How To Interpret Your Soil Test Report

Soils are the source of thirteen of the sixteen essential3. What do the numbers in the report stand for?
plant nutrients and can be viewed as suppliers ofSoils usually contain much higher amounts of nutrients
nutrients to plants. Plants absorb available nutrients,than what we see in the reports, because lab results
which can be replenished by adding fertilizers.describe only the available nutrients to plant. To
To achieve good yield and quality, nutrient balance hasestimate the amounts of nutrients which are actually
to be maintained. Nutrient imbalance may result inavailable to plants, different testing methods were
deficiencies, toxicities or interference of one nutrientdeveloped. Some of these methods give empirical
with the absorption of others.values or measures.
This may result in stress to the crop, causing a4. Don't look only at the numbers in the report
decrease in quality and/or yields. Soil analysis is anIt's true, lab reports can be confusing: different labs use
important tool for evaluating or avoiding problems ofdifferent testing methods, resulting in different results
nutrients balance.for the same sample! They may even use the same
Why is soil analysis important?methods, but express the results in different units.
You can roughly estimate just how much fertilizersTo correlate the numbers in the soil analysis report
you need to apply according to general growingwith crop response to added nutrients, numerous field
recommendations for your crop. But is it too much, orexperiments are required. The reason is that the same
maybe too little? This is where soil analysis comes in.numbers may lead to different recommendations in
Soil analysis eliminates at least one unknown from thedifferent soils, different areas and under different
"equation": when adding nutrients to the soil, knowingconditions. The numbers in the report, coupled by the
the starting point is a very valuable piece ofdescription of the nutrient content in the soil, can
information.indicate if the predicted crop response to fertilizers will
Here are the basics of how to make sense of soilbe favorable or not.
analysis reports.5. Choose the right lab
1. Take the soil sample correctlyGood labs, with good experience, use their regional
Taking the sample correctly is the number one stepdatabase to give a description of each nutrient
for any reliable soil analysis result. The soil sampling(indicating if its level is too high, too low or adequate)
should be well planned and preformed. For example,and even fertilization recommendations.
the sample site should be far from roads, fences, treeDon't take these recommendation as "instructions".
groups, piles of fertilizers and manure or any otherRemember that no one knows your crop better than
object that can locally affect the soil properties andyou do. You are the best judge of your crop needs
content.and specific conditions.
The sample should represent the entire field as closely6. Use your experience
as possible. If the field is not uniform, and consists ofThe soil analysis report, together with your close
different areas with different properties, each areafamiliarity with your crop and field conditions, give you
should be sampled. Compiling results from completelythe starting-point to tackle the next question: how
different areas and averaging them into one report, willmuch fertilizers to apply?
obviously give us a very misleading result.First thing to remember is that different crops remove
2. Consider all growing conditionsfrom the soil different amounts of nutrients. So
Keep in mind that there are many factors that affectknowing your crop needs is essential. Next is your
the plant growth. The soil analysis will not supplycrop target yield. Generally speaking, higher fertilization
answers to poor or inadequate conditions, such aslevel gives higher yields, but only up to a certain point.
critically low or high temperatures, inadequate drainage,Beyond that, adding fertilizers will not increase yields
wrong application of fertilizers, accumulation of salts,and may even reduce them as a result of salts
plant diseases, pests damage, competition with weedsaccumulation in the root zone.
etc.Bottom line is that soil analysis lab reports give us a
Assuming you took samples correctly and yougood starting point for making better
acknowledge the many factors that may affect youfertilization-management decisions. They should be put
crop, how do you proceed to interpret the numbers inin context and their interpretation should be adjusted to
the soil analysis lab reports?the individual crop behavior and specific field conditions.