We used to get living Christmas trees, and plant them in the yard in January. I have one at each end of the barn, one in the west yard and one in the front yard. I had a chicken pen for a couple of years between the trees by the barn. Mind you, our barn is a barn-shaped storage building I think it's 8x12, so the trees are pretty close together--maybe 20' apart. Last year I asked a neigbor (she is a soil scientist, with a consulting business to farmers, golf courses etc.) what was wrong with the pine tree in the front and west yard. She came over to take a look and make recommendations. As she rode up on her bike, she commented that the front yard pine looked fine--pretty typical. Same comment on the one in the west yard. Then we walked into the regular part of the yard and she saw the two by the barn...and said "OH! Now I see why you are concerned about the others. The two by the barn are lush and green with thick branches full of dark green needles. The other two are yellow-ish green with much thinner branching and needles, many of which are brown. All are the same species: eldarica, aka Goldwater Pine. Apparently two years worth of lots of chicken manure did a pretty good job. I buit a coop by the west yard tree, so hopefully it will eventually become as lush as the barn ones. No way to safely put a coop in the front yard, so I pounded in a bunch of fertilizer spikes. Probably time for more of them.
I regularly take the manure and put it at the base of plants that look like they need "something." I have yet to have anything except positive results.