Suzy's Chicken Tractor vs. The Lawn
When I was first deciding if I wanted a tractor, I asked this question. What the heck is it going to do to my lawn? I see other people ask this question from time to time. Now I have the answer, and I thought I would share it. Here are some photos of what my tractor does to my lawn in a week.
Here are my facts:
I have four hens in a 4x8 run. I move the coop and run daily (which takes less then five minutes). My lawn is a pretty well-established mix of grass and weeds. These photos were taken in October in Central PA. The weather had been partly rainy, and partly sunny that week. It takes a full week for my lawn to recover from a single day with the chickens. There is a trail of little rectangles where the tractor had been. Sometimes the chickens leave me little dust-bath holes. They look a lot like the holes I dig weekly with our zero-turn mower, though, so we're kind of used to them.
Here are my photos:

The hens are in their tractor scratching up my grass.

The hens were here yesterday.

The hens were here 2 days ago.

The hens were here 3 days ago.

The hens were here 4 days ago.


The hens were here 5 days ago.


The hens were here 6 days ago.


I couldn't be sure where the hens were on the previous Sunday.
The lawn had recovered.
Here's a shot of the total area where the tractor had traveled during the week.
Update for November: This month was different than earlier months. The grass was barely growing anymore, so it didn't recover as quickly. But the chickens weren't digging as much, either. Maybe they didn't need to cool down in the dirt so much. Maybe the frost had killed the yummy stuff. Anyway, my lawn wasn't as terrible looking after a day with the chickens. But it took a much longer time for the chicken remnants to fade.

the coop and
days 1 and 2
days 3, 4, and 5
days 6, and 7
days 8, and 9

days 10, and 11
The lawn was still pretty
rugged two weeks after
the hens had occupied it.
Update for December/January/February: I changed my system once the weather included days that never warmed up above freezing. I am now moving my tractor only once a week. I need to be near electricity for my water-heater, and I want the girls to be close to the garage for emergency shelter. It's also a much bigger job to move the tractor now that I have a wind break built out of very heavy, water-logged straw bales and leftover plywood w/cinder blocks. Here's what's happening to my lawn under these conditions. I'm crossing my fingers for a quick rebound come Spring.

These three rectangles are really obvious.
Each one housed the hens for a week.

Here's a look of the whole area in
March. A bunch of stray pine shavings
and lovely bright green rectangles. Pretty small impact overall.