The irrigated area decreased to 5,000 ha in 1998, and increased to 37,000 ha (about 10 per cent of the area under crops) in 2010. Currently, most crops are cultivated without irrigation, and crop yield largely depends on w eather conditions. In the Gobi region, the average wind speed is 3-4 metres per second or even stronger, which can cause significant soil moisture loss and erosion. It is estimated that, over the past 30 years, an average of 35-50 tons of soil have been lost per hectare of cultivated land.