IRRIGATIONIRRIGATION

Agriculture is the dominant economic activity Agriculture is the dominant economic activity in the Murray-Darling Basin. Further, the in the Murray-Darling Basin. Further, the Basin is Australia's most important Basin is Australia's most important agricultural region, accounting for just over agricultural region, accounting for just over 41 per cent of the nation's gross value of 41 per cent of the nation's gross value of agricultural production. agricultural production.

Irrigation involves a variety of irrigation Irrigation involves a variety of irrigation methods and equipment. They can be methods and equipment. They can be

summarised as follows: summarised as follows:

flood,flood, some with laser land forming, especially for pastures and rice some with laser land forming, especially for pastures and rice production; production;

furrowsfurrows, the predominant method for horticultural and field crops, and, , the predominant method for horticultural and field crops, and, particularly in the older schemes, for vines and tree crops; particularly in the older schemes, for vines and tree crops;

sprinklers:sprinklers: various types of overhead sprinkler systems, depending on various types of overhead sprinkler systems, depending on the crops; particularly for tree crops and vines, but also include centre the crops; particularly for tree crops and vines, but also include centre pivot systems used for growing fodder crops, lucerne, vegetables, etc.; pivot systems used for growing fodder crops, lucerne, vegetables, etc.; systems can be fixed or portable, though the latter can involve systems can be fixed or portable, though the latter can involve considerable labour input; increasing use of under-tree and micro-considerable labour input; increasing use of under-tree and micro-sprinklers resulting in much greater water use efficiencies; sprinklers resulting in much greater water use efficiencies;

trickle/drip hoses:trickle/drip hoses: even more efficient, due to much more direct even more efficient, due to much more direct application of water; and application of water; and

sub-surface drip systemssub-surface drip systems. .

Example of Irrigation equipmentExample of Irrigation equipment

Figure 1 Major areas of irrigation and irrigated crops and pastures in the MDB

                                                                                                                                                                                    

Major irrigation Areas

Irrigated crops and pastures x 5,000 hectares

Irrigated crops and pastures x22 hectares.

SCALESCALE There are 14,743 farms with irrigated crops There are 14,743 farms with irrigated crops

and/or pastures, which is 28.5 per cent of and/or pastures, which is 28.5 per cent of the total number of farms in the Basin, and the total number of farms in the Basin, and 47.2 per cent of all Australian farms with 47.2 per cent of all Australian farms with irrigation. Not surprisingly, irrigation irrigation. Not surprisingly, irrigation dominates water use in the Basin - over 95 dominates water use in the Basin - over 95 per cent according to the latest study per cent according to the latest study (MDBMC 1995) - and in Australia - some 70 (MDBMC 1995) - and in Australia - some 70 per cent of all water used in Australia is per cent of all water used in Australia is used by irrigation in the MDB used by irrigation in the MDB

An historical overview An historical overview

The initial establishment of irrigation in the Murray-The initial establishment of irrigation in the Murray-Darling Basin can be seen as a response of Darling Basin can be seen as a response of settlers from the well watered lands of Europe to settlers from the well watered lands of Europe to the dry and unpredictable environment of the dry and unpredictable environment of Australia. In particular, it was a desire to overcome Australia. In particular, it was a desire to overcome the variability of the Australian climate; it was seen the variability of the Australian climate; it was seen as a means of providing protection from some of as a means of providing protection from some of its harsh features; it provided a form of security. It its harsh features; it provided a form of security. It was also regarded as an endeavour to make the was also regarded as an endeavour to make the 'deserts' green (Powell 1993).'deserts' green (Powell 1993).

ECONOMYECONOMY

The Basin has been termed Australia's The Basin has been termed Australia's agricultural heartland, its 'food basket', but it agricultural heartland, its 'food basket', but it is much more than that, as its agricultural is much more than that, as its agricultural output makes a major contribution to the output makes a major contribution to the national economy. Agriculture provides the national economy. Agriculture provides the raw materials for most of the MDB's raw materials for most of the MDB's manufacturing activity, as well as many manufacturing activity, as well as many processing companies beyond the Basin processing companies beyond the Basin

Budget stuffBudget stuff

For the Basin as a whole, the gross value of For the Basin as a whole, the gross value of agricultural production in 1991-92 was agricultural production in 1991-92 was estimated as $8,555,983,514, 41.04 per estimated as $8,555,983,514, 41.04 per cent of the Australian total of cent of the Australian total of $20,848,019,725**. $20,848,019,725**.

