Connecticut State law allows lower tax benefits to land classified as farm, foresrt or open space.  The statute for farm land designation as as follows:
Sec. 12-107c. Classification of land as farm land. (a) An owner of land may apply for its classification as farm land on any grand list of a municipality by filing a written application for such classification with the assessor thereof not earlier than thirty days before or later than thirty days after the assessment date, provided in a year in which a revaluation of all real property in accordance with section 12-62 becomes effective such application may be filed not later than ninety days after such assessment date. The assessor shall determine whether such land is farm land and, if such assessor determines that it is farm land, he or she shall classify and include it as such on the grand list. In determining whether such land is farm land, such assessor shall take into account, among other things, the acreage of such land, the portion thereof in actual use for farming or agricultural operations, the productivity of such land, the gross income derived therefrom, the nature and value of the equipment used in connection therewith, and the extent to which the tracts comprising such land are contiguous.
The statute for forest is as follows:
section 12-107b (2) The term “forest land” means any tract or tracts of land aggregating twenty-five acres or more in area bearing tree growth that conforms to the forest stocking, distribution and condition standards established by the State Forester pursuant to subsection (a) of section 12-107d, and consisting of (A) one tract of land of twenty-five or more contiguous acres, which acres may be in contiguous municipalities, (B) two or more tracts of land aggregating twenty-five acres or more in which no single component tract shall consist of less than ten acres, or (C) any tract of land which is contiguous to a tract owned by the same owner and has been classified as forest land pursuant to this section;
 The statute for open space is as follows:

Sec. 12-107e. Classification of land as open space land. (a) The planning commission of any municipality in preparing a plan of conservation and development for such municipality may designate upon such plan areas which it recommends for preservation as areas of open space land, provided such designation is approved by a majority vote of the legislative body of such municipality. Land included in any area so designated upon such plan as finally adopted may be classified as open space land for purposes of property taxation or payments in lieu thereof if there has been no change in the use of such area which has adversely affected its essential character as an area of open space land between the date of the adoption of such plan and the date of such classification.

(b) An owner of land included in any area designated as open space land upon any plan as finally adopted may apply for its classification as open space land on any grand list of a municipality by filing a written application for such classification with the assessor thereof not earlier than thirty days before or later than thirty days after the assessment date, provided in a year in which a revaluation of all real property in accordance with section 12-62 becomes effective such application may be filed not later than ninety days after such assessment date. The assessor shall determine whether there has been any change in the area designated as an area of open space land upon the plan of development which adversely affects its essential character as an area of open space land and, if the assessor determines that there has been no such change, said assessor shall classify such land as open space land and include it as such on the grand list. An application for classification of land as open space land shall be made upon a form prescribed by the Commissioner of Agriculture and shall set forth a description of the land, a general description of the use to which it is being put, a statement of the potential liability for tax under the provisions of section 12-504a to 12-504f, inclusive, and such other information as the assessor may require to aid in determining whether such land qualifies for such classification.

 Application forms are available on http://caao.com/farmforestopen-space/