Which sub clover suits a short growing season under 375 mm in the northern or eastern wheatbelt?
Izmir is our first choice for this country. It flowers in about 78 days, needs 350 mm, suits moderately acid soils across the northern and eastern agricultural areas, and is the direct replacement for Nungarin below 375 mm. It has more hard seed than Nungarin, and its seed softens later in summer and autumn, giving better protection from false breaks.
Nungarin, at about 77 days and from 300 mm, is the other early option. Sow Izmir at 10–15 kg/ha alone or 6–10 kg/ha in a mix.
My sub clover doesn't come back well after a crop year. Which variety handles tight rotations?
Pick a harder-seeded variety. Izmir and Urana carry more hard seed than Dalkeith, giving a bigger reserve in the soil to regenerate from; where trial sites were cropped, Izmir's seedling density was 34% higher than Nungarin's. Dalkeith is not hard-seeded enough to regenerate reliably in 1:1 crop and pasture rotations and does best with a pasture phase of two years or more.
Seaton Park, with about 23% hard seed, is also unreliable in 1:1 rotations and can germinate on false breaks.
How do I choose the right sub clover maturity for my district?
Match flowering time to your season length: the variety must flower and set seed before the soil dries out in spring. Approximate days to flowering in Perth are Nungarin 77, Izmir 78, Dalkeith 96, Urana 105, Seaton Park 108 and Riverina 122. Short, dry seasons need the early end of that list, while long, wet seasons suit later types such as Riverina or Leura.
Where spring rain is unreliable, sowing a mix of an early and a later variety spreads the risk.
Clover scorch and root rot keep thinning our sub clover in a high rainfall area. What's more resistant?
Riverina is the strongest choice. It is resistant to race 1 and at least moderately resistant to race 2 of clover scorch, with high resistance to phytophthora root rot and good resistance to powdery mildew. It is a white-seeded yanninicum type that also withstands waterlogging, and suits 425 mm and above.
Seaton Park tolerates phytophthora root rot but is susceptible to scorch. Dalkeith and Nungarin are susceptible to scorch, so they are best kept to lower rainfall areas where it is generally not an issue.
Our wheatbelt loams are neutral to alkaline. Which sub clover should I sow?
Seaton Park is the sub clover for these soils. Unlike most sub clovers, which prefer moderately acid ground, it needs a soil pH of 6 or more (CaCl2) and suits neutral to alkaline, well-drained loams, including cracking, self-mulching and stony soils. It needs 425 mm, persists well under heavy grazing and has low formononetin.
Sow 15–20 kg/ha alone or 6–10 kg/ha in a mix. It doesn't tolerate much waterlogging, so keep it off wet flats.
How much sub clover seed should I sow per hectare?
It depends on the variety and whether it's sown alone or in a mix. Sown alone: Urana and Riverina 20 kg/ha, Seaton Park 15–20 kg/ha and Izmir 10–15 kg/ha. In a mix with grasses or other legumes: Urana and Riverina 6–8 kg/ha, and Seaton Park and Izmir 6–10 kg/ha. Nungarin and Dalkeith have a general rate of 6–20 kg/ha.
Use the top of the range where you want quick ground cover and a strong seed set in the first year.
How deep and when should sub clover be sown?
Sow sub clover early, at or soon after the autumn break into moist soil, and no deeper than about 1.5 cm. Early sowing gives plants time to develop before they flower and set seed in spring. Inoculate with Group C inoculant, especially where clover hasn't grown for several years or the soil is acid, and apply phosphorus based on a soil test.
Control weeds before or at sowing so the young clover has as little competition as possible while it establishes.
Do I need to take stock off sub clover while it's flowering?
In the first year, mostly yes: graze lightly through flowering and seed set, because overgrazing then cuts seed yield. Once established, sub clover handles grazing better than most legumes because it buries its burrs. Seaton Park, for example, thrives under set stocking and can be grazed moderately hard while flowering, and lax grazing can let taller plants shade it out.
Over summer, keep the dry feed grazed down so the paddock is ready for the next germination.
I want more winter feed from sub clover in a 400 mm-plus wheatbelt district. What should I sow?
Urana is the variety for winter growth. It is very winter active, and WA trials showed herbage increases over Dalkeith of 10% in year one rising to 25% in year two. Its indeterminate habit keeps it growing into spring while moisture lasts, and it has more hard seed than Dalkeith for cropping rotations.
Urana needs 400 mm and suits sands to loams with pH from 4.5 (CaCl2), though not deep sands. Mixing in ryegrass adds extra bulk over the season.
Our season runs well into spring in the high rainfall south. Which sub clover gives late spring feed?
Choose a later-flowering variety. Leura is a later-maturing sub clover that keeps producing into late spring where moisture lasts. It suits high rainfall districts with long seasons on well-drained, moderately acid soils, can be sown with perennial or annual ryegrass, and its spring bulk suits silage or hay.
Riverina, a mid-season type at about 122 days to flower, is the option for wetter ground because it withstands waterlogging. Ease grazing during flowering and seed fill so either variety regenerates well.
