The movie star reveals he has been part of a "grass roots" organisation and he's fascinated by the idea of growing more food in developing nations for less outlay.
He tells WENN, "I try not to make it too loud but I have something called System of Rice Intensification that I'm involved with promoting.
"It's not just for rice but other crops and I've been going around the world on a grass roots level directly to the farmers, teaching a method of growing rice that uses 50 per cent less water and 90 per cent less seed, and yields four times as much rice.
"It's an incredible thing."
Now he's seen the process at work in different countries, he's urging fans and those keen to help spread the word to check out his foundation at www.BetterUFoundation.org.