Measurements on slivers and tops - Woolwise€¦ · Web viewFigure 19.2 Cross-sections of (a)...

19. Case Study B: Southern Western Australia

Kevin Bell

Learning objectivesAt the end of this topic you should understand: The reasons for land degradation in the south-west of WA The major problems confronting farming businesses Indicators to measure and monitor soil, pasture and farm attributes Remedial techniques offering a best bet at this stage to be put into practice

Key terms and conceptsSustainability, land management unit, soil hydrology, soil acidification, catchment planning, biosecurity, succession planning, monitoring and benchmarking.

Introduction to the topicThe southern aspect of Western Australia was largely cleared of perennial native vegetation, mostly forests, from early in the 1900s until 1980. At that time a generalised ban on clearing was implemented, after which any removal of native vegetation was strictly controlled under permit.

The changes in soil characteristics and soil hydrology associated with this change in vegetation have progressed to the extent that many of the farming systems and practices in common use are now considered unsustainable. The ability of land to permit plant growth has been severely compromised over wide areas of the state, and the profitability of agriculture considerably reduced. Not only farmland is affected, but also native vegetation and urban areas.

Many of the specific causes of problems are now well understood; much of past practice was perpetuated in ignorance. The current state of knowledge and awareness is such, however, that remediation is possible, and certainly continued farming will depend upon changes in many areas.

A case study for a farm in the ‘South Central’ zone is presented (see Appendix A for zone classifications). For examples of alternative sustainable farming systems in other zones, refer to Trevenen and Fosbery (1991) for the Eastern Wheatbelt and to Peek et al. (2002) for the Northern Sandplain in the Readings section.

19.1 Overview A farm historyTo place this topic in perspective, it is useful to reflect on the history of the property being considered here; it is very likely a similar history to many such areas of land in the south-west of WA.

The current owner’s great-grandfather acquired half the property around the turn of the century, in the early 1900s. At that stage there were about 100 ha cleared and pastured, with the remaining 600 ha an unfenced bush block. Much of this was heavily timbered with jarrah (Eucalyptus marginata), wandoo (E.wandoo) and marri (E calophylla). This reflected a large percentage of the district, the clearing being predominantly along the lower aspects of the undulating topography, very often river or creek flats. In these areas soils were generally deeper and of better fertility, an important consideration where chemical fertilisers were unavailable. The gentle slopes also made cultivation and harvest by horse-drawn equipment possible, and were close to house and sheds.

© UNE acting as the agent of the Australian Sheep CRC RSNR403//503 19 - 1

As time, labour and money permitted, surrounding areas of timber were cleared and pastured; a mixture of native grasses and some introduced annual ryegrass (Lolium sp.), along with the recently recognised legume subterranean clover (Trifolium subterraneum) from South Australia. Over time other grasses came to form part of the grassland community, introduced along with imported hay and grain. Cattle and Merino sheep were the livestock managed, with a small area of oats cultivated for grain and hay supplement.

In the 1950s the opportunity arose to acquire another farm block nearby, of similar area but higher in the catchment. It had been similarly managed, but was very run down. With government incentive, a large scale clearing programme was gathering momentum throughout the south-west, and was commenced on both properties. Local timber mills arose to manage the huge quantities of high quality virgin timber available.

Until the 1960s, pasture carrying capacity had been low – possibly 2 sheep/ha on the better land. During the 1930s, subterranean clover had been introduced from South Australia; it had persisted and certainly resulted in better quality spring and summer feed, but like the grasses was lowly productive. The value of phosphatic fertiliser was recognised, but expense and availability limited its widespread use. A government subsidy changed this, and superphosphate was liberally applied from then on, in recommended quantities. Pasture quality and quantity increased dramatically, stocking rates rising to 3 or 4 sheep to the acre (7-10/ha).

Trace element deficiencies became recognised as hindering plant establishment and growth, and also being responsible for animal health issues; they were remedied by the application of copper, zinc and molybdenum.

