APPENDIX 3
Reflections on irrigation for sheep and wool production
in the 1960s on the Basalt Plains
By Jim Murphy

Production under irrigation

I joined the Irrigation Branch of the Department of Agriculture in 1953, stationed at the State Research Farm, Werribee. The Research Farm had 500 acres (200 hectares) of summer-irrigated pasture of white clover, perennial ryegrass and cocksfoot. This pasture was utilised predominantly for dairy production, but some of the experimental areas were grazed by Corriedale and Border Leicester/Merino sheep. I was responsible for the conduct of experiments on the fertilizer requirements and grazing management of irrigated pasture.

Thirty sheep per acre could be carried on 40-year-old irrigated pasture in October, November and December: twenty per acre through January, February and March; and ten per acre from April to the end of September with no supplementary feeding required. Annual yields of 190 lb (180 kg) of wool and 400 lb (86 kg) of liveweight gain per acre were achieved. At 1965 prices the gross value of this production was about $130 per acre.

Expansion of sheep numbers

The 1950s saw sheep numbers almost double in the western region of the Basalt Plains. Hamilton vied with Yass in New South Wales for the title of ‘Wool Capital of the World’. Expansion of the area of improved pasture replacing the less productive native pasture, greater use of superphosphate and increased fodder conservation provided opportunities to increase the stocking rate of pastures. At the Pastoral Research Station at Hamilton, for instance, sheep numbers increased from 1000 to 3000 between 1959 and 1963 and hay reserves from 3000 bales to 18 000 bales (Weekly Times, 30 April 2003, page 26).

Six DSEs per acre became a feasible stocking rate. The gross value of production at this stocking rate at 1965 prices was of the order of $60 per acre, compared with the irrigated pasture figure of $130 per acre. Eight DSEs per acre were achievable in good seasons but not sustainable without irrigation. Progressive graziers on the Basalt Plains considered the possible use of irrigation from on-farm storages of rainfall run-off to intensify and to provide greater security for their high stocking rate enterprises. The 1967 drought also provided a sobering experience for numerous high stockers.

Water harvesting

Low-cost systems of water supply and irrigation were essential for profitable irrigation for sheep and wool production. Fortunately, by the 1960s the principles of water harvesting had been established and publicised by Professor Hector Geddes of Sydney University. He sought out economical sites on the undulating country at Badgerys Creek near Sydney for the construction of gully dams to store run-off water. The dams needed to be sited high enough in the catchment to allow gravitational irrigation from them through a valved pipe through the embankment.

Economy of storage

The Storage/Excavation (SE) Ratio is a measure of the economy of a storage site. It is the ratio of volume of water stored to the volume of earth excavated for the bank. Geddes looked for sites with SE ratios of 5:1 to 6:1 for economic storage. At SE 6:1, water could be stored at a capital cost of $66 per acre foot.

The site requirements for a low-cost storage are:

1. a relatively flat gully gradient of 1 in 100 or flatter

2. a narrow neck in the gully for the embankment

3. sides of the storage basin widening out upstream of the embankment site.

The undulating topography of the Branxholme area was well suited for economic water storage and low-cost irrigation. Lake Cicely on Lanark, for instance, had an SE ratio of 12:1. The cost of water storage was $33 per acre foot in 1966. It was a remarkably low capital cost for its storage capacity of 60 acre feet.

Contour ditch irrigation

The Keyline System of land and soil sustainability was promulgated by P.A. Yeomans in the 1950s and developed on his two properties 65 kilometres west of Sydney. It had significant elements of water storage and low-cost irrigation.

Contour ditch irrigation, a slightly modified form of Keyline irrigation, provided a low cost method of irrigation for sloping country. Irrigation water is gravitated from a dam in an excavated channel or ditch on a slight gradient of about 1 in 1000. The channel is blocked at successive intervals causing water to overflow and irrigate the land below. The system can be imposed on an existing pasture, the only earthworks being the construction of the channel. This was often done with a rotary ditcher.

This system of irrigation is not new. It was introduced into Spain in the Middle Ages by the Moors. On several Spanish mission properties in San Antonio, Texas, crops were irrigated in the eighteenth century by this means. Water was diverted by gravity from a diversion dam on the San Antonio River into ‘acequias’, the Spanish term for channels. The system is still operational after three centuries. The Hanging Gardens of Babylon may well have been irrigated by similar means in the second century BC with water lifted from the Euphrates River by slave labour.

