Soil Testing - Testing Your Garden Soil pH Level
How to test your soil, and how to change the pH level
To make sure that your garden will give you the healthiest and biggest yield of crops, you will need to periodically take a soil test to gauge the pH level of your garden beds. Testing your soil every three years is a good way to ensure that your plants are healthy and that they continue to producte high yields.
pH – How can two little letters (ok, one little letter and one big) be so important to a garden’s success? Everything (soil, food, even a person) has a pH level. pH is a measurement of how acidic an entity is, and a soil test is the best way to find out how acidic your soil is.
Plants thrive in garden soil with the particular pH level that’s best for that plant type. For example, tomato plants prefer a soil pH level that's between 5.5 and 7.5. If you place plants in garden soil that does not match their pH level needs, it can cause weakened plants that are more open to plant diseases, insect infestations, slower plant growth, smaller crop yield, and fewer nutrients being passed from the soil to your fruit, herbs or vegetables.
Most plants will grow well in soils that test within a pH level in the range of 6.5 to 7.0. For information on individual plant pH level soil preferences, you can look up your favorite plants here (check under the "How to Prepare the Garden Soil" subheading for the plant's pH level requirement):
Gardening Advice Tip: A soil test will quickly tell you what your garden plot's pH level is. Keep in mind that the pH level of one area in your yard may not be the same as another. Gardening plots that have been worked more with organic matter or mulched over the years may read differently than a brand new garden bed.
Soil Testing - How to Test Your Garden's pH Level
Option 1: purchase a pH soil testing kit from any garden supply store (they are simple to use and inexpensive), and follow the instructions provided.
Normally, your pH soil testing kit will have a container, a testing solution, and a color chart. To conduct your soil test, the process is generally that you scoop up some garden soil and place it in the container. Add the recommended number of drops (of testing chemicals) to the container. Mix (shake) the container for the time recommended on the package's instructions. Compare the resulting color to the chart provided and pick the best match to identify your garden plot's soil pH level.
or
Option 2: take a sample to the local county or university extenstion office's soil testing facility. They will often test your soil for you (with a more in-depth test) for a minimal fee.
Reading your pH Level Results
The results of your soil test will show a pH level for your garden plot, measured on a scale of 1 to 14.
1 = the highest acidity and the lowest alkalinity
14 = the highest alkalinity and the lowest acidity
A reading of 7 is considered neutral soil. Below 7 is considered acidic soil (the opposite of acidic). Likewise, a reading of above 7 means that you have alkaline soil (the opposite of acidic).
While at first, the difference in the results of your reading may seem insignificant, the reality is that the slightest reading change can have a big impact on your soil's productivity. On the scale, each whole number is 10 x the acidity/alkalinity of the neighboring number. For example, a reading of 6 is 10 times more acidic than a 7. A 5 is 10 times more acidic than a 6, and 100 times more acidic than a 7.
Note: You may also want to test your water's pH level. Deep wells can often be alkaline, and thus watering with them will help lower your soil's acidity. City water varies in pH, so it's a good idea to test it also.
Some plants prefer acidic soil, some prefer neutral soil, and some prefer alkaline soil.
Gardening Advice Tip: Don't forget to do a soil test for the pH for the plants in your container garden, or your house plants!
Changing Your Garden Plot's Soil pH Level
The absolute best additive for your soil (whether too alkaline, or too acidic) is well-rotted organic matter, like compost. Compost acts as a neutralizer in both circumstances, and provides the additional benefit of adding nutrients to your soil (for your plants, and also for the fruits and vegetables you plant to eat from them).
Changing Alkaline Soil:
How to change the soil pH level to a lower reading
(the pH level reading is too high)
If your soil test shows that the garden bed is too alkaline (the pH level is too high) for the plants you wish to grow there, you will need to add compost or other organic matter. Soils that are highly alkaline, tend to have significantly fewer nutrients available in the soils. Adding significant amounts of organic matter to your garden bed will help correct this deficiency.
Another alternative is to add sulfur. Sulfur loosens soil and reduces the pH level. Please consult your local county or university extension office for recommendations for ratio of application of sulfur for soil in your area. Also, there should be an application chart/guideline on the package. If you are unsure of the application ratio, opt for a lighter application, and adjust it over time.
Apply the soil additive to your soil and rake it in to the top level of soil in your garden plot. (The majority of your plants roots will be near the top, so this is where they will be feeding most heavily from the soil). Thus, this is where you want the soil to be most compatible to the plant's needs.
How to change the soil pH level to a higher reading
If your soil test shows that your garden bed is not alkaline enough (in other words, that your soil's pH level is too low (ie. too acidic) for the plants you wish to grow there, you will need to raise the pH level of your garden plot's soil.
Lime is commonly used to raise the soil's pH level. You should be able to easily find lime at your local garden center. Mix it in well. Fall and/or early spring are the best times of year for this adjustment. Allow some time before planting for the soil and lime to mix and meld (in other words, it's best to do this a good while before planting time).
NOTE: Correcting soil where you've added too much lime, can be very difficult and take a very long time. Therefore, it is STRONGLY recommended that you consult the extension office in your county for recommendations for ratio of application for soil in your area. Also, there should be an application chart/guideline on the package of your lime/limestone. If you are unsure of the application ratio, opt for a lighter application, and adjust it over time.
The lighter the texture of your soil, the more quickly the lime works to lower the acidity (ie. raise the soil pH level). So, if you have sandy soil, it will take less lime to reduce the pH level to one that's less acidic. Heavy clay soils will require the most additive. Loam and silt soils come in second. Sandy soil requires the least amount of lime to change the pH level to one that is less acidic.
The rate that lime acts is also affected by the type of lime you use. For quick acting: use finely ground hydrated lime (or even quick or burn lime). If you use ground limestone, it will take longer for it to lower the acidic pH level to the desired results. Make sure that they type of lime you purchase is finely ground for best soil absorption. For ground limestone, you'll need about twice as much as you would the hydrated lime. On the other hand, ground limestone stays in the soil longer and will help keep the soil's acidity level down for a longer period of time.
Apply the lime/limestone to your soil, and rake it in to the top level of soil in your garden plot. (The majority of your plants' roots will be near the top, so this is where it will be feeding most heavily from the soil).
Gardening Advice Tips From Our Readers:
Have a great idea to share about testing or improving your soil? Submit your own tips to us at: gardeningtips@howtogardenadvice.com
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