More San Diego farmland will be eligible for an agricultural conservation program under new rules the San Diego County Board of Supervisors has approved. San Diego has lost much of its farmland over the past decade. Since 2009, about 60,000 acres — 20 percent of San Diego County’s agricultural land — has been converted to other uses. The county has tried to stem that decline through the Purchase of Agricultural Conservation Easement, which is called the PACE program.