AGRICULTURAL ENVIRONMENT

Australia's average elevation is the lowest of any continent, with a mean elevation of only 330 metres. The dominant topographical feature of the continent is the Great Dividing Range, which spans the length of the eastern seaboard and has a profound influence on regional weather patterns and land use.

Australia's agricultural landscapes support a wide range of soils. Most are ancient, strongly weathered and infertile by world standards, with deficiencies in phosphorus and nitrogen. Those on flood plains are younger and more fertile. Very few are considered good quality soils for agriculture. To offset nutrient deficiencies, superphosphate and nitrogenous fertilisers are widely used, particularly on pasture and cereal crops. Fragile soil structure and a susceptibility to waterlogging are other common features of Australian soils, while large areas are naturally affected by salt or acidity. These soil characteristics restrict particular agricultural activities, sometimes ruling out agricultural activity altogether.

With the exception of Antarctica, Australia is the world's driest continent. More than a third of the continent is effectively desert, and over two-thirds of the continent is classified as arid or semi-arid. The wet summer conditions of northern Australia are suited to beef cattle grazing in inland areas and the growing of sugar and tropical fruits in coastal areas. The drier summer conditions of southern Australia favour wheat and other dryland cereal farming, sheep grazing, beef cattle and dairy cattle (in the higher rainfall areas). There is also a high degree of annual rainfall variability within regions and this is most pronounced in arid and semi-arid regions.

Rainfall variability is very high by global standards and often results in lengthy periods without rain. The variability and seasonality of rainfall in Australia requires that water be stored. Under normal seasonal conditions, the ability of primary producers to store water ensures that there are adequate supplies for those agricultural activities requiring a continuous supply. The development of large scale irrigation schemes has opened up areas of inland Australia to agricultural activities that otherwise would not have been possible.

Evaporation is another important element of Australia's environment, affecting agricultural production, with hot dry summers causing high rates of evaporation in many parts of the country.

Since European settlement, the vegetation of Australia has altered significantly. In particular, large areas of Australia's forest and woodland vegetation systems have been cleared, predominantly for agricultural activity. The areas that have been altered most are those that have been opened up to cultivation or intensive grazing. Some semi-arid regions previously cleared of timber and scrub to allow grazing of native grasses, now show signs of returning to their previous condition. In recent years, various state and territory legislation has seen restrictions applied to the area of old growth and regrowth forest and woodland that can be cleared without a permit.

LAND USE

In spite of Australia's generally harsh environment, agriculture is the most extensive form of land use. During 2009–10, the estimated total area of businesses with agricultural activity was 399 million hectares, representing 52% of the total land area – 6.5% of which had been cropped (table 16.7).

16.7 LAND USE BY AGRICULTURAL BUSINESSES—Year ended 30 June
	Area planted to crops(a)	Area of farms(b)	Farms as a percentage of total land area(c)
	('000 ha)	('000 ha)	%
2008	24 374	417 288	54.2%
2009	27 511	409 029	53.2%
2010	25 968	398 580	51.8%
(a) Excludes crops harvested for hay and seed, and pastures and grasses. (b) Total area of agricultural businesses with an estimated value of agricultural operations (EVAO) of $5,000 or more. (c) Total area of Australia includes Jervis Bay. Source: Agricultural Commodities, Australia (7121.0).

Queensland had 130 million hectares devoted to agricultural activity, while Western Australia had 94 million hectares (graph 16.8). Land area not used for agriculture consisted of unoccupied land (mainly desert in western and central Australia), Aboriginal land reserves (mainly located in the Northern Territory and Western Australia), forests, mining leases, national parks and urban areas.




IRRIGATION

High variability in annual rainfall and river flow is a feature of the Australian environment and this means that successful ongoing production of many crops and pastures is dependent on irrigation. In 2009–10, 30% (40,816) of all agricultural businesses reported irrigation activity and in total 6,600 gigalitres of irrigation water was applied – an average application rate of 3.6 megalitres per irrigated hectare.

