Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]

Farmers join in a spring ploughing ceremony in Xiang Cha Village, Kangxung Township, Rinbung County of Shigatze Prefecture in southwest China's Tibet Autonomous Region, March 16, 2014. Farmers in Xiang Cha Village held the annual ploughing ceremony to mark the beginning of spring sowing. [Photo/China Tibet Online]