After each crop we spread 10 cubic yards per acre of compost. The compost is made of food waste coming from San Francisco and Oakland. We have been using it since 2000 and it works well for us. The compost facility is south of Dixon so the trucking cost is relatively low. Each year I try to budget more money for compost.
We have been asking the compost supplier, Jepson Prairie Organics, to add one ton of limestone per 10 cubic yards. This enables us to get two jobs done at a time and the compost seems to flow better also. Our soil needs lots of calcium and we have some hungry calcium loving crops such as tomatoes.