The average family farm income fell by 21% in 2018, according to a new Teagasc report.
Dairy farms were the worst affected, with their average income falling from €89,000 in 2017 to €61,000 last year.
The report shows adverse weather conditions played a significant role in the decline, which many farmers struggled to cope with.
"A lot of those farmers have had to take part-time work to supplement their income in order to rear their family and pay their bills," said IFA President Joe Healy.
"With those figures that are out today on the drystock, suckler farms and on the tillage and sheep farms it would be impossible on the average farm to pay all that have to be paid and raise a family," he added.