I think Sam means grass too, if there were a clear area after your ground roll, maximum performance chart for ground roll only:
Hard, dry runway; SL; 15c = 1200ft at MGTOW so roughly 365m. You'd be looking at a minimum of 440m on groundroll on short dry grass (excluding CAA safety factor)
But then again - if you're flying super-light ie: no more than an hour of fuel and only you on board... A little 10kt headwind component, you might be able to do it - my chart says 1000ft groundroll - so including the short dry grass but not the CAA safety factor you'd be looking at 365m.
I think it might be safer to fly a Cub in there....