the 1991 Census indicated an average the 1991 Census indicated an average figure for the Basin of over 16 per cent of figure for the Basin of over 16 per cent of the workforce directly engaged in the workforce directly engaged in agriculture, agriculture,

RiceRice

Except for a small quantity grown in Queensland Except for a small quantity grown in Queensland and the Northern Territory, all of the Australian rice and the Northern Territory, all of the Australian rice crop is grown in the MDB*****. In the MDB, rice is crop is grown in the MDB*****. In the MDB, rice is grown on 1,288 farms, with a total area of 109,186 grown on 1,288 farms, with a total area of 109,186 hectares, 95.8 per cent of the Australian total of hectares, 95.8 per cent of the Australian total of 114,000 hectares, producing 928,533 tonnes, 97.0 114,000 hectares, producing 928,533 tonnes, 97.0 per cent of the Australian total of 957,000 tonnes. per cent of the Australian total of 957,000 tonnes. The crop was was valued at $176.0 million, 96.1 The crop was was valued at $176.0 million, 96.1 per cent of the national total of $183.1 million.per cent of the national total of $183.1 million.

THE PROBLEM WITH RICETHE PROBLEM WITH RICE

there are resource constraints, not only in terms of there are resource constraints, not only in terms of the availability of irrigation water, but also because the availability of irrigation water, but also because of the environmental consequences of the large of the environmental consequences of the large quantities of water and flood irrigation methods quantities of water and flood irrigation methods that are used. Up to half of the water that that are used. Up to half of the water that percolates down to groundwater from irrigated percolates down to groundwater from irrigated areas in southern NSW comes from rice areas in southern NSW comes from rice production. This represents some 200,000 ML of production. This represents some 200,000 ML of water every year, worth over $2m. Not only is this water every year, worth over $2m. Not only is this water wasted, it is an undesirable addition to water wasted, it is an undesirable addition to already high watertables. already high watertables.

Irrigation ControversyIrrigation ControversyIn comparison with many other countries, Australia has long had a low rate of return on its investment in irrigation largely due to the fact that the bulk of the irrigation water used in the southern Basin supports mixed farming and low-value commodities.

This situation is complicated by the fact that a number of the commodities produced are also inefficient users of water .

For example, while fruit, vegetables and dairying are among the most efficient, rice and grazing are the most inefficient, with cotton in between .

Table 3 Water required to make $100 profit Table 3 Water required to make $100 profit

(source: adapted from Hall et al. 1994)(source: adapted from Hall et al. 1994)

Agricultural Agricultural commoditiescommodities

Water use, in litresWater use, in litres

FruitFruit 200,000200,000

VegetablesVegetables 460,000460,000

Dairy productsDairy products 500,000500,000

CottonCotton 760,000760,000

RiceRice 1,850,0001,850,000

PasturePasture 2,780,0002,780,000

Table 1 Major land degradation problems in Table 1 Major land degradation problems in the Murray-Darling Basinthe Murray-Darling Basin

wind erosionwind erosion water erosion, including gullying, rill and sheet erosion, water erosion, including gullying, rill and sheet erosion, mass movement of hill slopes mass movement of hill slopes dryland salinity dryland salinity irrigation-induced salinityirrigation-induced salinity soil surface scaldingsoil surface scalding Waterlogging Waterlogging soil aciditysoil acidity soil structure decline soil structure decline soil fertility decline or nutrient losssoil fertility decline or nutrient loss vegetation decline and degradation, such as weed infestation and lack vegetation decline and degradation, such as weed infestation and lack

tree regenerationtree regeneration loss of flora and fauna and hence of biodiversityloss of flora and fauna and hence of biodiversity Source: MDBMC 1987.Source: MDBMC 1987.

Wind erosionWind erosion

Water ErosionWater Erosion

Mass MovementMass Movement

Dryland SalinityDryland Salinity

Cotton= chemicalsCotton= chemicals

Figure 1 Aspects of land degradation in the MDB (source: Land Assessment a Policy Unit, Figure 1 Aspects of land degradation in the MDB (source: Land Assessment a Policy Unit, CRCSLM; Spencer et al. 1996; Noble 1997)CRCSLM; Spencer et al. 1996; Noble 1997)

Murray darling basin

Woody weed effected area

Acidic soil at surface

Acidic throughout

Alkaline soil

400mm rainfall

BILIOGRAPHYBILIOGRAPHY

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