How to Make Compost

Composting can look many different ways. It can be an active system or passive process; carefully observed or haphazardly managed. No matter what, organic materials will break down, but the end product of that decomposition will look very different depending on your composting approach. I think composting can be broken into two main categories: waste management or resource management. From a waste management standpoint, organic material can pile up wherever, preferably out of sight, and the end product is inconsequential, as the main goal is to simply deal with waste. But if you are looking at composting from a resource building standpoint, the process matters a great deal and the end product is invaluable. As soil degradation continues to be a real threat to food production in the US and beyond, composting our organic waste in a way that adds value to the land seems imperative. Below you will find some tips for composting from a resource management (and thus a soil building) perspective. And stayed tuned for a future blog about even more reasons why to compost.

Choose Your Composting Site.

Whether you choose to compost within some kind of vessel or structure or to just create a pile on your farm, considering the placement of your composting operation is important. Your pile should be somewhere easily accessible. People often tend to tuck it away out of sight, but one of the most important parts of a successful compost program is good observation. It should be in a location where you can keep an eye on it, easily add to it, and turn it when needed. Land should be relatively flat, some kind of cover is helpful, and access to water is handy. 

Determine Your Recipe.

As you build your compost piles (or revive existing piles), strive for the appropriate ratio of carbon to nitrogen. You can find really technical information about building a recipe, but recipes will vary depending on nitrogen, or “greens” (food waste, manure, fresh field residues, etc), and on available carbon, or “browns” (wood chips, straw, sawdust, etc). To the extent possible, add a diversity of materials and find a balance of wet and dry, “green” and “brown”, coarse and fine. Your own observations are invaluable as you dial in your recipe. Smell, temperature, and moisture of your pile are all indicators that a recipe is working (or not). Take copious notes as you are dialing in your recipe and make adjustments as necessary.

Build Your Pile.  

It is important to build the pile large enough to generate and hold enough heat to keep the aerobic microbes happy. Small piles will lose heat easily, especially in cooler temperatures. A pile should be at least one cubic yard (or 3’ x 3’ x 3’). If you go larger, turning and aerating becomes more important, because it is harder for air to move through more material, meaning you will find very different conditions (ie: temperatures, thus decomposition rate) in the middle of a big pile compared to the outside of a pile.

Keep it Active.

During active decomposition (which can take anywhere from 2-4 months depending on the conditions) keep your compost aerobic at all times. Do this by turning or fluffing as needed to prevent anaerobic microbes from developing. In piles, this can be done with a pitchfork, or tractor bucket/forks. In bin systems, this can be done with a compost auger. Anaerobic conditions are created when the pile is too wet, or too compact. You’ll know that your pile might be anaerobic if temperatures are low and the pile smells bad. 

Monitor Piles.

Check the temperature of the pile every few days and record your findings. To kill weed seeds and other harmful pathogens, all material in your pile should reach at least 131 °F for three consecutive days. If temperatures are low, check the moisture level. To determine the moisture of the pile, you can use a simple squeeze test. When material is picked up and squeezed it should hold together in a ball and you should just start to see moisture glistening between your fingers. If you squeeze and the material falls apart, add water. If you squeeze and water drips out, add carbon and aerate. If moisture is good, the pile may need to be aerated. Turn the pile and recheck the temperature the next day. If the pile is still active and moisture level is correct, the temperatures should increase with aeration.

Allow Time for Life to Build.

Temperatures will remain high throughout the primary and secondary (though less so) decomposition. Active decomposition is complete when temperatures drop, when there are no strong odors, and no visible food scraps remain (other than things like bones).  At this stage, compost is stable and should have high levels of bacteria. While compost could be used at this phase, with time this compost could be much more valuable to your soil. As compost piles sit, fungal activity takes off and higher order organisms that feed on bacteria can flourish. WIth little management (other than protecting piles from getting too wet or too dry and keeping it free of weed seeds), compost can go from a bacterially dominant amendment to one with a vast network of diverse micro and macroorganisms. It is this biologically active ecosystem that is most valuable to your soil.

Spread Compost.

Once your pile has finished curing (let’s say 1-2 months of sitting after it has stopped heating), you are ready to spread on garden beds, pastures, and field crops. Save a little of your finished compost to inoculate your next pile with all the life you have grown. Ideally, this is added once you have finished active decomposition, otherwise higher level organisms may be killed or forced out by high temperatures.

Questions?

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