An article in the recent issue of the Journal of Soil and Water Conservation reports that "filling ephemeral gullies on an annual basis during tillage operations may be more harmful to soil and water resources than previously realized."
The study finds that "routine filling of empheral gully channels during tillage practices may result in markedly higher rates of soil loss as compared to allowing these gullies to persist on the landscape, demonstrating a further advantage of adopting no-till management practices."
News release from the USDA Agricultural Research Service:
Gordon, L.M., S.J. Bennett, C.V. Alonso, and R.L. Bingner. 2008. Modeling long-term soil losses on agricultural fields due to ephemeral gully erosion. Journal of Soil and Water Conservation 63(4):173-181.