LINCOLN – A rural state senator called Tuesday for providing financial incentives for farmers to use less nitrogen fertilizer and help clean up the state’s groundwater. Legislative Bill 1368, introduced by State Sen. Teresa Ibach of Sumner, would pay no less than $10 an acre for farmers who reduce their use of synthetic fertilizers, such as anhydrous ammonia, and switch to “biological” alternatives, such as coating seeds with microbes that draw nitrogen from the air.