Not exactly an elegant topic but to the gardener quite an important one.
As defined: “Compost is organic matter that has been decomposed and recycled as a fertilizer and soil amendment and is a key ingredient in organic farming. The process of composting requires simply piling up waste outdoors and waiting for the materials to break down from anywhere between 5-6 weeks or even more. Modern, methodical composting is a multi-step, closely monitored process with measured inputs of water, air and carbon and nitrogen-rich materials. The decomposition process is aided by shredding the plant matter, adding water and ensuring proper aeration by regularly turning the mixture. Worms and fungi further break up the material. Aerobic bacteria manage the chemical process by converting the inputs into heat, carbon dioxide and ammonium. The ammonium is further converted by bacteria into plant nourishing nitrites and nitrates. Compost can be rich in nutrients. It is used in gardens, landscaping, horticulture, and agriculture. The compost itself is beneficial for the land in many ways, such as a soil conditioner, a fertilizer, addition of vital humus or humic acids, and as a natural pesticide for soil.”
Sounds pretty simple—right? Just throw all your grass clippings, weeds, plant material from the garden, leaves and left over lettuce, egg shells, coffee grounds, meat fat trimmings, chunks of meat, chicken or fish and whatever comes off the table after a meal, or scraps from preparing that meal onto a heap. Turn it once in a while and water it a little to help with decomposing and let the worms and bugs take care of it for you.
Actually for one style of composting that is essentially how it’s done. What’s just been described above is referred to as “cold” composting and this is the way most gardeners accomplish “compost.” It takes a while (as long as two years–see aging below) and does provide you with a source of compost to be used for fertilizer or fill, but this method has its drawbacks. Major among them is that not enough heat is generated with this style of composting to kill off weed and plant seed and harmful bacteria and a number of other factors that come into play when you use it.
A second and I think more efficient, method of composting is “hot” composting. Hot composting provides for sufficient heat buildup in your pile to kill off human pathogens—-i.e. parasitic worms, eggs, bacteria, viruses and protozoa—-as well as plant disease organisms and seeds. Using the hot method makes it practical to even add things like spoiled fried chicken to the heap because the heat buildup breaks it down to a safe, usable substance.
This is a picture taken of our compost pile after one week of hot composting. One week ago the majority of this pile, were fresh fallen leaves which I ran through the shredder before adding to the pile. I watered down the leaves as I added each layer and then mixed them so there were no real dry spots. You can see the breakdown of the leaves beginning to happen. There was visible heat rising from the pile when I turned them over and you could feel the heat.
A CAUTION: Everyone has probably heard of spontaneous combustion, where a pile a trash, grass etc. suddenly begins to burn on its own. To avoid combustion of your compost you NEED to turn it over every few days. This helps release the excess heat that causes spontaneous combustion. If your pile should happen to combust and it’s sitting next to a building or under a tree it could prove pretty darn interesting.
Everyone has heard the term “fishing worms” at one time or another I’m sure. Well, fishing worms of the red wriggler variety (or pretty much any worm) can be a great ally in helping to turn your compost into useful fertilizer. You’ll want to add in a couple hundred worms to you pile. They help keep the pile loose, aid in ventilation, provide for good drainage and of course add their own fertilizer in the form of worm casings. I don’t know what the rate of reproduction of worms is but it seems that within a short time of adding them to the heap you can’t turn over any of it without uncovering a goodly handful of worms. If you fish—what better source of worms than your own compost heap.
OK. How do you go about getting a good hot compost pile going? In going over the requirements I decided that one of the key elements for ANY compost pile is:
Location. Downwind of the BBQ grill is at the top of the list as well as keeping it several feet from any combustible materials that might prove embarrassing to have go up in flames should spontaneous combustion occur. When considering location you want to keep it fairly accessible so you’re not often tempted to just toss out what should go into the pile.
