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Tips on How to Use Horse Manure for Compost

I am getting a huge truck load of horse manure this week and I would love some tips about how to use it. I've only been gardening 4 years now so compared most most of you I'm still a newbie :) My current garden is about 12'x12' and my plans for this load of manure is to let it compost until spring and then use the composting spot to plant another garden plot.

I do know to leave it piled up with a tarp over it to let it compost before using it in the garden but here are a few other questions:

I have read that horse manure is great for non-flowering or fruiting plants like lettuce or corn. I will grow some lettuce but I really love growing peppers, tomatoes, and cucumbers. Is there anything I can add to this pile that will make it more suitable for fruiting plants?

Horse manure is really "hot". Will it be hot enough to kill seeds from old weeds? I have quite a few big weeds growing in areas on our property that are too steep to mow.

Anything else I should know?

Greener Thumb
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Joined: Thu Sep 09, 2010 8:50 pm
Location: MO

Re: Tips on How to Use Horse Manure for Compost

Not sure what you mean by hot as there are multiple definitions. Hot as in high nitrogen and can 'burn' plants - this can happen with any fresh manure that has not composted yet. But I assume you're talking about hot temperatures, in other words, if you put those weeds in the pile with it, will it kill the seeds? The answer is yes, if the pile is hot enough and large enough to retain the heat for awhile. Also the outside edges are not as hot so make sure the seedy weeds are near the center, or at least get turned into the center during the hot phase.

Is this manure mixed with straw or shredded wood bedding? If so it already has some low-nitrogen 'browns' with it. You will have to evaluate the balance. If it's VERY hot and smells bad, it needs more browns - straw, sawdust, dry leaves, shredded paper. Ideally it should be about 140F. Mix in whatever materials seem appropriate, make sure to keep it moistened (damp, not drippy). Observe and adjust.

Careful with the tarp, it's OK to keep out heavy rains but an active hot pile needs to breathe so don't seal it off esp during the hot phase.

As to the flowering/fruiting vs. green growth, composting is the great equalizer and well balanced mixes will go toward a central point in terms of nutrients in the final product. Having said that, there are differences. I would not avoid using the compost completely on flowering and fruiting plants, but it may be a bit higher in N and lower in P than non-manure based composts. Or not. I tested a couple dozen bagged commercial composts in my area several years back, and found that N levels in manure based composts were all over the map. The highest of all the samples was my own home made compost, which had NO manure at all in it. So I wouldn't worry too much about where to use it. Generally speaking, any compost is better than no compost at all, especially if your soil is poor and in great need of compost anyway.

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Location: hawaii, zone 12a 587 ft elev.

Re: Tips on How to Use Horse Manure for Compost

As mentioned, good compost is usually made up of a blend of different materials not just one thing. Manures contain the nitrogen and that will be used by the bacteria and does help to heat up the pile. It still needs to be balanced with browns.
The pile needs to be at least 3 ft high, 3 ft wide and as long as it needs to be. It can be higher.

The browns and greens (fresh manure is a green because of the high nitrogen), should be layered and moistened as it is built. Once you have completed building the pile, don't add anything more to it because you want it to cook.

If it is done properly it should heat up and start to steam. To make the compost faster, after one week the pile should be turned incorporating the cold material from the outside and put into the middle. The more the compost is turned the faster you can make compost. The other way would be to turn the pile less frequently and let it sit for a longer time.
If you are letting the pile sit over winter, you still should try to turn it at least a few times to add air, turn in the material on the outside of the pile and to make sure it has the right moisture levels.

The final layer should be a brown. Tarps are used mainly for times when there is a lot of rain and the pile has too much water. Cardboard and burlap is sometimes used as a cover. If you are turning your pile less you can add air by inserting 4 inch pvc tubles that have holes drilled into the sides of the tube. The pvc tube is buried vertically in the middle of the pile with the one end sticking out near the top. It allows air to get to the middle of the pile.
Happy gardening in Hawaii. Gardens are where people grow.

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