How to Test Your Soil

It’s that time of year again: gardening is around the corner! Before you dig into your garden beds, it’s important to know the soil you’re working with. Read on to learn what to look for, what to test for, and where to get the right tests for you. 

Why should you test your soil?

small seedling in good soil

Soil is a combination of clay, silt, sand, and organic matter. The balance of this mix can make or break the success of your lawn or garden. This is because different plants thrive with different levels of pH, different levels of water retention, and different percentages of certain key nutrients. Many plants will actually need different things depending on the time of year! Since plants are so sensitive to the soil they are in, it’s very important to know what is already in your soil before you start adding fertilizers or amendments. 

Maryland has recently passed laws regarding lawn fertilizers, in order to help protect the Chesapeake Watershed. You can read more about ​​​​Maryland’s Lawn Fertilizer Law here. There are certain times when you have to test your soil before you are legally allowed to add certain nutrients – this is why it is important to either do lots of research if you are starting your lawn yourself, or to hire professionals who have more experience with lawn fertilizer laws.

Do you need a soil test kit?

lots of types of soils lined up together

To make a general assessment of your soil’s makeup, you may not need a soil test. This is if you are concerned with the water retention of your soil, the organic life living in your soil, and the texture of your soil. We will discuss ways to roughly estimate whether your soil is mostly clay, mostly silt or mostly sand later in this blog. To see how many worms are living in your soil, dig a few holes in various areas of your garden, and count the number of worms you find. More is a better indicator of soil health. 

 

To evaluate the specific nutrients and pH in your soil, a test kit is highly recommended. There are home kitchen hacks for testing pH but they are very difficult to master. There are two levels of soil test kits, both of which we offer. 

 

The first kind of kit is an at-home test kit. These are great if you want fast results that don’t have to be perfectly accurate, since you can do them at home. We offer a variety of at-home kits that will help you evaluate both the nutrient make-up of your soil and the pH levels.

lab technician processing soil tests

We also offer professional soil test kits that you can send to the University of Delaware for a full assessment. We do not charge for the kit, but you will need to pay the University of Delaware a small fee for processing. (The University of Maryland no longer performs soil tests and recommends the University of Delaware as one of the closest resources). 

This lab test is the best tool for an accurate report of all the vital nutrients in your soil, your soil’s makeup, its pH, and even whether or not there is too much salt or lead in your soil. If you are in a new area, putting in a new lawn, or really need accuracy to understand why your vegetables or flowers aren’t growing the way you want them to, this is the best option available.

How to collect an accurate soil sample

field gardener putting soil in a bag with gloves

In order to use either of these methods, you need to collect an accurate sample of soil. Here are the steps to get the best possible soil collection. Take note: we recommend you do a separate test for each type of area around your home. Lawns, vegetable gardens, flower beds, and shady areas under certain trees will all need to be evaluated separately since they will probably need very different kinds of amendments for your plants to thrive. 

 

  1. 1. Clean your tools. You shouldn’t use tools that have ever been used to scoop fertilizers or amendments; those can leave trace elements even after you clean your trowel or shovel. If you’ve only used the tools for general gardening, simply give them a good clean and dry them well.

 

  1. 2. Wear clean gardening gloves, since you should not touch the soil sample. Again, don’t use gloves that you have used to handle fertilizers or amendments with already.

 

  1. 3. On a day when your soil is dry, dig 5 – 10 holes in different spots around the area you are testing. Remove some of the lawn, plants, or weeds from one edge of the hole.

 

  1. 4. With a sharp, clean shovel or trowel, take a ½” to 1” wide slice out of the edge of each hole, on the side where you removed the grass. It’s best if this wedge is about 5 – 8 inches long (3” – 5” for lawns).

 

  1. 5. Place your sample soil wedges into a clean bucket together.

 

  1. 6. Mix up your soil samples well. Again, this is best done when your soil is very dry. You can let the soil dry out in the bucket for a little while if it is still moist.

How to use your soil test kit

test lab dividing soil into test vials

If you are using the University of Delaware soil test kit, then place this mixture into the bag provided, fill out all of the paperwork, and mail it in as directed. They include a great pamphlet on how to choose where to collect your samples. Again, it is best if you order a separate test for each area you want to test. 

 

If you are using an at-home test kit, then follow the instructions included. Typically, an at-home test will include a small container for the soil, a capsule with the chemical testing solution, and an eye dropper to add the right amount of water. Using distilled water can help with accuracy. 

Then you will match the solution to a color chart after everything has been mixed together, and the color will determine the pH or nutrient percentage.

How to estimate soil makeup yourself

healthy loamy soil with good crumb

There is a quick way to assess the general makeup of your soil. Grab a handful of soil that is very slightly moist, and squeeze it in your fist. If it balls together into a solid lump, it is likely made up mostly of clay and needs more drainage. If it crumbles into tiny pieces and doesn’t stick together at all, it is most likely a sandy soil and will need some silt and clay to help with retention and structure. If it comes together and then slides apart again into a small puddle in your hand, it is probably made of mostly silt, and will need some sand for drainage and some clay for structure. If it crumbles like an oreo cookie (“has a nice crumb”) and sticks together just a little bit, it is probably a good loamy soil and is an even mixture of all three types of soil. 

 

You can also fill a hole with water and watch to see how quickly the water drains away. The faster the water empties into the soil, the more sand you have in your soil. The slower it drains, the more clay you probably have.

A note about nitrogen:

Nitrogen is integral to the life cycle of both plants in your garden and the microorganisms that benefit your plants, and it is notably very difficult to test.

A good way to estimate how much nitrogen you have in your soil, aside from a test, is the health of your leaves and plants. Plants with yellow, pale leaves and stunted growth are probably lacking in nitrogen. Plants that have very dark green leaves, lush growth, leaves with burnt crispy edges, but very little fruit or flowers are probably having an issue with too much nitrogen.

nitrogen deficient leaves on rose

How to amend your soil with your results

Now, it’s time to fertilize! With your results, you should be able to better understand if your soil needs more acidity (a lower pH), higher alkalinity (higher pH), better drainage, better structure, or more of a key nutrient. Most lawns and garden plants do best in a loamy soil with a balanced pH between 6 and 7, with some exceptions. 

 

Fertilizers are labeled with an NPK number to better help you understand what is in the fertilizer and what you need: N for Nitrogen percentage, P for phosphorus percentage, and K for potassium percentage. ( A “10:10:10 fertilizer” has the same amount of all three for its NPK value, and is a better fertilizer for gardens than it is for lawns). 

 

The University of Delaware usually will provide recommendations with their results. Their website also includes lots of information and resources for understanding test results

 

If your at-home test says you are low in some elements or high in others, you can use organic methods to balance your garden or you can use fertilizers. Organic ways to add nitrogen are the best, since it is exchanged between organic life so frequently. Mulch, worms, and regular compost are great for a healthy soil ecosystem. 

NPK balanced fertilizer in a bag

Use the NPK number to find a fertilizer that helps you reach your soil goals, depending on what your plants need. More nitrogen is good for growth but less nitrogen is better for fruits and flowers. 

 

Espoma offers a great range of organic fertilizers and soil amendments for every situation and we carry many of their products. They have an acidifier, lime, bone meal, worm castings, and other products that naturally balance soil. They also have specific products that are designed for specific goals or plants, taking the guesswork out of the equation.  

 

Come in and ask our team if you have any questions about testing your soil or the products to use to rebalance your soil. Early spring and fall are the best times to test your soil, since both seasons are ideal times to plant new plants in your garden.

University of Delaware Soil Test Offered By Patuxent Nursery