In the northern Salaheddine province of Iraq, puddles of black crude oil dot the ground, contaminating vast swathes of farmland. "What is happening is that oil has damaged all that the land can give, every seed we plant gets damaged … This land has become useless," says one farmer. While local authorities blame the Islamic State group - which controlled large areas of Syria and Iraq in 2014 - farmers criticise the state for not doing enough to clean up the mess.