Heating bills are not the only place Minnesotans will feel this winter's soaring natural gas prices. Expensive natural gas means expensive fertilizer -- and an uncertain spring for the regions' farmers. Minnesota Public Radio's Jeff Horwich has this Mainstreet report (There's not much farming to be done in January, so John Wojtanowicz brings his mammoth potato picker in for a tune-up. Before the picker sees any action this spring, his 1200 acres of potatos will need hundreds of pounds of nitrogren. The same goes for his 2000 acres of corn and kidney beans, hungry for anhydrous ammonia and urea -- two popular fertilizers made by mixing raw nitrogen with natural gas.