I just finished with a NRCS guy............and found out I don't really understand soil erosion.

We maintain a 10-15 ft greenbelt around every field.........inner and outer borders.  For example, if a ditch runs thru a field, there will be 10ft of green along each side. 

I thought that if there were no washed out cut areas in the crop ground, the waterways were dished out without high edges, and there is no soil buildup in the grassed areas at the bottom of hills, etc., that soil erosion was probably pretty much "under control"............ie, if there are no new nor deepened gullies, and there is no evidence of "moved" soil in the green fringes, that the soil must not have moved.

I was told that erosion is based solely on tillage practices and slopes of fields..........and that the amount of soil lost cannot be measured physically, that it can only be "computed", based upon charts established by some professors in-------I think---------Ohio.

The Rusl II index??

Explain to me that if there is no evidence of movement, how there can be significant erosion? 

I can see where certain tillage practices can increase the probability of erosion, but to stand on the fact that there IS erosion because there OUGHT to be erosion does not make a lot of sense to me.

Educate me.

Thanks for the edification.......in advance.  (Don't look for any compensation for your edifying comments--------I just paid fertilizer bills.)