 In addition, improvements in agriculture contributed to economic growth as new strains of rice resisted droughts and disease, and fertilizers allowed double cropping of fields with better irrigation techniques to help farmers produce greater surpluses.The use of copper-alloy coins greatly facilitated Japanese estates to sell extra produce in the marketplaces.In addition, merchants began to form their own communities and began to exercise economic power and great wealth even though Japan was dominated by a feudal-military system led by warrior samurais and daimyos who exercised great control over various competing semi-autonomous domains across the Japanese archipelago.