Unit
Saltland UniExplore SolutionsGenies AdviceGenies MapsGenies LibrarySaltdeck Cards
Unit 1 - What's in it for me?
Unit 2 - Saltland Basics
Unit 3 - Can I trust the technology?
Unit 4 - Plant and animal performance
Unit 5 - Sheep, cattle and conservation
Unit 6 - Do the $$$'s stack up?
Unit 7 - The saltland toolbox
Site Assessment
Solution 1: Exclude grazing
Solution 2: Volunteer pasture
Solution 3: Saltbush
Solution 4: Saltbush & Understorey
Solution 5: Tall Wheatgrass
Solution 6: Puccinellia
Solution 7: Vegetative grasses
Solution 8: Temperate perennials
Solution 9: Sub-tropicals
Solution 10: Legumes
Solution 11: Revegetation
Solution 12: Messina
Solution Explorer
Genie's Advice
Genie’s Maps
FAQ
NSW
SA
TAS
VIC
WA
Farmer Stories
Case Studies
Film Clips
Research Reports
International Salinity Forum
SALTdeck Cards
Published Products
SALT Magazines
Photo Gallery
Saltland Pastures Association
Farmer Stories
Case Studies
Film Clips
International Salinity Forum
Research Reports
NDSP Archive
Saltdeck
Published Products
Photo Gallery
Saltland Pastures Association
Catchment Management Plans
Farmer Stories
Case Studies
Published Products
Photo Gallery
Research Reports
Genie Film Clips and YouTube
Catchment Management Plans
Saltdeck Cards
Saltland Pastures Association
NDSP Archive
Salt Magazines



SOLUTION 5

Tall wheatgrass

 

5.5  Establishment & management of tall wheatgrass pastures

NextPrevious

Choosing the right variety

Until 2000, Tyrrell was the only variety available in Australia. The cultivar Dundas was released in 2000, developed from Tyrrell and 2 US varieties by selecting plants with improved forage quality and increased growth rate. Dundas is now generally regarded as the variety of choice, except where farmers are harvesting their own seed from old Tyrell stands.

It is not uncommon to sow puccinellia with tall wheatgrass, however they tend to occupy somewhat different landscape zones, so that it might be more economical to assess the site carefully and use the species mix only where these zones are likely to overlap.

Companion legumes are necessary to ensure the continued vigour of the pasture. Balansa and Persian clover are both annual clovers that are generally compatible with tall wheatgrass. These persist in areas of low salinity, balansa being particularly adapted to waterlogging, but they tend not to regenerate in soils of moderate salinity. They should be direct-drilled the year after the tall wheatgrass is established, to ensure that the perennial has established well. Strawberry clover is a perennial legume that should be sown with tall wheatgrass, particularly in higher rainfall districts.

Top

Site preparation

It is best to fence to control grazing as tall wheatgrass does not make strong early growth, and is often sown into soil that soon becomes very wet and vulnerable to pugging by livestock. Temporary electric fencing may be sufficient, particularly for small areas where separate grazing is impractical.

If waterlogging is likely to present a problem at sowing, shallow drains can be used to remove excess water. Diversion or reverse interceptor banks will reduce the movement of runoff water onto the area, but care should be taken that these banks do not go through sodic soil that might give way and lead to erosion. When designing drainage systems it is important (and possibly a legal requirement) to consider the impact of water disposal on downstream biodiversity and on other landholders, and ensure that no harm will be done.

It is important to control weeds, especially annual grasses, most often sea barleygrass, by spray topping the previous spring. It may still be necessary to kill germinating weeds prior to sowing with a knockdown herbicide because germinating annuals will easily out-compete tall wheatgrass seedlings.

We recommend that the suitability of sites be judged on the basis of the salinity in the subsoil and the depth to watertable. However, as with any new pasture establishment it is sensible to take soil samples from the top 10cm and test these for salinity and major nutrients.

The soil should be lightly cultivated or scarified prior to the break of the season. It should not be harrowed as the rough ground allows some leaching of salt with the opening rains. With both cultivation and herbicide use, the time without vegetation should be minimised to reduce the capillary rise of salts to the surface.

