Soil Testing 101: Why, When, & How

Soil testing is critical to the long-term success of any grazing or forage production system. Knowing how, where, when, and why to soil test are the key factors in gaining value from soil testing.

 

There are three types/reasons for soil testing:

1. Preparation for planting/re-planting a pasture or field

2. Gaining an understanding of your soil's health

3. Part of an ongoing soil health monitoring program.

Your objective will determine which type of soil test you conduct and when it is tested.

Two Types of Soil Tests:

Basic Soil Test

If you are preparing to plant a new field of grass or re-planting into an existing stand, a basic soil test is incredibly valuable and could save you a lot of time, effort, and money. All because planting into an environment with the wrong conditions (too high or low of pH, not enough soil fertility, toxic levels of certain elements, etc.) could at best lead to disappointing forage performance and availability, or at worse result in failure of the desired forage to get established. A forage test well ahead of the anticipated planting date can help set a planned planting project up for success.

 

Snapshot Soil Health & Biology Test

Healthy soil is living soil. There are more living creatures in a large handful of healthy soil than the number of all the humans who have ever lived! With an increasing number of soil tests offered that help you understand not only the physical and chemical nature of your soil (provided by a basic soil test) but also the biological conditions and health of your soil.

 

Make sure your soil test at least provides SOM (soil organic matter), which provides a broad understanding of your soil biology, and is a good indicator of your soil’s overall health. Increasingly there are additional tests, with increasing cost, that provides a more in-depth understanding of your soil’s biological health. The Haney Test is becoming a popular test and is recommended to those who want to learn more about their soil beyond physical and chemical properties. Also, there is an increasing number of specialized “Soil Food Web” labs that will identify actual microbial species and populations and, most importantly, the ratio across the various types of healthy microbes. For example, the ratio between fungi: bacteria are a key indicator of overall soil health since healthy soil needs a diversity of microbial life, which dramatically influences the availability of specific nutrients.

 

When to Test

If your objective is to prepare for a successful planting, we recommend you test at least a month in advance to give you enough time to fertilize, etc. ahead of planting. Please realize that some soil amendments require much greater time to improve soil health effectively. If, for example, you are planning on planting in the spring, it is usually best to perform a soil test in the fall and then follow-up with an analysis late winter or early spring ahead of planting. This will allow you to plan, to apply the recommended amendments, and test if your soil is optimal condition to support the seeding.

 

If your objective is to test soil health as part of an ongoing soil health monitoring program, then testing in the fall is usually advised. However, in this case, we suggest you consult with the lab who will be conducting the tests. Not only can they supply you with test sample kits, but also instructions on when and how to test.

 

IMPORTANT: Your objectives will influence when you take your samples and send them to the lab.

How to Test

As just mentioned, consulting with your soil testing lab ahead of taking and sending in soil samples is always a good idea. Nonetheless, there are a few necessary procedures that will increase the value of soil testing.

  1. Start with an idea of the variation in soil types and terrain in the pasture/field you plan to test. Generally, the idea is to take various samples and then mix them and then send the combined sample to the lab for analysis. However, if your pasture or field is relatively small or has a minimal variation (in soil type, etc.), then taking and combining fewer samples could be appropriate and will save time and money. However, it is usually advised to take at least several samples (as many as 10) mix them and send the combined sample to the lab. Determining how many samples to take is often the most challenging part of soil testing. If you have any questions, we encourage you to consult your local Forage Extension or county extension agent, NRCS agent, or other qualified individuals for guidance.
  2. Some people think you need an expensive soil probe to take a proper soil sample. Although a soil probe certainly helps it isn’t necessary, and just because you don’t have one shouldn’t keep you from sampling your soil, in most cases, a standard spade shovel will work just fine. The important thing is that you conduct regular soil samples, the exact equipment you use doesn’t matter as much as following these simple guidelines: A. Be consistent in the way to take your samples. For example, if your combining samples to submit to the lab, use soil from the same depth (profile). B. Be mindful of management units…If, for example you’re taking samples from multiple pastures and combining them, the resulting lab results may not allow you to make meaningful changes since the data will represent to broad of an area.
  3. Use a reputable lab and seek guidance from a trusted source. Rock River Lab and Ward lab are just a couple of respected labs. However, there are many others. Advice from a trusted source such as your NRCS agent, state or county Extension agent, etc., can help you not only with sampling procedure but also recommend a lab to use.
  4. If all of this is too much for you, there are soil sampling services that, for a fee, will sample your soil, send it in to a lab for analysis, interpret the results and even provide the products & services to make the recommended amendments. Of course, this will cost you money, but the services they provide maybe well worth the investment.

Soil Testing

It doesn’t have to be difficult, although, like anything, it is an investment that takes both time and effort. However, in almost every case, the results make the investment well worth it. By following some simple guidelines, soil testing can be a powerful tool to help your next planting be a success, and it is just as powerful a tool to help you understand the health of your soil over time, which is the ultimate indicator of management success.

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