Thank you Strawberryhill! It's nice having the science behind the observations. Knowing the analysis of the manure should help in balancing out the fertilizing menu.

I had the anectdotal information from some Avocado growers in Ventura County (CA) that outbreaks of Oak Root Fungus were brought under control after heavy mulches of fresh horse manure. I used copious amounts of it for years in Newhall and never had serious issues with fungi other than on specific, climatically unsuited roses. Too bad we can't buy that stuff in bags like we do others. Kim

Very interesting info Strawberryhill! I would be curious to know what the horses were eating that produced the manures tested. Would manure content test the same for horses fed bermuda grass, orchard grass, oat hay, timothy, alfalfa, another grass hay or legume, or any multitude of combinations?

Generally horse owners tend to feed the hay(s) that are most commonly grown in the area in which they live. Not always but often. Some horse owners do have trucked in different hays from great distances away (but that can get expensive!). Certain areas of the country particular hays simply grow better (some don't like the heat and favor cold/cool conditions while others thrive in the heat). Timothy for one grows better in cooler areas and is fairly expensive in Southern California as it has to be trucked in from a distance away. Alfalfa does great in the southwest and is a popular horse hay in southern California, but it can mold in the bale in areas with high humidity or if rained on, so horse owners may avoid it or not have access to it due to local conditions in other parts of the country. Also horses in particular stables may be fed grains while others not. So I'd be interested to know for the manures tested just what the horses were eating.

In addition, there are feed-through fly control products sometimes used that are effective in manure. It would depend on the active ingredients whether they might effect pests/beneficials in the garden. I've never fed any of these pest control feed throughs to my horses, so the question never came up for plants in my garden, and I haven't kept up with all the various offerings. However, I do recall reading several years ago or so that one at least had an ingredient that was potentially harmful to the horses that ate it (and may possibly have been removed in the newer products).

I'm providing a link to one of the catalogs with info on multiple of the currently-available products.

Melissa

Here is a link that might be useful: Fly Control Supplements

Does it have to be horse manure? I ALWAYS top dress with well rotted organic cow manure after every hard spring prune. It also forms a nice little weed barrier crust and then breaks down into the soil with each spring rain. I still get a little BS...which I HATE.

Susan, no it doesn't HAVE to be horse manure. The important information from the first post is:

"The most interesting research is how pseudomonas fluorescens in manure can suppress plant pathogens. Chicken manure is best, and least is cow manure. Vermicillium Wilt spores breed after 1 day of saturated soil, and black spot spores breed after 7 hours of wet leaves. From my experience horse manure dries fastest after a heavy rain, and the soggiest is lawn clippings, followed by tree bark. "

Follow this with your, "I still get a little BS...which I HATE." Perhaps, if you could find a convenient source for chicken or horse, you might be able to reduce or even eliminate your BS problem. Kim

Did someone say Verticillium wilt? Because I did a little research on this pesky problem a while back and found that Verticillium does not like broccoli! Detests it in fact.;) I was looking for interesting/more environmentally friendly ways to deal with it (had some wilted snapdragons that looked suspiciously as if VW was involved). Found many references to organic soil amendments being used instead of toxic chemicals. The one that caught my attention most was the one discussing using broccoli. Hmm that would be easy to try. So I pulled up the wilty snaps and filled the holes with chopped broccoli. Take that you nasty buggers, eat your broccoli!!!! Did it work? Well nothing else nearby collapsed (including plenty of volunteer tomatoes), so perhaps. I enjoyed myself regardless!

Have a bunch of other references if anyone is curious.

Melissa

Here is a link that might be useful: Soil and Wilt in Cauliflower

The high pH of the horse manure concerns me since the pH of my soil is already 7.3. I add magnessium sulphate (Epsom salts) because that is the only element that is low in it aside from adiing a little urea (the soil is extremely high in calcium) for nitrogen. Would the sulfer content be enough to counteract the pH of the manure, or is adding horse manure like adding oak leaves as mulch, doing little to affect the pH at all?

Steve

Clarification of the Rutgers Education info. about horse manure, regarding the high iron of 3614, that's ppm dry weight, and different from % dry wt. ratio of NPK, calcium, and magnesium.

The equal measurement is to the far right of the table. Here's in % lb/ton: N of 2.8, P of 1.4, K of 2.4, calcium of 1.2, magnesium of 0.4, sulfur of 0.2, and iron of 0.5. Now it looks much better, and the iron is not out of whack.

Adding lime to deodorize the stall varies with stables, so aged horse manure varies from 7 to 10 in pH (someone reported a 10 pH in a soil forum). The most accurate test done on the effect of different growing medium is found in this website: http://www.uky.edu/Ag/HLA/anderson/orgfert3.pdf

The above experiment is to learn about the efficiency of organic fertilizers and composts: fish emulsion, Omega 6-6-6, horse manure, cow manure, and worm castings.

Highlights of this study: "Pepper plants treated with Peter's are normal. Plants treated with cow manure are somewhat better. Plants with horse manure are smaller. In tomato: plants grown in the worm casting, the horse manure, and no fertilizer control are stunt. This demonstrates that the worm and horse manure were probably NOT fully composted and they stole nutrients from the mix.

The composted worm castings had a high pH, and very high nutrient levels. The composted cow manure had a very low pH and low phosphorus, and high levels of nitrogen, calcium, and magnesium. The composted horse manure had a very high pH and high phosphorus and potassium, with typical levels of nitrogen, calcium, and magnesium. But the plants performed poorly in horse manure, probably because this was INCOMPLETELY composted.

Their conclusion: Omega and fish emulsion fertilizer can be used to grow vegetable transplants. A 20% to 30% of composted cow manure may be effective for transplants ... but worm castings and horse manure were NOT effective.

My conclusion: it's always good to measure the pH of any manure before using. Someone reported a pH of 4.5 in their cow manure, while others reported a pH of 8 in a composted horse manure (it depends how much lime the stable uses to deodorize the stall).

In the UK garden forum, someone reported a low pH in the horse manure - so it all depends if lime is used in a particular stall.

Steve: I forget to answer your question regarding lowering pH of horse manure. It's important to add nitrogen to horse manure since the mixed in wood shavings and straw decomposes, robbing the soil of nitrogen. I mix alfalfa meal with horse manure when I mulch my roses.

Here's the best website I found to solve the pH and the nitrogen-deficiency problems in horse manure:

http://www.extension.iastate.edu/publications/PM820.pdf

As to why cow manure is so acidic, down to 4.5 range. Here's the answer from Cornell University:

A pH between 5.5 and 8.5 is optimal for compost microorganisms. As bacteria and fungi digest organic matter, they release organic acids. In the early stages of composting, these acids often accumulate. The resulting drop in pH encourages the growth of fungi and the breakdown of lignin and cellulose. Usually the organic acids become further broken down during the composting process. If the system becomes anaerobic, however, acid accumulation can lower the pH to 4.5, severely limiting microbial activity. In such cases, aeration usually is sufficient to return the compost pH to acceptable ranges.

For more info. on how composting can lower pH, see: http://compost.css.cornell.edu/chemistry.html

As to why cow manure is the least effective in suppressing plant pathogens, it's from the antibiotics that the livestock industry use, killing beneficial bacteria in the process.