By 1980 about 80% of the total area managed had been cleared and pastured; there were some large blocks of remnant bush, either on land less suitable for clearing (for reasons of being any one of steep, rocky or poor soil, e.g. sandy, or because the area contained dense stands of poisonous plants, most notably York Road or prickly poison amongst the Gastrolobium spp.). Large individual trees were left scattered throughout most cleared pasture paddocks, both for shade and shelter, or because they were too big for the land-clearing equipment available at the time.

With the precipitous drop in wool prices in the 1990s, combined with dramatic improvement in crop production technologies (species, herbicides, insecticides, machinery etc.), the proportion of farm area cropped increased dramatically – from 100 to 400 ha. Opportunities for sustainable cropping rotations were aided by the availability and development of canola, which could commence a cropping phase into unmanipulated pasture.Over this time of progressive farm evolution, subtle changes (some subtle, some abrupt) had been taking place in soil and landscape. By and large these had not impacted upon the farm productivity to date, but the inexorability of the events, and more advanced changes in other, more susceptible landscapes, provided indisputable reason for concern.

Issues to confrontListed here are the main areas of change on the farming system under examination which are considered to impact upon current land and animal productivity. They are not necessarily in order of emergence or severity, but give a perspective of the issues to deal with. Some are interrelated, but are listed as they were not necessarily noticed simultaneously.

1) Waterlogging in low-lying areas2) Death of lone trees in the landscape3) Slow but progressive increase in topsoil pH4) Gully erosion5) Appearance and perpetuation of unproductive or damaging plant species6) Inability of subterranean clover to persist in some paddocks7) Rising groundwater tables in much of the landscape8) Seepage of highly saline water at isolated points on the landscape, and rising salinity in

some creeks

19 - 2 RSNR403/503 © UNE acting as the agent of the Australian Sheep CRC

9) A flat area at the junction of two creeks, which has lost most of the pasture cover and is overtly saline

10) Increasing salinity in some farm dams, to a degree where the large dam supplying water for the homestead is unusable for the garden

11) Loss of ground cover during mid summer in some areas of many grazed pasture paddocks, resulting in obvious soil loss with wind during summer-autumn and with precipitous rainfall events at the break of the season in some years

12) Biosecurity – the maintenance of a sheep flock free from major disease, in the face of unknown disease status of neighbouring flocks.

In spite of this seemingly daunting list of ‘problems’ very little impact has been noticed to date on actual productivity; in fact use of good farming practices has been associated with improvements in crop yields, pasture production and stock carrying capacity. However their progression would alert the manager to take action at this stage. Also, neighbours with less undulating landscapes and lower in the catchment profile have been seriously affected with loss of a significant proportion of the land under their management.

These issues will be dealt with in the following sections, combining them where the cause and solutions are associated. The solutions adopted are not necessarily the only ones, but they are proposed as:(a) economical, in that the average farm business can afford to fund solutions(b) current accepted industry practice, in a discipline where new knowledge and awareness is a feature.

19.2 Waterlogging and rising groundwater levelsThe removal of native forest vegetation has changed irrevocably the water balance between input through rainfall and use; annual pastures and crops cannot use rainfall over an annual period, with the consequence of recharge of groundwater tables (George et al. 1997). To compound this problem, ocean salt deposited in rain over thousands of years and stored in the soil profile is being mobilised by the rising water table and brought to the surface.A schematic representation of drainage issues in a typical south-western WA site is provided in Figure 19.1.

Figure 19.1 Generalised pathways for the transport of water and nutrients within catchments. Source: Reuter (1998).


The initially very productive flatter paddocks along creeks and rivers have been the most affected. Although not overtly saline, waterlogging is sufficient to modify pasture composition, and has been partially responsible for depletion of soil potassium levels. Clovers have not found this environment compatible with optimum growth, and these areas are now grass-dominant and less productive. Poorer palatability has compounded the problem with stock avoiding the area.

Remedial measures outlined in the following sections for waterlogged sites are also used for saline sites; the principles of alleviating water presence are common to both. Remedial and sustainable practices are dealt with below.

FencingTo allow management of the affected areas, fencing to land management type is essential. This will be a recurring recommendation over the whole farm. Historically, fencing was often done as land was cleared, and as a result multiple soil types and slopes were included in the one paddock. Land management in these circumstances could never be efficient or optimum.

