Improved forage crabgrass varieties are not weeds, but high-quality, high-producing forages that fit well from the Mid-Atlantic region through the Southeast. With good fertility and moisture conditions, crabgrass forage can yield 3-5 tons of dry matter. As a low-growing summer annual crop, crabgrass maintains quality over the course of its rapid growth – unlike many taller summer grasses that require more lignin early on to structurally support the plant. It rivals many cool season small grain forages for quality.
Easily spot crabgrass by its creeping growth habit and long, fine hairs that emerge from the stem at 90-degree angles. It has clumping growth that spreads by stolons, or runners. It is fairly drought tolerant and prefers well-drained sandy loam soils; its ability to grow in a wide pH range – 5.5-7.5 – makes it handy and adaptable.
Crabgrass can be creatively built into a double-crop rotation with annuals and perennials. In a perennial rotation, filling in with crabgrass and other summer annuals increases overall carrying capacity and improves animal performance. Its forage quality is high in summer when most perennial forages are stalled out and low in quality.
It’s often managed as a reseeding companion in a perennial pasture. The resulting volunteer crabgrass makes up a minority percentage in the stand and helps fill in thin areas and boost forage production from June through September in the southeastern climate. Toward the end of the season, the crabgrass is left to go to seed (remove animals 2-3 weeks before the first frost), and results can be improved by working the ground lightly the following spring. Late summer and fall production is lower in quality (becoming basically unpalatable after a killing frost), so leaving this last growth for seed production is convenient this time of year.
Crabgrass’ light, fluffy seeds are rough in texture, qualities that can interfere with its flow through equipment. Coated seed improves results by adding bulk and weight to the seed. Raw seed is also sometimes mixed with a fertilizer application for improved establishment.
If you are rotating with a winter annual small grain forage or removing a pasture, the crabgrass can be drilled into a prepared seedbed (up to 1/4 inch deep for best results; sunlight is needed to stimulate germination). Alternatively, crabgrass can be overseeded into the standing small grain. This is especially effective if you have plans to graze the small grain forage, as the animals’ hooves will help work the seed into the ground.
Germination of volunteer stands can be improved with a harrowing or light tillage the spring following a self-reseeding.
Mixtures with annual ryegrass are more difficult to manage than those with small grains, since ryegrass will be more aggressive in spring and can smother the crabgrass.
Research is currently underway to evaluate how well crabgrass mixes with various clovers, which will depend on finding complementary lifecycles and competitiveness of growth.
Crabgrass should be rotationally grazed. Start grazing at 12 inches and remove animals at 3-6 inches. A 30 day cycle will be the norm with adequate moisture. Unlike perennials, most of the energy reserves for regrowth come from the leaves, not root or crown stores. Leaving some leaf material is the best way to ensure thick, rapid regrowth. Hay cuts can be taken at boot or heading stage, 18-24 inches.
It makes a good companion to bermudagrass or bahiagrass – often improving quality of the hay – although it dries a little more slowly (yet quicker than sorghum-sudan or millet). If the mixed hay is to be sold, it can also cause purely cosmetic problems, since its color and texture is conspicuous in the hay bale, and many customers associate a more uniform bale appearance with higher quality. The hay is also darker, which may also lead to (incorrect) assumptions of lower quality – both in a mixed or pure crabgrass bale.
Like many forages, disease isn’t often a challenge because the vegetation grows rapidly and is generally harvested before disease pressure can impact productivity.
Conservation with Crabgrass
Crabgrass fills the conservation niche well. We know that it shines in minimum-till and no-till systems (in addition to clean-till), and can leave winter killed protective residue after frost. Crabgrass is good for rapid soil cover, spreading into a moderate sod.
Annuals like crabgrass are great helpers in diversifying a forage system. A solid perennial foundation is important (especially in grazing systems), with annuals to fill in during the less productive times, like summer. Perennials’ deep root systems find water more reliably, but annuals have greater growth potential and performance during a short time.