DENILIQUIN, Australia: Lindsay Renwick, the mayor of this dusty southern Australian town, remembers the constant whir of the rice mill. "It was our little heartbeat out there, tickety-tick-tickety," he said, imitating the giant fans that dried the rice, "and now it has stopped." The Deniliquin mill, the largest rice mill in the Southern Hemisphere, once processed enough grain to satisfy the daily needs of 20 million people. But six long years of drought have taken a toll, reducing Australia's rice crop by 98 percent and leading to the mothballing of the mill last December.