Earth Sciences Commons^™

Focus Catchments : A New Approach To Salinity Research : National Dryland Salinity Program, Steve Porritt

Journal of the Department of Agriculture, Western Australia, Series 4

Dry/and salinity is a major threat to the resource base of many rural industries around Australia. More than 1.8 million hectares of once productive land are affected by salinity, with a further 1.6 million hectares at risk in the next 15 to 25 years in Western Australia alone. Much of the past Commonwealth and State expenditure on salinity programs and activities has been poorly targeted and coordinated. In view of this, a national dry/and salinity program that supports specific State salinity management programs has been established jointly between the Commonwealth and State government agencies.

The Upper Kent River Catchment is …

Salinity Action Plan, Department Of Agriculture And Food, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

In November, the Premier of Western Australia, Richard Court, released his governments strategy to tackle one of the State's most serious environmental problems - salinity. This article provides a summary of the action plan, full details are available in a two volum set 'Salinity - a situation statement for Western Australia' and 'Western australian salinity action plan'.

Copies of the reports are available from Publication Section, Agriculture Western Australia, 3 Baron-Hay Court, South Perth 6151. Phone (09) 368 3729

No-Tillage Sowing Decreases Water Erosion On Loamy Soils And Increases Earthworm Activity, Kevin Bligh

Journal of the Department of Agriculture, Western Australia, Series 4

No-tillage sowing places seed and fertiliser in the soil without loosening all of the topsoil. Soil is cultivated only in the sown rows, leaving the inter-row areas largely undisturbed.

No-tillage sowing reduces both wind and water erosion. Soil structure is generally improved, and pasture regeneration is increased because seed is not buried too deeply for re-establishment.

Two long-term trials were establis_hed on loamy soils to determine effects of tillage and cropping on runoff and soil loss.

Results Of Stubble Research In Western Australia, Michael Perry, Ron Jarvis, Mel Mason, David Tennant

Journal of the Department of Agriculture, Western Australia, Series 4

Few farmers would question the desirability of retaining stubbles, both for control of erosion by wind and water, and to return organic matter to the soil. While the present debate is focused on the short term management of stubbles, longer term effects also need to be considered.

The Department of Agriculture has several long-running trials intended to measure long term effects.

How To Reduce Spending On Land Conservation, Tim Negus

Journal of the Department of Agriculture, Western Australia, Series 4

Heavy spending on capital works for land conseroation is usually out of the question in the present financial climate, but the recession does not mean that landcare must be abandoned. There are many aspects of landcare that involve little or no extra cost. Soil conseroationist Tim Negus discusses them in this article.

Unique Co-Operative Landcare Venture In The Avon Catchment, Darrel Brewin, John Collett

Journal of the Department of Agriculture, Western Australia, Series 4

The Avon catchment is bustling with landcare activity generated by a unique co-operative venture between farmers, the Department of Agriculture, the National Soil Conservation Program and Alcoa of Australia Ltd. The Avon Catchment Landcare Program was initiated by the Department of Agriculture and Alcoa, in support of the national Decade ofLandcare. The program provides financial, human and technical resources to undertake catchment and farm planning and demonstrations of rehabilitation techniques that tackle soil and water degradation problems. We know that without specially planned landcare programs and substantial changes in land management, land degradation will continue and further losses of agricultural …

Shallow Drains For Reducing Waterlogging And Salinity On Clay Flats, Don Mcfarlane, Tim Negus, Arjen Ryder

Journal of the Department of Agriculture, Western Australia, Series 4

Flooding, waterlogging and salinity are problems which commonly occur together on the broad valleys of the wheatbelt. Drainage lines often become poorly defined once they reach the valleys and flood waters spread out, causing inundation and waterlogging. This excess water needs to be controlled because it contributes to salinity

Seepage Interceptor Drains For Reducing Waterlogging And Salinity, Don Mcfarlane, Jim Cox

Journal of the Department of Agriculture, Western Australia, Series 4

Shallow interceptor drains can reduce waterlogging on sloping sites. Such drains will more than pay for themselves from the increased crop yield. Recent work has shown that these drains also decrease salinity so that they are cost-effective in the long as well as the short term.

