In terms of agriculture, we could use basic research into perennial staple crops. [1] It’s a promising area, but still a ways off. The result, as mentioned in the article, is less soil disturbance and more long-term carbon sequestration. From a policy perspective, Victory Gardens [2] were a successful strategy during WWII. It would be great to mobilize a similar effort to get people growing food in their own backyard…
It's a fine hobby if you enjoy gardening and find satisfaction in the honest simplicity and hard work of digging over soil, weeding, and spreading manure.
But the truth is: supermarket food is incredibly cheap, and you'll be putting in 50 hours of labour to grow $20 worth of vegetables.
If you enjoy the process and don't mind not getting much output, by all means enjoy it as a hobby. But as a way to feed the nation? I'm skeptical.