**has their food production been better or worse since they started doing this?**
just to supplement several answers,
“In 1998, Zimbabwe had 3.2 million hectares (7.9 million acres) of arable land, covering 8% of the country’s total land area. Most of what is now central Zimbabwe was sparsely populated when Europeans first settled into the region, gradually transforming the bush into fertile farmland...About 63% of the economically active population was engaged in agriculture in 1999.
http://www.nationsencyclopedia.com/Africa/Zimbabwe-AGRICULTURE.html#ixzz3PijCgpW7
From page 1 of a report dated 2011: “Over the
last decade or so, traditional surpluses in agricultural products and industrial raw materials have either diminished
or disappeared turning Zimbabwe into a net importer of agricultural products. “ [diversity of exports have also declined]
I hope that some of these farmers get their families out of the country and then surreptitously sabotage their tractors, wells and other equipment before escaping.