Summer forages in central Queensland

George Lambert, formerly of Department of Primary Industries and Fisheries.

Forage sorghum is our main dry land summer forage. Millet, lablab, milgara butterfly pea and cowpea are other options. Forage sorghum and maize (for silage) are suitable for irrigation. Weight gains on summer forage are generally lower than from winter forage.

This note covers forage sorghum, millet, pennisetum millet, lab lab and cowpea agronomy and grazing management.

Tips

• Match species with feed requirements
• Plant forage grasses and legumes in separate paddocks
• Fertilise older country
• Use forage sorghum to carry large numbers of animals during the summer and autumn periods.
• Use lablab, milgara butterfly pea and cowpea for fattening cattle.
• Bale, ensile or agist excess feed
• Forage sorghum can cause prussic acid poisoning under certain conditions. Do not graze with hungry cattle, crops that are stressed or below 600 mm tall.
• With forage sorghum, try sulphur and salt supplements if animal growth is poor.

Forage sorghum

Forage sorghum produces more feed and is more drought tolerant than other summer forages. However, the ability to finish cattle is lower than legume forages due to the large bulk of lower quality feed. Expect weight gains of 0.6 to 0.7 kg/day on sorghum growing on fertile soil.

Varieties

Hybrid and open pollinated forage sorghum are grouped below. This is not a complete list of available varieties.

Hybrids

Sudan grass x sudan grass:
Trudan, Superdan, Bulls wool

Grain sorghum x sudan grass:
Ag-Feed, Cowpow*, Grazer NZ, HighPro, hybrid forage sorghum, Jumbo*, Kow Kandy, Rising Fast, Lush, Speedfeed, Sudax 6+, Superchow, Zulu, Superzu, Betta-Dan, Super Sudax

Sweet sorghum x grain sorghum:
Sugarsweet, Supersweet

Sweet sorghum x sweet sorghum:
Hunnicut, Honey drip, Sugargraze

Sweet sorghum x Sudan grass:
Bully Beef, Nectar

Grain sorghum x grain sorghum:
Chopper, Feed and Seed (grow to 2 m high)

Open pollinated

Sudan grass
Common Sudan grass, Greenleaf Sudan grass, sweet Sudan grass, Silk sorghum

Sweet sorghum
Sugar drip

Notes

• The Sudan grass crosses give faster regrowth and tend to contain less prussic acid levels than sweet and grain sorghum crosses. They are better suited to heavy grazing.
• Sugar drip and sweet sorghum hybrids give the most palatable carryover feed for winter but they do not ratoon as well as the Sudan and grain sorghum hybrids.
• * Varieties marked with an asterisk have been selected for short day flowering. They remain vegetative until early autumn when they flower. They are easy to manage and give highest yields for grazing and haymaking.

Table 1. Major uses of various summer forage crops

Requirement	Plant
Quick, early spring feed	Millets, Super Cow, Betta-Dan, Bully Beef
High quality feed	Lab lab, milgara butterfly pea, cowpea, millets, pennisetum millets or fertilised forage sorghum (100 kg N/ha)
Bulk of feed	Sudan grass types of sorghum
Forage on low fertility soils	Lablab, cowpeas
Green manure	Lablab/high density Cow pow, Jumbo, Betta-Dan
Stand-over feed	Sweet sorghum types, e.g. sugargraze, sugardrip, or lablab
6 to 18 months grazing	Cow pow or Jumbo. (Sugardrip also makes good carryover winter feed)
Silage	Maize, Grain Sorghum, Chopper
Hay	Cow pow, Jumbo, Betta-Dan, Bully Beef -All high density and heavily fertilised (dryland or irrigated).

Planting time

Preferred  - September to October, January to February

Range - September to early March

Soil temperatures need to be at least 18^oC and rising. In this area, this occurs in the first week of September.

Standover sweet sorghum and grain sorghum types should be planted between January and early March.

Planting rates

Sudan grass 8 to 11 kg/ha
Grain sorghum x Sudan grass 5 to 8 kg/ha
Hybrid sweet sorghum 4 to 11 kg/ha
Sweet sorghum 8 to 11 kg/ha
Sweet sorghum x gr. sorghum 4 to 5 kg/ha

For irrigated or baled forage sorghum double or triple the planting rate.

Fertiliser

Apply phosphorus (P) and potassium (K) fertilisers according to soil test results. Apply nitrogen (N) fertiliser according to age of cultivation, soil type and fallow period or seek advice from your local agronomist. In general, 50 kg/ha of N would be suitable for old cultivation paddocks with good moisture.

Weed control

Good fallow weed control is essential for forage sorghum. Ensure a good plant population by planting at the right rate into good soil moisture.

