Yes, sub-surface, or drip close to root zone, is perfect -- however that's really expensive, in terms of capex as well as maintenance, harvesting, etc.

Drip systems tend to require a) a lot of pressure, and b) a very consistent pressure, to get reliable output. These are also expensive to buy & run.

Drip or leaky-hose type underground systems are difficult to maintain (I've tried!) just because you can't see them. The way you find out something's wrong is usually because a plant or an area is looking very very happy, and other plants / areas are dying off.

Under-mulch is good, but doesn't lend itself to broadscale cropping as described in TFA.