A feature of the revised fencing layout is that much of it is along the contour, resulting in, quite often, long and narrow paddocks. This in fact does not prove an impediment to stock or crop management. The issue that may need accommodating is stock water, as such areas are not ideal for sinking a dam, which in the past may have been higher in the profile. It may be necessary to provide troughing in some cases – not a favoured practice as extra supervision would be needed, but nonetheless of long-term benefit.

A benefit of the revised fencing is that fertiliser application can now be much more specific. The potassium deficiency can be rectified without unnecessary application, and phosphate perhaps reduced (long-term application with less and less pasture growth has led to luxury phosphorus levels in the soil).

The other benefit is that such a paddock can be treated as a unit in a cropping rotation; in many years it may be unsuitable to crop.

Fencing of the whole farm to land management units (LMUs) is a key aspect of current and future profitable and sustainable practice. This refers to including similar soil types in paddocks and fencing on contours as much as possible. Rivers and creeks are fenced off to be managed as water movement channels, the exclusion of stock being associated with regrowth of grasses, shrubs and trees to control water flow.

DrainageWith the paddock fenced along the contour, efficient drainage is usually possible to restrain water from reaching and accumulating on the flat land. The water is diverted more directly into the creek system which is fenced to be managed for water flow. Depending on slope, a number of such drains may be sited between the top of slopes and the creek system. Some of this water may be divertible into existing farm dams in cases where catchment is limiting and where the dam site is suitably placed; however this must be carefully planned as excessive flow into dams may constitute a potential erosion hazard in its own right. Unless productive use can be made of water stored on farm, the construction of extra dams to accommodate all water is not a cost effective strategy in the short to medium term. In addition there are not insignificant environmental issues associated with stored water use, particularly where dam sites are not ideal (an example is localised salinity and waterlogging).

It has been demonstrated that excess water in duplex soils is effectively removed by drains, and that this can be cost-effective (McFarlane and Cox 1992). In Western Australia, surface drains are preferred to subsurface drains. Although production is lost from the 8 to 10% of the land which is occupied by the drains, the advantage of overland flow interception is significant. Compelling crop cultivation activities along the contour is a benefit which cannot be ignored.


Figure 19.2 Cross-sections of (a) reverse, (b) conventional bank seepage interceptor drains and (c) a WISALTS interceptor bank. Source: McFarlane and Cox (1990).

One case study (Bathgate and Evans 1990) showed that an increase in stocking rate of only 0.4 DSE/ha was needed for interceptor drains to be profitable. This was less than a 4% increase in production, and was very likely to be easily achieved in many situations, and would be further increased by the increased yields of subsequent crops. This analysis was done using a financial spreadsheet program called DRAINS, a useful tool for farmers and advisers (Salerian and McFarlane 1987).

Promotion of optimum plant growthThe greater the growth rate and biomass of plants, whether pasture or crop, the greater the usage of water. Although annual plants cannot match perennials in annual water use, they can transpire a surprisingly significant volume of water over the whole growing season. Of course perennials are superior in this regard. Best practice in plant density, species chosen and fertiliser application is considered crucial. Not surprisingly it is beneficial for farm profit also!

19.3 Saline land rehabilitationThe overt presence of salinity of a magnitude to preclude the growth of all but the most tolerant vegetation is an obvious cause for concern. The undulating nature of the topography tends to reduce the actual area affected, in that it is mainly the lower, flatter areas which are most severely debilitated. Not much further inland, in the eastern wheatbelt regions, the much flatter topography has resulted in large areas being devastated. Up to 30% of the area of some properties is unable to be utilised and public and private road maintenance has become an issue.


The saline seepage in an isolated area of one paddock has been traced to a subsurface dolorite dike in the underlying rock. The saline watercourse has been forced to the surface and discharged down the slope. Although not much land is lost in this instance, it is a sign of impending subsurface problems. Repair of this individual scar is unlikely to be cost effective, but implemented from an aesthetic aspect. It involves excavation to expose the rockform, destruction of enough to allow water flow, and diversion to the creek system. This can be by deep surface drainage or subsurface drainage, the latter being more expensive but aesthetically more pleasing. Land is also not lost to production. (See Figure 19.3)

Saline land and creek flows are a result of the generalised rise in saline groundwater tables and although some local remediation is possible the underlying causes will need treating. However local remediation has proved quite successful elsewhere and is implemented here.

