Reduce atmospheric carbon dioxide use Carbon Buster™ grasses and legumes
Plant: Tufted perennial grass growing 1 – 2m tall, and up to about 30cm diameter at the base.
Stems: Smooth and shiny, sometimes slightly waxy.
Leaves: Young shoots are flattened at the base, and the leaves folded (not rolled). Leaves are generally hairless, soft to the touch and bluish grey-green in colour, often reddish around the stem; leaf blades to 50 cm long and over 1 cm wide.
Seeds: Very small, averaging about 1.5 million/kg.
Seedhead: Seeds are borne on a bristly, cylindrical “spike” 6 – 25cm long, and about 1cm across, varying in colour from golden to dark brown.
Good for intensively grazed permanent pastures in the humid subtropics, and upland and southern tropics, as well as for hay production.
Setaria is mostly sown in areas receiving an average annual rainfall of over 1,000 mm, and is well-suited to irrigation.
It grows well on most soils providing moisture and fertility are adequate. It is not well adapted to alkaline, very acid, or saline soils.
Grasses: normally not sown with other grasses.
• twining: Glycine, siratro.
• trailing: Greenleaf and Silverleaf desmodium.
• creeping: Maku lotus, pinto peanut, Shaw vigna, white clover.
Setaria competes strongly with companion species for plant nutrients in less fertile soils, and may suppress them in the absence of added fertiliser.
Sowing/planting rates as single species
2 – 4 kg/ha for nitrogen-fertilised grass
Sowing/planting rates in mixtures
1 – 2 kg/ha bare seed and 3 – 6 kg/ha coated seed, depending on seed coat weight, the lower rate for creeping legumes
It can be sown successfully from spring to early autumn. As a general rule, it is best to choose a suitable sowing time for any associated legume.
Because it grows best in at least moderately fertile soils, it is advisable to use an establishment application of say 200 – 300 kg/ha of superphosphate and 50 kg/ha of muriate of potash on less fertile soils. A post-emergence application of 100 kg/ha of urea (= 46 kg/ha N) is beneficial in pure stands.
Annual dressings of up to 200 kg/ha of superphosphate and 100 kg/ha of muriate of potash (depending on soil fertility), are required to maintain high production levels. In pure stands, where high levels of fertiliser nitrogen are used (e.g. up to 300 kg/ha of nitrogen in three split applications), occasional dressings of lime may also be necessary to overcome increasing soil acidity.
Although it is fairly tolerant of mowing or grazing, it will give way to creeping grasses such as blue couch or mat grass if grazed heavily over a prolonged period. Setaria decline is more rapid if nitrogen fertility is low.
Ability to spread
Setaria spreads effectively by seed, and readily colonises disturbed areas such as roadsides.
Although listed as a weed in some regions, it rarely invades undisturbed areas.
Severe attack by armyworm and pasture webworm can destroy much of the leaf, particularly young leaf. Buffel grass seed caterpillar can cause considerable damage to seed crops from late January onwards.
Pyricularia leaf spot is prevalent under hot humid conditions and can retard the growth of ungrazed stands.
Setaria is susceptible to glyphosate..
Protein content of the grass depends on nitrogen fertility of the soil, and age of regrowth of the stand (best if less than 4 weeks’ regrowth). Young leafy regrowth (3 weeks) can have digestible dry matter levels of 70%, but after 6 – 8 weeks, digestibility levels drop to 50 – 55%. Sodium levels are often low requiring supplementation in the diet. See “livestock disorders/toxicity”.
Setaria is extremely palatable when young, but becomes stemmy and unacceptable with onset of seeding.
Setaria develops high levels of oxalate in the leaf, especially in young, well-fertilised, vigorous growth. This causes hyperparathyroidism (‘big head’ disease) in horses and donkeys, and can cause nephrosis (kidney disease) in ruminants. It can also lead to hypocalcaemia (milk fever) and/or hypomagnesemia (grass tetany) in ruminants, particularly in high-producing dairy cows. This is less of a problem in animals that graze setaria regularly. ‘Kazungula’ and ‘Splenda’ develop the highest oxalate levels, followed by, ‘Narok’ and ‘Solander’, with ‘Nandi’ the lowest.
Kazungula, Narok, Solander, Splenda