Serradella

A pasture plant namely serradella

Serradella is a winter-growing annual pasture legume

Serradella is a winter-growing annual pasture legume. It is adapted to the sandy soils that occur in a band west of the Condamine River from Leyburn in the south to Miles/Roma in the north.

It is also adapted to soils of the Granite Belt, where clovers provide a range of legume options. These sandy-surfaced soils are acid in the pH range 4 to 6.5 and well drained. Serradella is not well adapted to shallow or hard setting sands, loams, clays, or soils that waterlog.

It is palatable, non-bloating, providing high quality protein forage when the feed value of associated summer-growing grasses is low.

Seed will regenerate each year, germinating in mid to late autumn after rain. With early rain, it can produce a large quantity of forage before winter. It grows slowly during winter, making its best growth after spring rain, when it flowers and seeds before dying in the heat of summer.

Varieties

Two serradella species, Yellow and Slender, are used commercially in Queensland. Seed of French serradella is also commercially available. The annual seed supply for individual varieties will fluctuate depending on the quantity of seed produced, mainly in Western Australia.

Yellow serradella (Ornithopus compressus)

Yellow serradella is hard seeded. Four varieties are available but only Madeira and Santorini are recommended for southern Queensland.

Santorini is early flowering. It has performed reasonably well on sandy solodic soils west of the Condamine River. Santorini performs well on low pH soils containing high free aluminium.

Madeira is early-mid flowering. It is adapted to solodic soils with pH 5.5 west of the Condamine River where its performance has been generally superior to other varieties. Seed production is more difficult than for Santorini or Charano, and seed is becoming difficult to obtain.

Yelbini is very early flowering. A new variety developed in Western Australia has reasonable levels of hard seed but has not performed as well as Santorini.

Charano is early flowering. This new cultivar from Western Australia has been sown in trials on the Granite Belt, Queensland and on sandy solodic soils where its performance has been inferior to Santorini and Madeira.

Slender serradella (Ornithopus pinnatus)

Jebala is mid flowering and hard seeded. It can tolerate poorly drained soils (shallow, stony soils that can become very wet) better than Yellow serradella, and can produce a good bulk of forage in late spring. It is suited for sowing in southern Queensland though seed may be difficult to obtain.

French serradella (Ornithopus sativus)

Cadiz is very vigorous, producing a very high quantity of dry matter and is earlier flowering than most French serradellas. However, it is soft seeded and few plants regenerate after the first season. Seed is readily available.

Erica is a new variety, similar in production to Cadiz. It has a prostrate habit with higher levels of hard seed than Cadiz. It could be a useful pioneer plant in serradella pastures or sown as a winter forage. Seed is readily available.

Margurita is a new variety similar in production to Cadiz. It has an upright habit with higher levels of hard seed than Cadiz. It could be a useful pioneer plant in serradella pastures or sown as a winter forage. Seed is readily available.

French x yellow serradella hybrid (O. sativus x O. compressus)

Spectra is a new variety. It too is soft seeded and few plants regenerate after the first season. It provides its bulk of forage later than Cadiz and could be useful as a pioneer component in serradella pasture particularly on the Granite Belt.

Variety sowing options

Granite Belt uplands - a mixture of Madeira 25%, Santorini 25%, Spectra or Cadiz 20% and Jebala 30%; or Jebala alone.

Eastern solodic soils - a mixture of Madeira 45%, Santorini 20%, Erica 25% and Jebala 10%.

Western solodic soils - a mixture of Santorini 35%, Madeira 35%, Erica 20% and Jebala 10%.

Sowing

When to sow

March to May on the Granite Belt, April to May in other areas.

Seed

Serradella seed has been traditionally sown as pod segments, in which the pod itself constitutes three quarters of the pod weight. Podded seed is very hard and little will germinate unless scarified through a dehulling machine. If the pod trash is not cleaned from the seed, it acts as a filler, making planting easier.

Free seed may be obtained from sources in Western Australia. Serradella seed can be mixed with oats for sowing. However the seed of Slender serradella is very small and would need to be mixed with an inert carrier such as sawdust or pollard if sown alone.

Hard seed

Newly harvested serradella seed pods may contain more than 90% hard seed that will not germinate immediately, resulting in very low establishment in the first year. This will occur with all varieties of yellow and slender serradella, but not with French serradella.

Merchants and farmers can negotiate the supply of dehulled free seed from merchants in Western Australia.