DrainageAs is common to most problems of this nature, preventing as much water as possible from reaching the flat saline areas is a first step. Contour drains as described above will most likely be used. Also, a ’W’ drain through the middle of the area will remove more water. Drainage principles have been discussed.

Planting salt-tolerant speciesTesting of soil and water has indicated that a number of species could prosper in the environment revealed. A mixture of perennials and annuals is commonly utilised effectively. The mixture here is tall wheat grass (Thinopyrum ponyicum), a perennial, and Balansa clover (Trifolium michelianum), an annual legume. These are ideal companions in that they have similar grazing requirements and can persist in the salinity levels present.

Both can tolerate soils with pH (Ca) > 4.5. Balansa clover can tolerate moderate salinity (up to 180 mS/m) while tall wheat grass can tolerate higher levels. Tests are carried out at the end of summer, before attempted establishment.

There are good guidelines for establishing and managing such a pasture (see Robinson 2000). By achieving good establishment it can be grazed in the summer of the first year after the Balansa has finished setting seed. The tall wheat grass is most palatable soon after.

Figure 19.3. Example of deep drainage involving rock fracture and dislocation. Source: Photo taken by K. Bell.


Before drainage – bare saline land and discharge of deep saline groundwater forced to surface. Source: Kevin Bell (2006).

After fracture of rock and drainage – restoration of soil to support pasture

Modelling has demonstrated that revegetating such moderately saline land with perennials should lift farm profit by 5%.

An economic benefit from this pasture is the provision of feed in late autumn at a time when the rest of the farm is depleted of pasture. It is also of great value to defer the grazing of conventional pastures after the autumn break. In some situations it can provide shelter for sheep off-shears in times of weather alerts, the tall wheat grass component being allowed to grow to 30 cm or more for a moderated microclimate.

Limiting recharge of groundwaterA farm catchment survey had indicated that a sandy slope above the affected area was serving as a very significant source of water for the flats below. Not supporting much pasture itself, it has long been an area limiting the productivity of the farm. Return on fertiliser applied was scant, and the loose top quickly bared off in the summer to constitute an erosion hazard.

A very acceptable solution for this was to plant maritime pine trees (Pinus pinaster) over the area. Now in the third year since planting, there was already a demonstrated lowering of the watertable below, and it was taking longer in winter for the flats to become seriously water and salt-affected. The trees would be thinned when indicated, and a good return from timber yields was expected. Initial thinnings would supply posts for the rapidly expanding vineyards in the south-west.

Perennial pastures on recharge areas provide the same benefit. In other areas lucerne is demonstrating excellent ability to survive and significantly lower watertables, as well as providing very high quality livestock feed at times of the season when the annual pastures and stubbles have been depleted. The development of winter-active cultivars has accelerated the benefits of this plant in the cool Mediterranean region, and extended the range of potential planting sites.

19.4 Soil aciditySoils on our case study farm are typically of the order of 4.5 to 5.5 in pH (Ca); isolated areas of paddocks may be as low as 4.2. The lowest of these levels have not generally been an impediment to the growth of subterranean clover-based pastures, but identified as an issue for canola crops. For this reason some paddocks have had lime applied at recommended rates of 2 t/ha. By applying this at the cropping phase it is incorporated into the topsoil and has had a relatively rapid effect, typically increasing soil pH by 0.5 to 0.8 units. Lime of varying quality is obtained from sites on the south and west coast, and strict product specification enables evaluation of its neutralising ability.


Soil acidification is a natural process, however the rate has accelerated under intensive farming systems: essentially the more produce removed from land the greater the rate of acidification. The pH (Ca) of local soils in the natural state was (and still is where the land is uncleared and stock excluded) of the order of 6.0 to 6.5. In the early, less productive years of agriculture there was only a very small rate of change in acidity. Only in recent years has there been any cause for concern on the case study farm, although it has been under improved pasture and crop for nearly 100 years.

