The proposed mechanism: minerals absorb broader wavelengths of sunlight and convert them into energy that alters water’s physical properties, including hydrogen-bond structure, making water easier to split during photosynthesis.
[...]
In the field method described by the team, mineral powder was added to ordinary irrigation water at about 0.5 per cent, stirred under sunlight for one hour and then allowed to settle, with the clear water above the settled materials then used for irrigation.
Because the minerals did not dissolve in the water, the materials at the bottom could be reused, they said.

It's just homeopathy.