Top

Weed and pest control

The main weeds are capeweed and annual grasses such as sea barleygrass, which should be sprayed in the spring before sowing to reduce the seedbank. Tall wheatgrass should not be sown with annual legumes, because the vigour of the annuals will suppress the growth of the tall wheatgrass seedlings, particularly on areas of low salinity. Buck’s horn plantain and summer-growing salt-tolerant perennial grasses do not represent strong competition for tall wheatgrass, and are useful within a tall wheatgrass-based pasture. A full kill of these species is not necessary to establish tall wheatgrass.

Red-legged earth mite (RLEM) can challenge wheatgrass during establishment. The Timerite® program is an excellent tool for controlling RLEM in the season prior to seeding, as timely application of chemicals can be difficult on very wet sites.

Top

Sowing

Pasture mixes

Single species pastures are the easiest to manage, and since the productivity from tall wheatgrass is very management dependent, this is an important consideration.

Companion species can include puccinellia, balansa clover, strawberry clover, persian clover, tall fescue and lucerne, depending on site salinity, waterlogging, average rainfall and other site conditions. The grasses help to balance the pasture by extending the grazing season and taking advantage of variations in soil condition across the paddock. The legumes contribute valuable fixed nitrogen to the grasses and protein to the grazing animals.

Typical recommended mixes include:

  • ECe: <4 dS/m: TWG, tall fescue*, strawberry and balansa clovers**.
  • ECe: 4-8 dS/m: TWG, strawberry and balansa clovers.
  • ECe: 8-16 dS/m: TWG and puccinellia.

*Victorian trials have shown that Resolute and Advance tall fescue will germinate and grow at ECe levels up to approximately 8 dS/m, losing up to 50% of productivity at this higher salinity level.

** The early-flowering Frontier balansa has the advantage that it can set seed before salinity levels escalate in spring.

Under favourable conditions legumes (particularly balansa clover) will out-compete young tall wheatgrass seedlings, particularly when sowing after an opening rain has flushed some salt from the topsoil. Balansa clover is not particularly salt-tolerant and this initial flushing of salt greatly enhances its dominance. Therefore, under conditions of low salinity, balansa clover should not be sown with tall wheatgrass in the first year, but rather a year or two later.

When sown in a mix some species will colonise different zones. For example, tall wheatgrass or puccinellia will be quite distinctly favoured by variable local salinity or waterlogging conditions, so considerable expense can be avoided if these conditions are anticipated and the most appropriate species sown.

A tall wheat grass/puccinellia mix poses significant grazing management compromises.Tall wheatgrass should be grazed heavily over spring and summer to prevent clumpiness, puccinellia is best left standing over this period and then grazed down in autumn. Puccinellia is more palatable than tall wheat grass and is therefore eaten first, leaving the more saline areas without vegetative cover.

Seeding rates

Tall wheatgrass is usually sown at 15-20kg/ha if sown alone as a single species pasture. The seed loses viability rapidly after 2 years, and in any event seed germination tests are strongly recommended. Germination of 50-90% should be expected for viable seed and sowing rates should reflect this.

The higher the seeding rate, the stronger the stand, but beyond a certain rate the cost will outweigh the benefit.

The following rates are recommended for tall wheatgrass in typical pasture mixes:

  • Use 10-15kg/ha with puccinellia at 4-10kg/ha.
  • Use 4-5kg/ha in a shot-gun mixture with other grasses or legumes which together might be medics @ 2kg/ha, clovers @ 0.5-2kg/ha, lucerne @ 2kg/ha, phalaris @ 2kg/ha.

If legumes are to be sown the year following the tall wheatgrass, the latter should be sown at the lower rate suggested for mixed species. However this can lead to weed invasion while the grass is thickening up.

Fertilisers and downtime

As with all new pastures, a soil test is advisable. Like most grasses, tall wheatgrass responds to phosphorus and nitrogen, but where other grasses typically get their N from companion legumes this opportunity is not always available to tall wheatgrass in saline conditions. Nitrogen applied in late winter or early spring will boost productivity and maintain plant palatability. If sown with legumes, the pasture should be sown for the legume requirement  of approximately 1 kgP/dse to maintain production and persistence of the legume.

