In a previous post I discussed some research findings that suggest a healthy application of compost may be all you really need for your plants to thrive. I reviewed in another post on how I make compost, and several different methods to achieve results of rich “black gold.” In yet another series of posts (starting here) I reviewed my thoughts on growing soil. You might say, I am a believer in healthy soil.
So then, what actually is compost? Ideally compost is a dark, crumbly material that smells “earthy” that is decomposed organic materials such as leaves, grass, plant matter, manures, etc. In all actuality, composting happens naturally around us and we may not even realize it or take the time to appreciate it. The next time you are taking a hike in the woods, venture off the path and pick up a handful of the “black gold” and see what I mean. It will be earthy smelling, dark and crumbly, as well as a fantastic resource for plants. What you have just picked up is decades worth of fallen leaves and plant matter that has decomposed with nothing but mother nature to keep an eye on it. Depending on how you make your compost it should have most, if not all, of the macro and micronutrients that you garden will need for a healthy growing season.
So why do we make compost?
Besides the obvious benefit to our gardens there are “fringe benefits” as well of using and making your own compost.
1. Composting reduces the amount of landfill waste. Almost 60% of our municipal waste (13% yard waste, 12% food waste, 34% paper) can be composted and therefore be doing good work in our gardens as opposed to piling up in our landfills.
2. Composting will save you money (as opposed to buying organic inputs) while improving soil tilth, aeration, water holding capacity and returning much needed nutrients.
3. Compost can suppress some soil born disease by out competing the pathogens and adding beneficial microbes.
What are the basic considerations when making compost.
This question can be answered in a variety of ways, as it can be as difficult or as complicated as we want to make it. By now, you should know, that I prefer the K.I.S.S. (KEEP IT SUPER SIMPLE) method in just about anything I do. The only materials you really need, at the bare minimal input levels are carbon and nitrogen sources, water, and air. Sure a fork to turn it with, and some fancy barrels to roll it in are nice, but honestly you really only need three things.
Carbon sources (Browns): Fall leaves, corn stalks, straw*, paper, wood chips/sawdust.
Nitrogen sources (Greens): Vegetable waste, grass clippings, cow manure, horse manure, poultry manure, coffee grounds.
An ideal carbon to nitrogen ratio (C:N) is 30:1. This number is not crucial, but know that too much nitrogen will make it cook hotter, and too little will slow down the process. Do not be confused by the green and brown terms regarding carbon/nitrogen ingredients. Just because something is brown does not automatically render it a carbon source, this is a general statement as there are exceptions:
1. Coffee grounds are an excellent source of nitrogen (and calcium) for the compost pile even though it is brown.
2. Grass, while green, is an excellent nitrogen source, but when it dries to brown, becomes a carbon source. It is actually recommended to leave your grass clippings on the lawn as they will supply roughly 50% of the feeding for you lawn for the year. The same concerns that I mentioned below regarding straw, should be a consideration for grass as well. Unless you are sure the source of grass is chemical free, it should not be used. Many community composting sites have outlawed the use of grass clippings for this very reason.
3. More on manures in a few minutes.
4. I prefer to use most, if not all, of my kitchen waste in a vermicompost system. This will be covered in another post in detail, but if you do not utilize worm composting for castings, I would highly encourage any gardener to consider it.
5. I think I have covered fall leaves ad nauseum, so no need to be specific here other than use them as much, compost, vermicompost base and whenever you can.
Water should be added periodically to your compost pile on an as needed basis, and more importantly in the beginning when creating your pile. Rain may not be adequate to fulfill the hydration needs of a compost pile, 40%-60% moisture. To gauge water content of compost, take a handful of it and squeeze it into your fist. If there is no water leakage, it is likely too dry. If it drips more than a few drops it is too wet.
Air and temperature are typically regulated by similar methods, so I have decided to combine them here. Proper compost turning should give adequate airflow to the pile to create an aerobic process. If your compost pile is slimy or smells foul, it has likely gone anaerobic (lack of air) and could be in trouble. Turn it, turn it, turn it! Anaerobic composting has a high likelihood of growing pathogens as opposed to beneficial microbes and can cause serious health concerns.
