Farm equipment makers insist the sales slump they face this year because of lower crop prices and farm incomes will be short-lived. Yet there are signs the downturn may last longer than tractor and harvester makers, including Deere & Co Farmers and analysts say the elimination of government incentives to buy new equipment, a related overhang of used tractors, and a reduced commitment to biofuels, all darken the outlook for the sector beyond 2019 - the year the U.S. Department of Agriculture says farm incomes will begin to rise again.