The grounds left over after you brew a pot of coffee.
I've been using cow manure longer than a lot of you have been alive. Not only is it a good fertilizer,it's a great soil conditoner. If it's been composted,it's damned near impossible to over fertilize with it.
Now the real bomb as a fert is chicken manure,but I'm not telling how to use it. It's a family secret.
420G,I used to use carp in my plots. Catch a mess in the fall,throw 'em onto the prospective plot,cover them with dirt,then plow it up for planting in spring. I always felt like I was doing a public service getting those damned things out of the local creeks and rivers.
The local bear population started to boom in the late 80's,so I had to give my carp treatment up. Damned bears would root 'em out as soon I could put them in.
BTW,I like your use for deer. Damned walnut brained pests are overrunning the country,eating crops and causing wrecks and deaths. At least you've found something they're good for besides eating.
Remind me to rant about coyotes and coydogs later.