Algae’s Role in Soil

February 19, 2024

In exceptionally healthy soil, it has been estimated that there should be about 8000 pounds of biology per acre. Of these 8000 pounds, there should be about 2600 pounds of bacteria, 1300 pounds of actinomycetes, 2600 pounds of fungi, 90 pounds of protozoa, 45 pounds of nematodes, 445 pounds of earthworms, 830 pounds of insects and other arthropods, and – less known – about 90 pounds of algae.

What is the role of algae in soil?

Algae are in some ways similar to bacteria, and in other ways very different. One important distinction is that algae are more like plants in the respect that they actually photosynthesize just like plants do. This is a really big deal because it means that a second source of energy is being produced – a second source of carbohydrates is being pumped into the ground to feed the soil life. These carbohydrates are quite often the limiting factor that is holding back the soil biology. Not always, but sometimes.

Now – unlike plants – algae do not have roots, leaves, or stems, although the cell walls do contain some cellulose. This is true of the green algae and the yellow green algae – but not for diatoms, which is another form of algae. The cell walls of diatoms are largely comprised of silica – a very rich source of it – and when the diatoms die, the skin now becomes what is known as diatomaceous earth.

Even though the activity of algae is largely limited to the top several inches of soil – because of their need for sunlight – they can still have a major impact on soil health. One of the major benefits is that they help jumpstart the soil aggregation process. As these algae photosynthesize, they produce sticky substances – glues – that help the soil maintain structure and aggregate stability.

Another major benefit is that they can also literally “create” new soil over time by producing carbonic acids that break down rock. Of course, if they can break down rock, they can also break down the much “softer” minerals that are already in the soil – making them more available to the plants, which is exactly what you as a farmer needs.

On the more negative side, soil algae are very sensitive. They can be almost completely destroyed from one application of harsh chemicals applied to soil. What we don’t know is how fast they can rebuild their populations without being re-introduced into the soil.

While we don’t have much personal experience with re-introducing algae, we do have text books that we can use to learn about it. Even more exciting is the fact that several well-known scientists and consultants are very impressed with the results. James White, for instance, did some incredible research on the algae that we now distribute. His research indicates that this particular strain of algae improves seed germination, and promotes seedling growth, root hair development, more root exudates, and encouraging the rhizophagy cycle.

If this is something that you want to experiment with, we are recommending to start with 8 ounces per acre,
and applying it 3-5 times per season, either in drip irrigation or foliar, although drip irrigation may be preferred.

In summary, I am excited about the possibilities that algae can bring to the table, and while we don’t yet have extensive personal experience with it, it is a proven product that has been heavily researched.