pastures are fertility, seeding method and depth, and planting and grazing timing. If these are followed properly (and Mother Nature cooperates), the dream mentioned at the beginning could become a reality!
Gerrish, Jim. "Using Annual Forages to Beef Up Perennial Pastures." The Stockman Grass Farmer, 2017, pp. 1-4.