Soil Analysis

Most soil science professionals consider soil testing the starting point in determining what action is required to produce a high-yielding, high-quality crop. We at A & L Western Laboratories are proud to provide cost-effective and comprehensive soil testing packages. It can be a useful and valuable tool if you take the time to properly sample your soil. Please see our soil sampling guidelines if you are unsure about how to best sample your soil.

Soil Sampling Instructions

See below for some sampling guidelines

Sampling Tools

Tools that may be used to take a soil sample include a soil-sampling probe, an auger, or a spade.
Tools should be either stainless steel or chrome-plated to avoid contamination of the sample.
Collect in a 1-gallon zip lock bag. Fill bag ½ – ¾ full. Must submit 1000g or 2 lbs of soil. Anything less will be rejected.

Determining the Area to be Sampled

Areas that differ in soil texture, color, plant growth, or treatment should be sampled separately, provided the areas can be treated separately.
Site-specific farming may necessitate sampling by the acre.
A soil map or plant response map can be of help in distinguishing areas.
Unless of specific interest, avoid dead furrows, corners of fields, end rows, and areas that are poorly drained or have had fertilizers or amendments dumped on them.
Stay at least 50 feet away from barns, roads, lanes, or fence rows when sampling fields.
Perennial crops may be sampled by tagging specific trees or vines and returning to the same stations each time sampling is done.
Home gardens or landscapes may be sampled according to the area of concern.
Submitting at least two samples from different areas will help determine the degree of diversity, whereas one sample will provide only an average of all conditions present.

Collecting the Soil Sample

The soil sample collected with a probe should be a composite from 15 to 20 locations within a selected area.
Sample from areas of main root development.
Before collecting each subsample, scrape away surface residue then sample soil to a depth that reflects the active root zone of the crop. Please specify the sample depth.
Deeper profiles may be sampled separately if a concern. For example, nitrate nitrogen may be sampled at 1-foot increments down to 3 feet or more. Sodium, chloride, boron, and free lime may be more predominant deeper down.
For turf areas, it may be sufficient to sample only the top 6 inches.
Send 1000g or 2 lbs of the composite sample to the laboratory.
Submit a separate sample for nematode testing. Collect in a 1-gallon zip lock bag. Fill bag ½ – ¾ full. Include soil and roots in the sample. Must submit 1000g or 2 lbs of soil.
Annual sampling may be necessary to monitor residual nitrogen and problem soils.

Banded areas: It takes only a trace of fertilizer to contaminate a sample. It may be wise to avoid these areas altogether when sampling.
Low-volume fertigation (micro irrigation): Do not sample directly below emitters. Consider sampling from around half the radius of the wetting zone.
Nematode Sampling: Sample only from moist soil and always try to include feeder roots. This may be the top six inches for turf or down to three feet for many deep-rooted crops. Avoid sampling from completely dead plants.

Identifying and Submitting Samples

Identify each sample with numbers and/or letters, by depth for example, or good versus bad.
Avoid numbering samples simply as 1,2,3, … as it may lead to confusion later.
Indicate specific analyses to be run and provide complete information on plant type and age and whether pre-plant or maintenance fertility guidelines/recommendations are required.
Select either the standard format (five samples per page) or the graphical format (one sample per page).

Shipping Samples

If samples are very wet, they should be air-dried to a workable condition before packaging. (Nematode samples are an exception. They should be kept cool and moist).
Include a completed soil sample information sheet or cover letter with instructions within the same package. Processing will be delayed if sent separately.
Also, include payment if you do not have an established account.
Samples should be shipped by a carrier such as UPS or FedEx, or by first-class mail.
Ensure that samples are not packaged loosely, as they are likely to shift around and burst open during shipping.
Caution: Do not submit organic amendments or soilless nursery media as “soils”. They require different testing.