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Earth Matter NY accepts and processes food scraps as part of the NYC Compost Project Local Organics Recovery Program funded by the NYC Department of Sanitation. Click here for more info.

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Featured here are some of the 14 students gathering "background information" in Lyn Neeley's biology class. From left to righ: Alesha, Eric, (adult educators Karen Hatch with bucket and  Shig Matsukawa with hat) Kenny, Emmanual, Ilyara, (steam from working compost pile,) Kianni and Laura.

I am a novice at composting. I live in Stuyvesant Town on 14th near Avenue B in Manhattan, and there are no composting centers there. I thought about burying food waste in an empty spot of a rose bed near my apartment but knew the sneaking would be too stressful. The complex’s new gardener has set up giant mulch bins for all the dry leaves that are collected in the fall (an incremental improvement on past wasteful gardening practices here) but composting has not come to StuyTown. Therefore I was happy to learn that I could bring my compost to Open Road Park on 11th Street between A and B.

I volunteer to help out the East Side Community High School class that meets in the greenhouse on Tuesdays, so I collected a good batch of food waste to bring with me. There were a few items that I was not sure belonged in compost. I knew that meat was not good for compost, but how about shrimp exoskeltons? What about those spots of carbon where I burned the pumpkin bread? The white paper towel I used to filter out the coffee grounds? The rusted steel wool pad that I had used to scrub my pots? Would the iron in the pad be helpful in supplying the nutrients to a plant like spinach or kale?

On Tuesday morning the class gathered to take the temperature and ph of each of three compost bins constructed there, and then to add any food waste and turn the compost. Before they started the work I asked them my questions and learned a lot. Shrimp shells are okay, but problematic in the city because they attract rats. White paper towels (no dye) are fine if they are torn up. No metals are allowed in compost.

The class members also informed me about the three composting bins set up in the greenhouse. The three bins are called Mesophilic, Thermophilic, and Hotbox. They are 3’ by 3’ by 3’ or 1 cubic yard for a reason. When a compost bin of this size is filled to the top with a cubic yard of food waste and leaves there is a critical mass of the materials needed for the thermophilic process. In this process the material heats to 140 degrees, killing the bad bacteria (otherwise known as pathogens) but leaving the good bacteria. The heat also speeds up the process of decay so that after about 12 weeks a cubic yard of dried leaves, cut up branches and food waste looks and smells like good rich soil.

Earthmatter and the class are doing an experiment with the three bins. Hotbox and Thermophilic (of course) use a thermophilic process for making compost. Mesophilic uses a mesophilic process.

The mesophilic bin does not reach 140 degrees. The food waste, soil, dried yard clippings and leaves in this bin are being added gradually—no critical mass to begin with. As people come to the park with their food waste is added in with an equal amount of soil. This bin is only 1/3 full at this point. Once a week the mesophilic compost is pulled out of the bin and turned by the students with shovels and pitchforks. Sticks and stalks and large food items are cut or chopped down to the size of a hand or smaller if possible in order to speed up the decay. The mesophilic process is slower and cooler.

The two thermophilic bins both were filled with a critical mass of one cubic yard of materials, but they are constructed differently. Like Mesophilic, Thermophilic has it’s contents pulled out and turned once a week and they look exactly alike. They are both constructed with a wood frame and covered with chicken wire, so there is plenty of ventilation. Hotbox is made of solid wood with about three pvc pipe vents on the sides. This bin does not get turned with shovels and pitchforks. It’s obviously less labor intensive and some say it makes better compost, but that’s what the students will find out. So far Thermophilic, and not Hotbox, looks and smells the most like it’s ready for the garden. Hotbox is a little more chunky, smelly, and fly infested.

Having the students explain what was going on in the greenhouse was a win/win for all of us. I learned a lot and the students communicated and reinforced their collective knowledge which will come handy when it’s time for them to write their papers on their science experiments.