African lovegrass

Introduction

The Consol cultivar of African lovegrass (Eragrostis curvula) is a hardy perennial grass with special attributes as both a pasture plant and a soil binder. Its main growing season is from mid spring to mid autumn.

Consol (mature seed head shown right) was developed in the 1980s by the Soil Conservation Service of NSW for revegetating sites which were too harsh for other perennial grasses. Trial plantings have persisted in areas where the climate and soil types are unsuitable for species such as lucerne, phalaris and pigeon grass. The results showed that Consol can make a valuable contribution to sustainable land use.

Consol is best suited to areas in New South Wales with a 400–700 mm average annual rainfall. It is sown more widely in northern and central NSW than in the south, mainly because Consol responds well to summer rainfall which occurs more reliably in these districts. During drought Consol stays green longer than buffel grass, Rhodes grass and lucerne, and unlike most other summer grasses, its top growth survives frosting. It is not permissible to sow Consol in areas of NSW where African lovegrass is a declared noxious weed (see under ‘Sowing approval needed’).

Consol grows best in lighter soils but is suited to a range of others, from sands to loams. It is particularly useful where the soil is too acid for grasses such as phalaris and cocksfoot, or too impoverished for species like buffel grass, Rhodes grass and lucerne. It has performed well where pH(CaCl2) is as low as 4.1 and where aluminium levels are high (up to 30% of cation exchange capacity).

Consol is not suited to soils that crack open after they dry, such as black earths or heavy clay soils, because cracking disrupts the fine surface root system of Consol, which can kill established plants.

Consol is suitable for grazing by sheep, cattle and horses. Its fresh growth is highly palatable, and its nutritive value is moderate to good, but for grazing use it requires at least moderate soil nitrogen. This can be supplied by fertiliser or, preferably, by growing it with a companion pasture legume such as serradella, medic or subterranean clover. Although Consol needs high levels of soil nitrogen for maximum growth, it does not require high rates of applied phosphorus. However, for legumes to grow successfully with Consol, soil deficiencies such as phosphorus, sulfur and molybdenum must be corrected.

Description

Consol lovegrass forms a compact tussock which, over several seasons, increases in diameter to form a ring of independent plants with independent root systems.

In peak growing conditions the stems and leaves growing from the tussock base will eventually obscure it, much as the tussocks of an unmown lawn are hidden. When the stems and leaves die off, either because of drought or at the end of the growing season, new buds form in the tussock.

These grow as conditions become increasingly favourable.

Consol is easily recognised by its flowering stems, which are short (300–600 mm), erect and stiff, and by its conical flower heads consisting of stiff lateral branches and heart-shaped florets, which are the flower parts that hold the seeds. Its leaves are also stiff and somewhat erect, 150–250 mm long, tapering to a point which may curl and die in extremes of temperature.

The leaves, stems and seed heads are dull green to blue-green. In summer, the leaves and stems become waxy blue-green in response to moisture stress and high temperatures, and the leaves roll inwards to reduce water loss.

Consol seeds are very small (3.5 million to 5 million per kilogram), oval, golden to orange coloured and translucent. A ripe seed breaks easily and cleanly from the husk. The seed of Consol is similar to most other lovegrass seeds, although the seeds of some native and annual varieties are smaller.

Pollen produced by Consol during flowering may cause an allergic reaction (‘hayfever’), thus when harvesting seed or handling hay it is advisable to take precautions against pollen and dust.

Uses

Stock use

Consol is palatable to most classes of livestock. Normally grown with companion cool-season legumes, Consol provides good summer pasture (pictured below) for sheep, cattle and horses. Observations from trial sowings of Consol in New South Wales indicate that the performance of both sheep and cattle is equal or superior to that of stock grazing other summer pastures. At Binnaway (Central West, 600 mm annual rainfall), a landholder with a 500 ha trial sowing recorded a 20% improvement in animal productivity over four seasons. Grazing experiments at Wagga Wagga in southern NSW have shown that during summer, the carrying capacity and liveweight of wethers grazing Consol were similar to those for grazing lucerne, and superior to grazing phalaris.

Consol will also add substantially to spring and autumn feed. In medium rainfall areas in New South Wales, the total feed yield over the three seasons has been recorded at over 6000 kg of dry matter per hectare per year.

Grazing promotes the cycle of nutrients, particularly nitrogen. The nutrients keep the sward active, promote new growth and maintain feed value, and grazing controls the leaf area, keeping the sward actively growing for longer into the summer.

Like most summer-growing grasses, if Consol forage is allowed to build up and mature, its feed value and palatability declines markedly. Studies in southern NSW have shown that 4-week-old forage is much more acceptable than material accumulated for more than 6 weeks. To make the most of Consol, it should be grazed when the total pasture mass reaches about 2000 kg/ha. It should than be grazed down to about 800 kg/ha over a period of about 2–3 weeks. Forage accumulated to meet an autumn feed gap should be grazed heavily in late February so that its feed value is maintained for mid to late autumn, and to encourage early germination of annual grasses and legumes.

Continuous grazing should be avoided. Prolonged overgrazing can uproot the plants, so it is important to check that newly established plants are well anchored before grazing them. Avoid grazing pastures to less than 800 kg dry matter per hectare. It is often noted that cattle and sheep will selectively graze seed heads in early summer. This may reduce seed yields considerably. Although Consol plants are long-lived, it is a useful strategy to allow Consol to set seed occasionally in order to maintain seed reserves in the soil. Closing off paddocks for 6–8 weeks in mid spring is enough to allow seed set. Seed will set throughout summer and until the first frost.

Consol also serves as a pasture after a cropping sequence.

Lovegrass varieties have been used since the 1930s for livestock production in South Africa, Argentina and the USA, especially in western areas of Texas and Oklahoma. Overseas results indicate weight gains as high as 1.0 kg per beast per day for cattle fed on nitrogen-fertilised lovegrass.

Soil conservation and weed control

Consol is a persistent plant in difficult environments such as roadside embankments, contour banks, mine sites and gravel pits. It will grow on shallow skeletal soils or sites where the soil is disturbed, on sand ridges, and in horticultural rotations where windblown sand is a problem. It persists on ‘hard’ country, such as stony ironbark ridges.

It will also serve as a ground cover for an established crop, for example, an orchard or vineyard, or as a ground cover for pastures which are degraded, overgrazed or fire-ravaged.

Consol controls invasion by weeds. A vigorous grower, it competes successfully against spiny burrgrass and broadleaf summer-growing weeds such as blue heliotrope or caltrops.

Consol allows for a more flexible revegetation schedule, as its seed may be sown at most times of the year.

Reduced soil acidity

Unlike most other pasture species, Consol tolerates soil acidity. Acidification of lighter soils is

common, for example, with legume-based pasture improvement; the inclusion of a hardy perennial such as Consol, with its deep rooting habit and appetite for nitrogen, should slow the acidification rate.

Water use and salinity control

Consol’s deep roots and summer growth rhythm give it a water use ability similar to lucerne. Controlling salinity is related to the capacity of pastures to dry the soil before the onset of the winter wet season in southern and central districts, and while the evaporation rates are high in northern areas. The main advantage of Consol compared to lucerne is that it will grow and persist in areas where lucerne could not be recommended, either because of soil or climatic limitations, or due to lack of control over grazing.