Cool Planet Energy Systems has opened a plant in Camarillo to manufacture an additive to improve crop yields while using less water and fertilizer. The biofuels startup, which moved its headquarters from Camarillo to a Denver suburb last year, has sited the operation at a research and development facility it retained in Ventura County. The company said that field trials completed of its CoolTerra additive resulted in a 56 percent increase in strawberry production and a 40 percent decrease in fertilizer use, and a 50 percent reduction in water use in turf grass trials with a municipality. Rick Wilson, vice president at Cool Planet, said the results and early interest from growers indicates the company’s product could be high demand amid the state’s drought and likely water restrictions. Strawberries are Ventura County’s biggest crop, generating nearly $700 million in revenue in 2012, according to the Farm Bureau of Ventura County. “While untreated soil allows water and nutrients to evaporate or leach into the ground, away from the root zone of plants, CoolTerra retains water and nutrients in the root zone due to its engineered properties,” Wilson said in a prepared statement. Cool Planet’s primary business also develops biofuels from wood chips and energy crops such as miscanthus. Investors in Cool Planet include Google Ventures, the venture capital division of Google Inc., in Mountain View; General Electric Co., in Fairfield, Conn.; BP plc, in London; and North Bridge Venture Partners, in Palo Alto. It moved its headquarters to Greenwood Village, Colorado, after receiving state tax rebates. The company did not say how many workers it expected to employ at the Camarillo plant.