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Northern Australia receives substantial rainfall, but its population is minimal.

For instance the Kimberley region in the state of Western Australia gets more than 20 in. of rainfall per year, but has a population density of less than 1 person per 3 sq. mi.(!)

Is there a reason northern Australia is unattractive for human habitation and agriculture?

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  • $\begingroup$ The answer for this question would have to discuss politics, sociology, climate & resources. I'm not confident a purely earth sciences answer could do justice to this question. $\endgroup$ – Fred Jun 19 '17 at 9:13
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    $\begingroup$ I changed the title to reference agriculture. Asking why people don't live somewhere isn't really an Earth Science question. $\endgroup$ – kingledion Jun 19 '17 at 10:53
  • $\begingroup$ Odd, here in Florida my dad and I were just wondering about this in Australia the other day!?! But I think you're right that almost always living locations boil down more to geography/agriculture than politics/sociology and such. $\endgroup$ – JeopardyTempest Jun 19 '17 at 13:56
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Erratic Climate

Lets take Broome, Australia as our example. Broome gets 615mm of rain a year (24 inches), including 58/182/180/102mm in Dec through March. Coupled with average highs in the low 90s, this would be fine for the sort of agriculture you see in South Texas. However, Broome's rainfall is very erratic. For example, in 2016, the rainy season started January 15th, with 23 mm of rain over three days. In 2017 (really 2016, again) the rainy season started December 4th. December 2016 also featured 222mm of rain (remember the average is only 58mm) including 113mm on Dec 23rd and 24th. 2016-2017 featured 222/230/249/114mm of rain, with significant rainfall later into April. 2015-2016 featured 0/119/26/28mm of rain. One year saw too little rainfall to grow even millet, while the next year had enough rain to support paddy rice.

Laterite

Old tropical soils in rainy or monsoonal rainy regions tend to have their soils leached of useful nutrients. The resulting soil is called laterite, and it is heavily enriched in aluminum and iron ore. On the one hand, this explains the mineral wealth of tropical Australia. On the other, laterite (alternately called ferralsols, especially by the UN Food and Agriculture Organization (FAO) ) is hard to farm, with few minerals for the plants, poor moisture retention, and the tendency to form an iron-hardened crust in the dry season.

Not enough people

This is sort of a meta-reason, but Northern Australia is a long way from anywhere. Without very many people, it is hard to build a stable agricultural economy. If a bunch of people where sent there and forced to survive, they'd probably eke something out (for example, like the people who first populated Sydney, or South Africa). But since that never happened...population of the reason never happened. Sort of circular reasoning, but without ever having a reason for a lot of people to show up in Northern Australia (prison colony, religious persecution, etc) no one has ever made the infrastructure that successful farming operations could be based off of.

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    $\begingroup$ Interesting. Have to think it's mostly the laterite, as if it proved reasonably arable, people inevitably would venture there, there's always a reason for a "new start". This question was a related topic of recent. The variability might slow it down a little, but water can be stored and irrigated. This suggests it's never been a popular living location, and I can only think it's the soil. $\endgroup$ – JeopardyTempest Jun 19 '17 at 14:00
  • $\begingroup$ This seems on the right track. However, it is possible to use irrigation for agriculture and wikipedia notes of lateritic soil: " It is possible to rehabilitate such soils, using a system called the 'bio-reclamation of degraded lands'. This involves using indigenous water-harvesting methods (such as planting pits and trenches), applying animal and plant residues, and planting high-value fruit trees and indigenous vegetable crops that are tolerant of drought conditions. They are good for tea, coffee and cashew cultivation. " $\endgroup$ – Colin Jun 19 '17 at 19:44
  • $\begingroup$ also from wiki: "The erratic climate and extreme soil poverty have defied all attempts to develop large-scale agriculture in any part of Northern Australia apart from the Wet Tropics, where sugar cane and banana growing is a major industry, and the Lake Eyre Basin .... Beef cattle are raised ... in the Northern Territory and Kimberley, but the quality of meat is very low because animals are slaughtered at quite an old age compared to cattle elsewhere in the world." $\endgroup$ – Colin Jun 19 '17 at 20:05
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Kingledion's answer speaks to the challenges of the soil and climate for agriculture in northern Australia. However, it seems there is nevertheless significant untapped potential.

Arable Soil

The Australian government agency Commonwealth Scientific and Industrial Research Organisation has concluded that there is "at least 16 million hectares of soil that’s suitable for intensive agriculture".

Irrigation Potential

CSIRO further reports (ibid.) "around 15,000 GL [of water annually]—enough to irrigate almost 1.5 million hectares—could be made available for irrigation" with improved infrastructure.

Political Will

The Australian government is pursuing modest agricultural expansions. The 2015 White Paper on Developing Northern Australia announced an A$170m allocation for water development in northern Australia, including expanded funding for the Ord River Irrigation Scheme.

Developments must contend with the wishes of local stakeholders and state funding limitations.

Proposals for transformative agricultural developments, including perhaps soil improvement and settlement policies, apparently lack political will. The Kimberley Plan, a WWII-era scheme to resettle Jewish refugees in northern Australia, was vetoed by the Australian government in 1944 on the grounds that it would "depart from the long-established policy in regard to alien settlement in Australia". Immigration remains restricted in Australia, and the government is unlikely to import massive foreign manpower as part of a development scheme. The population and economic pressures within Australia are evidently insufficient to motivate a large-scale development of the north.

Further CSIRO info is available here.

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    $\begingroup$ The government tends to be optimistic regarding agricultural potential but there are opportunities. The lack of nutrients and organic matter are soil constraints as are the physical effects of clay rich soils on drainage and runoff. $\endgroup$ – haresfur Jun 19 '17 at 22:13

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