African Lovegrass
African Lovegrass
Sowing
Because Consol seed cannot be easily identified from the seed of unpalatable naturalised lovegrass, it is essential to use only certified seed. Certification is the only protection growers have against impure seed. Some lovegrasses are highly unpalatable.
Sowing time
Consol can be sown successfully at any time in areas where winters are mild, even if rainfall is highly variable — for example, in north-western New South Wales.
In the southern part of the state the best sowing time is early spring, when the store of soil moisture is at its best, rainfall is reliable and soil surface temperatures are rising. Also, competition from cool-season plants can be better controlled if preparations for sowing commence in late winter.
In areas of high summer rainfall, for example on the Northern Tablelands and adjacent slopes, Consol is most commonly sown in late summer to early autumn.
It is common for seed not to germinate with the first rain after sowing. In trial sowings, seed has been dormant for up to 2 years. Storing seed for 6–18 months may assist early germination and uniform growth.
Consol sown in spring or summer should be oversown with an annual legume the following autumn, while autumn-sown Consol should be concurrently oversown: in the Coonabarabran district (north-western New South Wales), mixed Consol and legume pastures have been sown in early autumn.
The autumn-sown clover, shown here at early germination stage, provides winter feed and boosts nitrogen levels in the soil (Consol thrives on nitrogen). By late winter or early spring the clover will dominate.
Alternatively, autumn-sown Consol may be oversown with a cereal crop. While some seed may establish and survive from early autumn sowings, low temperatures will prevent seed used in mid to late autumn sowings from germinating until spring. If sowing with cereals, ensure sowing depth is satisfactory for lovegrass seed (see ‘Sowing, germination and establishment’ below).
Seeding rates
The recommended Consol seeding rate is 0.3 to 1.0 kg/ha. Rates lower than 0.3 kg/ha are applicable only in ideal, weed-free growing conditions. A rate greater than 1.0 kg/ha can produce a stand of grass that is too dense, in which individual plants compete against each other; they will not grow to full size and will suffer moisture stress earlier because of competition for a limited supply of moisture.
Sowing, germination and establishment
Direct drilling, or broadcasting and harrowing, is generally effective in uncultivated, relatively weedfree, loose soil. Establishment will be slowed if there is shading and competition from other plants. For example, if broadcasting seed into killed pastures the stubble must be heavily grazed.
Sowing depth is a major factor affecting establishment. Most establishment failures have been due to sowing too deeply. It is important not to bury seed deeper than about 5 mm in sandy soils, and 2–3 mm in loamy or clayey soil. The most critical factor in accurately setting the sowing depth is to set it in the paddock, remembering that most sowing equipment ‘digs in’ when the soil is soft and friable. The best technique is to drop the seed mixture onto a fairly even soil surface and cover it using light covering harrows or press wheels. (Turning the harrows upside down may often give a better result on loose sandy soils.) A band seeder adjusted to ensure shallow sowing can also be used. Press wheels or rollers may be useful in loose soil, but sow on the contour as far as is practicable.
A seed carrier such as single superphosphate, dry coarse sand, cracked wheat, moist sawdust, or cracked sorghum helps to achieve uniform distribution during sowing. The carrier must contain a fair proportion of fine particles, otherwise the Consol seed will quickly separate. Rather than sowing large areas at a time, if separation is observed, the machine should be refilled often. Sowing equipment should be calibrated to deliver the correct proportions of seed and carrier, thoroughly mixed.
Consol is best sown in rows 10–30 cm apart — use narrow rows in spiny burrgrass country.
Seed requires a minimum soil temperature of about 10°C (to be read at 7 cm depth, at 8 am EST). Higher average temperatures increase the rate of germination. The rate peaks at about 20°C.
In the first few weeks, Consol seedlings grow very slowly, developing their root systems and preparing to tiller. When they tiller at 6–8 weeks, the seedlings should be well established and drought hardy. Under reasonable conditions, the first seed heads show in 10–12 weeks.
