The colloquial Australian-English noun spud-cocky designates a potato farmer.

This noun occurs, for example in the following passage from Illywhacker (St. Lucia (Queensland): University of Queensland Press, 1985), by the Australian novelist Peter Carey (born 1943) [page 228]:

When I was forced to line up with the unemployed at Bungaree at spud-digging time, in Mildura when the grapes were on, at Kaniva and Shepparton for the soft-fruit season, I held myself aloof from my fellows. I, having shone my boots and ironed my shirt, was not one of them. When some stirrers up at Bungaree tried to organize a strike against the spud farmers who were paying only sixpence a bag, I was called a scab. There were plenty of us, don’t worry, and it was us scabs who brought in the spuds for those celebrated spud cockies at Bungaree.

The noun spud-cocky is composed of:
– the noun spud, designating a potato;
– the noun cocky, designating a farmer working a small-scale farm.

Here, cocky is a shortened form of the noun cockatoo, designating a farmer working a small-scale farm.

This acceptation of cockatoo perhaps arose from the claim that in the early years such farmers used a small area of land for a short time and then moved on, in the perceived manner of cockatoos feeding. (The noun cockatoo designates a kind of parrot from the Australasian region.) The following explanations are from Letter XV. Everyday Station Life, dated Broomielaw, January 1867, published in Station Life in New Zealand (London: Macmillan and Co., 1883), by the British author Mary Anne Barker (1831-1911) [page 110]:

These small farmers are called Cockatoos in Australia by the squatters or sheep-farmers, who dislike them for buying up the best bits of land on their runs; and say that, like a cockatoo, the small freeholder alights on good ground, extracts all he can from it, and then flies away to “fresh fields and pastures new.”

—Cf. also:
– the origin of ‘spud’ (potato);
– ‘spud-barber’: meaning and origin;
– ‘spud-bashing’: meanings and origin.

The earliest occurrences of the noun spud-cocky that I have found are as follows, in chronological order:

1-: From Aboriginalities, published in The Bulletin (Sydney, New South Wales) of Thursday 2^nd March 1911 [Vol. 32, No. 1,620, page 13, column 2]—this text also contains the noun cow-cocky, designating a dairy farmer:

“J. G.”: “Leo Lear,” in his defence of the cocky (B. 26/1/’11), wants to know if the cocky is more dishonest than lawyers, loafers, reporters and various others. Maybe he isn’t; but then they don’t continually cackle about their honesty, and the cocky does. “Lear” has never found the cocky that helped to fill his potato bags with soil and stones. I have. One time I was spud-digging for a cocky who was simply delighted when the rain came during operations. He explained to me that the wet weather meant that the earth would stick to the potatoes; consequently it would not take so many tubers to fill a bag. In fact, it is a general thing for spud-cockies to urge their diggers to root out the spuds like blazes when the ground is wet. Did “Lear” […] never see the cow cockies in the old creamery days pour water in the milk they took to the creamery?

2-: From Notes from “The Ranges”, by ‘J. G.’, published in The Elmore Standard (Elmore, Victoria, Australia) of Saturday 23^rd November 1912 [page 5, column 5]:

Although this is a good potato country, there is a potato famine on now, potatoes being retailed at from 2d to 3d per lb. This is due to the ravages of Irish Blight the season before last, which resulted in the past season’s crop coming on to a comparatively bare market, and thus selling at good prices. Although rates were good at potato-digging time, they are much higher now, and there are plenty of “spud cockies” pulling their whiskers and wishing they had held on to their tubers.

3 & 4-: From Jargon from Torbay Junction, by ‘Jinghie’, published in The Southern Districts Advocate (Katanning, Western Australia, Australia):

3-: Of Wednesday 13^th May 1914 [Vol. 1, No. 52, page 2, column 5]:

Concerning crops, well the swamp lands are becoming more first favorite day by day since the Government drained Grassmere and Attwell country. If the elements remain favorable for a week or two longer all the spud cockies are confident that the average will be increased this year. Mr H. S. Jackson, east of Narrikup, had a fair yield; off about six acres he averaged about eight tons per acre. To make a long story short, everything in the garden is lovely.

4-: Of Wednesday 27^th January 1915 [Vol. 2, No. 115, page 3, column 4]:

The season is proving a source of consolation hereabouts, being the ideal thing for spud cockies, good crops now being assured.