King Conservation District offers soil testing for local lands

September 13, 2011

By Tom Corrigan

Homeowners can take advantage of free soil tests from the King Conservation District.

The conservation district offers up to five free soil studies per address for anyone within King County, with a few geographic exceptions. The exceptions do not affect anyone in the Issaquah area.

One main idea behind soil sampling is to prevent overfertilization, said Marcie Myers, a resource planner for the King Conservation District.

And, she added, there are several reasons why using too much fertilizer is a bad idea.

Myers said the free sampling program was first intended for farmers within the district, but officials decided there was no reason not to expand the offer. Myers said sampling could benefit all types of gardens, from vegetable to flowers, as well as lawns.

On the Web

For complete sampling instructions or more details on the King Conservation District’s sampling program, go to

Samples are tested by a private laboratory for pH, nitrate, phosphate, extractable cations — potassium, magnesium, calcium and sodium — organic matter and cation exchange capacity.

Pronounced “cat ions,” almost as if it were two words, cations are positively charged nutrients in the soil. The exchange test calculates the level of nutrient holding capacity present in the soil. The higher the number, the more nutrients the soil can hold, Myers said.

Soil testing results generally are available within three weeks and are mailed to the home of the participant along with a guide to interpreting those results.

Excess fertilizer sets off what might be described as a chain reaction that is not at all beneficial to the overall environment, according to comments made by Myers.

First, soil will only absorb so much fertilizer material. The excess material can end up contaminating groundwater or join rainwater in heading for storm sewers and, in either case, eventually reach local waterways. Once there, the fertilizer can cause algae blooms, robbing water of oxygen, which in turn hurts the local fish population.

Myers added that if you still are unconvinced too much fertilizer is a bad thing, just remember you could be paying for fertilizer you just don’t need. Some gardeners simply need a little education on the proper use of fertilizer, she added.

For example, Myers said people sometimes assert that if they cover their lawn with twice as much fertilizer as they think they need, it will last twice as long.


Myers said the excess simply would run off or leach into groundwater long before it is of any benefit.

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