Pass the Test: Soil Testing For Improved Fertility

Will you pass the test? Soil testing is a fabulous tool that you can use to determine the fertility of your soil. And you don’t have to study.

By testing your garden spaces you will be able to establish long term goals that help you improve soil fertility and develop productive and prolific plants.

Your long term goal is having a garden that produces abundant amounts of healthy fresh vegetables and fruits. It does not matter how big or small your garden is or if you garden directly in the ground or in raised beds. The soil must meet the needs of the plants.

Keep reading to learn all about when, why, and how to test your soil so that you get maximum yields.

When To Soil Test

Basically, you can test your soil at any time of the year. Your soil should not be frozen or overly wet. It should crumble in your hand. If your soil is good for planting, meaning right temperature and consistency,  it is good to take a test.

I like to test in September or October. Fall is a great time to send off a soil sample because then you have the fall and winter to work on making improvements. Some soil amendments take several months to break down and become part of the soil.

If it is spring and you are testing then you can always work on one section of your garden at a time. You can also add amendments as you are planting. Just be sure that whatever you add in spring will not burn your plants.

What Is Soil Testing

Basically, a soil test looks at what nutrients are in your soil and the level of the pH. These results will help you to provide the best “ingredients” to nourish your plants. Soil testing lets you know if you need to add anything or possibly reduce something to make your soil have optimum levels of fertility.

This is where some gardening experience helps. Different plants may require more or less of certain things. For example, tomato’s need an extra calcium boost or they are prone to blossom rot. Greens and brassicas benefit from more nitrogen.

We often think of soil tests as a vegetable gardening activity. But you can take a soil test anywhere – the front yard, flower beds, berry patch, orchard…. Wherever you want to improve the soil and produce healthier plants.  

Most soil tests target the big three, Nitrogen, Phosphorus, and Potassium, as well as pH. They may also look at secondary macronutrients such as calcium, magnesium, and sulfur as well as micronutrients.

To learn more about soil nutrients check out my article What Do Your Plants Need

What Type of Soil Tests Are There?

There are many different options for testing your soil. You can purchase a DIY kit on Amazon or from a seed catalog. Another option is to send it to a lab for analysis.

Purchase a Home Do It Yourself Kit

There are a variety of home kits on the market. Some work very well and some give poor results. Do your homework, read the reviews and analyze for accuracy and ease of use.

I sometimes use DIY kits because it is nice to have something on hand to get a quick reading. For example, if I have a plant that has purplish leaves I would think that I either have a nutrient deficiency (phosphorus) or a disease (fungal leaf spot).

The DIY tests do not give detailed information, just a range of where you fall. This can make it harder to decide how much of a nutrient you may be deficient in or what you may need to add.

DIY kits can be purchased as separate kits such as just for nitrogen. They also come in kits that contain N,P,K and pH. Most DIY kits do not cover the lesser elements such as calcium, phosphorus or magnesium.

LaMotte Soil tests are considered to be the best do-it-yourself kits available. They are often used certified organic farmers and landscapers. While more expensive then the DIY versions, they will do multiple tests. That way you can do multiple areas or just recheck every few weeks to make sure your soil fertility is where you want it to be. LaMotte has excellent customer service and provides excellent instructions. One thing I dislike about LaMotte is that you must compare your results to a color chart. I always find this difficult because invariably I feel I am in between colors.

If you choose to go the DIY option check out the LaMotte tests. There are many to choose from. I think this one is the most comprehensive.

Send Your Soil To A Laboratory

This is what I do every year. I guess I am programmed since I have been USDA and CNG organically certified. I really like that the lab test provide me with accurate numbers. I can compare these numbers to the norms as well as my past years results.

You can locate a lab and send your sample via the post office. Use the internet to find a laboratory near you. You will want to check out their website and make sure they offer the tests you need. Most labs have packages for you to choose from. Also inquire what their turn around time is, especially if it is spring and you are in a rush.

Professional lab workups are the  most expensive option. However, the results are thorough and accurate. Costs will run you anywhere between $25 - $50. The cost will depend on what tests you decide to have done.

I use Logan’s Lab because they have excellent customer service, answer all my questions and are quick.

Extension offices often have a testing affiliate with the state land-based university. They normally charge anywhere from $5 - $20 dollars. Quality of extension tests vary on what state you live in. In addition, the test is not quite as complete.

One of the things I did not like about extension testing for my state is that it is more set up for commercial farmers. My recommendations from the University of Kentucky were to apply 10-10-10 fertilizer which would not be suitable for my organic operation.

What You Need

You need some basic tools such as a trowel and a shovel to dig into the soil. If you want to be fancy smancy or more professional try using an auger or a soil probe.

I use a nice pointed trowel that I can push down into the dirt

Remember you want your soil sample to be clean so you get the best results. No contaminants – so wear either latex or clean work gloves. In addition, you want to have a nice clean bucket ready to put your soil in. You can also put soil directly in your plastic sample bag.