• Atrazine and starane are registered for forage sorghum.
• Atrazine is best used at planting (post plant, pre emergent) for grass and broadleaf weeds. It can also be used as a post-emergent herbicide for broadleaf weeds.
• Rate: - 2.5-4.5 l/ha for pre emergent. 2.5-6.5 l/ha for post emergent
• Starane is a post emergent herbicide used for broadleaf weeds at 0.3 to1.0 l/ha.
• A mixture of Starane at 250 ml and atrazine at 2.0 l/ha gives both knockdown and residual control of a large range of weeds.

READ THE LABELS AND FOLLOW THE DIRECTIONS CAREFULLY.

Grazing

Allow forage sorghum to reach at least 600 mm before grazing. Graze before flowering to maximise quality. For best regrowth, do not graze shorter than 15 cm. For standover sweet sorghum and grain sorghum types, grain heads provide high quality feed.

Stocking at two beasts / ha should achieve 60 to 100 kg live weight in 85 to 140 days.

Under dryland conditions, two grazings should be possible. Under irrigation, expect three to four grazings. Intensive strip grazing allows quick recovery and better grazing control.

Prussic acid

All species of sorghum contain prussic acid. However, prussic acid poisoning is rare in Central Queensland. Problems are most likely when grazing hungry cattle on:-

(a) stressed seedling crops,
(b) drought affected or frosted regrowth, or
(c) crops less than 50 cm tall.

Treatment: Drench cattle with 60 ml of photographic hypo in 550 ml of water.

Millet

Millet provides quick, high quality feed compared with forage sorghum. However, dry matter production and drought tolerance are lower. Millet does not contain prussic acid.

The seed of millet is small making establishment difficult on heavy clay soils.

Do not plant deeper than 3 cm. A press wheel planter will assist establishment.

There are no herbicides available for grass weed control.

Varieties

Echinochloa millets

Japanese, Shirohie and Siberian (White Panicum) are suited. They provide less feed than pennisetum millets.

Japanese millet is the fastest growing of the group, providing grazing in 6 weeks. It is the most drought tolerant echinochloa millet.

Shirohie is also quick to feed with slightly better regrowth than Japanese.

Siberian has higher yield and re-growth potential than either Japanese or Shirohie, but is slower growing.

Pennisetums

These provide more feed with better regrowth and length of grazing than echinochloa millets.

• Open pollinated pennisetums include Tamworth Pearl (quick), Ingrid Pearl (intermediate) and Katherine Pearl (late maturing).
• Hybrid pennisetums include Supermill (1 to 2 m tall), Feedmill (dual purpose-1 m tall) and Nutrifeed (late flowering-1 m tall).
• Nutrifeed has produced similar weight gains to oats.
• Seed is more expensive than for echinochloa millet.

Caution: Under drought stress, hybrid pennisetums can become inedible. For this reason, they should only be planted in high moisture situations.

Planting time

Preferred - January

Early planting - Late August to early October

Echinochola millet can be planted once soil temperatures reach 14^oC (late August). Soil temperatures need to be at least 18^oC and rising for hybrid pennisetums.

Planting rate

Echinochola millet 8-10 kg/ha
Pearl millet 6-10 kg/ha
Hybrid pennisetum
(dry land) 2.5-6 kg/ha
(irrigated) 5-8 kg/ha

Fertiliser

Apply the same principles and rates as for forage sorghum (above).

Weed control

A weed free fallow and seed-bed is essential for the small seeded millet.

24-D is the only herbicide registered for broadleaf weed control in millet. Spray only small broadleaf weeds with a maximum of 1.1 l/ha of 50% 24-D amine. Spray at tillering and after secondary root development.

White French millet has tolerance to atrazine residues.

Grazing

Before grazing, ensure secondary roots are well developed.

Commence grazing Japanese millet at 15 to 20 cm high and before stem elongation. Spell when 7 cm high, otherwise recovery will be slow.

Commence grazing Pearl millet at 40 to 50 cm high and spell at when 10 cm tall.

Pennisetum millet should be grazed at 30 to 80 cm high or 5 to 7 weeks after planting. Spell when 15 cm high.

Maize

Maize (or corn) has been used for grazing, green chop, and for silage. Select adapted grain varieties or use specially selected silage types, e.g. Hycorn S or GH 5010. The best yielding grain types are the best for silage production. The protein content of maize silage is usually about 8%.

Forage legumes

Legumes such as lablab, Milgara butterfly pea and cowpeas produce high protein summer and autumn forage. They provide better quality feed but are not able to carry the same numbers of animals as forage sorghum. They are ideal for milking and/or fattening cattle.

These legumes (lablab in particular) improve soil N substantially. The most improvement occurs on low nitrogen soils making them ideal for crop rotation with grain crops.

For best results and less wastage, avoid mixing with forage sorghum and millet. These legumes are less palatable than the grass forages. Instead, plant separately or in adjacent paddocks as this will give better control over the timing and intensity of grazing.

