Brown clover
Trifolium badium (Schröter, 1888)
BOTANY
Perennial to triennial, with a robust taproot and abundant tillering; besides numerous flower shoots there are also nobudding leaf rosettes. The plant dies off after fruit ripeness.
Stems cespitose, mostly ascending to procumbent, seldom totally erect, more or less branched, mostly 10-20 cm long, with short appressed hairs, later becoming glabrous.
Foliage leaves with long petioles, yellowish to verdigris, glabrous, the topmost ones almost distichous. All leaflets similarly short-petiolate, but in various shapes and sizes, 1-2 cm long and half to a third times as wide; elliptic to deltoidic, mostly rounded or truncate, sometimes emarginate or blunt with a point, circumferentially with fine and sharp teeth; up to more than 20 pairs of lateral veins which are straight and non-furcate; scarcely ciliated only at the margins and on the midvein (if not glabrous at all).
Stipules herbaceous, ovate-lanceolate, acute, 1-1.5 cm long, highly connate with the petiole, mostly glabrous.
SUITABILITY FOR RESTORATION
This central and south European species occurs in the Alps, in the subalpine and alpine zone. It grows in moist meadows, pastures and alpine meadows. In the cooler parts of the Alps, it is found on alkaline soils, in warmer regions almost solely on lime-deficient soils.
Wide range of use, very hardy, low to intermediate resistance to drought, deep-rooting plant, accumulating nitrogen, fair tolerance of nutrients, low to densely grown, valuable forage.
SEEDS
Seeds 1.4-1.8 mm long, 1-1.4 mm wide and 0.4-0.8 mm thick; ovoid with an inclined kidney-shaped indentation.
Radicle half as long as the cotyledons. Sulcus often indistinct. Hilum round, lying within the indentation, slightly darker than its surroundings.
Surface two-coloured, yellow up to twothird, remaining part greenish with smooth transitions.
Pods one-seeded with a long, thin, dark brown, glossy beak.
Thousand seed weight: 0.70-0.85 g.
Seeds
REQUIREMENTS
(soil and climate)
Intermediate, deep soils that are rich in humus, with a pH above 6 are preferred. Preference should be given to sites with as low a weed infestation as possible.
CULTIVATION
Because of the plant’s low growth height and very slow juvenile development, it has extremely high requirements. The seedbed has to be fine, crumbly, compact, flat and without stones.
According to recent experience, cultivation underneath spring corn is not recommended. Because of the absence of specific herbicides, the comparatively high competition of weed species and its slow development cultivation of brown clover often results in failure. Seeding at the middle of June to end of July at the latest has proved to be best.
Seed rate: 10-12 kg/ha.
Row spacing: 12-20 cm, depending on the seeder. Where there is specific weed control by means of band sprayers or mechanical machines the row spacing should be adjusted accordingly.
FERTILIZATION
Phosphorus and potassium: brown clover requires few nutrients. Before cultivation, basic fertilization with manure (15-20 tonnes/ha) is considered sufficient. Using mineral fertilizer, an application of 30-60 kg/ha P2O5 and 80-100 kg/ha K2O is recommended, depending on soil content.
Nitrogen: brown blover meets its nitrogen requirements by means of nitrogen-fixing bacteria. As for all legumes, fertilization with 20-30 kg N is recommended for open sowing in order to stimulate juvenile development.
MAINTENANCE AND WEED CONTROL
Weed control starts with the selection of the site and the seeding time. Seeding in late summer (after the corn harvest) allows sufficient soil preparation; crop areas or parts of them should be preferred that are known to have a low weed infestation. Many species such as Veronica spp. and Viola arvensis cannot be sufficiently controlled by the few usable herbicides and may cause serious trouble in the populations.
Single plants
Because of the late sowing time it is advisable not to use a curry comb.
Until autumn brown clover only grows up to 3-5 cm and mainly invests in its root system. The species is sensitive to alternating frost, especially in early spring. Rolling the population in time is therefore sometimes necessary. The following spring, brown clover needs a surprisingly long time to produce leaves and develop inflorescences. Therefore there is a short period when specific weed control should be carried out by means of wiping wick and total herbicides (Glyphosate).
Controlling weed grasses is relatively trouble free.
Pathogens: serious problems caused by nematodes have not yet been observed.
HARVEST AND YIELDS
Resistance to lodging: high.
Shattering tendency: low to intermediate.
Ripeness: immediately after flowering the flowers change colour from yellow to brown, with a metallic gleam. Because of this quick change of colour, producers are tempted to harvest too early. The seeds are ripe when the flowers change colour to black-brown and appear to be dried up. Like kidney vetch, the seeds then become two-coloured. Until complete ripeness is reached there is a very low shattering tendency, which then increases considerably.
Ripening period: quite early, in the last decade of June to the beginning of July, depending on climate and location. In stable weather, harvesting can be carried out once 80 percent of the population is ripe, while under unstable conditions harvesting is recommended when 60 percent of the population is ready for threshing.
Harvesting technique: Because of the low growth height of 8-12 cm the harvester board should be kept very low. When there is a sufficient degree of ripeness and with proper settings of the thresher, almost all the seeds will be rubbed off the flowers without any trouble.
Crop yields: yields depend on the success of the weed control. Cultivation already carried out has led to yields between 40 and 120 kg/ha. Potential yields certainly exceed 200 kg/ha. Insufficient weed control can otherwise reduce the yield to zero. Only one harvesting year is possible.
Flowering plants