Irrigation management

Sheep and wool production is at the bottom of the list for returns from irrigation. Irrigated pasture utilised for city milk production, for example, at Badgerys Creek showed a gross return of $350 per acre with city milk at 50 cents per gallon. For irrigated pasture to be profitable for sheep and wool production its management had to be at a high level. The gross return was only $130 per acre.

The first requirement, once water storage and irrigation systems have been settled, is to introduce white clover and cocksfoot into the pasture to optimise its production in summer. Sod-seeding into an already improved pasture of sub clover and perennial ryegrass is practicable. If the area to be irrigated is still under native pasture it needs to be cultivated and properly sown down to an irrigation pasture mixture of white clover, cocksfoot and perennial ryegrass.

Irrigated pasture requires heavier dressings of fertilizers than dryland pasture. Some form of rotational grazing is desirable to prolong its productive life. Utilisation solely by grazing should be the aim. Cutting irrigated pasture for hay should be avoided. Regrowth after hay cutting is slow. Production of green feed may be reduced by as much as 35 per cent in the six weeks following hay cutting. Fodder conservation should be confined to the non-irrigated pastures on the property.

Mature sheep, two-tooth and older, fatten readily and their wool production is intensified when grazed for only 50 per cent of the time on irrigated pasture. Stocking rates of up to 25 per acre are possible through spring, summer and early autumn.

Irrigation provides the opportunity to have fat sheep available in autumn when store condition is the norm. It needs to be noted, however, that lambs do not fatten as readily on irrigated pasture as do mature sheep. Corriedale and Merino cross sheep are better suited to utilising irrigated pasture than are straight Merinos.

Irrigation also is not completely reliable. Dams did not fill in the 1967 and 1983 droughts. The dry years since 1998 have also restricted supplies of irrigation water.

A property needs to be close to full development before irrigation is introduced. Pasture improvement, fertilizer usage, grazing management and increased stocking rates yield better returns than irrigation. All of these aspects need to be intensified when irrigation is introduced. There is an increased labour component as well. Another aspect to be considered in the economic assessment of a proposed irrigation scheme is the loss of production from the area inundated by the dam.

Irrigation on Lanark

The Fentons toyed with the idea of irrigation even to the extent of contructing Lake Cicely, but did not proceed further. Was it an opportunity lost? Arguably yes, but there were sound enough reasons for their decision. It was a first-class irrigation site and 40 acres (16 hectares) could have been irrigated from the 60-acre-feet (74 000 cubic metres) storage.

However, John and Cicely were committed to raising a young family and to wresting a living, without hired help, from their 2000-acre (800-hectare) property. Irrigation would have required more intensive stocking, additional management commitments and a greater labour input. The cost of hired labour required would have greatly reduced the profit from irrigation. Restoration of Lanark’s natural environment and diversification into farm forestry also loomed large on the Fentons’ priorities.

Irrigation of woodlots was not a considered option for Lanark in the 1960s. In retrospect it would almost certainly have augmented the returns from farm forestry.

Lake Cicely has been a boon to Lanark in numerous ways even without irrigation. Indigenous planting around its perimeter and its combination of shallow and deep water are ideal for supporting a rich and varied wildlife. Stock water supply and fire protection are assured. The landscape quality of Lanark has been enhanced and its land value improved by the attractiveness of this body of water.

Present-day opportunities

The principles established for profitable irrigation for sheep and wool production are still basically valid. Prices of wool and meat are a far cry from what they were in the 1960s, but costs have also escalated.

The live sheep export trade to the Middle East has been a saviour for the sheep meat industry. It has given a boost to the returns from fattening sheep on irrigated pasture. The trade has expanded tremendously since its introduction in the 1960s. Originally confined to culled-for-age sheep, it has been a thriving market since the early 1970s for younger sheep in good condition, the type readily produced with irrigation. In the year 2000 live exports from Australia of 6 million sheep averaged $67 per head, a price undreamed of in the 1960s.

Storage of rainfall run-off on farms for irrigation is no longer the regulation-free procedure it was in the 1960s. A licence is now required for irrigation from a dam prior to its construction. A licence for construction of the dam may also be required. Restrictions may be placed on the size of the dam. In addition to licence fees there is also an annual charge of about $7 per megalitre.

Careful consideration of the pros and cons of intended irrigation schemes for sheep and wool production is still essential. The gross returns are greater than in the 1960s, but are eroded more by increased costs of all inputs especially fertilizer, labour and water charges.