The application of lime, in terms of amount and timing, is a subject of some economic significance. Timing is not as imperative as, for example, the application of phosphate fertilisers, where immediate response is the case and a response curve (within limits) does exist. With soil acidity approaching a level of response, it is not profitable to apply lime years before it is to exert an effect – return on investment is negative. There is a strong case at the moment to invest in lime in years of high farm profit, only on paddocks likely to be responsive in the very near future.

There is a case to apply lime to pasture paddocks never likely to be cropped with a 5 year lead time to allow for slow movement through the soil profile, as there is not the benefit of incorporation. A comprehensive summary of soil acidity and liming for Western Australian conditions is provided by the publication Soil Acidity - A Reference Manual (Leonard 1996).

19.5 Catchment planning Recognising that landscapes and water catchments extend beyond farm boundaries and comprise many independently managed farm units, it is imperative that sustainable farming of a single farm enterprise must encompass cooperation across boundaries.

Obvious areas for consideration are drainage, tree-planting, watercourse management and stock movements. The majority of farming districts in Western Australia have active and well facilitated catchment planning groups, and cooperation and planning within these is an ongoing aspect of sustainable farming. All the activities so far discussed would be carried out with neighbourhood catchment considerations in mind.

19.6 Soil erosionSoil erosion has been insidious on the case farm. Nonetheless it is acknowledged to be a most definite threat to productivity and sustainability, as most loss is valuable topsoil.

Losses relate to a number of situations:

Areas of paddocks becoming devoid of pasture ground cover as summer and autumn progress, as a result of continual removal by grazing sheep. Stubbles (crop residues) can be similarly affected. The loss is compounded by treading and microbial degradation, accelerating as humidity increases in late February. The farmer is encouraged to leave sheep in the paddocks in this state because the bare area is a minority of the paddock, and feed resources are diminishing. With the loss of cover the soil is loosening and particularly in the evening a pall of dust is seen to accompany a mob of sheep as they traverse the affected areas. The risk is twofold: wind and water erosion, both becoming more likely as the autumn progresses

Cultivation of land for cropping is followed by heavy rainfall events, such that the loose soil is transported downslope

Cultivation of firebreaks down a slope. The loose soil is particularly vulnerable to water erosion, and deep gully erosion can result.


Prevention of soil erosionMaintenance of ground cover in practical circumstances is the recognised way of minimising the chances of erosion in this case.

Monitoring pasture or stubble by recording feed on offer (FOO) is reliable, in that stock can be removed before critical levels are reached. To overcome the problem of uneven pasture cover and greatly varying degradation rates within paddocks, fencing to LMUs will help. For example, maintaining 50% stubble cover is recommended as a safe amount to largely prevent serious wind or water erosion in WA stubble paddocks (Leonard 1993). Anchored stubble is more effective than loose straw at minimising wind erosion. The stubble should contain at least one third anchored material.

19.7 Farm biosecurityAs a component of profitable farming involving both livestock and crop enterprises, freedom from profit-limiting diseases is a major consideration. A number of threats exist in Western Australia for sheep enterprises, and if managed properly they can be eradicated from a flock and a farm. This frees up time and money that would otherwise be spent on prevention and control, as well as allowing the sheep to exist without a production-limiting disease.

Maintenance of farm biosecurity As a first step, secure boundary fencing is a prerequisite for biosecurity, preventing the

movement of sheep into or from neighbouring properties where disease status may be unknown

The custom of moving sheep along roads is discontinued, as escape into neighbouring properties is hard to prevent; also, recent movement of other flocks may be a hazard for disease transmission

The introduction of any sheep other than new rams is avoided; in fact there is a case for maintaining a totally exclusive flock by introducing new genetic material only by semen, using artificial breeding technology. In this case a breeding nucleus is necessary, and skilled breeding procedures followed

Vehicle movement onto the farm is controlled; weed seeds as well as some sheep diseases can be transferred this way.

