. . . where the chicken poop is.
Seriously, though, chicken manure is super high in nitrogen. Plants love nitrogen; they grow more and larger leaves when they have an abundant supply of nitrogen. Grass blades are the 'leaves' of the plant.
Everywhere my broiler pen sits during the course of raising our meat birds each season later tells the tale. I can look out at my orchard and see every single spot the broiler pen was parked. Because the grass is greener. Way greener. And thicker.
My hope, in using the orchard as the location for the broiler pen, is that some of that nitrogen from the chicken manure is soaking down into the soil, where the fruit tree roots can soak it up and nourish the trees, making them strong and healthy. And more resistant to disease and insect pests.