Soil Test Interpretation Calculator for Alaska Gardens

Directions: This interactive calculator is intended as an exploratory tool to help you interpret your soil test results for a single soil sample.  Calculations are based on a generalized model of soil variable for Alaska soils.  The white column of boxes labeled "Enter Your Values Here" is availabe for you to enter information.  This calculator will only make calculations for the data you have entered.  You will need to double click in the box to activate the spreadsheet so that you can enter data.  There are many variables listed that you may enter.  Depending on the soil test you have obtained, you may not have data to enter in every box.  To start over and enter information from a different soil test, click the refresh button of your browser.  If you are having difficulty with this calculator and would rather seek assitance directly from an extension agent (click here).


LOW - A nutrient or other component interpreted as "low" will likely limit plant growth and yield. There is a high probability of improved yield from an addition and/or higher level of this component. If the level is very low, several years of corrective fertilizing may be necessary to achieve an optimum soil level. In this case, close monitoring by yearly soil testing is recommended.

MODERATE - A nutrient or other component interpreted as "moderate" has a moderate probability of an improved yield from an addition and/or higher level of this component. A moderate nutrient level may limit plant growth or yield by the end of the growing season or in years of very good growing conditions, but it may be adequate for some low-demand crops in some cases. Corrective fertilizing is usually recommended in moderate amounts to result in a slight increases in soil levels and yield in years of average growing conditions or to support exceptional yield during years of excellent growing conditions.

OPTIMUM - A soil component listed as "optimum" is in the theoretical ideal range to support plant growth and maximum yield. There is a low probability of an improved yield from a higher level of this component. Corrective fertilizing is not recommended. Any amendments recommended for components listed as "optimum" are to compensate for crop removal, so that the soil level of nutrients can be maintained from year to year. A small amount of starter fertilizer containing this nutrient may also be recommended.

ABOVE OPTIMUM - An "above optimum" level of soil component indicates a level higher than needed to support normal plant growth. The probability of an improved yield from a higher level of this component is very low. In some cases, increases of this component may inhibit growth and yield, either because of direct toxic effects to plants or because the overabundance of one nutrient may interfere with the uptake or availability of others. Additional application of something already at an above optimum level will only increase the likelihood of reduced yield. There will be no recommendation for futher additions of this component under ordinary circumnstances. Crop removal and other natural losses over time should eventually reduce the nutrient in the soil, after a few years.

CAUTION - Increases of this component may inhibit plant growth and yield. Soil management practices should be evaluated to help determine why levels are increasing and how to prevent further increases.

EXCESSIVE - An "excessive" rating indicates that at current levels, plant growth and yield may be inhibited. Soil management practices should be evaluated to help determine why levels are high. It may be possible to reduce levels of this component in the soil. Corrective measures to reduce soil levels of this component are advised.

* - When "*" is used, this means there is no established recommended value currently listed for this soil nutrient/component.

OK - A rating of "OK" indicates that current levels of this component are suitable for normal plant growth and soil function.

APPLICATION OF AMENDMENTS - Your soil fertility amendments should be applied before planting and worked into the top 6 to 8 inches of soil. Additional in season fertilizer applications should be made according to crop needs.

BORON - If Boron is recommended, you may apply household or agricultural grade borax (11% B) at the rate of 1 tablespoon per 100 sq.ft. Apply the borax evenly and mix thoroughly with the soil. It may be easier to dissolve 1 tablespoon of borax in 1 gallon of water and apply the solution evenly with a sprinkling can over a 100 square foot area of soil. Do not apply the solution over existing plant leaves. You can find borax in the cleaning supplies section of most grocery stores.  Be cautious! Excessive quantities of boron are highly toxic to plants. One application of borax should be sufficient for up to 3 years or until another soil test is made. 

Back to Top