Seems like Terra Preta and biochar are the answer here. Terra Preta soils are the most fertile in the world. They can be replicated today by biochar. Biochar has shown extreme efficiency in nutrient retention, increased CEC, and much more efficient use of mineral fertilizers.

Why don't the Brazilians look back at the smart techniques of the ancient Amazonians? Biochar could slash fertilizer consumption and open an era of sustainable tropical agriculture.

The economics seem to go in favor of Terra Preta more and more as ag inputs get more expensive and GHG emissions from deforestation and agriculture become a bigger and bigger worry.

With biochar you can both sequester C and slash fertilizer use. The thousand year old human-made black soils in the Amazon, which are still exceptionally fertile today, show the way.