John K Jordan
>>>I have to second the geotextile.
The overwhelming advice from farmers and builders is to use geotextile in such situations. It works in a variety of soil and subsoil conditions. Some provide anecdotal "evidence" questioning the need in specific cases and some cases indeed don't benefit, but it's good insurance for universal use in a huge variety of conditions. I consider it as important as a foundation for a building, as important to paying attention to the frost line. Just my opinion (and the experiences related by other farmers and builder friends.) It's cheap insurance.
The use of geotextile is required by certain government agencies that provide funding to individual for ag-related improvements.