Why is China buying so much U.S. farm land?

China is buying up millions of acres of farm land in and around U.S. military bases. Why??

China’s portfolio of government debt in May dropped to $980.8 billion, according to Treasury Department data released Monday.
It marked the first time since May 2010 that China’s holdings fell below the $1 trillion mark.

My guess is, there was a transfer of debt into US farm land.
State Department spokesperson could not just say: Well we owe them money, so we exchanged it for land!
Or worse, US government is literally selling out the country!