OREGON STATE UNIVERSITY
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Herbaceous, short-lived perennial legume widely used in temperate regions for forage, soil improvement, and as pollen and nectar source for bumblebees. Valued in mixtures with plantain and white clover as high-quality finishing pasture.
Inflorescence is a spherical head composed of scores of rose-purple to magenta flowers.
Pubescent stems are mostly upright with lower branching.
Palmately trifoliolate leaves have oblong leaflets with crescent-shaped watermarks. Large stipules have green or red veining.
Short taproots may be replaced by secondary roots after first year.
Seeds are mitten-shaped; ~ 2 mm long and 1.5 mm wide; color light yellow to dark purple; about the same size as alfalfa (272,000 /lb; 598,000 /kg).
Upright growing stems that originate from a narrow crown near the soil surface. Short-lived perennial. Persistence reduced by winter injury, high temperature, low moisture, and flooding.
Extensively grown in the humid region of North America, from Ontario and Quebec to Tennessee and South Carolina and intermountain and northwest regions [USDA Plant Hardiness zones 4-8; Jan mean minimum of -22 °F, -30 °C)]. Requires 25-40 inches (635-1000 mm) of precipitation or irrigation.
Grows best in fertile, well-drained to somewhat poorly drained soils of high moisture-holding capacity. Tolerates strongly acid soils (pH 5.1-8.4) but maximum yields require pH of 5.8-7.5. Moderately sensitive to saline conditions (1.5-3 dS/m).
Red Clover Suitability Tolerance Values
|
Suitability Class |
Ave Ann Extreme Min (°C/°F)* |
July Max (°C/°F) |
Annual Precip (mm/in)** |
Soil pH*** |
Soil Drainage† |
Soil Salinity (dS/m)# |
|
Well-suited |
-33/-27 |
32/90 |
815/32 |
5.8-7.5 |
MWD-WD |
<2 |
|
Moderately suited |
-35/-31 |
33/92 |
710/28 |
5.5-8.0 |
SPD-SED |
2-3 |
|
Marginally suited |
-37/-35 |
34/93 |
610/24 |
5.0-8.5 |
PD-SED |
3-4 |
* USDA Plant Hardiness Zones 4a-8b.
**Precipitation requirement: 25-40 inches (600-1000 mm).
Rooting: Tap, many branched; to depth of two feet (75 cm).
*** Soil pH: NRCS Range and Pasture Handbook, Chapter 3 classification for red clover is Strongly Acid to Moderately Alkaline (5.1-8.4).
Classifications – tolerant of soils that are: (1) Very strongly acid to strongly alkaline, 4.5–9.0; (2) Very strongly acid, 4.5–7.3; (3) Strongly acid, 5.1–7.3; (4) Moderately acid, 5.6–7.3; (5) Moderately acid to moderately alkaline, 5.6–8.4; (6) Slightly acid to moderately alkaline, 6.1–8.4; (7) Near neutral, 6.1–7.3; (8) Alkaline, 6.7–9.0.
† Soil drainage: NRCS Range and Pasture Handbook, Chapter 3, Table 3-4; Classification for Red Clover is Tolerant of PD to WD Soils.
Soil drainage class abbreviations: (1) VPD, very poorly drained; (2) PD, poorly drained; (3) SPD, somewhat poorly drained; (4) MWD, moderately well drained; (5) WD, well drained; (6) SED, somewhat excessively drained; (7) ED, excessively drained.
Percent Relative Yield for Red Clover for the classes 1-7: 24, 45, 75, 100, 100, 55, 30.
Flooding tolerance: (1) Very long (>30 days); (2) Long (7-30 days); (3) Brief (3-6 days)
# Soil salinity: NRCS Range and Pasture Handbook, Chapter 3, Table 3- classification for red (and alsike, Berseem, white, strawberry) clover is Moderately Sensitive (1.5-3 DS/m).
Classifications are: (1) Tolerant, 6–10 dS/m; (2) Moderately Tolerant, 3–6 dS/m; (3) Moderately Sensitive, 1.5–3 dS/m.
Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.
(Red clover adaptation and use map.)
More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.
The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.
| Climate Factors | Soil Factors | Combined Factors |
|
Minimum Temperature |
pH |
Climate and Soil |
|
Maximum Temperature |
Drainage |
All Soil |
|
Precipitation |
Salinity |
All Climate |
| Climate Factors | Soil Factors | Combined Factors |
|
Minimum Temperature |
pH |
Climate and Soil |
|
Maximum Temperature |
Drainage |
All Soil |
|
Precipitation |
Salinity |
All Climate |
| Climate Factors | Soil Factors | Combined Factors |
|
Minimum Temperature |
pH |
Climate and Soil |
|
Maximum Temperature |
Drainage |
All Soil |
|
Precipitation |
Salinity |
All Climate |
| Climate Factors | Soil Factors | Combined Factors |
|
Minimum Temperature |
pH |
Climate and Soil |
|
Maximum Temperature |
Drainage |
All Soil |
|
Precipitation |
Salinity |
All Climate |
As a cool-season legume, majority of growth is produced in late spring and early autumn. For hay and silage, red clover is harvested 2 or 3 times at early flowering stage. Rotationally grazed on pastures, with majority of production contributed by the accompanying grass.
Two types: early flowering or ‘medium’ and late flowering or ‘mammoth.’ Use late flowering types north of 60° N latitude. ‘Kenland’, ‘Kenstar’, ‘Arlington’, and ‘Marathon’ are improved medium-type cultivars with specific resistance to anthracnose and mosaic virus strains. ‘Cherokee’ has resistance to rootknot nematode.
Highly palatable and digestible forage with high percentage of rumen by-pass protein.
Bloat hazard when >30% of pasture mixture. Older cultivars produce compounds with estrogenic activities that can interfere with livestock breeding.
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