Last year more than 60 percent of farm program spending-- $11 billion -- went to crop insurance.
This government-subsidized insurance not only pays farmers if they've had losses due to bad weather or pests, but also if crop prices drop.
UC Davis economist Dan Sumner is an author of the study that finds farmers have responded by changing what they grow -- and where and how they grow it -- because crop insurance will cover their losses:
SUMNER: "Crop insurance has tended to encourage producers to move to marginal lands, which tend to have more negative environmental consequences."
In some cases farmers have planted their crops too close to waterways or on land that's vulnerable to erosion.
Sumner says his study focused mainly on the Midwest and the South. But increasingly California farmers are taking advantage of the substantial crop insurance subsidies, and the same problems could occur here.