The Planning Board has given its approval to a proposal by Crop Production Services to build two structures for a showroom and a storage facility in a small industrial park on Marion Drive in North Carver. The company sells fertilizer, pesticides, and insecticides to commercial farmers. Cranberry growers in Carver and neighboring communities are among the firm’s customers. Town Planner Jack Hunter said in a telephone interview last week that the proposal approved by the board represents a change from the company’s original plan. That would have resulted in a single, large 12,000-square-foot building that would have required a costly sprinkler system according to town rules. The company chose instead to build two smaller structures, each under 7,500 square feet, one providing space for offices and a showroom, and the other for product storage.