[AlotOfReading]

Grass doesn't prove it's fertile before modern fertilizers. Natural grasslands are often resource-poor places that most other plants can't tolerate. We sometimes replace one for the other because our main crops (wheat, maize, rice, sorghum) are all grasses, but e.g. Versailles probably would have had more forests, lakes, or a vineyard if it didn't have the gardens and lawns.