If you pick up a handful of rich, black dirt, you’ll be holding a lot more than soil. That’s because healthy soil is a tiny ecosystem, complete with plants and animals. And it’s a good thing, too. This “organic matter” provides nutrients to plants—nutrients that you eat to make your body healthy.

Healthy soil isn’t only important for the food you eat. It’s also a key element in pretty much any ecosystem. Soil with a good level of organic matter retains more water, so it resists periods of drought. It’s also less likely to wash away in a heavy rain. And some of that plant matter takes carbon out of the atmosphere and keeps it sequestered for a very long time, so the more organic matter in our soils, the less CO2 is in the atmosphere causing havoc with our climate.

It’s long been thought that organic cultivation, which adds compost and other natural substances to the soil instead of chemical fertilizers, results in healthier soil with more organic matter. Now, new research proves it.

Researchers at the National Soil Project at Northeastern University collected more than 600 soil samples from both organic and so-called conventional farms located throughout the United States. They specifically wanted to measure the levels of humic substances—humic and fulvic acids—because these long-lived soil elements play a key role not only in the productivity of the soil, but also in water retention and carbon sequestration.

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The soil samples were tested with a variety of methods to determine a number of factors: the total percentage of organic matter, the concentration of humic and fulvic acids, and water retention. Because regional variation can have an impact on these factors, the test results were tabbed by location, as well as by farm management practices.

Not surprisingly, the results from all types of farms and all regions showed a wide range of variation. But when the researchers completed their statistical analysis of the samples, they found higher levels of organic matter, including the vital humic and fulvic acids, in organically managed soils.

The study also shows that organic farming can be a vital tool as we face increasing food insecurity due to climate change. Since it retains more water, organically managed soils can help combat climate-related droughts; and its heavier soil structure helps preserve topsoil losses due to erosion.

Possibly most notably, humic and fulvic acids remove climate-warming carbon from the atmosphere. “The findings support that not only is organic management, on average, healthier for soil health,” the researchers conclude, “it also suggests that organic is a critical tool for sequestering carbon in the soil, thus mitigating climate change through long-term greenhouse gas reduction.”

To read more about the project, visit the National Soil Project website.