The issues relating to sheep in WA include:

FootrotThis condition, although not as widespread as in eastern Australia, is still present. An eradication program has reduced prevalence to about 50 properties (Higgs 2005) a number which is slowly reducing. The costs of eradicating it are considerable, and it is to be avoided.

LiceAt any one time it can be expected that one quarter to one third of properties in the south-west of WA will have lice, with new infestations arising from a variety of reasons. If present, considerable economic loss is sustained, and eradication, especially if every year, is expensive.

OJD (Ovine Johne's disease)WA was thought to be free of this condition, but it is clearly quite widespread, even if of low prevalence; the State is now considered to be of the same status as Victoria. Management through vaccination is successful, but it is a cost to be avoided if at all possible.

Anthelmintic-resistant wormsNow recognised as a very likely introduction to farms with foreign sheep, parasites resistant to all the currently available drenches are widespread in WA. For the ‘woolbelt’ where most sheep are run, parasites constitute an ever-present economic, productivity, health and welfare threat. Although considerable progress has been made in breeding worm resistant Merino sheep, effective anthelmintics are still an essential part of ongoing management.


As well as avoiding the introduction of worms of unknown status, it is important to minimise the use of drenches on farm and to use only those of maximum efficacy. To enable this, regular monitoring of farm worm resistance status using a faecal egg count reduction test (FECRT) is important.

19.8 Cropping issuesBecause most farming systems in Western Australia include rotations of pasture and crop, activities to do with the cropping phase must be modified if they conflict with overall farm business sustainability practice. These will not be covered in detail here, but key issues are:

Tillage practice. Minimum tillage technology is now well established. Reduced tillage and direct drilling of seed lead to improved soil structure, reduced erosion, compacting and crusting and to preservation of soil organic matter and microflora

Use of break crops to break plant disease cycles, rather than cultivation. Canola is a prime example, providing a break crop to be followed by a cereal

Stubble retention, for as long as possible in the autumn. This helps to conserve water and prevents soil erosion. Stubble management may include reduction in the amount before sowing if stubble-borne diseases and toxins are considerations

Plan crop rotations, including pasture phases, carefully to maximise growth at all phases. Optimum plant growth is associated with maximum possible water usage.

For a little more detail, see “Research for profitable and sustainable cropping” (Anon. Undated) in the Readings section.

19.9 Enterprise scale Looking to the future, the farm owners recognise that farm margins will continue to be affected by adverse terms of trade for all commodities. Although adopting best practice and having achieved good returns, the farm area managed (1500 ha) is not large by district standards, and more could be managed on a larger scale more efficiently. Spreading labour and other overheads would be a recognised way of achieving greater margins. With net wealth generation over time, the family is in a position to make decisions regarding investment in land for farming or in off-farm areas. After all, the farm is an asset which can now be used as security to borrow for a variety of business ventures.

In summary, future sustainability involves considerations of whole business scale, which may or may not include expanding the area of land farmed. If the family business partners desire to expand the farming enterprise, there are considerations of diversification (in enterprise and in climatic region) and family member skills and preferences. These are to be discussed in succession planning, an ongoing aspect.

19.10 Succession planningSuccession planning is the business of putting in place procedures to plan for family long-term security. This is a very important part of sustainable farming for our farm, as experience has demonstrated time and time again that poor planning can undo many great initiatives. It is more necessary to plan in this area now than in the past, because of:

lower commodity prices/higher costs (lower margins) farm land values lower by comparison with urban property new taxes and laws changing personal expectations by both parents and children age pension unlikely to be available to the parents on retiring.


The current owners/managers of our case farm are relatively young, a married couple in their early 40s. The three children (two girls and a boy) are under 10. Although there are no apparently urgent issues, a family meeting is organised, involving the couple in question, his parents (now living in town, but frequently visiting the farm and having contact with the family), and the male farmer’s brother (an engineer interstate). This is a venue to explore all personal feelings and expectations with regard to the on-going management of the farm and its finances. The brother is involved because of future inheritance issues, and ongoing communication precludes the escalation of ill feeling and misconceptions, so often the cause of family disruption. Such a meeting is convened at least once a year – not at Christmas, but at a dedicated time at which priority can be given to the subject.

