Soils 101: Building Soil with Compost

The idea of building soil might sound a bit strange. How do you build something that appears to have no real structure? Soil building simply means to improve both the chemical makeup and the physical characteristics of the soil so that it can sustain quality plant growth. This is done over time but more quickly with the use of organic materials (amendments) such as compost. It can also include the addition of manures, natural fertilizers or growing green manure crops (crops grown to simply turn over into the soil) which will decay and increase the organic matter in the soil.

If compost is so critical to building soil, what is it? Compost is the result of a controlled, aerobic (oxygen required) process that converts organic materials (leaves, grass clippings, appropriate food scraps, etc) into a nutrient-rich soil amendment or mulch. It is dark, crumbly and loaded with microbes. As mentioned in last month’s article, microbes are an essential part of having great soil for plant growth and they are needed to break down organic matter into compost which substantially enriches soil for maximum plant growth. So, is compost beneficial in ways other than introducing microbes into the soil? The answer is a solid, yes. Incorporating compost builds soil by:

• Improving soil structure to allow for improved air and water movement.
• Improving moisture and nutrient retention, regenerating poor soils.
• Attracting beneficial organisms to the soil, which can reduce the need for pesticides and fertilizers.
• Sequestering carbon in the soil and building resiliency to the impacts of climate change.
• Promoting healthy root systems and higher crop yields.

Learn more about the compost process, including what can and cannot be composted. Though compost can be purchased in bags or in bulk, it can also be a relatively easy DIY project as part of the school garden. Composting options are limitless and curriculum connections are abundant. As always, dream big, but start small. One simple starter idea is “baking” a compost cake, a fun, hands-on activity.