what is Bill Gates wanting to do with Iowa farm land?

Bill gates is one of the largest farmland owners in the world (or at least was - I last checked about 10 years ago...) He hires people to work on his farm, and managers to manage it. Food is the most important thing for modern society and the reports I have suggest he is trying to raise food in the most sustainable fashion possible (organic is often not sustainable)

Same as any other big real estate investor: speculate.

Collect rent.

That's all rich people do. The premise of capitalism is that the people best at collecting rent should also be in total control of resource allocation.