A whiff of wind near Galong west of Yass suggests they're right.

Cropping and grazing farmer Danny Flanery has stepped where none of his neighbours dared go when he accepted thousands of truck-loads of Sydney sewage.

Recognised nationally for his environmental nous, Mr Flanery prefers Bondi's sewage because Malabar's was so smelly for neighbours that he couldn't use it.

''The Malabar stuff, from all different nationalities and foods, makes it smell differently - and it really does smell, so we can't bring it here,'' he said.

''Different foods make it smell worse. So the Bondi crew's biosoil is the least smelling because they probably eat better, less spicy foods.''

Sydney Water says biosolids produced at different treatment plants will vary depending on the waste water received and the treatment processes applied.

''Different demographic areas may have different waste water due to differences in industrial and commercial inputs and behaviours of residential customers,'' it says.

Mr Flanery was wary when first approached by Sydney Water six years ago.

''I was a bit scared and wondered where it all would end up, whether my farm could be quarantined because of it,'' he said.

He spends $1000 a tonne on synthetic fertiliser and so worked through the figures and decided to investigate biosolids further.

He checked Harden Shire on wear and tear to roads from hundreds of trucks delivering to his property. Then he spoke to a soils expert in Queensland, who told him to grab the biosolids before others did.

Biosolids are not applied where livestock are grazing.

Mr Flanery spreads it at a rate of 50 tonnes a hectare for crops and up to 150-plus tonnes a hectare for trees. The latest delivery will give 6000 eucalyptus trees to be planted in August a tremendous start.

Heaped in the cold weather, lumpy black cakes have formed a sealed exterior after receiving a good drenching of rain.

''Don't get it on your shoes, because you will regret it,'' Mr Flanery said, before warning his kelpie to forget about rolling in it.

''I used to have dry, lifeless soils, now they are all active, lots of worms, and organic matter has doubled,'' he said.

His wheat is thick, lush and deep green. His soil breaks down stubble that previously did not break down.

Now his neighbours are using biosolids and his biggest concern is having enough to go around.

Sydney Water produced 172,310 wet tonnes of biosolids in the 2011-12 financial year.

A spokesman said all biosolids were used, with about 68 per cent going to agriculture and 32 per cent to compost.

While farmers pay a small fee, the biosolids beneficial use program costs Sydney Water about $15 million a year.

Transpacific Industries Group delivers it to farms. Senior project manager, technical services, Matthew Griffiths, said demand from farms that could accept biosolids was the biggest issue. Not all farms were appropriate.

Sloping ground, waterways, proximity to neighbours, access for heavy vehicles, soil chemistry and method of tilling are all factors.

ACTEW Water operations manager David Glavas said biosolids from the Canberra sewage treatment plant were incinerated to remove pathogens.

This left behind an ash-based product, rich in nutrients and lime, which was used in NSW's agriculture industry.