Activity – Hydrogen peroxide addition to soil and compost

Supplies

□2 glasses or clear plastic jars with lids □ 6 percent hydrogen peroxide (available at any drug store) □ Small shovel or other tool to dig up your samples □ Compost and “regular soil” from the ground

Instructions

1. Pour a hefty scoop of soil into one clear plastic jar and a hefty scoop of compost into the other jar.

2. Add three to four tablespoons of hydrogen peroxide.

3. Record your observations of the two samples.

Observations

Soil:

Compost:

Interpretation

When you combine hydrogen peroxide with soils or compost, it mainly reacts with the organic matter. The reaction results in a visible fizzing. This fizzing is due to the hydrogen peroxide resting with the organic matter and, in the process, producing carbon dioxide bubbles. The more organic matter in a sample, the more fizzing you will observe.

If we are ultimately putting the compost onto the soil, why can’t we mix feedstocks directly into the soil?

When you add feedstocks (garden waste, food waste, manure) directly onto or into the soil, the additions will likely not be well mixed and may be large chunks of different materials. This means that the nutrients in these feedstocks will also be patchy. At a microbial scale, the distance between those patches of resources can be huge, so instead of getting a well-balanced diet, there will be some areas with microbes that can slowly eat wood chips, and other areas with microbes that rapidly eat sugary waste like an apple slice. In a composting system, the feedstocks are small and well-mixed, so the waste products from each of those microbes will mix and create new food sources for other microbes, and it is a much more efficient—and quicker—way to break down all the waste.

Another consideration is that you are not controlling the air (nor the water, depending on your irrigation and watering system) in the soil, so conditions will not be ideal for microbes and worms to start decomposing your feedstock additions.

Microbes feeding on browns only (like wood chips in the soil) can “steal” the other nutrients, especially nitrogen, from the soil, and as a consequence, that nitrogen is not available to your plants. This competition for nutrients defeats the purpose of providing a soil amendment. Don’t worry— wood mulch is still a valuable management tool, but you have to be mindful of when and where you use it. Mulch is meant to protect the top of the soil and not be incorporated into the soil. We will discuss more about protecting the soil in Chapter 2 when we discuss the Healthy Soil Principles.