Milgara can be used as a perennial pasture and can be mixed with a grass.

Weed control

A weed free fallow and seed-bed is essential.

Trifluralin is registered for weed control in forage legumes (grasses and some broadleaf weeds). See label for rates and use as directed.

Spinnaker (pre-emergent) has been successfully trialed against weeds in milgara pea. This herbicide must be applied 2 weeks before planting and will provide residual control of grasses and non-legume broadleaf weeds. In general, don't use legumes where parthenium is a problem. Plant sorghum and use atrazine.

Species

Lablab

Lablab has a long growing season and can even last for two seasons. It can tolerate heavy grazing and disease, but not frosts. It cannot tolerate water logging. Lablab will provide much more grazing than cowpea. The foliage is susceptible to attack from looper grubs, army worms and heliothis grubs. Flowers and seed pods are attacked by heliothis and green vegetable bugs. Control of these insects is necessary for seed production.

• The variety Rongai has white flowers, light tan seed and resistance to root rot. It flowers in June-July making it risky as a seed crop.
• Highworth is an earlier flowering variety than Rongai. Flowering normally starts in April. It has purple flowers, black seeds, and moderate resistance to root-rot.
• The two varieties give similar animal production.

Cowpeas

Cowpeas are annuals and are quicker to the first grazing than lab lab. They have a shorter growing season, quicker regrowth but much less bulk. Insect pests are the same as for lablab.

• Red Caloona is the main variety. It is resistant to phytophthora root-rot.
• Grey Caloona is susceptible to root-rot under wet conditions.
• Reeve is a higher yielding variety but susceptible to root-rot under wet conditions.

Milgara butterfly pea (Clitoria ternatea)

This is used as a perennial pasture when planted with companion grasses at a low population. However, it is showing great promise as a perennial forage crop or as a short term lay pasture species on cropping soils. At Emerald, short-term animal performance from a pure stand of Milgara equalled that from lablab and it has no trouble lasting 4+ years. However, it is slow to establish and is very vulnerable to weeds at the seedling stage. Use spinnaker as a pre-emergent herbicide if weeds are known to be a problem. Apply two weeks before planting.

Milgara is susceptible to frost, defoliating mature plants and are killing seedlings.

Planting time

Lablab: September to February
Cowpeas: September to March
Milgara: September to March

Planting rate

Lablab: 20 to 30 kg/ha
Cowpeas: 17 to 22 kg/ha
Milgara 4 to 8 kg/ha

Use higher planting rates for hay, seed production and irrigation.

Inoculation

Inoculate seed before planting. Use group I for cowpea and group J for lablab.  Milgara has its own special inoculant.

Insect pests

Insect control is not usually a consideration unless they are being grown for seed.

• Bean fly can attack late-sown crops. Spray seedlings at the 2-3 leaf stage with a dimethioate spray if insects are detected.
• Heliothis can affect flowering and seed set. Spraying with endosulfan, lannate or lorsban will control the grubs.
• Green vegetable bugs (and other pod sucking bugs) are controlled with endosulfan.

Grazing

Budget on 0.6 ha/head from forage sorghum.

Expect an extra month of feeding from lablab compared with cowpea. Milgara will provide grazing most of the year when used as a perennial pasture. Spell for 4-6 weeks through the growing period to allow seeding.

• Commence grazing when crops reach 45 cm tall (8-10 weeks).
• Avoid prolonged heavy grazing. Remove stock after all leaves have been eaten and before stems are damaged.
• Bloat is a remote possibility from summer growing legumes. Ensure stock have full stomachs before introducing them to the paddock.

When making into hay, use a conditioner to dry stems quickly.

Weight gains

Weight gain/head/day is generally higher on millet than sorghum. However, gain/ha from millet is lower because of the lower stocking rates and shorter grazing season. A rough guide for livestock productivity (kg liveweight gain /head/day) on all summer forages is given in Table 2.

Table 2. Estimates of livestock gain on summer forages

Forage type	Livestock gain
	As a % of oats	kg/head/day
Echinochloa millets Pennisetum millets Forage sorghums Forage sorghums with access to lablab Forage legumes	up to 90% 80-100% up to 70% up to 90% 80-100%	0.7-0.9 0.8 -1.0 0.5-0.7 0.7-0.9 0.8-1.0

Further information

Contact the DPI&F Call Centre on 13 25 23 (Queensland residents) or +61 7 3404 6999 (non-Queensland residents) between 8am and 6 pm weekdays, or email callweb@dpi.qld.gov.au

Alternatively from the the publication Sown Pasture Notes - Central Queensland (1996), Lambert, G. and Graham, G editors. Department of Primary Industries and Fisheries Information Series QI96118

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Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.

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Last reviewed 05 April 2006