Reduce atmospheric carbon dioxide use Carbon Buster™ grasses and legumes
Plant: Tufted perennial grass 1 – 2m tall, spreading by looping runners forming new plants along the runners (stolons).
Stems: Smooth and shiny; creeping stems 4 – 5mm diameter, and upright stems 2 – 4mm diameter.
Leaves: Leaf blades are hairless except at the base near the stem, and usually of the order of 30 – 40cm long and 3 – 5mm wide, tapering to a point.
Seeds: Light and fluffy, 3.5 mm long, each bearing a long (‘Callide’) or short (other cultivars) awn (bristle); 4 million (‘Katambora’) or 7 – 10 million (other cultivars) seeds/kg. Seeds contain a small dark brown grain (caryopsis), with 2 million caryopses/kg..
Seedhead: Mostly a single (sometimes double) circle of radiating light, greenish brown (ripening to darker brown) branches 4 – 15cm long.
Rhodes grass can be used as permanent pasture or a short- to medium-term pasture ley. It is also useful for erosion control by virtue of its spreading growth habit. It makes good hay if cut at or just before early flowering, and provides better standover feed than buffel grass or the panics.
It is usually sown in areas receiving an average annual rainfall of 700 – 1,200mm, and is well-suited to irrigation. While it can be successful at lower annual averages (as low as 500mm in NSW), it is not suited to areas of very high rainfall (more than 1,800 mm/yr).
Rhodes grass will grow on most well drained soils, providing fertility is adequate. It prefers well-structured loams and clays of volcanic origin, but is not suited to very heavy clays. It is best in soils with pH between about 5.5 and 7.5, but will grow down to pH 4.5 (if available aluminium and manganese levels are low) and up to 10. It is the most salt-tolerant of the commonly sown tropical grasses, tolerating soil salt levels where electrical conductivity exceeds 10 dS/m.
It has moderate frost tolerance, with ‘Katambora’ and ‘Pioneer’ types being less affected by frost than is ‘Callide’. All are generally less affected than are green or gatton panics.
Grasses: NuCal™ guinea grass, buffel grass, green and gatton panics, setaria.
Legumes: Carbon Buster™ stylo, burgundy bean, butterfly pea, glycine, lotononis, lucerne, medics, serradella, siratro, and white clover.
Sowing/planting rates as single species
1 – 4 kg/ha bare seed. 3 to 12 kg/ha coated seed depending on coat weight. Seed should be sown on the surface of a well-prepared seedbed. For broadcasting, seed is best mixed with sawdust or fertiliser, and for drilling, it flows more readily if pelleted (coated).
Sowing/planting rates in mixtures
0.5 – 2 kg/ha bare seed. 2 to 6 kg coated seed depending on coat weight.
It can be sown from spring to early autumn. As a general rule, it is best to choose a suitable sowing time for any associated legume.
It is advisable to use an establishment application of say 200 – 300 kg/ha of superphosphate on less fertile soils. A post-emergence application of 100 kg/ha of urea (= 46 kg/ha N) in pure stands will stimulate more rapid stand development.
Split applications, each of 50 – 100 kg/ha N, are used in pure stands when economically feasible.
Rhodes grass is very tolerant of cutting or grazing. The stand should be maintained in a leafy condition by fairly regular cutting or grazing, since feeding value declines rapidly with onset of flowering. However, too frequent cutting or grazing (say every 14 days) leads to production losses and stand decline. Annual winter legumes are favoured by heavily grazing the pasture in late summer.
Ability to spread
Rhodes grass is commonly found on roadsides and other areas of disturbance throughout the tropics and subtropics. It spreads readily by seed and runners.
It invades disturbed ground and is a weed of cultivation. However, it usually dies out after 4 – 5 years in the absence of further disturbance or nitrogen fertilisation. It rarely invades natural areas.
Severe attack by armyworm and pasture webworm can destroy much of the leaf, particularly young leaf – largely restricted to coastal areas.
No serious diseases.
It is very susceptible to the selective grass herbicide, haloxyfop (Verdict®), even when mature. While weakened, by glyphosate at normal rates, it mostly survives unless resprayed.
Crude protein levels vary with age of regrowth and level of available soil nitrogen, from about 17% (on a DM basis) in very young leaf, to 3% in old leaves. Similarly, digestibility may vary from 80% in very young growth to 40% in older growth.
Young growth is very palatable, particularly in ‘Callide’. Palatability declines with age, more rapidly with the onset of seeding.
It can carry about 1 – 4 beasts/ha depending on pasture productivity and size of animal. Annual liveweight gains of up to 170 kg/head are achievable. Production levels decline without a vigorous legume or the use of fertiliser nitrogen.
Katambora, Callide, Pioneer