Horse manure as a fertilizer

Pjn106 at Pjn106 at
Thu Oct 5 12:03:01 EDT 2000

I began using horse manure with sawdust bedding this year. I had some 
reservations about using sawdust based on what I've read, but I couldn't pass 
it up because unlimited amounts are available, and I get it delivered for 
free. I also just let the material sit for six months in a windrow about 5 
feet high by 5 feet wide before applying it to my fields. I found that some 
of it was moist, but most of it was quite dry even though it had been exposed 
to a lot of rain. The moist areas had broken down nicely while the sawdust in 
the dry areas had apparently decomposed very little. I applied this 
relatively undecomposed material at the rate of 20 tons/acre in April, tilled 
it under with a rye cover crop and put in transplants of a variety of 
vegetables about 3 weeks later. I applied no other fertilizer. These initial 
plants did not fair well for the first few weeks and appeared to show signs 
of nitrogen defficiency. I suspected that the sawdust was "tying up" nitrogen 
in the soil. Fortunately, the plants recovered and actually grew and yielded 
quite well as the season progressed. Sweet corn germinated well and grew 
exceptionally well with no other fertilizer. I suspect that nutrients 
eventually became available to the plants as the sawdust decomposed over the 
course of the season. Weed seeds were not a problem initially, but I suspect 
that the rye cover crop suppressed germination. By the end of the season, the 
texture of my clay soil was greatly improved. 

This spring after determining that the mixture did not decompose well, I set 
out to make a high quality finished compost with it. Here are some 
observations/tips based on my experience...

-The pine shavings will take several months to break down under ideal 
conditions. If      the condtions are not ideal, it will take much, much 

-Try to determine the carbon/nitrogen ratio in the mixture. This will be 
contingent upon the relative amounts of pine shavings and manure. The pine 
shavings will need ample nitrogen to decompose. Build your pile so that the 
overall carbon/nitrogen ratio is around 30/1. Green grass clippings work well 
for N; straw works well for C.Temp. should rise to more than 150 deg. F. and 
remain above 150 for several weeks. That will kill most of the viable weed 
seeds that pass through the horse. Weed seeds will be present regardless of 
where the manure is collected .

-It is essential that all the material in the pile is always moist. If not, 
the pine shavings will take forever to break down. I use a couple of drip 
tape lines for each windrow and add water as necessary when I turn the pile.

-Turn the pile at least twice. More frequent turning will hasten 

-Cover the pile with straw or soil.

I added lots of green grass clippings, some old hay, and some straw to the 
manure/sawdust mixture, kept it moist at all times, and turned it four times. 
After 6 months the sawdust had broken down very well.

Next year I am going to continue to experiment with different compost 
mixtures, and I will test the soil frequently to get a handle on how it's 
affecting my soil. I would suggest that you also use soil tests to determine 
what's going on, especially if you decide to take the lasse faire approach 
and just let the stuff sit for 6 months. Good luck and let me know how it 
works out for you. 

Jan Nagel
Rolling Hills Farm
Bedminster, PA  

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