According to Official Guinness Records,
The most golf balls hit simultaneously is 1,873 and was achieved at an event organised by Crow Legacy Company, at the Real Federacion Español de Golf course, Madrid, Spain, on 27 September 2009.
The attempt was in support of Madrid's bid for the 2016 Olympics and to encourage the recognition of golf as an Olympic sport during those games.
For a complete list of 2009 records, please visit 2009 Guinness Records in Spain.