In the CA regs for upland game, the rule is that you can hunt over anything that is "the result of normal agricultural operations." So, once a field has been harvested, the seeds or melons left on the ground are completely legit for hunting grounds. Per the regs, one can't just knock down a crop and leave it for bait, but there are other reasons for knocking down crops and leaving them on the ground. About 15 or 20 years ago the owner of the best wild pheasant fields in the Imperial Valley got so upset about asparagus prices that he disked all his fields and just left the asparagus there. Pheasants were running around everywhere, but not for long.