I would like to suggest that bare ground does not have to be the status quo in a chicken run, even if that run is small enough that they have stripped it of all vegetation. IMO, bare soil is well on it's way to becoming UN healthy soil. Mind you, this is just my opinion. In a bare chicken run, there is no vegetation to catch the rain run off. All there is is compacted soil, or muddy soil, or dusty soil, and more often than not, it is crusted with chicken poop which is very high in nitrogen, as well as other nutrients. These nutrients are great when balanced, and when they can soak into the soil, and feed the plants and micro-organisms in a well balanced yard. But a bare run with a nutrient overload becomes toxic even to the micro-organisms which would otherwise flourish in the soil. How to fix it? Deep litter. Get as much organic material as you can get your hands on, starting with lots of leaves, adding chopped hay, straw, weeds, grass clippings, stable litter, shavings from the coop, shredded trees from landscaping companies, and layer it into the run. The chickens will spend hours churning this stuff up, it will absorb the chicken poo, and over time, it will attract beneficial micro-organisms and insects, giving the chickens even more goodies to add to their diet. This DL will provide a deep spongy layer, similar to the humus found on a healthy forest floor, and the chicken poo will melt into the ground. NO smell!