19.11 Techniques and resources to monitor sustainability

Many opportunities exist to measure and monitor economic, business, soil and livestock health and performance for farming enterprises. Listed in Table 19.1 are the main attributes which might be measured on a farm in south-west WA, and the tools which might be used, with a comment on their applicability. A practical guide to monitoring practice for WA conditions can be found in a manual compiled by Hunt and Gilkes (1992).

Table 19.1 Attributes of a farming business that may be measured and monitored and the tools available to assist in doing so. Source: Kevin Bell (2006).

Attribute Comment

Pasture growth rate (PGR)

http://www.pasturesfromspace.csiro.au/Colour-coded maps display PGRs for each shire in south-western Australia. Free.

Feed on offer (FOO) Personal estimation by experienced eye has been demonstrated to be highly accurate and repeatable.Satellite–based FOO and PGR are available for individual farm paddocks via a commercial service. Cost about $500/year.

Plant mineral status Plant tissue testing laboratories provide commercial service.

Soil health and mineral status

Soil testing laboratories. Major elements, pH, organic matter routinely tested, trace elements on request. Widely used and reliable. Tests also available for soil morphology and physical condition.

Potential for salinity Shallow bores (2-6 m). Give advance warning of salinity. Monitor at least twice a year.Deep bores (piezometers) show how much pressure groundwater is under. Over time show effect of continuing recharge.

Economic and physical

performance

Benchmarking of farm performance with local enterprises. Can give warning of performance slippage, and motivate investigation. Accepted benchmarks are locally derived for crop and livestock production, and for enterprise financial strength.

Sheep genetic merit Ewe and wether trials. Local trials best, managed to robust standards for accurate evaluation.

Anthelmintic effectiveness

FECRT. Indicates sustainability of worm control program. Should be done every 3 years.

Sheep worm burden status, pasture contamination

Monitoring of sheep flock worm egg count (WEC) is an integral, on-going aspect of worm management. This can be done on farm, or a commercial service used.


Readings The following readings are available on CD

1. Anonymous Undated, Research for profitable and sustainable cropping systems. CSIRO Land and water care program publication.

2. Peek, C., Rogers, D. and Stockdale, C. 2002, Future farming systems for the medium rainfall northern sandplain. Miscellaneous Publication No.13/2002, Department of Agriculture, WA.

3. Trevenen, S.J. and Fosbery, G.G. 1991, ‘Farming with a whole farm system approach in the eastern wheatbelt of Western Australia’, in Dryland Farming. A Systems Approach, (Eds. V. Squires and P. Tow), Sydney University Press, pp. 298-301.

ActivitiesAvailable on WebCT

Multi-Choice QuestionsSubmit answers via WebCT

Useful Web LinksAvailable on WebCT

Assignment QuestionsChoose ONE question from ONE of the

topics as your assignment. Short answer questions appear on WebCT. Submit your answer via WebCT

SummarySummary Slides are available on CDThe issues associated with farming sustainability in the south-west of Western Australia are discussed, using as an example a typical farming business, in one region. Variations to farming enterprise mix and intensity exist due to climate and soil characteristics; examples of issues confronting other regions are appended. The history of agriculture in the region is outlined, with the fundamental altering of the natural forest vegetation being ultimately responsible for current issues in sustainability. The factors which have become apparent over recent decades as compromising agricultural system stability are: waterlogging in low-lying areas rising groundwater tables in much of the landscape damaging salinity levels in soils within plant root zones slow but progressive rise in topsoil acidity soil erosion linked to extreme weather events (rain, wind) changing economic relativities, such that scale of enterprise may need to increase development of a range of plant and animal diseases, and pathogen resistance to chemicals,

making farm biosecurity of increased significance

Treatment and prevention of the issues is by a range of measures. In the case of groundwater table management, all the answers are not currently apparent, but best practice would include a combination of the following:

fencing to a plan accommodating LMUs drainage (surface) promoting optimum plant growth – pastures and crops sowing perennial pastures strategic tree planting to limit recharge of deep groundwater


Soil acidity is managed by strategic application of agricultural lime of adequate neutralising value, readily available locally. Best farming and business practice is outlined to address the remaining issues likely to impact upon physical and financial sustainability of the enterprise.

