Cal. RTC § 422.7

(a) For purposes of this section, the term “open-space land” includes land subject to contract for an urban agricultural incentive zone, as defined in subdivision (b) of Section 51040.3 of the Government Code. For purposes of this section, open-space land is enforceably restricted within the meaning of Section 8 of Article XIII of the California Constitution if it is subject to an urban agriculture incentive zone contract.

(b) (1) Open-space land subject to contract for an urban agricultural incentive zone pursuant to Section 52010.3 shall be valued for assessment at the rate based on the average per-acre value of irrigated cropland in California, adjusted proportionally to reflect the acreage of the property under contract, as most recently published by the National Agricultural Statistics Service of the United States Department of Agriculture.

(2) Notwithstanding the published rate, the valuation resulting from the section shall not exceed the lesser of either the valuation that would have resulted by a calculation under Section 110, or the valuation that would have resulted by a valuation under Section 110.1, as though the property was not subject to an enforceable restriction in the base year.

(c) The State Board of Equalization shall post the per-acre land value as published by the National Agricultural Statistics Service of the United States Department of Agriculture on its Internet Web site within 30 days of publication, and shall provide the rate to county assessors no later than January 1 of each assessment year.