Sweet clovers

What is the difference between yellow sweet clover and white sweet clover?

Sweet clovers are versatile plants that can be used for cover crops on marginal lands. There are two sweet clovers that can be seeded in Michigan: yellow and white. Sweet clover can be an annual or a biennial depending on where it is planted as well as the cultivar used. Sweet clovers are an excellent soil-builder because they have a deep taproot that extends through the soil profile which takes up nutrients and minerals that can be used by crops.

So what is the difference between yellow and white sweet clover? The biennial yellow sweet clover takes two years to produce a flowering plant. The first year, the yellow sweet clover grows vegetatively in a rosette. After a vernalization period it produces a shoot and flowers. It can produce up to 2.5 tons of dry matter and can grow up to 24 inches. If conditions are favorable, it can reach up to 8 feet in the second year. Below ground, its tap root can extend down 5 feet by the end of spring. White clover does not produce as much biomass as yellow. It is taller and stemmier plant that is better for soil building.

Drought resistance is also another difference between these sweet clovers. Yellow clover is more tolerant to drought. White clover is easier to establish when compared to yellow. White clover flowers 10-14 days after yellow clover.

Sweet clover has historically been used for grazing or as an emergency feed. But Kim Cassida, Michigan State University Extension forage specialist does not recommend it because it can be toxic to livestock. "The toxic factor is dicumarol, which is formed from coumarin only when the sweet clover is spoiled by certain kinds of mold. Poisoning is more likely from hay than from silage/haylage and it has been reported in cattle, sheep, pigs and horses. Poisoning has occasionally occurred while grazing. Sweet clover forage does not have to be visibly moldy to be toxic. Most varieties of sweet clover hay, haylage and silage should only be fed with great caution and when no other options are available. A few varieties of yellow (‘Norgold’) and white (‘Cumino,’ ‘Denta,’ ‘Polara’) sweet clover have been bred for low coumarin content and thus safer forage use, but these varieties are not as widely available as those typically used as cover crops." The Merck Veterinary Manual sweet clover entry is a good source of details on sweet clover poisoning.

Sweet clover is a hardy plant that can fit in most cropping systems. For assistance in determining what type of sweet clover would best suite your cropping system contact Paul Gross, Michigan State University Extension Educator at grossp@anr.msu.edu or Christina Curell, Michigan State University Extension Educator at curellc@anr.msu.edu.

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