A private sector survey has found Australian farmers' biggest concerns are easing commodity prices and the strong Australian dollar.

Rabobank's quarterly Rural Confidence Survey shows 37 per cent of farmers expected the agricultural economy to worsen over the next 12 months, versus only 15 per cent who expected conditions to improve.

The survey of around 4,500 farmers found that almost half of those expecting tougher times cited falling commodity prices as the reason.

Connected with this, as most agricultural commodities sold overseas are traded in US dollars before being converted back into local currency by the producers, around a third of respondents said the high Australian dollar was a big concern for their bottom lines.

Rabobank's group executive for country banking in Australia, Peter Knoblanche, says many growers are reliant on international markets for the bulk of their income.

"We've got a big export of our agricultural produce - 90 per cent odd is exported - so farmers really think about the strength of the Australian dollar, it does have that impact on commodity prices," he told ABC News Online.

Mr Knoblanche says there are some benefits to farms from the high currency, but they are far outweighed by the costs.

"Some equipment is cheaper in Australian dollar terms, and that's certainly a benefit, but most of the costs incurred by Australian farmers are around the labour and the energy input prices ... the labour's been pretty tight and expensive for farmers versus the mining sector," he explained.

High input costs were the key concern for 21 per cent of farmers surveyed.

The survey shows the stronger sectors were the dairy and sheep producers, with dairy farmers more confident about prices over the next year than many other producers.

"They're all starting to see, or expect, that prices will increase over the next twelve months for dairy commodities, and that's due to tight supply around the world," he added.

However, grain and beef producers were the most downbeat.

Mr Knoblanche says it is typically for grain grain growers to be concerned around this time of year, as they await autumn and winter rains for their next crop, while northern beef producers did not get the usual amount of summer rains meaning grazing conditions were worse than expected.

Overall, he says Australia's farmers have had a reasonable decade, as rising demand from Asia has pushed prices for most major agricultural commodities higher.

"At the moment you could say that it's challenging times, but we actually still see it fundamentally as a very strong sector, the agricultural sector, with a strong future for most of the farmers in Australia - they actually compete well against the rest of the world, and especially if our Australian dollar could come down a little," Mr Knoblanche concluded.