So, I'm trying to picture in my mind what that field is going to look like when those huge radishes die and decompose.  Will it leave an uneven soil surface?  Will it leave a "hole" where it was growing?  Will that soil heave thru winter and fill in, or are you going to have an uneven planting bed?

Again, wouldn't it be better to have a high plant density, smaller radishes, and lots of roots penetrating down thru the soil? 

Am I missing something here?