This is about food security.
Only 10% of Chinese soil is arable. This is what drives the South China Sea (Oil/Nat Gas & Fish) -fish are found near islands NOT in the middle of the ocean. Spratlys & Paracels.
This is also what drives Chinese building farms, roads, railways, and ports in Africa.
Food. 1.5 billion Chinese. 10% land to grow it on.
The Chinese "Belt & Road Initiative" (BRI) is largely food driven.
They want to get away from US farm output dependency, but the US is too efficient. ie Trade talks Round One signing coming up.