Level Banks Used To Decrease Waterlogging Can Increase Salinity, Don Mcfarlane, Richard Engel, Arjen Ryder, Maurice Eales

Journal of the Department of Agriculture, Western Australia, Series 4

Some farmers have used level W1SALTS banks to control surface zvaters above areas affected by ivaterlogging and salinity. Because the amount of waterlogging has been reduced, crop yields have increased downslope of some banks. However, the banks divert fresh surface water into deeper salty groundwater and, in the long term, worsen salinity. This article details an investigation of the effect of level WIS ALTS banks on saline groundwaters and discusses alternative methods of preventing the waterlogging of saline areas.

Waterlogging : One Reason Why Our Crops And Pastures Are Not Achieving Maximum Yields, Department Of Agriculture And Food, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

Water, either its lack"or excess, is the main factor affecting the yield of crops and pastures in Western Australia.

Gypsum Use In The Wheatbelt, M R. Howell

Journal of the Department of Agriculture, Western Australia, Series 4

One of the limitations to crop productivity in the wheatbelt is the poor structure of heavy textured soils. Many years of clearing and cultivation have caused the loss of soil organic matter and breakdown of soil aggregates - particles of sand, silt and clay - in the surface layers. This has led to the development of unstable soils with poor physical properties.

Although loss of soil structure is a serious problem, it can be reversed by altering the tillage practices that caused the problem. This improvement in soil structure and return to productivity can be a slow process. However gypsum …

Water Quality For Irrigation, P R. George

Journal of the Department of Agriculture, Western Australia, Series 4

Although irrigation and salinity problems are frequently inseperable, there is a range of management methods that can be used to handle marginal quality water. Freuently these methods are simple, but require careful planning.

The wide range in tolerance of crops to salinity can be exploiter to ensure that appropriate crops are selected for the water available.

Because crops vary in their sensitivity to salt uptake in the leaves or the roots, watering methods can be changed to avoid problems. For profitable production enough water should be applied to ensure adequate water is available for plant growth as well as to …

Salinity Control In Northern China, G A. Robertson

Journal of the Department of Agriculture, Western Australia, Series 4

China has vast areas of saline land, perhaps as much as six million hectares. Some of this saline land is a result of marine influence in coastal areas and some is the resultof soil formation in areas with saline geological deposits and inadequate rainfall to leach out the salts at that time.

However, most saline soils in China are as a result of secondary salinisation processess induced by a hydrological imbalance resulting from over-clearing of the land or irrigation. This imbalance has produced rising watertables bringing the salt closer to the soil surface.

In this article, G..A. Robertson, Commissioner …

Water Supplies : Dams And Roaded Catchments, W J. Burdass, T. R. Negus, A. L. Prout, I. A. F. Laing

Journal of the Department of Agriculture, Western Australia, Series 4

Western Australia's Upper and Lower Great Southern statistical areas include most of the broad-scale agricultural land south of a line from Perth to Hyden. Much of the area is well-developed and carries 13.4 million sheep, 203 00 cattle and 95 000 pigs, almost half the State's livestock.

There are few natural rivers and lakes to water livestock in summer and much of the bore water is salty. On-farm waterr conservation, therefore, consits mainly of excavated earth tanks (dams) which are filled by surface runoff or shallow seepage. In the drier areas and in the sandplain roaded catchments have neen built …

Dam Site Selection In The North-Eastern Wheatbelt, J L. Frith

Journal of the Department of Agriculture, Western Australia, Series 4

Western Australia's wheatbelt farm dams are dug three to eight metres deep and are generally sited in soils which either are inherently impermeable or can be made so during construction.

