Thanks to all that responded there was some guess's i would not thought of.
 In this case the answer is rye drilled on the field border last fall as a cover. One thing of interest is that  strip still has some moisture in the soil profile that might explain why the plants are still green. It was a balancing act because the upper part of the landscape was shorted of moisture due to the rye drying the soil in the seed zone so some seeds didn't emerge, but the rest in other parts came up fine. Now my question is what is the reason why there is more soil moisture where the rye cover is?