Rice, cotton, grapes, vegetables and nurseries/cut flowers/cultivated turf are the most intensively irrigated crops, with 100%, 100%, 95%, 86%, and 78% respectively of their total growing areas being irrigated in 2009–10. However, the total area of land irrigated, about 1.8 million hectares in 2009–10, represents less than 1% of the total land used for agriculture (table 16.9).

Most irrigated land is located within the confines of the Murray-Darling Basin, which covers parts of New South Wales, Victoria, Queensland and South Australia, and all of the Australian Capital Territory.

16.9 PASTURES AND CROPS IRRIGATED, By state and territory—2009–10
	NSW(a)	Vic.	Qld	SA	WA	Tas.	NT	Aust.
AREA IRRIGATED (ha)
Pasture and cereal crops used for grazing or fed off	133 035	240 917	^50 683	^45 565	^15 890	55 988	44	542 121
Pasture and cereal crops cut for hay	39 719	^45 789	^27 201	^20 818	^896	4 215	^303	138 940
Pasture and cereal crops cut for silage	^18 465	^16 731	^11 199	*3 588	np	np	–	53 307
Rice	np	np	np	–	–	–	–	18 931
Other cereals for grain or seed	151 487	^18 702	37 076	^5 137	np	3 772	np	217 632
Cotton	80 075	–	73 114	–	–	–	–	153 189
Sugar cane	np	–	np	–	–	–	–	212 615
Other broadacre crops	^21 100	np	^13 876	*1 438	3 014	17 140	np	59 055
Fruit trees, nut trees, plantation or berry fruits	26 455	45 553	33 578	14 940	7 469	^3 057	3 170	134 221
Vegetables for human consumption	14 761	25 158	29 383	11 775	8 007	14 565	675	104 324
Nurseries, cut flowers and cultivated turf	^3 854	3 042	4 013	^775	^1 154	np	np	13 143
Grapevines	37 275	^38 069	np	71 915	^11 180	^1 313	np	162 602
Total	550 158	440 719	502 600	186 494	50 815	104 803	5 021	1 840 610
VOLUME APPLIED (ML)
Pasture and cereal crops used for grazing or fed off	299 901	^797 760	^154 718	^214 316	^89 479	165 289	^139	1 721 602
Pasture and cereal crops cut for hay	^141 445	^109 455	^87 836	^74 744	^5 628	10 462	^3 263	432 833
Pasture and cereal crops cut for silage	^41 787	^27 542	^28 348	*11 836	np	np	–	118 336
Rice	np	np	np	–	–	–	–	246 909
Other cereals for grain or seed	393 866	^31 762	112 499	*6 621	**15 533	np	np	567 821
Cotton	468 843	–	383 107	–	–	–	–	851 950
Sugar cane	np	–	np	–	–	–	–	756 317
Other broadacre crops	*42 314	np	32 416	*3 175	20 879	34 616	np	^139 292
Fruit trees, nut trees, plantation or berry fruits	116 531	259 716	122 668	103 372	36 519	^7 649	8 208	654 663
Vegetables for human consumption	68 552	93 797	87 576	73 272	50 315	44 322	1 395	419 229
Nurseries, cut flowers and cultivated turf	^18 629	11 247	18 438	^2 880	10 783	896	610	63 483
Grapevines	150 649	^155 293	^16 279	174 513	^14 019	np	np	515 484
Total	2 002 797	1 504 742	1 823 870	711 991	252 058	281 953	18 628	6 596 040
np not available for publication but included in totals where applicable, unless otherwise indicated ^ estimate has a relative standard error of 10% to less than 25% and should be used with caution * estimate has a relative standard error of 25% to 50% and should be used with caution ** estimate has a relative standard error greater than 50% and is considered too unreliable for general use – nil or rounded to zero (including null cells) (a) Includes Australian Capital Territory. Source: Water Use on Australian Farms (4618.0).