In the eastern and north-eastern wheatbelt, however, only a small proportion of the soils meets these criteria. Dam site selection in these areas therefore depends on a good knowledge ofwhich soils aresuitable and on our being able to locate them efficiently by using surface indications such as surface soil, natural vegetation or topographic features.

Improved Catchments For Farm Dams, I A F Laing

Journal of the Department of Agriculture, Western Australia, Series 4

The amounts and frequency of runoff from unimproved farmland catchments in Western Australia's cereal and sheep districts are notoriously variable and unreliable. As a result many farmers have constructed improved catchments to ensure better reliability of farm dams for livestock and homestead water supplies.

Improved catchments which are used extensively on these farms are all of the compacted or bare-earth type. These include roaded catchments, flat batter dams and, to a lesser extent, scraped catchments. This article mainly discusses roaded catchments, the most common of the improved catchment types on farms.

Sandplain Hardpan : A Different Dam Construction Material, A F. Mccrea

Journal of the Department of Agriculture, Western Australia, Series 4

Before 1980, the Department of Agriculture did not believe that suitable farm dam materials could be found in light land soils. However Beacon earthmoving contractor, V> J> Pavlinovich, has demonstrated that where suitable cemented subsoils or 'hardpan' existed, a succcessful dam site could be found.

This material should not be confused with compaction or traffic hardpans ehich are dense layers of soil found near the surface. Traffic hardpans result from compaction of soil materials with the passage of vehicles and farm machinery. Rather, the hardpan referred to here is a natural subsoil layer that has been cemented by silica and …

Chemical Sealing Of Earth Dams, R G. Pepper

Journal of the Department of Agriculture, Western Australia, Series 4

Leakage is not a major cause of failure of farm dams in the Western Australian wheatbelt, but it is a problem in some districts where it can limit stock carrying capacity. Leaking dams are especially common in the West midlands, the north-eastern wheatbelt and the 'jarrah-belt' which extends from Bindoon, southward to Manjimup and Mt Barker (see map and Table 1).

Some dams which leaked when first built have sealed themselves over the years. Others have been successfully sealed using sodium tripolyphosphate.

Northern Wheatbelt Water Supply Study, I A F Laing, R. M. Pridham

Journal of the Department of Agriculture, Western Australia, Series 4

Department of Agriculture surveys have shown that many farms in Western australia's northern wheatbelt have inadequate water supplies. More than 80 per cent of all farms in that area depend soley on groundwater for watering livestock, a much higher percentage than for most other farming areas. Because groundwater salinities have increased in recent years, concern is held for the long-term future of this recource.

In contrast to more southern agricultural areas, farm dams in the northern wheatbelt are relatively uncommon. Only 30 per cent of the existing dams in the northern wheatbelt constitute effective water supplies. More than half of …

Drought Proofing The Farm : Case Studies, J L. Frith

Journal of the Department of Agriculture, Western Australia, Series 4

For many years, Western Australia's north-eastern wheatbelthas suffered chronic shortages of water for stock and domestic use. The area's averageannual rainfall is generally low - less than 300 millimetres - and droughts in the 1970s caused futher problems. manydams in the area leak or have inadequate catchmentsand groundwater is scarce ormofmpoor quality.

In March 982, the Western Australian Government provided $100 000 for the Department of agriculture to demonstrate the potential of establishing permanent, drought-proof water supplies on farms in the north-eastern wheatbelt. The methods were to use exixting techniques to build dams and catchments. In a year of low …

Increasing Groundwater Salinity In The Northern Wheatbelt, R J. Mcgowan

Journal of the Department of Agriculture, Western Australia, Series 4

Every farmer in western Australia's northern wheatbelt will know of a groundwater supply, be it bore, well or soak. that has become increasingly saline. The groundwater may have become more saline over a period of 15 years or more, or have been noticed only recently. Inevitably, the bore will lie within an area cleared for agriculture. This increase in groundwater salinity may be associated with soil salinisation. Although researchers have some understanding of the processes causing salinisation of groundwater in the wheatbelt and the extent of the problem, little is known about the rates of salinisation and groundwater rise. A …

