Before you start applying fertilizers and lime treatments to your soil, take a sample and have it tested, either at home or professionally. Soil tests are like DNA kits for your gardens. So many people amend their soil without even knowing what they’re trying to fix. DIY soil testing can often prevent the need for additional “fixing” later on down the road, as healthy soil is ultimately key to success. Every three to five years is a good testing timeline.
What Soil Testing Achieves
pH testing is the most basic test of your soil, and it can be done at home. Achieving a healthy soil pH is essential to providing plants with the necessary nutrients for growth. If your soil acidity is too high, the soil builds up a toxic level of nutrients. If your soil pH is too low or acidic, it will deplete the soil of nutrients, keeping the plant from growing at all or killing it. Without an adequately balanced environment in which to grow, cultivating a thriving garden becomes almost impossible.
If you really want to know what’s in your soil, you need to buy a soil testing kit and send it off to the lab. If you haven’t already, it is crucial to examine your soil for toxins and lead. With a thorough soil test, the texture of your soil—silt, clay, or sand—will be identified as well as its acidity level (pH). The existing levels of essential nutrients like magnesium, calcium, phosphorus, and potassium will also be calculated. You may need to buy multiple tests, generally broken up by nutrients, texture, pesticides, and lead.
There are a ton of soil testing services out there these days. Some come with subscriptions that offer advice on how to fix your specific soil. If you expect your test to come back poorly, it might be worth investing in a service like that.
Alternatively, many universities, like Cornell University or the University of Massachusetts, have soil testing programs, however they won’t always give you all the data you need. For example, they may only be accepting routine soil analysis at certain times, and won’t deliver information on lead, mercury, or other toxins. Shop around before deciding where to have your soil tested.
How to Test Your Soil at Home
If you don’t have the money or patience to wait for a lab report, there are also many DIY soil testers you can use in your own garden. I suggest the Luster Leaf Rapitest Soil Test Kit. This kit has been used for generations and tests for pH, nitrogen, phosphorous, and potash (potassium).
In this test, you’ll simply use a clean trowel or spade to remove a sample of soil from at least 4 inches below the surface of your vegetable garden bed. Try not to touch the soil, and avoid clumps and large rocks, as you want a good representation of the area’s soil. Then you’ll mix the samples with water, just a few drops for the pH, and a few cups for the other tests. After a little waiting, you’ll get a color that will tell you your results. The test also comes with suggestions on how to fix your soil.
If you have multiple raised beds, you can either test them individually, or take multiple samples and mix them together in a large clean jar. Mixing is particularly useful when you’re testing for toxins like pesticides and lead, because the tests are expensive. Testing beds individually makes more sense if you designate different beds to different plants and, for example, want to know how healthy a bed is after a major tomato crop.
For a tried and true pH test recommended by the Old Farmer’s Almanac, try the vinegar test!
- To test the alkalinity of your soil, take 2 tablespoons and mix it with 1/2 cup vinegar in a bowl. If effervescence occurs, then congratulations—you have alkaline soil!
- To test your soil’s acidity, combine 2 tablespoons of soil with some distilled water in a bowl. After mixing, add 1/2 cup baking soda and observe the reaction. If you see bubbling or fizzing, then you have acidic soil!
- If the soil shows no reaction to either test, it can be determined that its pH is neutral. When soil pH is either too high or too low, plants can suffer from nutrient deficiencies or toxicity.
When the pH level is neutral (7), microbial activity reaches its highest point and plant roots can absorb nutrients most efficiently. For optimum nutrient absorption, maintain a pH range of 5.5 to 7 in your soil, unless your seed packet suggests otherwise.
In my experience trying to plant many different veggies in small kitchen gardens, I’ve discovered that if you have a bed with soil in the 6.2 to 6.5 range, that will please most plants.
Amending Your Soil After DIY Soil Testing
So you have your results, now what?
- pH: To combat acidic soil and elevate pH levels, lime-based compounds like dolomite or agricultural lime are the most effective. Additionally, baking soda, crushed eggshells, or wood ashes can be used to increase pH levels in the ground. To reduce the soil pH, you can utilize one of three agents—elemental sulfur, aluminum sulfate, or sulfuric acid. The ideal agent is contingent on how quickly you wish to see a change in your plants’ environment and what type/size they are.
- Nitrogen: Nitrogen is essential for the growth of lush foliage in plants. To replenish this nutrient, you may wish to add manure or compost. Alternatively, dried blood meal, alfalfa, soybean, or cottonseed meals can be used as substitutes. Ten pounds of blood meal supplies an equal amount of nitrogen compared to 10 to 20 bushels full of manure, but lacks all the additional organic matter that comes with it.
- Phosphorus: Phosphorus is essential for any plant’s health and development—be it germination, or producing robust roots, flowers, or succulent fruit. It also helps plants absorb minerals as well as form strong stems to resist ailments. To improve levels, rock phosphate is used and offers not just phosphorus but also magnesium, along with micronutrients that make an excellent soil supplement! It’s long-lasting, so it only needs to be applied every three to four years, though bone meal is another option and is a faster acting source of phosphorus.
- Potassium: Potassium, also known as potash, is essential for controlling the water flow in plants, enables flowering and fruiting, and improves disease resistance. If you’re low in potassium, your plants will have weak stems and stunted growth. To increase levels, use granite dust or greensand made from glauconite. Wood ashes also contain potassium, so feel free to spread them in your garden if you have a fire pit or wood stove. Wood ash can also increase the pH of your soil, and offers calcium as a bonus.
Want another indication of good soil health? The Old Farmers Almanac says that once your soil is 50 degrees F on a moist spring day, you should be able to take a shovel to your beds and pull up at least 10 earthworms in the soil. If not, you need to add more organic material like manure and compost.
Do you have any tips to add to this tutorial on simple DIY soil testing? Let me know in the comments.
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