Utilizing Clover in Forage Production Systems

Montgomery Alison, Pitman, William D.

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M.W. Alison and W.D. Pitman

Several attributes should be considered when deciding whether to utilize a particular forage plant in a production system. Persistence, dependability, quantity of production with adequate quality, the growing season and whether the forage has toxicity issues are important considerations. Most producers recognize clovers offer benefits in livestock production systems. Clovers are typically higher in quality (crude protein and energy) than grasses, do not require nitrogen fertilization and can extend the grazing season when mixed with warm-season perennial grasses. With these benefits why are clovers not widely used in forage systems?

Research has shown overseeding perennial warm-season grass pastures with red or crimson clover can provide approximately 0.5 to 0.75 tons more dry forage per acre, respectively, than the perennial grass before the end of April. This same research showed overseeding these grass sods with red clover provided similar total annual forage production as applying 100 pounds of nitrogen per acre to the warm-season grass. Planting crimson clover provided similar forage quantity annually as applying 50 pounds of nitrogen per acre to the grass. Obviously, the forage production from the perennial warm-season grass pasture overseeded with clover was spread over a longer part of the season.

There is abundant nitrogen in the atmosphere, but it is not in an ionic form that plants can use as a source of nitrogen. Similar to almost all legumes, clover roots can be infected by specific bacteria that can convert atmospheric nitrogen into a form useable by plants, so clovers may not respond to nitrogen fertilization. This symbiotic relationship does require the presence of the appropriate bacteria, so clover seed inoculation is important. Although clovers may not require nitrogen fertilization, adequate levels of Phosphorus and potassium available in the soil and pH near 6 are important for clover production. The application of Phosphorus and potassium should be based on soil test results. Research in Louisiana has shown significant yield response by white clover to both Phosphorus and potassium applications when initial Phosphorus and potassium levels were low according to soil tests. In a five-year study, white clover yield increased with addition of 40 pounds K2O per acre when soil potassium levels were low and continued to increase with application rates up to 320 pounds per acre. In the same study, white clover production was better when soil pH was maintained above 5.8 than when allowed to decline to 5.3.

Clovers tend to be more site specific than grasses in that some need well-drained soil while others can tolerate periodic soil saturation. Crimson, red and arrowleaf clovers tend to be more productive on well-drained soils while ball, berseem, Persian and white clovers tend to thrive better on bottomland sites. Berseem clover thrives in alkaline clay soils, but crimson and arrowleaf clovers do better on sandier soils. Even on the most suitable sites, clovers can be much less reliable than the warm-season perennial grasses or annual ryegrass. The clovers listed above are primarily annuals and it is even rare for red and white clovers to act as perennials in Louisiana. So, clovers in Louisiana pastures are primarily a result of natural reseeding or annual planting. Timely rainfall, control of competing vegetation and mild winter temperatures contribute to clover stands and their productivity.

Peak production period also varies among clover species. Crimson clover provides the earliest production and begins significant growth in late February and continues through early April when it starts maturing (Figure 1). Arrowleaf, red and white clovers tend to be later in production but can provide forage into June. The production season of berseem clover spans from March into May, while ball clover is most productive from March to mid- or late April. Primary forage production from red and white clovers tends to begin later in March or early April but can extend into June and July when adequate moisture is available. Mixtures of different clovers can expand the production season, although grazing early growing species can be beneficial so that not much growth accumulates to arrest development of the later growing species. In plot stands, mixed seedings have provided early growth of crimson clover with continuous clover production as ball clover grew through the maturing crimson clover stand (Figure 2). Red and white clovers can survive through the summer and provide forage in the next season under certain environmental conditions and management particularly on moist bottomlands. These are the only clovers typically utilized in Louisiana that are not definitively considered annuals. Annuals must establish from seed each year.

Reports that clovers can fix 50-125 pounds of nitrogen per acre into useable form for plant growth are widespread. Even though this can be true, the associated grass does not necessarily perform as though 50-125 pounds of nitrogen was applied. The nitrogen fixed by clovers is primarily used for clover growth and little is directly available to the grass. This fact indicates grazing management will have to adjust to accommodate the change in seasonal forage production. In the study mentioned above, the red clover grass mixture produced approximately 1 ton more dry forage by the end of May than the monoculture perennial warm-season grass fertilized with 100 pounds nitrogen per acre. But the fertilized grass provided about 1 ton more dry forage per acre than the red clover grass mixture during June and July.

Several studies have shown better animal performance when clovers were included in the forage mix. These animal performance results have occurred when clovers were planted in a mixture with ryegrass or when ryegrass and clovers were planted in separate areas of a pasture. Although clovers can require more management attention than grasses their inclusion in pastures can be quite beneficial and their use should certainly be considered. Along with the increased pasture management compared to that typically needed for nitrogen-fertilized warm-season perennial grasses, contingency plans are needed for provision of forage in adverse seasons when clovers are not productive. Such management requirements can be worthwhile especially when the economics of nitrogen fertilization are uncertain.

M. W. Alison is an extension forage specialist and associate professor at the LSU AgCenter Macon Ridge Research Station. W. D. Pitman is a professor at the Hill Farm Research Station.

This article appeared in the fall 2022 issue of Louisiana Agriculture.

Clover grows in a field of grass.

Figure 1: Crimson clover flowers in mid-April. Photo by Neal Hickman

Clover grows in a field of grass.

Figure 2: Ball clover grows through maturing crimson clover in late April. Photo by M.W. Alison

12/15/2022 10:10:24 PM
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