Average family farm incomes in Ireland fell by 30% last year to €11,968 (£9888), according to a survey by The Irish Agriculture and Food Development Authority (Teagasc).
On more commercial full-time farms the average farm income was €24,214 (£19,979), down €13,000 (£10,726) from 2008.
The fall was most pronounced on specialist dairy and tillage farms which were hit by lower cereal and milk prices.
Subsidy payments continued to prop up farm incomes, with the average direct payment to Irish farms worth €17,109 (£14,136) in 2009, accounting for 36% of gross output and 143% of family farm income.
Teagasc said Irish family farm incomes had fallen 40% since 2007.