Establishing tall wheatgrass is slow and often a 2-year process. Light grazing is possible in the first spring (assuming autumn sowing) provided the site is not waterlogged and salinity is sufficiently low (ECe < 4 dS/m) so that the wheatgrass has made good growth. Generally some seed set should be allowed in that first year to enable the grass to thicken up.

Establishment costs are about $300/ha for seed, cultivation, herbicide and fertiliser, plus a further cost for fencing which will depend very much on the size of the saline area. In addition there is the opportunity cost associated with the establishment downtime, but in most cases the opportunity foregone on unimproved saltland is very small.

Time of sowing

As with all pastures, but perhaps more so on saltland, options for sowing times are largely dependent on weather condition and the state of the paddock. These options come down to:

  • Autumn sowing after the autumn break (in southern Victoria this should be before the end of April).
     
  • Dry sowing in April if the autumn break is late (this may lead to excessive weeds).
     
  • Spring sowing, as soon as the area is trafficable after the end of winter. This option works well in years with dry winters and extended springs, but if the area is not trafficable until late spring, there will be insufficient time for the plants to establish before the onset of higher salinity levels in summer. Sowing in spring is of course not an option if an annual such as balansa clover is to be included.

For more information, see Victoria Agriculture Notes: Management of Tall Wheat Grass.

Top

General principles

Management of tall wheatgrass can mean the difference between having a productive pasture contributing significantly to a grazing enterprise, and having a troublesome paddock of tussocky unpalatable grass. The specific management requirements for tall wheatgrass mean that despite the fact that it is often sown as part of a shotgun mix, it is actually a poor partner species for other grasses such as puccinellia.

Like most perennial grasses, tall wheatgrass should be grazed rotationally to ensure persistence and to better control excessive growth in late spring.

Pastures intended for grazing usually comprise a variety of grasses and legumes that optimise productivity and reduce the risk from false breaks. The legumes provide nitrogen, the perennials respond to out-of-season rain, and different species and varieties adapt to the range of soil conditions throughout the paddock, even where fencing has been to soil type. This principle applies equally to saltland pastures, except that the range of available species is smaller and the range of soil conditions often greater.

Typical recommended mixes for differing salinity levels include:

  • subsoil ECe: <4 dS/m: tall wheatgrass, tall fescue, strawberry and balansa clovers.
  • subsoil ECe: 4-8 dS/m: tall wheatgrass, strawberry and balansa clovers.
  • subsoil ECe: 8-16 dS/m: tall wheatgrass, puccinellia and/or saltbush.

Starting from the point of establishment, managing tall wheatgrass should be seen in 2 phases

  • the year of establishment; and
  • subsequent years.
Top

Managing new stands – year 1

The year of establishment is critical for tall wheatgrass as it is not a vigorous seedling, but it does persist well once established. It will respond to nitrogen and phosphorus in spring, although N might not be economical if the pasture is to be only lightly grazed and if growing with a legume.

Careful grazing is essential in the first year to maintain leafiness and allow seed set and thickening of the pasture.

Sites with low salinity (summer ECe values 2-4 dS/m)

Tall wheatgrass can be grazed lightly in spring provided the site is not waterlogged and the seedlings are firmly anchored in the soil.

As mentioned in section 5.5d, balansa clover as a companion might be avoided in the first year as its vigour can suppress the grass. However, if balansa is sown, stock should be removed in time to allow the clover to flower and set seed during spring. As with Puccinellia, the grazing management needs for balansa conflict quite strongly with the need to maintain grazing pressure on the tall wheatgrass during spring to ensure it remains vegetative.

A compromise is to avoid grazing when the balansa is setting seed, but once that is complete, and then crash graze the pasture to bring it down to a uniform stubble of about 10cm. Removing the excess growth will help control weeds, encourage better leaf growth and make grazing management over summer much easier. However, is not easy in practice to get the time right as the tall wheatgrass quickly becomes unpalatable when ungrazed and it can be difficult to force animals to graze it unless significant weight loss is acceptable.

Grazing over summer-autumn should be conservative, aimed mainly at strengthening a permanent pasture rather than maximising immediate production. Grazing down to about 5cm will promote strong root development and removing thatch will provide good conditions for regeneration of clover with opening rains. 

