OREGON STATE UNIVERSITY
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Winter-active annual clover, originated from Asia Minor (modern Turkey). Alternative to white and subterranean clovers in poor soil drainage and drought conditions. Versatile forage crop that typically does not cause bloat in grazing systems and can be used for hay, silage, or green manure with its high N-fixing capacity in both rainfed and irrigated conditions. Excellent ability to suppress weeds when sown as a cover crop. While it is relatively a new forage crop in the US, it is extensively grown in Australia as a forage and N source in ley farming systems.
Inflorescence is a cylindrical or conical flower head 1-2 1/2 inches (2-3 cm) long containing many small white-pink florets.
Erect growth habit typically up to three feet (~1 m) in height, although its glabrous and hollow stems can reach more than 12 feet (3.7 m) in length.
Fine, trifoliolate leaves can have smooth or serrated edges, with varying shaped leaflets.
Taproot and numerous fibrous roots extend 30-35 inches (75-90 cm) deep.
Seeds range in color from yellow to red-brown and black. Produces large amount of small seeds (0.8–1.2 mg/seed) with up to 98% hard-seededness.
Erect growth habit, typically three feet (~1 m), but stems can reach 8 feet (2.4 m) in height. Annual.
Winter annual adapted to Mediterranean (summer-dry) climate but it is more tolerant of cold winter temperatures than crimson clover [to -14 °F (-26 °C) USDA Plant Hardiness Zone 5b]. Heat tolerance to July mean maximum temperatures of 79-82 °F (26-28 °C). It can be grown successfully in the Pacific Northwest and California. Early-flowering varieties can be grown in drier areas (14 inches, ~350 mm, annual rainfall). Once established, it produces more biomass at lower temperatures than most other clovers.
Grows well on a range of soils type and conditions. Tolerates strongly acid to moderately alkaline (pH 5.0-8.6) and mildly saline soils (3-5 dS/m). It can grow on high clay soils to sandy soils, and tolerates water-logged soils and brief periods of flooding.
Balansa Clover Suitability Tolerance Values
|
Suitability Class |
Jan Min (°C)* |
July Max (°C) |
Annual Precip (mm)** |
Soil pH*** |
Soil Drainage† |
Soil Salinity (dS/m)# |
|
Well-suited |
-20 |
26 |
550 |
5.8-7.3 |
MWD-WD |
1-2 |
|
Moderately suited |
-23 |
27 |
450 |
5.5-7.5 |
SPD-SED |
2-3 |
|
Marginally suited |
-26 |
28 |
350 |
5.0-8.0 |
PD-SED |
3-4 |
*Low temperature: USDA Plant Hardiness Zones: 5b-9b
Rooting: taproot to 3 feet (90 cm).
*** Soil pH: Strongly Acid to Moderately Alkaline: 5.0-8.6.
† Soil drainage: Tolerates water-logged 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 balansa clover for the classes 1-7: 15, 40, 75, 100, 100, 55, 20, respectively.
# Soil salinity: Mildly saline soils (3-5 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.
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.
Suitability curves were developed for each clover species for three climate variables (average annual precipitation, average July maximum temperature, and average annual extreme low temperature) and three soil variables (drainage class, pH, and salinity). For each variable and each species, the curves were fit using estimated yield data across the full range of values for the given variable.
The coefficients for the model equations were applied to spatial data layers representing each climate and soil variable, resulting in spatial outputs of percent yield for each of the clover species and each climate and soil variable. The percent yield layers were then classified into four suitability classes, as follows:
100%-75% - Suitable
75%-50% - Moderately suitable
50%-25% - Marginally suitable
25-0% - Not suitable
Finally, three "hybrid" suitability layers were produced for each clover species based on combinations of 1) the three climate variables, 2) the three soil variables, and 3) all six climate and soil variables together. These combined suitability layers were created by selecting for each location the lowest suitability value of the included variables, with the idea that the overall suitability for a species will be limited by the most restrictive factor.
|
Climate Factors |
Soil Factors |
Combined Factors |
|
Minimum Temperature |
pH
|
All climate and soil factors (most limiting)
|
|
Maximum Temperature
|
Drainage
|
All soil factors (most limiting)
|
|
Precipitation
|
Salinity
|
All climate factors (Most limiting)
|
Sown in the late summer or autumn, it is winter active, with peak growth in late spring and early summer prior to flowering.
Establishment: Not strongly competitive, best sown as a monoculture or with a non-competitive plant such as plantain. Useful addition to orchardgrass-subclover pastures for adding to total legume content. Weed control necessary if sown as a monoculture for hay. Can be broadcast with fertilizer in low rainfall areas (300 mm) where open ground allows it to establish with little competition.
Inoculate with Group CS (alternatively, B or C) rhizobia if not grown before. Use 5 lb/acre (5.6 kg/ha) pure live seed if drilled ¼-1/2 inch (0.6-1.3 cm) deep and if broadcast 8 lb/acre (9 kg/ha). For mixtures, use 3 lb/acre if drilled and 5 lb/acre if broadcast (3.4 and 5.6 kg/ha, respectively).
Harvesting: Balansa clover can be used for grazing or haying. It is more suited to rotational grazing than continuous stocking and can persist long-term in pastures, provided that stock are removed during the flowering period. It can tolerate heavy, close grazing in early spring but the seed production will be greatly reduced if the stand is closely grazed during mid-late flowering. Seed harvest does not require specialized harvest machinery.
‘FIXatioN’, developed in Oregon, USA is reported to be the most cold-tolerant annual clover. Early-flowering cultivars (e.g. ‘Frontier’ and ‘Enduro’) can be grown in drier regions that receive ~ 14 inches (350 mm) annual rainfall. Late flowering ‘Bolta’ and ‘Viper’ are suited to higher rainfall areas [24 inches (~600 mm)]. For regions that receive moderate annual rainfall [20 inches (500 mm)], mid-flowering cultivars ‘Paradana’ and ‘Taipan’ are recommended.
Highly nutritious forage with high crude protein and digestibility (25% and 15% CP and 80% and 65% DDM in early and late spring, respectively).
No known antiquality component.
Ballard, R.A., A.D. Craig, and N. Charman. 2002. Nodulation and growth of pasture legumes with naturalised soil rhizobia. 2. Balansa clover (Trifolium michelianum Savi). Australian J. Exp. Agric. 42(7): 939-944.
Brown, H.E., D.J. Moot, R.J. Lucas, and M. Smith. 2006. Sub clover, cocksfoot and lucerne combine to improve dryland stock production. In: Proceed. New Zealand Grassland Assoc. 68: 109-115.
Monks, D.P., D.J. Moot, M.C. Smith, and R.J. Lucas. 2008. Grazing management for regeneration of balansa clover in a cocksfoot pasture. In: Proceed. New Zealand Grassland Assoc. 70: 233-238.
Ross, S.M., J.R. King, R.C. Izaurralde, and J.T. O'Donovan. 2001. Weed suppression by seven clover species. Agron. J. 93(4): 820-827.