Weed control
Established stands of Consol are relatively weed free; however, weed control may be a problem in the sowing year as Consol seedlings are not as competitive or fast-growing as most annual weeds.
In favourable growing conditions with adequate soil fertility, good moisture and warm temperatures, good spring growth of sub. clover and ryegrass can severely suppress Consol pastures as they compete for moisture and light. Grazing management should aim to keep the temperate species under control.
For spring-sown pastures, broadleaf weeds are more likely to be a problem than grass weeds. Autumn-sown pastures may have to compete with ryegrass and clover.
Grazing can control weeds during establishment of the seedlings. Heavy stocking for short periods reduces pasture damage and minimises selective grazing of the seedlings.
No herbicide is registered for controlling weeds in lovegrass pastures in New South Wales.
Sowing approval needed
African lovegrass (Eragrostis curvula) is a declared noxious weed (category W2 or W3) in many areas of New South Wales.
Consol is a registered cultivar, and is palatable when well managed. It can be distinguished from unpalatable naturalised strains of the species, and is not known to cross or hybridise with other native or naturalised lovegrasses.
However, it cannot be sown without approval in some local government areas of the state. Before sowing Consol, ensure that the location in which it is to be sown is not in a local government area where African lovegrass is a declared weed.
Seed production
Consol lovegrass is a long-lived perennial seed crop; if well managed the stand should persist.
Yields in the first year are often low, stands may thin considerably and there may be significant weeds present. If plant density is reasonable (about 10 per square metre), the plants will compensate by growing larger and will quickly fill in bare areas. Seed crops in following years should be more productive.
Soils should be well drained, light textured and non-cracking, with pH of about 6 or less. Soil fertility is usually not a major problem provided sufficient fertiliser is applied.
Management of the crop should aim to have the seed crop maturing as evenly as possible. This is achieved by correct timing of burning, slashing, irrigation and fertilising operations.
Burning
Lovegrass seed crops are often burnt as a management strategy. Burning will remove the bulk of dead residue from the previous season and stimulate initiation of flowering stems. Ninety per cent of spring flowering seed heads are initiated in the autumn, and timing of burning should aim to leave as many of these as possible. For environmental reasons burning should be restricted to every couple of years in cool periods when the risk of uncontrolled fires developing is low. Lovegrass is highly tolerant of burning and highly flammable. Burning will help to control winter weeds.
Seed crop management should aim to produce seed heads with uniform maturity. Good seed crops are about 90 cm high with more than 800 seed heads per square metre. However, successive rainfall events usually stimulate more tillers and the seed crop may vary in maturity from mature seed heads to newly emerged tillers.
Seed in early tillers will most likely shatter before harvest, while seed in late seed heads will be immature and high in moisture at harvest time. Late tillers contribute little to the harvested yield.
Irrigation
Irrigation is beneficial for high yields and reliable seed production, although most seed production is based on dryland stands. Avoid areas subject to overwatering and poor drainage as it can lead to plant death, thin stands and weed invasion. Irrigate to provide a full soil moisture profile for at least 1.2 m. Under dry seasonal conditions, more than one irrigation may be required to fill the profile. Following irrigation, allow the seed crop to exhaust the soil moisture reserve, by which time the crop should have finished flowering.
Usually one irrigation is sufficient to grow the crop. Further irrigations will stimulate more tillers and uniformity of the seed stand will suffer.
Fertiliser
Irrigated.
For optimum yields, under irrigated conditions apply adequate nitrogen fertiliser. At least 50–150 kg/ha of nitrogen is recommended, applied in one application in early spring after burning in the autumn or winter.
Dryland.
Apply about 50 kg/ha of nitrogen to dryland stands after burning. Higher rates of nitrogen on dryland stands may promote excessive vegetative growth and the plants may use too much soil water before seed has filled, causing seed quantity and quality to decline.