Sites with moderate salinity (summer ECe values 4-8 dS/m)

Grazing on these sites might not be possible in the first year without damaging the poorly established grass and causing soil damage. Puccinellia, if sown in a pasture mix, will usually also benefit from a first year spell on such sites.

Top

Managing new stands – year 2+

A soil test every 3-5 years will help determine fertiliser needs, but this also should be balanced against cost-effectiveness and the purpose to which the pasture is put.

Where legumes do not persist, usually as a result of saline conditions, wheatgrass will benefit from annual applications of nitrogen with rates of 25-50kg N/ha. To maintain productivity, approximately 1kg P/dse might be needed annually. It is important to note that tall wheatgrass will show only limited response to N if exchangeable P levels are below a critical level. This value has not been determined for tall wheatgrass. However if clover is in the pasture, the critical level to maintain production and persistence is approximately 12-14 mg/kg (Olsen P) or 20-24 mg/kg (Colwell P).

DPI Victoria has an information booklet, Phosphorus for sheep and beef pastures, to help producers assess how much P is likely to be needed to maintain productive pastures. This enables estimates of annual P inputs per DSE, for different rainfall zones, soil and landscape types, grazing management and poor or improved pastures.

Grazing management of mixed pastures containing tall wheatgrass will need to be carefully considered where pasture species have different seasonal activities. Allowing seed set for legumes whilst controlling the same for tall wheatgrass involves compromises which can cause deterioration of the pasture.

Winter to early-spring grazing, in non-waterlogged sites will make use of other components of the pasture mix such as balansa clover. At the first sign of balansa flowering, careful (rather than crash) grazing of the pasture is needed to ensure adequate seed set and retention of the legume base. Experience in the South East of SA shows that moderate stocking rates during flowering (which also corresponds to a period of high growth) enables adequate seed set and regeneration. However, the pasture composition should be monitored and where the legume component is not regenerating it may be necessary the next year to further limit or stop grazing from flowering until seed set is complete.

Once balansa clover seed set is complete (which depends on the cultivar) the stand can be crash grazed to remove excess balansa growth and wheatgrass stems which will have started to run up to flower.

Continue grazing throughout summer and into autumn to maintain a pasture height below 10cm. Stock will avoid grass that has begun to go rank, exacerbating the problem of selective grazing, in which case it might be necessary to increase the stocking rate or set up electric fences to force grazing. These mature stands can be profitably harvested for seed.

Top

Rejuvenating old tall wheatgrass stands

Left unmanaged or poorly grazed, tall wheatgrass reverts to an unproductive monoculture of erect clumps up to 2m high. There is little grazing value in these stands, it is very difficult to traverse the land, and there is a risk of spreading seed to areas where the tall wheatgrass is unwanted. However these stands can be returned to production and the weed threat can be managed.

Slashing to a height of 10cm as the plants are sending up flowering stems maximises trash removal and protects the plant crown. However working in old wheatgrass paddocks can be hard on machinery and operator.

Mulching is the ideal technique, breaking stems into smaller segments to allow for quicker breakdown of trash, but this requires specialist mulching machinery which is not always available. Slashing is often more achievable, but leaves a heavier mat, which takes longer to break down and tends to smother the pasture regrowth. Burning is also effective in removing all old growth.

After the initial intervention grazing and management should then follow recommendations for managing new stands (year 2+).

Most old stands have no legume component which is critical for a good quality pasture. Where salinity levels allow, balansa clover seed can be broadcast with the fertiliser in early autumn. If soil conditions permit, and if rank grass is removed and some bare ground is visible between plants, balansa clover will readily germinate.

Top

Controlling weed escape

Invasiveness or spreading of tall wheatgrass from a planted site is a potential risk. However, studies of 60 tall wheatgrass field sites in the Glenelg Hopkins catchment, south-west Victoria, found little or no spread from the majority of those sites. Across the study sites, there was spread from the original sown area only when sites were allowed to routinely set seed (essentially, ungrazed sites).

The study found that preventing seed set, usually by grazing down to 10cm in summer-autumn, was the key to controlling the spread from the sown site. This implies that tall wheatgrass pastures should be fenced and contain their own water supply, so as to enable effective grazing management. Also there should be sufficient distance from the sown site to creeks and waterways, remnant vegetation, plantations and roadsides.

Top