[Foobar]

I'm planning to top some of my fields with a scythe.  I'm thinking that the stalks will just lie around on the top of the grass and look rather ... errr ... unsightly .  Will they rot down or will they hang around for ages and possibly rot on the top of the good grass underneath?
Am I right in thinking a mechanical topper crunches them up in to smaller pieces, so this is less of an issue then?
If I do it with the sheep still in the field, will the sheep eat said toppings and thus leave the field a bit tidier?

[Still playing with tractors]

Yes a flail will mulch the cut grass. a topper only tops the longer stalks.

The sheep will probably eat some of the cut grass but they will prefer the fresh stuff underneath. most will rot and blow away in a strong wind.

[smudger]

If grass is very thick it will ruin the grass below so might be better to rake it off. If its just the thin seedy grass tops I wouldn't worry (or if its short grass). When we got are haylage cut I always went round and raked away the bits the baler didn't collect as it just rotted and smothered the grass.