Aerial-Seeded Annual Clover Seed

Choose a hard-seeded aerial legume. Diamanti bladder clover seed is more than 97% hard off the header, and in regenerating stands 30–40% softens each season, so once a seed bank is built it suits 1:1 rotations. Casbah biserrula carries 95–99% hard seed and is ideally suited to a year-in, year-out cropping system. Bartolo bladder clover also regenerates after cropping. Soft-seeded crimson clover won't regenerate after a crop, and berseem and Shaftal Persian clover are single-season forages, so they don't suit this system.

Hykon rose clover and Casbah biserrula are both built for this country. Hykon does best where sub clover grows poorly, needs only 300 mm, handles soil pH down to 4.5 (CaCl2) and suits light sands to loams. Casbah also starts at 300 mm and pH 4.5, roots to around 2 m, tolerates moderate to high exchangeable aluminium and stays green about 4 weeks longer than sub clover. Neither copes with waterlogging, so keep them to well-drained ground.

Bladder clover is a strong fit. Bartolo suits mildly acid to alkaline sandy loams from pH 5 to 8 (CaCl2), needs 350 mm, tolerates heavy grazing and has hard seed that protects it from false breaks. Diamanti needs only 300 mm and flowers 10 to 14 days earlier than Bartolo, so it reaches further into the drier eastern wheatbelt. Bartolo doesn't produce well on saline or waterlogged soil and is susceptible to severe frosts. It is also sensitive to bromoxynil, Spinnaker and Raptor, so plan broadleaf weed control around it.

Paradana balansa clover is our pick for these flats: it has excellent waterlogging tolerance, mild salinity tolerance and handles acid soils, in areas with 500 mm or more. Kyambro Persian clover (500 mm and up) and berseem clover (550 mm and up, loams to heavy soils) also tolerate waterlogging and mild salinity. Treat these as mild-salt options only; badly scalded ground needs salt-tolerant grasses such as puccinellia. Avoid Bartolo, arrowleaf clover and biserrula on wet ground.

That sounds like photosensitisation, a known risk with biserrula. Casbah biserrula can cause it in livestock during spring if it is sown as a monoculture, and Australian research has found both commercial biserrula cultivars can trigger it in sheep. Move affected stock off the paddock onto other feed with shade, and talk to your vet. To lower the risk, sow Casbah in a mix, typically with serradella and sub clover at 0.5–2 kg/ha, rather than as a pure stand.

Prima gland clover is the toughest option: it is resistant to redlegged earth mite, blue green aphid and cowpea aphid, though moderately susceptible to spotted alfalfa aphid and lucerne flea. Bartolo bladder clover is moderately tolerant of blue green aphid and lucerne flea and less affected by mites than sub clover or medics. Prima suits 350 mm and up on sands to heavy soils, but not infertile sands, and it is easily out-competed while establishing. Keep checking new stands for pests regardless.

It depends on whether you want a regenerating pasture or a one-season forage. Kyambro is hard seeded and mid-season, about 120 days to flower, and is very persistent in permanent pastures if allowed to reseed in its first year; it needs 500 mm or more. Shaftal is soft seeded and late, about 140 days, built for multi-cut grazing, hay and silage in annual systems from 400 mm, and does best on clay loams to heavy clays. Sow Kyambro at 3–6 kg/ha and Shaftal at 4–6 kg/ha.

Biserrula seed needs scarifying before sowing to lift germination, then inoculating and lime pelleting with the specific biserrula inoculant, Biserrula Special (Group BS). Sow in autumn no deeper than 1 cm, at 3–6 kg/ha on its own or 0.5–2 kg/ha in a mix with serradella and sub clover. It can also be twin sown under a crop the year before the pasture. Graze lightly in the first year to maximise seed set. After that, Casbah tolerates heavy grazing, and grass-selective herbicides are safe to use on it.

Sow shallow, about 0.5 cm deep, as close to the autumn break as you can, and roll after sowing. Inoculate with Group C inoculant, the same as sub clover, and sow with 100 to 150 kg/ha superphosphate, or super and potash on sandy soils. Rates are 5–10 kg/ha for Bartolo or Diamanti bladder clover sown alone, or 1–5 kg/ha of Bartolo in a mix, and 4–6 kg/ha for Prima gland clover alone or 1–2 kg/ha in a mix. Diamanti can also be dormant sown over summer using stored seed.

Crimson clover is a good choice. Its showy crimson flowers attract bees and other beneficial insects, and it is deep rooted with high seed production, which is why it's popular in cover crop and regenerative pasture mixes. It suits 500 mm and above and soil pH from 4.5 (CaCl2), and does best on free-draining heavier soils and gravelly loams. Sow 3–10 kg/ha. Being soft seeded, it can germinate on a false break and won't regenerate after a crop, so plan to resow it.