Underground Water Supplies In The Wheatbelt, T T. Bestow

Journal of the Department of Agriculture, Western Australia, Series 4

Underground water originates from rainfall. The size of the underground recource in any region is broadly related to the amount of rainfall. However, rainfall intensity and seasonal distribution are just as importent as the quality. A relatively small annual fall which consists of a series of heasvy showers or storms close together, may be a more effective source of recharge to underground water than a larger fall that is more evenly distributed over a longer period.

A large annual rainfall, however, is no guarantee that underground water supplies will be readily available. This is because soils and the underlying rocks …

Water Supplies On Wheatbelt Farms : A General Picture, I A F Laing

Journal of the Department of Agriculture, Western Australia, Series 4

In good rainfall years, farm dams provide water fo more than 50 per cent of the total stock in the wheatbelt.

Other sources include ground water supplies and the piped Comprehensive Water Scheme.

The March 1970 census included questions on farm water supplies including how farmers coped in the 1969-70 drought.

Farm Dams In The Wheatbelt, I A F Laing

Journal of the Department of Agriculture, Western Australia, Series 4

Of the estimated 76 000 farm dams in the wheatbelt, about 8 per cent either leak or are salt affected. The remaining 70 000 dams are capable of holding water for livestock use and can be regarded as sercicable dams.

A great many of the serviceable dams are unreliable water supplies due to the combined effects of lack of runoff from catchments, shallow depth of storage and small size of storage in relation to expected demand from livestock and evaporation loss.

Test Sites For Farm Dams, Department Of Agriculture, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

A short article outlining procedures for testing potential dam sites.

Design Standards For Farm Surface Water Supplies, J L. Frith

Journal of the Department of Agriculture, Western Australia, Series 4

Design is usually concerned with getting adequate return from limited recources. Farm dams which dry up represent dam failure. Less seriously, so too do dams which, although not drying out, never fill; they waste a recource.

Groundwater In The Wheatbelt, E P. O'Driscoll

Journal of the Department of Agriculture, Western Australia, Series 4

In general six factors affect the occurence of groundwater; rainfall, topography, rock type, rock structurs, vegetation, and local evaporation.

Variation in even one of these can affect the potential yield of a bore or well, the groundwater salinity, and even whether any groundwater occurs at all.

Sealing Farm Dams, I A F Laing, R. G. Pepper

Journal of the Department of Agriculture, Western Australia, Series 4

Research over the past 10 years has shown that it is technically possible to seal many leaking farm dams. In some situations a cheap chemical treatment is effective but in most cases it is cheaper to construct a replacement dam.

This article reviews the situation in western Australia and outlines some of the methods used for sealing dams.

Salt Encroachment : The 1974 Saltland Survey, C V. Malcolm, R. C. Stoneman

Journal of the Department of Agriculture, Western Australia, Series 4

It has long been recognised that the clearing of land for agriculture in the south western Australia is followed by the development of saline soils and streams.

In 1955 and again in 1962, in conjunction with the annual statistical returns, farmers in Western Australia were asked to supply estimates of salt-affected land on their properties.

In 1974 a further survey was conducted, in co-operation with the Australian Bureau of Statistics, using questions covering only the basic information. As the information is again available on a Shire basis a direct comparison can be made with the 1962 survey except for some …

Efficiency Of Sprinkler Irrigation Systems, T C. Calder

Journal of the Department of Agriculture, Western Australia, Series 4

Shallow-rooted vegetable crops growing on sandy soils in hot, often windy summer weather, pose a difficult watering problem for most Western Australian vegetable growers.

Irregularities in wetting patterns are common. Wind effects are seldom taken into account in system design. The increasing popularity of knocker-type sprinklers makes these considerations particularily important.