Applications of other fertilisers like phosphorus, potassium and sulfur should be based on soil and crop requirements and previous paddock history.
Harvest
Consol lovegrass produces seed heads over a protracted period and if additional rainfall stimulates more tillers to grow, it can be difficult to decide when to harvest the crop. If management has enabled a single flush of seed heads, harvest should begin when seed in most of the seed heads has changed to light brown. The seed should be easily rubbed out by hand, and loss from shattering should be less than 10%. The plant is still green and actively growing when seed matures. Ripening takes 8–10 days and the seed head darkens to an olive-green colour from the tip downwards. Seed colour changes from white to whitish-brown, to orange and finally to light brown. Seed should be harvested immediately. Maximum yields occur about 21–28 days after flowering.
Delayed harvest, winds and rain can cause considerable shattering and cause seed to fall from the head.
Consol lovegrass seed crops are normally direct headed with a conventional header. Rotary headers generally produce seed with higher seed quality than those headers with transverse drums. Seed heads are normally well extended 45 cm above the last leaf and the crop is easily harvested.
Consult the manufacturer’s manual for harvester settings. As a guide, start with a high drum speed with the concave well closed. Close the air inlets to the fan, as sufficient light air flow is normally provided by the drum. The header operator should be prepared to adjust these settings during the day depending upon moisture of the crop, humidity and temperature of the air. Harvester ground speed should be low. Harvesting during early morning should reduce losses caused by shattering.
The harvester will not separate seed from crop residue. Due to the high moisture of the harvested seed and crop residue it may be difficult to empty the header box. To prevent blockage of the augers, seed should be emptied from the header box at regular intervals during the day, preferably before the box is about one-quarter full.
Crops may be windrowed and picked up by a header with a draper front attachment. This strategy will avoid potential seed losses by windstorms and heavy rainfall, resulting in more seed. However, other grass and weed seeds such as couch could be picked up. Seed purity of windrowed crops is normally lower than for direct headed crops, and for this reason the procedure is rarely followed.
If seed crops are windrowed, they should be cut about 21–28 days after flowering or about 52 days after slashing.
Immediately following harvest, the seed and crop residue should be dried to prevent seed quality deterioration. In inland areas with low humidity, seed is often dried on tarps on the ground by spreading the seed and residue about 100 mm deep and tur
ning it every 2 hours for the first day and then regularly thereafter to avoid any hot spots developing. Turning the seed can be as simple as raking or using an engine-driven rotovator.
Forced-air drying is commonly practised in more humid environments.
The simplest form of forced-air drying is aeration using a fan to move air at normal humidity and temperature. Turning the seed is still necessary to avoid heating of the seed. Most air dryers will begin drying using ambient air temperatures for the first couple of ho
urs. Often inland humidity of 30%–40% and temperatures of 20°C are sufficient for drying if the seed is turned regularly. Using this method, drying normally takes about 7–10 days.
Seed yields
Most commercial seed is produced from dryland stands, and average yields are in the order of 50– 150 kg/ha. The highest recorded commercial yield (at Rylstone in Central West NSW) has been 238 kg/ha from 12 ha under irrigated conditions.
Seed quality
Seed losses can be high if there are heatwave conditions at flowering or during seed formation prior to harvest.
Consol lovegrass seed usually has seed dormancy with moderate levels of fresh ungerminated seed in a seed test immediately after harvest. Dormancy may be reduced by placing seed in a cooler at 7°C for 7 days (called vernalisation). Seed test results quote the percentage of fresh ungerminated seed.
Note: Livestock health disorders
Pasture improvement may be associated with an increase in the incidence of certain livestock health disorders. Livestock and production losses from some disorders are possible. Management may need to be modified to minimise risk. Consult your veterinarian or adviser when planning pasture improvement.
Primary author; Bill Johnston, Senior Research Scientist, Department of Natural Resources
