It sounds to me like you have a shortage of browns. Are you adding leaves, shredded paper or something of that nature to your kitchen waste?

Use your horse manure, old hay, old grain, and garbage and mix it all together in the composter, or at least layer it. Don't add too much water, it should just be damp, not soaking.

Maryrecord is right, you probably need more dryish materials. Too much high-nitrogen stuff tends to ferment more than compost -- you can tell by the smell (stink). More dry old hay would be just fine. Or dry weeds. Or straw.

Sue

I agree with Mary and Sue. When you put together grain, garbage and lawn clippings, you assembled things that are all high in nitrogen. Horse manure composts well because it contains some nitrogen (urine/feces) but lots of carbon (either sawdust or hay/straw). Try your barrel again with an eye towards providing about three times as much carbon as nitrogen.

Your kitchen waste, garbage, is mostly material with a low Nitrogen to Carbon ratio, too much Nitrogen and not enough Carbon. Adding manure only adds more Nitrogen to a mix that already has too much. Plus kitchen waste tends to have a very large amount of moisture in it which helps keep air from the bacteria that will be digesting that material.
You need some dry, high Carbon material to mix with that kitchen waste in a ratio of about 3 to 1, straw, shredded leaves, even paper would work.

You may want to read the FAQ link at the top of this forum. Its a great place for beginners to start.

Your manure is composting well because of the larger volume and its mixed with straw.

I use shredded junk mail as the carbon additions to my kitchen scraps.

Good sources of browns:
dried grass clippings or leaves
loose hay or straw (available free at feed stores if you sweep it)
torn household paper waste: facial tissues, dinner napkins, coffee filters, cereal & cracker boxes, toilet paper rolls, etc

Make it simple & easy for the family to collect for you.

What really worked to increase our supply of browns was to set a step-on trash can next to the usual kitchen garbage. Now along with kitchen waste we're dropping in the paper napkins & other papers that were just thrown out before.

In the bathrooms I added separate receptacles for paper waste first using a small paper sack, then containers lined with paper to remind us to throw the paper in there. :o)

The paperboard boxes from cereal, crackers, mac & cheese, etc. are flattened after emptying & slipped next to the trash for tearing up later. My teen son & friends can tear them up quickly while watching a movie and put them in a paper sack or box for me to take to the bin.

They no longer ask me if I want paper for composting & just put it in the containers for it. If they tear up first I'm comment, but if not I just tear up a bit when adding to the bins outside. It may take a bit longer if the pieces are large, but I don't fuss too much with it & it still makes compost eventually.