• A
• B
• C
• D
• E
• F
• G
• H
• I
• J
• K
• L
• M
• N
• O
• P
• Q
• R
• S
• T
• U
• V
• W
• X
• Y
• Z

By Avril Baxter, Community Landcare Technician, Narrogin

Summary:

Case study of marginal valley flats regenerated for grazing on the Heffernan property 'Lomond Park' near Wickepin, Western Australia (rainfall 450 mm/year). Discusses soil salinity solutions, sheep condition trials, use of pines and tall wheatgrass, and value of remnant vegetation.

"I accept that I can no longer crop much of the valley flats, but I will not accept that I can no longer graze them." Tim Heffernan first saw tall wheatgrass (Thinopyrum elongatum) in 1984 when visiting a farm in South Australia. "The farmer showed me his salt problem, but all I could see was a paddock covered in waist high green feed in the middle of summer!"

Since then, Tim has gradually trans-formed 150 ha of marginal valley flats into forage areas for around $140 per hectare.

Figure 1. Farm plan for 'Lomond park', Tim Heffernan's property east of Wickepin, Western Australia.

Background

Tim Heffernan farms at 'Lomond Park', east of Wickepin, Western Australia, in a 450 mm rainfall area. Flats (salmon gum clays and sand over clay at 30 to 40 cm) occupy 25 per cent of the 1375 hectare farm. Upper slopes consist of sandy gravels over ironstone with patches of deep sand.

Salinity first appeared in crabhole depressions in the flats in the 1950s, spreading over larger sections of the flats in the 1960s and 70s.

Solutions

Tim's main aim in developing his farm plan is to stop the salt from spreading. Pines planted on deep sands and tall wheat-grass on the valley flats should take some of the pressure off the rising ground water system.

Figure 2. Tim Heffernan sows tall wheatgrass over the whole paddock and then broadcasts saltbush and Acacia saligna, allowing them to find their own niche.

Tim believes that growing trees in non-saline areas will produce valuable sawlogs. He no longer plants trees in saline areas, having recently watched a planting established 15 years ago die from a combination of waterlogging and salinity.

Remnant vegetation on slopes and uplands is also protected from livestock grazing and managed to improve its water use. Tim says that it is more important to protect these areas of existing vegetation than to plant trees in saline sites.

The farm is being re-fenced to separate salt land areas from cropping areas. Tall wheatgrass (Thinopyrum elongatum), saltbush (Atriplex sp.), blue bush (Maireana brevifolia) and golden wreath wattle (Acacia saligna) planted in salt land use water over summer. Vegetation cover prevents salt accumulation due to evaporation at the soil surface. Drying out the soil profile over summer allows winter rains to flush salts back down through the soil profile.

Dams with roaded catchments higher in the landscape supply good quality water to troughs in the valley flats which allows for grazing of salt land pastures.

Tall wheatgrass

Tim started planting tall wheatgrass in 1985. The valley flats were undulating with areas of ryegrass and barley grass saltpans. He thought it only a matter of time before the whole area would be covered with barley grass and decided to do something about it while he still could. Tall wheatgrass could use moisture from the soil profile over summer so that the ryegrass would survive and provide winter feed.

Water previously ponding on the surface over winter was drained via a system of 'W' drains. Tall wheatgrass was then seeded through the combine, and superphosphate mixed with saltbush, blue bush and Acacia saligna was spread over the area. The other seeds will establish where the tall wheatgrass fails on very saline land.

Tim says that weed control is very important. It begins the year before planting with spray topping. At the break of the season the area is ripped up, sprayed and seeded. The following spring a Loxon topper is used to cut the seed heads off ryegrass, allowing more light to penetrate to the establishing tall wheatgrass.

Tall wheatgrass looks very similar to ryegrass when it is very young as the familiar tussock does not appear for 12 months. Tim says, "It is easy to look at a paddock the first summer after sowing and think that the wheatgrass has not germinated and want to graze it off, but it should not be grazed for 12 to 18 months and then only lightly".

Tall wheatgrass is most palatable in January when it has fresh green shoots and a moist seed head, and is fairly bulky. This does not tie in well with the overall program as sheep are usually on the stubbles in January. However, Tim generally grazes it off whenever the bulk is there.

Tim establishes 25 hectares every two years. As the area cannot be grazed for 18 months, he is only losing a small amount of potential grazing each year and the area is back in production within two years. Tree planting would have delayed grazing for at least another year.

Tim has planted tall wheatgrass anywhere where there is summer moisture including hillside seeps.

Sheep condition trials

During February to April 1995, Tess Casson from the Katanning office of Agriculture Western Australia, monitored the weight and condition of 68 South Suffolk ewes grazing 24 ha of Tim's salt land pasture.

Estimates of pasture composition taken prior to grazing showed that there was 2.5 t/ha of available pasture: tall wheatgrass (55 per cent), annual ryegrass (24 per cent), barley grass (10 per cent), wavy leaf saltbush (4 per cent) and small amounts of clover, capeweed and puccinellia.

