China is offering more subsidies on farm machinery to maintain food self-sufficiency as the rural workforce shrinks.

In 2014 23.6 billion yuan ($3.9 billion) went on farm machinery subsidies, up from 70 million yuan ten years before when the subsidy program began, according to the Ministry of Finance.

More than 120 billion yuan has been spent on farm machinery subsidies since 2004, raising mechanization to 61 percent from 34 percent in 2004.

Subsidies will continue for at least the next three years, with more funds going to farmers who grow key staples as well as cotton and sugar.