in march 2008, kirchner introduced a new sliding-scale taxation system for agricultural exports, so that rates fluctuated with international prices. this would effectively raise levies on soybean exports from 35% to 44% at the time of the announcement. this new taxation scheme, proposed by minister martín lousteau, led to a nationwide lockout by farming associations, with the aim of forcing the government to back down on new tax system. they were joined on 25 march by thousands of pot-banging demonstrators massed around the buenos aires obelisk and the presidential palace. these demonstrations were followed by others at locations across the country that included road blockades and food shortages.