Australia is the leading wool exporter, and a leading cotton exporter.
So which fibre is more land friendly?
Calculated by Emma Hakansson, verified by Faunalytics
Total yields
Wool
There are around 70 million sheep in Australia
Total annual wool yield of 340 million kg greasy (shorn wool prior to treatment)
Bales should weigh between 120kg and 204kg
(unless the wool is under 18.6 microns, in which case they may be a min. Gross weight of 90kg)
Average bale weight (2013/14) is 176kg
AWEX
Total wool yield / average bale weight = 1.93 million bales
Cotton
More than 5 million bales of cotton were produced in 2011/2012
Australian cotton bales weigh 227kg (industry standard)
Cotton Australia, Queensland Government, USDA Foreign Agriculture Service
Total land use
Wool
More than 85 million hectares used by wool industry
Learn About Wool: Australian Wool Innovation and The Woolmark Company
Cotton
More than 583,000 hectares used by cotton industry (record year, 2011/2012)
Hectares per bale
Wool
85 million hectares / 1.93 million bales
44.04 hectares per bale
(440,400m2)
Cotton
583,000 hectares / 5 million bales
0.12 hectares per bale
(1,200m2)
From this we learn that a whopping 367 times less land is required to grow one bale of Australian cotton, as compared to growing one bale of Australian wool.
Note that both wool and cotton bales must be scoured and processed, so yield of usable fibre for yarn is less than bale weight.
Regardless, it is clear that cotton is a far superior fibre in the context of land use efficiency.