The U.S. Census of Agriculture is conducted every 5 years, with the most recent data available for 2012. Beginning in 1997, the Census of Agriculture has been conducted by the USDA, National Agricultural Statistics Service (NASS). Before 1997, the Census of Agriculture was conducted by the U.S. Census Bureau. The smallest geography for agricultural census data is county level data.
The Agricultural Census definition of a farm is any place from which $1,000 or more of agricultural products were produced and sold, or normally would have been sold, during the census year. The definition has changed nine times since it was established in 1850. The current definition was first used in 1974 and has been used ever since. This definition is also consistent with the definition used for current USDA surveys.
Below are links to materials from the last two Censuses of Agriculture in 2007 and 2012. These links provide two-page profiles of Ulster County. They also go to the website from each census containing both the complete agricultural data report for New York State and tables with data for various agricultural topics at the county level.