Compost

Composting is a great way to have a closed loop system at home and keep your plants happy without having to buy expensive chemical fertilizers, and it is a lot better for the environment too! The compounds from concentrated nitrogen or phosphorus fertilizers can spill into groundwater/rivers/the ocean and cause eutrophication, which leads to dense algae blooms. This can cause organisms in the water to die from lack of oxygen.

Composting also saves food scraps from going into the landfill and utilizes their nutrients to nourish new food production. Composting is also very fun!!! (We like to think so!) In a time when no one can leave their house to gather with others and form communal composting systems, this guide will show you how to create your own compost system at home. 

What Do I Need?

Food Scraps & Containers

For the most basic compost system, all you really need is fruit/veggie scraps! Grab a plastic container, such as a bin or bucket, and toss your food scraps in there. Make sure it's big enough to fit food scraps for long-term collecting. Those little countertop metal buckets are great for collecting a week's worth of scraps, but you want to also have a bigger container outside for the long haul. You can also add a handful of green weeds/grass and/or brown fallen leaves/straw to the compost whenever you dump your food scraps. Fresh greens add nitrogen to the finished product, and brown decaying matter add carbon to the compost. Nitrogen-Carbon-Potassium create nutrient-rich soil, and you can read more about it in this Compost Use and Soil Fertility Fact Sheet by The Center for Agriculture, Food, and the Environment at the University of Massachusetts Amherst. 

What Do I Not Need?

These things can create problems in your garden, soil, plants, and health if you consume food grown in soil with bad bacteria! 

Meat/Fish

Meat and fish are no goes! They create bad bad odors when decomposing and can introduce bacteria/pests that you don’t want in your compost.

Dairy

For the same reasons as meat, you don’t want dairy! No yogurt please. No eggs! But egg shells are fine.

Excessive Citrus

Citrus peels are very acidic and don’t create the best environment for the good bacteria working super hard in your compost pile. A little bit of citrus is okay! You probably don’t want to waste those orange peels by putting them in the trash, but be sparing.

Dog/Cat Poop

Dogs and cats are carnivores, unlike other animals, such as horses or cows, whose manure are great for compost. Dog and cat poop can contain bacteria and parasites that you don’t want being applied to your garden beds.

“Compostable” Plastic

This type of plastic needs hot hot HOT temperatures in order to decompose– far hotter than you’ll get in your backyard compost pile. In order to be decomposed, this type of plastic needs to go to an industrial compost facility.

What Do I Want in my Compost Piles?

• Food scraps
• Lots of nutrients!! Bugs/bacteria/fungi love to break these down!!
• Straw
• Also great for covering up sprouting cover crop
• Straw adds structure and lots of carbon to a compost pile
• Greens
• Greens are great! Leafy Greens! Flowery Greens! Tall Greens! Herbs! Compost loves them all for the nitrogen they provide to the finished product
• Weeds/garden clippings are what the Kresge Garden usually uses for greens
• Pruned sage/ other fragrant herbs make for really fun compost piles as they diffuse the smell of the rotting food scraps a bit
• Manure
• Horse/cow/rabbit/chicken manure are great for compost
• At the Kresge Garden, we’ve found our compost breaks down way better when we have access to manure for it
• Compost will break down regardless but can act a bit different depending on the inputs (too much straw can be drying, no manure can be slimy, etc)
• The science behind this is that the high nitrogen content of manure (why it's often used as fertilizer!) helps the bacteria in the compost piles break down the other stuff faster, which heats up the piles

What Do I Do?

1. Build your pile!

When you’ve obtained the 3-4 ingredients for your very first compost pile, it's time to layer! FUN FACT: the ideal shape of a compost pile would be a sphere. Because creating a sphere is pretty impossible, try to get the shape of your pile as close to a cube as possible. At the Kresge Garden, we usually start with a layer of straw at the bottom and end with a layer of straw at the top to keep moisture in. When you create your pile, find an order to layer in and stick with it (straw, food scraps, greens, manure, repeat). Keep layering until your pile is the height you want it (extra points for taller piles). It's super cool to be able to see the layers in your pile once you’ve finished. These layers will become less and less prominent as the pile breaks down and gets flipped. When you’re not working with your pile, keep it covered with a tarp, and secure with rocks so they don't blow away.

2. Maintain your pile(s)!

When your pile first gets created, there is a lot of oxygen and nutrients. The rapid and intense breakdown that happens for the next few days causes the temperature at the core of the pile to soar. It tends to peak between 120-170 degrees Fahrenheit, and then drop back down. FUN FACT: if you wrap potatoes in foil and leave them in your compost pile for like a day, you’ll have baked potatoes! They might taste like compost, but we’ve never tried it. 

Due to this rapid rise and fall of temp, you can take your piles temperature to figure out when you need to flip them. If you don't have a thermometer you can use, you can also see when the piles are storing a lot of heat if they let out steam once you start moving around and oxygenating the layers. Once the piles' temperatures start to drop again, flip! We have a special compost thermometer at the garden, but usually we flip them every 3 days or so. In the winter, we can flip them less since it's colder and takes more time to heat up. 

When it comes time to flip, pick an area next to your pile and take scoops from the top of your pile and place them on this new area. The pile should essentially be upside down from how it started when you are finished. The goal here to mix everything up and reinvigorate the pile with oxygen. Try to keep it a cube-ish shape still! You might notice steam when you get towards the center of the pile, this is totally normal and shows just how hot it gets in there! You might also notice some white, moldy stuff and a particularly foul smell. This can mean your pile has started to go into anaerobic decomposition. This is totally fine as you’re adding more oxygen as you flip! There are certain compost systems that decompose anaerobically (tubs of scraps you leave in the corner of your yard without mixing for months and months as an example). These systems decompose much more slowly!

Keep your piles covered! Tarps do a great job for this and keep some of the smell/flies contained (be prepared for possible clouds of flies when you lift the tarps up). When piles get super super dry in hot weather, the composting process can be slowed way down. If you notice a particularly dry pile, give it a lil water. 

When Am I Done?

It's hard to give an exact timeline as every pile has different components and behaves differently. However, you can tell when compost is finished if it looks like rich soil and smells earthy and sweet. You shouldn’t see any signs of decay/rotting– just nice, nice soil. When it reaches this stage, you’re ready to sprinkle it on your garden beds/incorporate it in when digging and have super happy dirt and plants! 

Don’t plant anything in pure compost. It's far too rich and can burn the roots with its high nitrogen content. It also gets very muddy when watered and doesn’t drain well.

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This page was written by Rivelin Wetherill (May 2020) and edited by Ashlyn Salao (September 2020).