ReferencesAnonymous Undated, Research for profitable and sustain able cropping systems, CSIRO Land and

Water care program publication.Bathgate, A. and Evans, I. 1990, ‘Economics of interceptor drains: a case study’, Journal of

Agriculture (Western Australia), vol. 31, pp. 78-79.George, R., McFarlane, D. and Nulsen, R. 1997, ‘Salinity threatens the viability of agriculture and

ecosystems’, Western Australia. Hydrogeology Journal, vol. 5, pp. 6-21.Higgs, T. 2005, ‘More good news on the fight against footrot’, Agricultural Memo, Albany District

Office, Department of Agriculture, WA, vol.17, pp.16. Hunt, N. and Gilkes, R. 1992, Farm Monitoring Handbook, University of Western Australia.Leonard, L. 1993, Managing for stubble retention, Bulletin 4271, Department of Agriculture, WA. Leonard, L. 1996, Soil Acidity. A Reference Manual. Miscellaneous Publication No. 1/96,

Department of Agriculture, WA.McFarlane, D.J. and Cox, J.W. 1990, ‘Seepage interceptor drains for reducing waterlogging and

salinity’, Journal of Agriculture (Western Australia), vol. 31, pp. 74-77.McFarlane, D.J. and Cox, J.W. 1992, ‘Management of excess water in duplex soils’, Australian

Journal of Experimental Agriculture, vol. 32, pp. 857-864.Moore, G. 1998, Soilguide. A handbook for understanding and managing agricultural soils, Bulletin

No. 4343, Department of Agriculture, WA.Peek, C., Rogers, D. and Stockdale, C. 2002, Future farming systems for the medium rainfall

northern sandplain, Miscellaneous Publication No.13/2002, Department of Agriculture, WA.Reuter, D.J. 1998, ‘Developing indicators for monitoring catchment health: the challenges’,

Australian Journal of Experimental Agriculture, vol. 38, pp. 637-648.Robinson, S. 2000, Tall wheat grass and balansa clover: a beneficial partnership for waterlogged,

mildly saline soils, Agwest Farmnote 44/2000, Department of Agriculture, WA. Salerian, J.S. and McFarlane, D.J. 1987, DRAINS: a method of financially assessing drains used to

mitigate waterlogging in south-western Australia, Technical Report No. 54, Division of Resource Management, Department of Agriculture, WA.

Trevenen, S.J. and Fosbery, G.G. 1991, ‘Farming with a whole farm system approach in the eastern wheatbelt of Western Australia’, in Dryland Farming. A Systems Approach. (eds. V. Squires and P. Tow), Sydney University Press, pp. 298-301.

Glossary of termsAs a guide to understanding and interpreting soil physical and chemical data, refer to Chapter 10 in Moore (1998).DSE Dry sheep equivalent, a unit of livestock carrying capacityFECRT Faecal egg count reduction test, used to measure the effectiveness

of sheep anthelmintics. Drench effectiveness is assessed as percent reduction; drenches used should always be at least 95% effective

LMU Land management unit. An area of land of similar soil type, soil hydrology and topography, such that best-practice management can be similar over most of the area

mS/m Millisiemens per metre. Unit of electrical conductivity used as a measure of salinity

pH(Ca) Measure of acidity. Most commonly used now in a calcium chloride solution; sometimes the measure is made in a water solution, in which case the figure is 0.7 to 1.0 units higher


EMS Environmental management strategy. This is a management process which enables agricultural producers to rigorously identify actual or potential environmental problems, adopt remediation and assess the effectiveness of the action

WEC Worm egg count. For on-going management of sheep parasite burdens and pasture infective larval levels

PGR Plant growth rateFOO Feed on offer. A guide to stock daily intake of green pasture


Measurements on slivers and tops - Woolwise€¦ · Web viewFigure 19.2 Cross-sections of (a)...

Documents

Transcript of Measurements on slivers and tops - Woolwise€¦ · Web viewFigure 19.2 Cross-sections of (a)...