A website from UGA Cooperative Extension

There are many different things that you can add to your soil. You may see ads for different products claiming that they’ll do miracles for your garden. Alternatively, maybe you’ve always seen your grandparents put a special mixture on their soil and it did wonderfully every year. Soil is alive with microbes and complex chemical reactions that are happening all the time. The amendments that we add may be helpful to those processes. Let’s talk about some common soil amendments and what they do to the soil

Real quick, what is a soil amendment? These amendments have nothing to do with our constitution. Rather, they are things that we mix in or incorporate into the soil. The overall goal of an amendment is to improve soil quality. That may be done by adjusting pH, adding nutrients, building organic matter, increasing soil biodiversity, or improving soil drainage. Amendments can be organic (from something that was alive) or inorganic (mined or man-made).

Fertilizer and lime are two of the most obvious soil amendments. Synthetic fertilizer provides a quick boost to the plants, but doesn’t really improve soil quality over time. Organic fertilizers must be broken down to be available to the plants, therefore, they will fertilize over a period. Lime raises the pH of the soil and makes the nutrients more available to plants. You can have too much of a good thing and over apply lime, resulting in a pH that is too high.

Coffee grounds can be added to soil. They will build organic matter in the soil. They also attract earthworms. Coffee grounds don’t have a big impact on the soil pH if you rinse them first. They can also be used in compost as a green material because they have nitrogen.

Compost is another amendment that people like to use. Compost is a great way to boost the quality of your soil because it builds organic matter. Compost will release nutrients to your soil over time. Releasing nutrients over time makes your plants use the nutrients more efficiently and gives you even growth throughout the season. One issue with growing plants in compost is that compost raises the pH of the soil. Growing in 100% compost can lead to nutrient deficiency problems because the pH is too high. Mixing compost with soil will help alleviate this problem.

Mycorrhizae can be added to the soil. Mycorrhizae are a fungus that attach to the roots of your plants. This fungus becomes like an additional network of roots. They will pass nutrients up the plant and the plant will send energy down to the fungus. It is a symbiotic relationship. Mycorrhizae can be beneficial to plants, but they’re not always effective. If there is too much phosphorus in your soil, the fungus won’t grow.

Compost tea is made from compost. You add the tea to plants to increase the microbes there. We need microbes in the soil, and the issue with this is that we don’t know all the microbes that we’re adding. There could be E.coli in the tea. A simpler thing to do would be to add the compost straight to the plants, and not worry about the tea.

I would recommend caution when looking into new products to add to your soil. There are many things out there and not all of them do what they claim. If you have questions about soil amendments, contact your County Extension Office or email me at Jacob.Williams@uga.edu.

Posted in: