1.     The compost will continue to breakdown to a humus rich substance, feeding beneficial micro-organisms in the soil and enhancing the “soil food web”.

2.     The organic acids in the compost will help mobilize the soil particles, causing them to form aggregates called “soil peds”.  rent a car bulgariaThis has the effect of loosing the soil (i.e., increasing soil porosity) and enhancing infiltration and moisture retention during the low rainfall months. 

3.     This loosening effect also enables plant roots to reach further down into the soil, resulting in healthier plants along with decreased soil erosion.

4.     As the soil begins to warm up again next spring, the soil biology will come alive, the nutrients in the compost will be released and the plants will thrive.  [Note: Spring is the worst time to get back on the pasture with farm equipment because of the likelihood of soil compaction. If you spread the compost in the fall, the job will already be done and you will not run this risk.

5.     This strategy also applies to spreading compost in your landscape areas and vegetable garden. 

I recently took a trailer load of 60-day old horse manure compost to our family friends’ home for use in their garden - and as an experiment, we screened the mix on a ½-inch screen.  It took approximately 45 minutes for us to screen two cubic yards and to move the coarse and fine fractions with a wheel barrow to respective holding piles in the back yard. 

What we learned is that the ½-inch plus “lumps and bumps” comprised about 1/3 of the total volume and that the remaining 2/3 was mostly fine wood particles.  My operating theory is that the majority of the nutrients are contained in the “lumps and bumps” and so I suggested tilling this material into their vegetable garden and spreading around the base of their landscaping plants.  In turn, I suggested that the fines be used as a mulch or weed barrier in their landscaping.  I will be doing laboratory testing on these two fractions this winter to learn more about how they differ in nutrient value.

My Response:
As I understand it from several of our veterinarian clients, a horse’s digestive system is only 17% to 20% efficient. Consequently, much of the hay passes through the gut and the manure has a very high cellulose content. Cellulose is resilient to biologic decomposition and therefore, even after composting, the manure balls will retain some of their structure resulting in a lumpy and bumpy compost. If you break into one of these lumps, you will see that it is dark throughout and is no longer manure. Often, it also has white specks throughout – these are Actinomycetes, a type of fungi that is working to break down the residual cellulose. This is also true of loose hay as well as straw used for bedding.

Bagged potting mix of every variety has been screened (and typically blended with other products), resulting in a uniform texture. This look and texture can be accomplished with your compost in one of four ways:

1. If you use a pasture vacuum, the manure balls will be macerated as they are drawn past the impeller, thus resulting in a uniform texture going into the compost system. By providing a fine texture material at this point, your composting time will also decrease significantly. We are in conversation with Greystone Pasture Vacs adn considering a working relationship to offer discounts when both a Greystone Pasture Vac and an O2Compost Training Program are purchased.
2. Following composting, you can screen the mix. I have built a 3-foot by 8-foot screen using 2″ x 4″s and hardware mesh, and it works quite well. Putting the screen on a ~30 degree slope, I toss some compost at the top end and then separate the fine material (”fines”) from the coarse material (”overs”) using a wide push broom. The broom is gentle on the hardware mesh and keeps the screen openings free of compost build-up. Note that drier compost is easier to screen.I place the screen overs (i.e., the lumps and bumps) around my landscaping plants (rhodendrons, azaleas and evergreens) – this is where the majority of the nutrients reside. I then use the fines as mulch layer between the plants as a weed barrier. This is somewhat labor intensive but it makes a great job for youngsters who want to make a few dollars. In fact, selling the screened compost (both fines and overs) in bags can yield a very nice income stream for teenagers. If this is of interest to you, please listen to the audio testimonial by Robert Garofalo.
3. Some of our clients take their finished compost and run it through a garden-sized limb shredder. This, no doubt, is also somewhat labor intensive but it reduces all of the lumps and bumps into a uniform fine texture. Many of these clients are using the shredded compost back in the stall as bedding. You can also combine screening with shredding of the coarse materials to oprovie a superior potting media.
4. The last way to reduce the lumps and bumps is the easiest, but it also takes the longest. Placing the finished compost in a holding pile on soil will encourage earthworms to find it and do the hard work for you. It helps to tarp the pile and it is important to keep the pile very wet, almost saturated. This process usually takes 6 to 12 months but, if you are not in a hurry, it will not only reduce the lumps and bumps to a minimum, it will also produce a batch of worm castings that have magical properties. Ohio State University has done a considerable amount of research on the benefits of using work castings in greenhouse applications – add 10% to any bagged product to provide optimum growing conditions. Castings can also be sold in small buckets and bags for top dollar.

ANSWER:   It sounds like everything is going as planned. In general, heat results from the biologic activity during the first 21-30 days but the actual duration of heat generation is a function of the available carbon and the amount of nitrogen in the feedstocks. With horse manure composting, the readily available carbon – simple sugars, proteins, etc. – are utilized quickly leaving the more resilient forms of carbon (cellulose and lignin) to be degraded over time. As as result, the pile temperature tends to jump up quickly and then fall off in 3 to 4 weeks. This is referred to as the “active phase”.

Following the active phase, the compost pile transitions into what we call “curing’. While active composting is a bacterial-driven process, curing is a fungal-driven process and takes place at cooler temperatures. You should see mushrooms growing on top and a white fibrous material growing in the top 12-18 inches. This is called actinomycetes and it is a very good thing given that it is working on the cellulose in the manure balls and lignin in the bedding. To produce a truly stable product, curing can take 30-60 days following active composting.

The one thing to watch for is the moisture content of your mix. Pile temperatures will plummet if the moisture content drops much below 45%. The mix should fee wet to the touch and when you squeeze a handful, you should be able to get a drip or two or a bead of water between your fingers. To determine this, take a posthole digger and dig a vertical hole and see what the materials look like, to to bottom.

Also, when we meet the oxygen demand of the micro-organisms during the active phase, additional airflow will actually cool the pile down because we are displacing the hot air with cooler air. To increase the pile temperature, try reducing the airflow and see if the pile temperatures rebound at all. If your mix is wet and you don’t see a rebound, then you are likely in the curing phase.