One of my general rules I follow for terrain on my blog is that it must be easy and cheap to make, everyone's time and pockets are pretty stretched already. I think expensive complicated stuff is not worth it because you can probably buy something that will be better unless you are a great terrain builder or just want custom made.
Now ploughed fields are pretty darn easy to make.
Take a suitable base, in my case hardboard, that's what we call it here, cut to desired shape.
Apply white glue and cover with sand.
Prime or base in chosen colour.
Followed by drybrushing of various shades of browns.
Easy, cheap and it looks very good!