Inoculum

The rhizobium for serradella does not occur naturally in the soil and has to be introduced with the seed at sowing. Inoculate pods or seed with Group G (lupin-serradella) inoculum which seems to nodulate serradella plants effectively on soils of pH 5.5-7.5. A new 'super serradella' inoculant has been developed for use on soils of lower pH.

Pelleting

Pelleting is not essential unless the seed is sown with fertiliser. Pelleting then protects the rhizobium bacteria from the acidity of the fertiliser.

Seed mixtures

On the Granite Belt, serradella may be sown alone or included as a component of a temperate grass (ryegrass, fescue) and legume (clover) pasture mixture. Some success has been attained in sowing serradella and Premier digit grass in the autumn on solodic soils.

Sowing rates

Yellow and French serradella 5-8 kg/ha podded seed (equivalent to 1-2 kg/ha pure seed)

Slender serradella 2-3 kg/ha podded seed.

Sow at the lower rate when sowing with other legumes, such as clovers. In other areas, serradella can be sown with 15 kg/ha of oats.

Sowing method

Sowing dry ensures the pasture seed is in the right position to take advantage of the next rainfall to start germination

Prepared seedbed

Seed of serradella, serradella plus oats, or serradella, grass and oats can be broadcast onto the surface of a prepared seedbed (e.g. one that has been fallowed for moisture accumulation and weed control).

Seed can be broadcast with a fertiliser spreader or a combine planter with the hoses removed and the tines just touching the soil surface (10 mm).

Seed can be shallowly drilled through pasture planters fitted with presswheels to consolidate rows.

Direct drill

Serradella can be direct drilled into grass pasture using sod seeding/direct drilling machines. This should only be carried out when the soil profile is wet to at least a moderate depth.

Sowing depth

Serradella is a small seed and should be planted shallow and covered by no more than 5-10 mm of soil. Seed and soil contact may be improved on non-crusting soils by rollers or presswheels that will firm the soil around the seed. Be careful if harrowing after sowing that the small pasture seed is not being buried more than 5-10 mm deep or the shoot may not have the energy to emerge and establish.

Fertiliser

Although serradella is more tolerant of low soil fertility than most other winter legumes, it responds strongly to applied phosphorus and sulfur fertilisers. Where micro-nutrient deficiencies of molybdenum, copper, zinc or boron have been identified, these should also be supplied at sowing.

Before sowing

Best results will be obtained by applying phosphorus and sulfur as superphosphate before sowing. Apply 200 kg/ha on the Granite Belt, and 150 kg/ha on the solodic soils. Sulfur superphosphate can be used to supply additional sulfur.

Maintenance

A maintenance fertiliser application of 125 kg/ha superphosphate after two years is suggested. After that, a useful rule of thumb is to apply fertiliser in the good seasons. This will maximise the response in both forage and seed production, and builds up the seed reserve in the soil. Serradella is not as demanding of fertiliser as clovers.

Diseases

Disease is not a problem in dryland pastures, but root and crown rotting diseases caused by rhizoctonia and colletotrichum can occur in irrigated stands (e.g. grown for seed production).

Insects

Heliocoverpa can cause severe damage to immature seed pods in mid-late spring, but this is a lesser problem in early maturing varieties. Aphids do not attack serradella.

Grazing management

Serradella persists well under continuous grazing, with a carrying capacity of 1.5 to 3 wethers per hectare, or for cattle one adult beast per three hectares depending on season. In the first year, stock should be removed when flowering begins to ensure a heavy seed set.

Do not graze serradella as you would an oats crop. It performs best with regular or continuous grazing at a lower stocking rate.

To maintain a high seed reserve, ensure a more lenient grazing during seed set if conditions are dry. The key to successful seed set is to graze the pasture moderately but continuously throughout the growing season.

Animal production

Serradella pasture, fertilised with superphosphate, has the potential to double wool production per hectare (compared with unfertilised native pasture), mainly through increased carrying capacity. In regions with reliable rainfall, this can be up to 2.5-3 Merino wethers/ha.

The improvement in gross margins can be in the order of 75%. Serradella pasture will also enable enterprise diversification to the breeding and growing of beef cattle on areas that were considered to be limited to sheep production.

Seed production

Irrigation is required for reliable seed production in Queensland.

Seed may be harvested by direct heading before the pod has fully matured and dropped. Alternatively, matured seed can be vacuum harvested off the soil surface later.

The varieties Santorini and Charano have been selected for their ease of harvest as their pods do not drop after maturity. The seed of these varieties is also easier to thresh.