Researchers from Norway figured out how to make nano-particle clay they could dissolve in water and just dump on sand. It penetrates deeply, so then you can add fertilizer and seed. Their process takes 7 hours from sand to a planted wheat field! The fungal mat you need for most plant growth thrives in this stuff.
Will it work on areas which aren't exclusively sand but which have been "desertified" by climate change? PS: Instead of using biodiesel for desal, why not use photovoltaic?
"The Best of the Leon Russell Festivals" DVD deepfreezefilms.com