I much directly into a Newer Spreader ($1300 ish), which is light enough I can drag it around the barn. After each stall, I put 1/2 cup 21-0-0 on top of the dirty bedding and about 1/3 quart pelleted lime. I spread about every 3-4 days depending on how many horses I have, and I spread directly into my fields with an ATV ($3000 used). Unless there is a big snowfall, I don’t have a manure pile. What small amount does accumulate due to snow sits for a year then goes into the garden.
I know people are going to say, “Don’t spread directly into your fields” but I am doing this per recommendations from Ohio State.
http://ohioline.osu.edu/factsheet/AGF-212
Why Does Horse Manure Stunt Crops?
Actually it doesn’t; but sawdust or wood shavings do. These wood products are the most common bedding used for horses. When horse manure and sawdust (or shavings) are put on soil the microorganisms in the soil start to break them down. Unfortunately, these wood products have a lot of carbon that the microorganisms use for energy but not enough nitrogen to build protein. In other words, the microorganisms have an unbalanced diet and they need nitrogen. They find that nitrogen in the soil and they collect it more efficiently than plants do. In fact, they do it so well that the plants growing in the soil can’t find enough nitrogen to grow properly. That’s called an “induced nitrogen deficiency” and it stunts crops.
The Nitrogen Enhancement System
The horse owner or the farmer can add nitrogen fertilizer to the manure/sawdust mix or to the soil. The added nitrogen can be used by the soil microorganisms to break down the manure/sawdust mixture. Therefore, they won’t need to steal soil nitrogen from the growing crops. The fertilizer should be added to the manure prior to spreading it on the soil. Another option is to work the fertilizer into the soil after the manure has been applied.
What Kind of Fertilizer and How Much?
Use only ammonium nitrate fertilizer with an analysis of 34-0-0 or ammonium sulfate with an analysis of 21-0-0. Other types of fertilizers (especially urea) can be lost into the air in a manure pile and do no good. Add about 10 pounds of ammonium nitrate or ammonium sulfate per ton of horse manure/sawdust mix. This is about 1/3 pound (about 1/2 cup) of ammonium nitrate or ammonium sulfate per 1,000-pound horse per day.