You will know when your compost pile needs turned when the internal temperature cools below 140 (60 degrees Celsius) degrees Fahrenheit. At minimum, your pile should be turned at least monthly until finished, if you want compost in a reasonable time period. Ideally your pile should “cook” between 140 – 160 degrees Fahrenheit, that’s 60-71 degrees Celsius for our metric friends in the east, um….and north, well actually in the south too. OK for 98% of the world! Your compost pile may safely reach as high as 180 degrees Fahrenheit a few days after turning, but should fall to cooking levels within a few days. Composting temperatures reaching 160 degrees F. should be adequate to kill pathogens as well as weed seeds, anything above a sustained 160 degrees F. risks killing beneficial microbes as well.
If you do not have a compost thermometer it is suggested to dig into the pile and feel the internal temperature. If it is too hot to keep your hand in for more than a few seconds, it should be adequate. The pile should steam when creating any opening or turning. A small fee of $25 -$50 will save you the trouble of hand testing, as you can find a reasonable compost thermometer on Amazon.
There are a few other items that are required of a good compost pile that you do have some control over.
Just about any compost pile of any particular C:N ratio will cook in 1-2 years without any work (turning, watering, etc.). Obviously most people do not want to wait that long, therefore turning it can speed up the process and finish in as little as 2-3 months in ideal conditions. Depending on the crop utilization for your compost, it is recommended that a pile sit/cook for a minimum of 6 months if coming in direct contact with the actual fruit or root crops, especially if utilizing manures in your compost pile.
Microbes are likely the single most important component of composting, however you should have little input regarding this. Scattering a few scoops, or shovels of finished compost into you new mix, should get you started with an adequate microbial count. “Compost activators,” in my opinion, are a waste of time and money. They are mostly nitrogen with some microbes, but do little to gain any significant advantage in your compost pile compared to the cost. Most research suggests negligible or no advantage in using these products when compared to a few shovels of compost or garden soil.
Size & Outside Temperature.
The size of your compost pile is important. A compost pile larger than 3’x3’x3′ (Thats 1m x 1m x 1m for the other 98%) will be adequate for cooking. Any smaller than this and you will likely have trouble gaining enough thermal mass to reach desired cooking temperatures, resulting in a longer cook. A proper compost pile can be ready in 6 months if cooking over the winter, that same pile can process in half the time during warmer months, especially over the summer. Outside temperatures play a major factor in composting times, but they are not critical.
What should you not compost?
It is generally advisable to stay away from composting any manure from humans, cats, or dogs (any carnivore really) as the gut flora of these animals increase the likelihood of contaminating your pile with pathogens, even with perfect composting technique and influences. I will not say that this cannot be done safely, as it can be, but you better know EXACTLY what you are doing in these methods as the margin of error is significantly higher. It is my opinion that the risk does not outweigh the benefit in this type of composting, just don’t do it.
Obviously adding anything treated with herbicides or pesticides is not advisable as these products do not “cook off”, even though some references suggest that they will. If there is any question regarding the viability of your compost, take a cup full and plant a few peas in it or other easy to grow seeds. If the plant sprouts, then dies off, you may have an issue with an herbicide.
*It is becoming more apparent that straw, of any type, is becoming contaminated. Herbicidal products, such as Round-Up (glyphosate) has finally found its way into the product and even with the best composting techniques, may still be present in finished compost. I had been listening to a composting lecture Barbara Pleasant gave at a Mother Earth News conference a few years ago when she discussed these “preliminary findings.” I have since read several articles and spoke to a few people that have had significant failures in their plants that were attributed to herbicides being present in their compost piles due to glyphosate contaminated straw. It is highly recommended that unless you are absolutely positive of a clean source of straw, that you do not use it.
In a nutshell, gather some carbon and nitrogen sources, make a pile in the garden in the fall, and it should be ready by spring planting if you are remotely close. That’s how I do it….