(a) The legislative body of a city or county shall deny approval of a tentative map, or a parcel map for which a tentative map was not required, if it finds that either the resulting parcels following a subdivision of that land would be too small to sustain their agricultural use or the subdivision will result in residential development not incidental to the commercial agricultural use of the land, and if the legislative body finds that the land is subject to any of the following:

1. (1) A contract entered into pursuant to the California Land Conservation Act of 1965 (Chapter 7 (commencing with Section 51200) of Part 1 of Division 1 of Title 5), including an easement entered into pursuant to Section 51256.
2. (2) An open-space easement entered into pursuant to the Open-Space Easement Act of 1974 (Chapter 6.6 (commencing with Section 51070) of Part 1 of Division 1 of Title 5).
3. (3) An agricultural conservation easement entered into pursuant to Chapter 4 (commencing with Section 10260) of Division 10.2 of the Public Resources Code.
4. (4) A conservation easement entered into pursuant to Chapter 4 (commencing with Section 815) of Part 2 of Division 2 of the Civil Code.

(b)

1. (1) For purposes of this section, land shall be conclusively presumed to be in parcels too small to sustain their agricultural use if the land is (A) less than 10 acres in size in the case of prime agricultural land, or (B) less than 40 acres in size in the case of land that is not prime agricultural land.
2. (2) For purposes of this section, agricultural land shall be presumed to be in parcels large enough to sustain their agricultural use if the land is (A) at least 10 acres in size in the case of prime agricultural land, or (B) at least 40 acres in size in the case of land that is not prime agricultural land.

(c) A legislative body may approve a subdivision with parcels smaller than those specified in this section if the legislative body makes either of the following findings:

1. (1) The parcels can nevertheless sustain an agricultural use permitted under the contract or easement, or are subject to a written agreement for joint management pursuant to Section 51230.1 and the parcels that are jointly managed total at least 10 acres in size in the case of prime agricultural land or 40 acres in size in the case of land that is not prime agricultural land.
2. (2) One of the parcels contains a residence and is subject to Section 428 of the Revenue and Taxation Code; the residence has existed on the property for at least five years; the landowner has owned the parcels for at least 10 years; and the remaining parcels shown on the map are at least 10 acres in size if the land is prime agricultural land, or at least 40 acres in size if the land is not prime agricultural land.

(e) This section shall not apply to land that is subject to a contract entered into pursuant to the California Land Conservation Act of 1965 (Chapter 7 (commencing with Section 51200) of Division 1 of Title 5) when any of the following has occurred:

1. (1) A local agency formation commission has approved the annexation of the land to a city and the city will not succeed to the contract as provided in Sections 51243 and 51243.5.
2. (2) Written notice of nonrenewal of the contract has been served, as provided in Section 51245, and, as a result of that notice, there are no more than three years remaining in the term of the contract.
3. (3) The board or council has granted tentative approval for cancellation of the contract as provided in Section 51282.