ALBANY, Ore. – Based on observation and simple tests, Willamette Valley gardeners and farmers can use a soil quality scorecard to do their own soil analysis and get results that are more thorough than traditional soil nutrient tests.
"The Soil Quality Card measures all three aspects of soil fertility – chemical, biological and physical," said Dan McGrath, Oregon State University Extension Service agent in Linn County and one of the developers of the card.
Willamette Valley farmers and a team of scientists from the OSU Extension Service and Agricultural Experiment Station and the Natural Resources Conservation Service developed the scorecard to measure the effectiveness of new soil conservation methods growers are using in their fields.
The scorecard is a checklist of 10 characteristics farmers identified as the most important indicators of long-term soil productivity. "It condenses years of experience and education into a concise primer on soil quality for the Willamette Valley," McGrath said.
Gardeners can use the same checklist to test the soil quality in their yards and gardens. A Soil Quality Guide also is available to help users understand their observations and score the quality of their soil.
For example, one indicator measures soil compaction. Repeated passes with heavy equipment or a garden rototiller can compact soil. To test compaction, simply push a wire flag into the soil. Does it hit hardpan and stop? Or does it pass easily below the level you have tilled? The wire flag represents the roots of your plants, and the Soil Quality Guide explains the journey roots make through the soil.
Another indicator measures soil structure. Soil that has been tilled too much can develop clods that are cemented together. When broken apart, the clods disintegrate into powder. Healthy soil has tiny pockets of air and a crumbly texture. The Soil Quality Guide helps assess if your soil is crumbly or cloddy and what difference it makes to water retention and plant growth.
Other indicators measure the abundance of soil organisms, water infiltration rate and condition of growing plants. Observations are scored and recorded on a card that can be purchased in sets of 25; results can be compared in different plots and as improvements are made.
The companion Soil Quality Card Guide explains the importance of each indicator, instructions for testing each indicator and how to improve the quality of the soil. It also outlines more in-depth tests that can be done with simple household materials.
The Soil Quality Card Guide (EM 8710-e) can also be downloaded for free.