I take multiple samples from different garden areas around my farm. So it is important for me to label each bag with the location. Keep in mind that that if you are sending your samples in the company will charge you for each soil sample.

There are several reasons you may wish to have multiple tests. You may be looking at putting in a blueberry patch. Blueberries have very specific soil needs so you would want an accurate reading for them. I have a number of smaller garden areas that measure between 400 and 800 square feet. It helps me to have separate tests for these.

For instance, I have numerous garden areas and I give them names and numbers. You can see in the photo I had G3 Hse and G2 Barn tested. Simply the house garden and the barn garden. If you are doing a lab test you can send notes to the lab such as “new blueberry patch” or “shade area for greens”.

How To Take Your Soil Sample

  1. Take off the top layer of the soil or sod and set it aside.

  2. Soil should crumble easily and not be to wet or to dry.

  3. Most instructions will have you go down six inches deep.

  4. Use your soil auger or clean trowel to scoop up the soil.

  5. If you want to send in just one test but have a large garden, take multiple samples and put them in your bucket and mix them together.

  6. Label your soil test so that you know where in the garden or yard it came from.

Areas Not Too Sample

Some areas of your garden or homestead are not good places in which to sample. These would be areas that have outside contamination such as around the barn where you feed livestock.  You don’t want to test close to structures such as homes, barns, driveways, sidewalks or streets .

Don’t test around your compost pile because that will give you false readings (often very good ones). That said sometimes people do test their compost to see where it is at with nutrition levels since it is a key factor in improving your fertility.

 Don’t Ignore Containers and Raised Beds

Don’t make the mistake of ignoring your plants that are growing in containers and raised beds. These plants are growing in a restricted area and may be even more prone to nutrient deficiencies because they can not spread out their roots.

Another place not to ignore is your fruit orchard and berry plants. Your perennials need regular fertilizing as well. Annuals use a lot of nutrients because they grow quickly .

Your perennials however, have a much longer lifespan and need to grow at a steady rate. You have probably seen cut outs of tree trunks where the growth lines may be closer or farther apart. Botanists and dendrologists tell us that is due to stress such as too little rain or nutrients.

Reading and Interpreting Your Soil Test

It is important to understand what your soil test is telling you. Are your nutrient levels to high or to low? These test results are the beginning of a process. Do not get upset if they are not what you wanted or expected. You are working that plan.

Read my post on garden planning if you need to set goals Work That Plan: Planning For A Productive Sustainable Garden.

For example, if you look at my test you can see Calcium. The calcium line gives the desired value and an actual value. For my barn garden, it shows that my actual value is a good bit less than the desired value.

I know that if I plan to put tomatoes in that garden then I will need to add calcium because tomatoes are heavy calcium feeders.

Some tests will give you a range such as normal, low or high. These can help you determine if you are good (normal) or need to add something (low). If you are high you will need to be conscious not to use any additional fertilizer with too much of that element. This can get tricky and you will want to read the labels on your fertilizers.

Balance And Working Together

When you are interpreting your results remember to think in terms of balance and working together. Sometimes certain elements need to work together so the plant can get what it needs. For example, calcium can not be absorbed directly from the soil. It needs something to help it get into the plant.

That something is water. When the weather is cold or the humidity level is high the water does not flow as readily through the plant. This may be frustrating when you have applied bone meal to your soil and still have blossom end rot. Calcium levels are also affected if the magnesium, or sodium levels are too high.

You may discover, like I did, that you need to add some calcium. Bone meal is a great source of calcium. Bone meal is a slow release so it is best put in the garden during the fall and tilled into the soil.

Other Ways To Tell If You Have Happy Soil

Earthworms! Earthworms  are a barometer of healthy soil. The more earth worms that are in your soil the better. Do a test. Dig a eight inch deep hole in the middle of your garden.

What are the results? No worms is not good. They have left you to find food.  Three worms and you are doing better. You have mediocre soil that can do a lot better. Six worms and you are doing fabulous. Good job!

Earth worms are important to the soil because they mix and aerate while they go about looking for food. They takes big bites of soil and plant materials that passes through there system. After they digest the soil their castings (poop) make nutrients more available to plants. Worm tunnels create loose soil and air pockets which allow your plants to send out roots to secure themselves and take in more nutrients.

Don’t Expect A Quick Fix

There is no quick fix in gardening. It is a process or a journey if you will. I talk a lot about making garden goals.  Well soil testing is a tool you will use to fulfill your long-term goals to improve your soils fertility and grow healthy plants.

Looking for ways to water your garden? EVERY DROP COUNTS: RAINWATER HARVESTING 101

Author, Ame Vanorio, is a freelance writer and director of Fox Run Environmental Education Center. She teaches classes locally and online about organic gardening, green building and wildlife conservation. Ame is a licensed wildlife rehabilitator. She lives off grid on her Kentucky farm with a myriad of domestic and wild animals.  Ame recently published her first children’s book Goober Goose.

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