President Mary McAleese has officially opened the 76th National Ploughing Championships in Co Offaly.
Speaking at the opening of the event, Mrs McAleese described the ploughing competitors as "the backbone of this occasion".
"They are showcasing Ireland's expertise at the ancient art of the plough, just as the whole site is showcasing the very best of Irish agriculture, its people, their skills, products, services, hopes, humanity and ambitions," she said.
The event, one of the biggest agricultural shows in Europe, is expected to attract around 150,000 people over three days to the 500-acre site at Annaharvey farm near Tullamore.
Government ministers, TDs and other politicians from throughout the country are expected to attend.
Taoiseach Bertie Ahern is scheduled to arrive on Thursday, and Northern Ireland's Deputy First Minister, Martin McGuinness, will attend tomorrow.
This year 300 competitors will battle it out for 18 national titles.
The Road Safety Authority and the Health and Safety Authority will be among the 850 exhibitors spread over 60 acres at the event.
Macra Na Feirme will be unveiling their 2008 calendar, showcasing some of Macra's female members from Limerick, to raise funds for the Samaritans.