Soil Testing: An Important Gardening Tool

Soil Testing: An Important Gardening Tool

Soil testing is a tool that guides gardeners. Test results indicate the need to adjust soil pH and nutrient levels for optimum plant growth. Often soil tests save money. Soil testing is a free service at Agway of Cape Cod

What Is a Soil Test?

A soil test is a measure of the soil’s ability to supply nutrients to growing plants. This analysis provides a guide to the soil pH and nutrient levels. This helps gardeners determine the right amount of lime and the type of fertilizer needed to grow the desired turf grasses and crops.

Why is soil pH So Important?

Soils change constantly. Erosion, leaching, growing and harvesting crops affect the availability of soil nutrients. A soil test indicates the current fertility and pH levels. If the soil pH level is too high or too low, plants will not be able to effectively use fertilizer nutrients. This means fertilizers are wasted when the proper soil pH is not maintained.

Many plants grow well over a wide range of soil pH as long as other growing conditions are ideal. Some plants, however, grow best within a narrow pH range. The soil pH test kit is an easy way to determine if a soil is acidic, neutral or alkaline. The pH scale is much like reading a thermometer with the range of alkaline and acidic materials divided into 14 points. Some plants (rhododendrons, azaleas, blueberries) like to grow in acidic soil with pH levels below 7.0. Most flowers, ornamental shrubs, trees, vegetables and turf grasses grow best in slightly acidic soils with a pH level between 6.1 and 6.9.

The availability of most soil nutrients is greatest at a pH near 6.5. When pH rises above this level, trace elements such as iron, manganese, copper and zinc become less available to plants. When the pH level falls below 6.5, calcium and molybdenum become less available.

When to Sample Soil

Test your soil every 3 to 4 years unless there is a particular problem or reason for a closer check on soil fertility. Soil samples can be collected and tested any season when soil conditions allow. Such tests are easily done with home soil test kits from Agway.

Steps In Taking a Soil Sample

1. Remove top debris, mulch or thatch from the area to be sampled.

2. Take soil from the appropriate level for the plants growing there. Flower, vegetable and landscape areas: sample 6-8 inches deep. Lawn areas: sample 2-3 inches deep.

3. Sample when soils are suitable for digging, but not soggy.

4. Sample plantings of specific types separately (i.e., sample rhododendron plantings separately from roses or vegetables).

5. Use a spade or trowel to make a hole at the proper depth and throw out the first spade full of soil.

6. Then cut a 1/2-1 inch thick slices of soil from the back of the hole and place within a clean plastic container. Repeat 5 or 6 times at different locations within the test area.

7. Thoroughly mix all the slices and allow to dry naturally.

8. When dry, take 2 cups of the composite sample and put in a clean plastic or glass container.

9. Closely follow the testing instructions found on the test kit.

What Do the Soil Test Results Mean?

The test results indicate the existing pH and nutrient levels. Ask your Agway dealer to recommend fertilizer and lime applications for specific plantings.

Test pH at Agway of Cape Cod