The "how" took some reading to find. Here it is:
> They filled one field with water, as is common in Bali, but they drained the other, wetting the soil only when hairline cracks were spotted in the earth
> They filled one field with water, as is common in Bali, but they drained the other, wetting the soil only when hairline cracks were spotted in the earth
But I guess that isn't the case.
Bali has reliably warmer weather than the Riverina in the winter months, so at a guess insulation would be less relevant for Balinese farmers.
[0] Australian rice growing is good for comparison because it necessarily has to be more water efficient and is more heavily industrialised than Indonesia