It’s Earth Day, and we thought we’d dive into a strategy that’s great for the environment and also for your garden, composting! So, we spoke to Chair of our Green Team CJ Ruch. CJ is an avid gardener and has experience working with the Rutgers New Jersey Agricultural Experiment Station (NJAES). Here’s what he had to say.
Why You Should Compost
The next time you eat a piece of produce, take a minute to really think about how that fruit or vegetable came to exist. That fruit is the sum-total of many different inputs utilized by the plant during its life cycle. These inputs include: mineral nutrition derived from the soil, inputs from the farmer, and water. One can think of plants essentially as pumps, or even miners. They “harvest” the raw materials they need to complete their life cycles from the soil that hosts them. They convert these raw materials into plant structures, including the parts we consume.
In nature, the discarded portions of the plant are generally returned to the earth to be recycled and used by future organisms. However, we’ve a habit of throwing away this compostable waste, sequestering it in landfills where it will not be returned to the biosphere to be re-utilized plants. Among other problems, these wastes take up valuable landfill space and are essentially lost to future generations of plants.
The Science Behind Composting
Composting is decomposition of organic matter via biological means. This is typically accomplished by microorganisms broadly classified as “decomposers”, which include bacteria, fungi, protozoa, insects, and even larger fauna. This process can be accomplished anaerobically (without, or low oxygen) or aerobically (with oxygen). The process aerobically is the most efficient and fastest way to generate usable compost from raw organic matter. The aerobic composting process is thermophilic, meaning that the organisms involved are heat tolerant (thermophilic = ”heat loving”), the process generates temperatures up to 130°f or even higher. By reaching these temperatures, most pathogens and weed seeds present in the raw material are destroyed.
This process requires Oxygen, moisture, and time to generate usable compost, so it is important to aerate your compost occasionally, and add water when necessary. I tend to turn my compost over with a pitch fork about once a week, and whenever adding large amounts of new material and will add water during this process if it needs it. This generally means watering the compost every time you turn it in the summer.
The Carbon and Nitrogen Ratio
Different compostable items have different atomic constituencies, the two most important for our understanding are Carbon and Nitrogen. In fact, there is a Carbon:Nitrogen ratio of materials that should be maintained to ensure the most efficient results. Microorganisms utilize carbon as an energy source, and use nitrogen for protein synthesis. If the C:N ratio is too high (too much Carbon vs Nitrogen) the composting process moves slowly. If the C:N ratio is too low (Too much Nitrogen vs Carbon), excess Nitrogen is lost to the atmosphere as NH4 (Ammonia). The Ideal ratio is somewhere in the range of 25:1 up to 40:1 Carbon:Nitrogen.
Obviously, you’re not going to test every item you place in your compost to ensure an adequate ratio, basically a rule of thumb is fruit and vegetable scraps are higher in nitrogen than carbon, while dry items such as paper, and old leaves are higher in carbon than nitrogen.
Here are the Carbon:Nitrogen ratios of a few commonly composted items:
- Grass Clippings 20:1
- Leaves 50:1
- Straw 90:1
Generally, all you need to do is if you add a bunch of leaves, try to add a bunch of grass clippings to balance out the leaves. Even if you do not have the ratio perfect, it only means that it will take a little longer to generate usable compost.
Items that You Can Compost
- Plant scraps (fruits and vegetables, yard waste)
- Paper (paper towels included)
- Coffee Grounds
- Non-animal based food scraps
As far as meat, oils, fats, etc. are concerned, while they can be composted, it is not necessarily the best idea. They can create a putrid scent while decomposing, and they can attract less than desirable animals and other pests into the compost pile. There is also the possibility of exposure to pathogens such as e-coli and salmonella from these items. I have done it in the past, but cannot recommend it.
- Compost piles: The most common method, basically just a pile of organic material, turned over occasionally with a pitch fork. Optimal pile size will vary based on local environmental conditions, but a general rule of thumb is that a pile 5’x5’x3’ works well.
- Holding Units: These are containers and bins that raw organic material is placed into, to be held and agitated over time with a pitch fork.
- Turning units: these are bins to hold the compost, but also incorporate some means of turning over the holding container to aerate the compost, without having to turn over the materials with a fork. These are VERY easy to use, and are available online, and at some brick & mortar store locations.
- Large scale-rows: This method is used for commercial compost production, to USDA standards. Municipalities that collect yard waste may sell this bulk waste to companies that manufacture compost in this way.
So there you have it! If you’d like to learn more, I implore you to use the resources made available by NJAES. Good luck with you gardening!