it is also used for sugarcane cotton rice and nut trees in australia deloitte access and olive trees vineyards and for greenhouse fruits and vegetables in spain and greece garrido et al this exceeds previous figures from which reported that groundwater irrigation covered at least in only a third of oecd countries oecd shares vary from a few per cent in countries with relative abundance of surface water eg estonia norway to higher shares for countries relying significantly on groundwater for irrigation eg germany denmark