If you decide to use the hot method you can put about anything in it—scraps of meat from the table, spoiled food of any kind and even cow or horse manure in addition to the usual veggie scraps etc. We don’t have easy access to horse or cow manure but we do have a couple dogs we need to clean up after. Tossing in some dog poop and then mixing it in to decay won’t hurt a bit. The amount of course depends on the size of your dog. We have a Chihuahua, Australian Cattle dog and then there’s Sam. Don’t know exactly what flavor Sam is but —well let’s just say that when the Sam makes a deposit it would make a T-Rex blush.
Construction: Some folks use pieces of chain link fencing, range fence, graduated fence and about any other form of fence available. We use spoiled hay/straw to make our “form.” We simply lay down 3-4 bales across the back and again for the front, 2-3 bales on each side and then place a couple more bales across each spot where the bales originally butted so they sort of lock the bales into place. I like to leave the front lower so it’s easier to turn the pile when needed.
Size: If you have the average sized garden or yard the size above is probably going to be too big for you but if it’s too big or two small the size is easily adjusted to meet your current needs by adding/removing bales or moving fence in or out.
There are a few essentials for a good hot compost pile:
Plenty of bulk—lots of stuff to put in the pile. Without sufficient bulk the heat won’t be retained very well. Adding in grass from your or your neighbors lawns is a good source of bulk and as the grass decays it adds nitrogen into the mix. (see–carbon/nitrogen below.) Leaves in the fall and anything in between that will decay can be used with this method. You can always throw in some hay or straw to help with the bulk but don’t layer it too thick—a couple of inches is plenty—or it can block thermal action.
Good aeration—to provide air to help heat buildup and provide oxygen for all those beneficial microbes that (hopefully) take up residence in your compost pile. Aeration also helps with the odor problem composting can present. Using 4” drain pipe with the holes in it works great for this if you can’t turn the pile on a fairly regular basis. Note: our piles run pretty warm so I turn about once every ten days or so. With some piles once a month might be sufficient. Use your best judgment on this.
Moisture—dry stuff doesn’t decay very well and it provides needed nutrients for all those microbes. Watering as you turn the pile is generally sufficient.
Decent carbon/nitrogen ration. This is going to get a bit technical but you for sure don’t have to follow this to the T. Microbes need nitrogen to add protein in the system and the carbon helps with about everything else. A carbon to nitrogen ratio of roughly 20 to 1 works great but don’t lose any sleep over it.
The following will give you a rough idea of what is going into your compost pile re carbon/nitrogen ratios. First is the by-product followed by the rough ratio of carbon to nitrogen. These are all approximates and will vary by time of year and location, soil etc.
Oat Straw. 70-1 Wheat Straw. 80-1 Hay. 13-1 Cow manure 20-1 Sawdust. All over the place at 100 to 500 -1 Grass. 10/25-1 Leaves. 40/80-1 Coffee grounds. (raid your local coffee shop) 20-1 Chicken manure. 10-1 Horse manure. 25-1 Corn stalks. (I’d suggest cutting or shredding before adding) 60-1
You can add in tomato vines, flower stalks, squash vines etc. Whatever happens to be available to you. We get spoiled hay for 1-2.00 a bale.
The ideal temperature for thermal compost is roughly 150 deg. F. (one of those long meat thermometers is great for checking temps ) At this temperature round worm and other eggs are destroyed along with most other harmful bacteria and viruses. Even salmonella, after just under a day is killed off. After roughly 2-3 weeks at 130 deg. or warmer you can be pretty certain your soil is safe to apply to your crops.
Aging of your compost: If along the way you’ve happened to add in any form of infected crops or animal matter you need to let your compost, using the thermal method, age for at least a year and at least two years if you’ve used the cold pile method. This helps ensure that all the harmful material has been destroyed. Otherwise, six months should be sufficient. You can check your compost material using radish seeds. Do a comparison test between a commercial seed starter and yours by adding in an even number of seeds (twenty is a good number) to each start container. Keep them evenly moistened and at 70 deg. F during that time. As they begin to germinate take notice of the percentage of seeds germinating in the commercial mix versus yours. If your germination percentage is noticeably less than the commercial mix (80% or less) you need to let your compost age more. Happy composting.