Crabgrass for Forage: Management from the 1990s/Improving Overall Forage Quality by Adding Higher Quality Warm-Season Grasses to the Bermudagrass Sward

Producers have been managing natural bermudagrass and crabgrass mixtures very well and adding crabgrass to bermudagrass, bahiagrass, and Old World bluestem pastures throughout the southeastern United States. Research at the University of Florida shows that a bermudagrass-crabgrass mixture can produce 14 percent more grass than bermudagrass alone (Dunavin, personal communication).

There are several important management inputs that make the mixture work at the upper level. A summary in prioritized order is below.

Mixtures are more dependable when produced on sandy soils that crabgrass grows well on but are also good on loam and silt loam soils. Mixtures succeed least on clay loam and other fine-textured soils. Excessive wetness and drought intensity cause more problems on the fine-textured soils.

Good moisture distribution and total precipitation make mixtures more consistent, productive, and dependable during summers with adequate rainfall in Oklahoma and the more humid areas of the southeastern United States. Regions with higher rainfall (30 inches or more per year) are better. In very dry regions or very dry seasons, crabgrass will not perform well in the mixture and will die before bermudagrass dries.

Proper tillage (or other surface-soil disturbance) has a very strong influence on crabgrass stand development, early forage production, and total forage production in farmed pastures such as double-cropped wheat and crabgrass. Disking and refirming with a drag or roller to disturb 30 to 50 percent of the bermudagrass or bahiagrass sod surface generally produces good crabgrass stands. This degree of tillage allows the bermudagrass to recover very well. Other tillage tools could be used, and some producers depend only on intensive grazing of the early bermudagrass. If cool-season annual grasses or legumes are in the stand, till in the fall.

Heavy winter to early spring grazing and pugging (trampling) of the permanent sod in wet winter weather are forms of crabgrass stand tillage and renovation.

Grazing must be rotational for the mixtures to succeed because crabgrass is much more palatable than the summer perennial grasses. Without a good level of rotation, the livestock will graze the crabgrass too short too often and drastically reduce its production capability, prevent seed set for volunteer stands, or kill it. Crabgrass should be topgrazed, left to grow 4 to 12 inches until the last grazing, and then allowed to regrow to 6 to 18 inches tall; some mature seed heads are necessary for long-term success. Anywhere from four to about twelve paddocks are needed for proper rotational grazing.

Part of grazing management is to keep the bermudagrass overstory reduced and the sod opened for a better early-season crabgrass habitat. The shorter the bermudagrass is grazed during spring (a 1- to 3-inch stubble), the better the crabgrass component. Once crabgrass is present, residue height should be about 3 inches. In general, frequent (about every three weeks) grazing and tall residue (3 inches or more) enhances crabgrass production in the mixture.

Proper fertilization is needed to sustain the mixtures. At Ardmore, Oklahoma, on loam and silt loam soils, a total nitrogen supply of 100 pounds per acre has been adequate to sustain the mixture. The nitrogen is applied from spring (April) to midsummer (June 15). At the Noble Foundation, Jerry Rogers and Wadell Altom conducted research on bermudagrass fertilization and found that the higher the amount and distribution of nitrogen, the better crabgrass performs in the mixture. Rates of up to 400 pounds of nitrogen per acre were used, but those over 100 pounds of nitrogen per acre seldom are used by producers. Nitrogen should be applied at the preemergence stage or after crabgrass is past the four-leaf stage, tillering, making stolons (runners), or over 2 to 4 inches tall.

Several precautions are in order. Failure to follow them can result in crabgrass stand damage or total loss: (1) do not use liquid nitrogen, (2) do not apply nitrogen to emerging or very young crabgrass (one- to four-leaf stage), and (3) do not apply poultry litter to very young crabgrass. Fertilizer components other than nitrogen, i.e., phosphorus, potassium, and lime, should be applied according to soil-test results.

I would like to thank Chuck West and associates, Altheimer Laboratory, Department of Agronomy, University of Arkansas, Fayetteville, Arkansas, for assisting in part of the chemical analysis.