During the 12 weeks of grazing, the stud ewes, which were in excellent condition when introduced to the paddock, remained in good condition (CS 4.5 to 4.0). There was a slight trend for ewes to lose weight gradually over the grazing period. The average liveweight in Week 1 was 77 kg, while in Week 12, sheep weighed an average of 72 kg.

Ryegrass and tall wheatgrass formed 80 to 100 percent of their diet. The pasture provided around 6000 sheep grazing days, allowing South Suffolk ewes to be grazed at 2.8 sheep/ha over summer. During this time the sheep were observed to remain in good condition without grain supplementation.

Tess, however, adds a note of caution. "Information from preliminary grazing experiments involving Merino wethers grazing tall wheatgrass or unimproved salt land pastures indicate that tall wheatgrass offered little improvement in liveweight or wool production to the unimproved pastures. It is important to remember that in this trial the sheep were not Merinos but South Suffolk ewes which were in excellent condition when the monitoring period began."

"Previous analysis of tall wheatgrass samples from saline and non-saline waterlogged areas indicates that the quality of this species increases as salinity decreases. Tall wheatgrass has a place in preventing further degradation of saline land and may be beneficial for animal production on non-saline waterlogged areas."

Pines for sawlogs

Tim planted Monterey pine (Pinus radiata) on small pockets of deep sands. He did not consider the areas big enough for grazing tagasaste, and preferred to plant pines for sawlogs.

Tree lines were ripped on the contour by a bulldozer to improve water harvesting and the rip lines were sprayed with Vorox. The paddock was initially cropped to wheat. Lupins and the pines were then planted into the lupin stubble. The paddock was again cropped to wheat to provide wind protection for the young pine seedlings.

Pruning

Tim pruned his first pine plantation when it was four years old. Pruning is needed to produce high value sawlogs with small knots. With pines, a general rule of thumb is to prune no higher than where the stem diameter is 10 cm, or no more than 60 per cent of the tree height. The tree size determines which rule applies.

Take care not to damage the collar of 'wrinkly wood' around the base of the pruned branch, as it produces new wood cells which form over the pruned area to prevent fungal attack.

Tim expects to prune the trees again at year eight when he will also thin out the poorer quality stems. The initial pruning of 2,500 trees took ten days over winter.

Thinning

Moisture is likely to be the limiting factor for the production of sawlogs on Tim's deep sands. As the trees grow, they deplete soil moisture reserves, and growth slows as the trees compete for limited moisture during summer. Thinning the poorer trees will leave more moisture and give faster growth for the best stems.

Culled trees of irregular shape and poor growth could provide a source of firewood. Thinnings at a later stage could be treated on farm, to provide fence posts. The aim is to leave 100 well-formed trees per hectare to grow into logs suitable for milling. Thinning also allows more light to promote grasses and provide a valuable stock shelter area.

Thinning should precede or coincide with pruning. Otherwise, the unpruned trees will out-compete the pruned trees, due to extra leaf area. Fertilising will also be necessary every five to ten years.

Remnant vegetation

Remnant vegetation on slopes is also being managed. Prior to fencing a remnant, dead wood is pushed into heaps and burnt along with the grass. Jams (Acacia acuminata) and sheoaks (Allocasuarina huegeliana) regenerate on the ash beds. Where possible the area is ripped and planted with seedlings.

Grass is prolific in the second year but levels usually drop after three or four years. If necessary, Roundup® is sprayed in very weedy sites.

Benefits obtained

Tall wheatgrass provides summer pasture that is readily used by Tim's South Suffolk flock. By drying out the soil profile in summer, water no longer ponds in the area over winter. This prevents fresh water recharging the saline groundwater system and contributing to its rise. Tim also has a solid base to drive on and no longer gets bogged.

Pine trees on the deep sands are cutting down wind erosion and preventing sand blasting of the surrounding crop. Two-year and four-year trees are using enough water to dry up soaks beneath them.

These benefits along with a windbreak program and the protection of remnants will help Tim achieve his ambition in farming. "I want to have a neat and tidy farm that is easy to manage. I want to minimise soil erosion. I want to be able to make a living and to pass the farm down to the next generation in the same or better condition. I guess you could call it farming with a conscience."

Figure 3. Four year old seedlings planted into an area of remnant bush.

Caution!

Perennial grasses appear to have potential in agriculture on valley flats with shallow watertables. However, these plants have become invasive weeds in other places. There is a strong concern that these plants will damage nature conservation values in remnants and reserves and may also affect other values.

Acknowledgments

Tim Heffernan can be contacted at 'Lomond Park', Post Office, Wickepin 6370.

This case study was developed with funding from the National Landcare Program project 'Revegetation strategies for Land Conservation Districts of the Western Australian wheatbelt'. The author would like to thank David Bicknell, Agriculture Western Australia, Narrogin, and Tess Casson, Great Southern Agricultural Research Institute, Katanning.