Gardening in the Sky: Life in the Soil

Our gardeners applying beneficial nematodes. Photo by Timothy Schenck.
While many people think of soil as inert, it is actually a lush ecosystem teeming with bacteria, fungi, protozoa, and insects. For High Line gardeners, studying and nurturing the complex life of our soil is one of the most fascinating parts of the job. Supporting this underground ecosystem is also one of the best ways to keep our plants healthy and beautiful.

Recently, we began using microscopes to take a closer look at the hidden world beneath our feet. By mounting a camera on the microscope, we've been able to record many of the microorganisms present in our soil. These organisms help to form a complex food web, which extend above ground to include mammals and birds. And at the center of this web are bacteria. Before chemical fertilizer was developed, only bacteria had the capacity to convert atmospheric nitrogen into the form plants use. When other critters in the food web feed on bacteria, they release the nitrogen and other essential nutrients stored in the bacteria's bodies back into the soil, where it becomes available to plants.

Nematodes, like the one shown in the video below, are one of the many organisms that feed on bacteria. Different kinds of nematodes have different diets. We can tell by the mouthparts that this nematode feeds on bacteria.

Moving through the soil's pores on the surface of water films, amoebas also feed on bacteria. Single-celled organisms that exhibit a flowing motion are generally referred to as amoebas. Unlike some amoebas, this "naked" amoeba does not have a protective shell.

All the members of the soil food web take part in cycling nutrients. Their movements also help to aerate the soil and reduce compaction. However, not every microorganism is beneficial to plants; some can actually be quite harmful. Because we usually cannot identify organisms beyond very broad categories, we look at biological diversity and population ratios to get a sense of soil conditions. Some types of organisms should be quite numerous, while others should only be present in very small numbers. If different populations are properly balanced, we hope competition will keep potentially harmful organisms in check.

As we learn more about life in the soil, we look forward to sharing more images from this fascinating world with you.

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