Fourth-generation rancher Loren Poncia calls himself a soil geek, and California wants to pay him for it. “If the soil is healthier, everything is better: the grass, the cows and the pocketbook,” said the rancher, gesturing toward the yellow perennial grasses streaked with green that cover Stemple Creek Ranch in the hills of Petaluma in Northern California. The planet’s climate might be better off, too. Increasingly more research shows that agricultural practices like cover cropping,…