Soil Testing for Trees in Salem and Polk County

The short version: Learn more about the health of your soil to optimize your tree health. The estimate is free and in writing, and the arborist looks at it in person. Call or text (503) 551-5141.

What a soil test tells you

A soil test measures the things a tree cannot do without: the pH of the soil, the major nutrients, and how much organic matter is there. Willamette Valley soils tend to be acidic and heavy with clay. In yards, the soil has often been stripped, filled or packed down during construction, and a tree planted in it can struggle for years before anyone asks why.

A test is worth doing when:

• A tree has yellow or undersized leaves, or thin growth at the top
• Several trees or shrubs in the same area are declining together
• You are about to plant and want to pick a tree that suits the site
• Someone has recommended fertilizer and you want to know if the tree needs it

What happens with the results

Numbers are only useful if someone explains them. We go over what the test found and what, if anything, to do about it. Sometimes that is mulch and water. Sometimes it is correcting the pH or relieving compaction. Sometimes the soil is fine and the problem is a pest, a root issue or an old injury, and the next step is an arborist’s assessment.

The point is to avoid spending money on treatments a tree does not need.

Free written estimate: call or text (503) 551-5141

What are the signs of a soil problem?

• Leaves that are pale, yellow between the veins or smaller than normal
• Thin growth and dead twigs at the top of the tree
• Water that pools after rain, or ground that is hard as concrete in August
• Mushrooms or soft, dark roots at the base
• A tree that never took off after it was planted

Compaction is the most common cause in yards. Construction traffic, parked cars and years of foot traffic squeeze the air out of the soil, and roots need air as much as water.

Is fertilizer the answer?

Usually not by itself. Most established trees in the Willamette Valley do not need fertilizer, and adding it to a stressed tree can make things worse. That is the point of testing first. If the test shows a real shortage, it can be corrected. If it shows the soil is fine, you have saved the money and we look elsewhere.

Which trees are most sensitive to soil?

Newly planted trees, because they have few roots and are often set too deep in soil that was graded and packed during construction. Japanese maples, dogwoods and birch, which have shallow roots and dislike both drought and standing water. And mature oaks and firs after a change around them: a new driveway, a trench for utilities, a raised bed built over the roots or a lawn sprinkler system added under a native oak. Oregon white oaks are adapted to dry summers, and regular summer watering under them is a common cause of decline.

If something changed near the tree in the last few years, tell us. It is often the most useful piece of information we get.

What helps almost every tree?

A wide ring of wood chip mulch two to four inches deep, kept off the trunk, and deep watering during the dry months for young or stressed trees. It is cheap, and it fixes more problems than anything that comes in a bag.