Soil Sampling

How Soil Tests Can Help Save You Money

Soil tests can reveal nutrient deficiencies you didn't know about. The tests can save you money on fertilizer by pointing out fields high in nutrients.

Fields that test high need less fertilizer than other fields.

If you have over-fertilized for several years, you may be able to greatly cut your fertilizer bill. And for best yields, your crop may need different fertilizers than before.

What Is A Sample?

A sample is a bag or box containing 20 cores or slices of soil from 15-20 acres. Avoid unusual "patches" when gathering samples. Dumping a few handfuls of soil in a bag is a waste of time.

When To Sample Soil?

Sample after discing the previous crop, but before you fertilize your next crop. If you pre-irrigate, sample after irrigation.

How To Sample - The Easy Way

Do this yourself or have your very trusty assistant do the job for you.

Divide Your Field

No field is the same all over. Even on a very uniform field, you'll need one sample for each 15-20 acres. Areas having different soil types, different fertilizer treatments, etc., are sampled separately.

Soil Sampling Tools

A clean plastic bucket or plastic gags, spade and trowel or soil probe.

Depth Of Sample Using A Spade

If you don't have a soil probe, use a spade. Take 1/2" thick slices as shown in the picture. Then trim sides leaving a I" strip like this. Dump these strips into a clean plastic bag or bucket.

Break Clods - Mix Thoroughly

Do it by rolling and "kneading" plastic bag of soil. or, mix soil in a plastic bucket. One quart of this well-mixed soil for each 15 to 20 acres is sent to the lab.

Label Bag Or Box

Label with your name, address and sample number. Write down where the sample came from.

Know What's Been Done On Your Fields

Write down past crops, herbicides used, nematode or disease problems and how much fertilizer was used on previous crops.

Take Sample To Lab

Before you go to a lab with your soil samples, be certain it's a lab that uses University of California test methods -- test methods proven on California farms by the University. Other kinds of tests may be useless. You don't need to remember the chemical names for these tests. Just use the list at the back of this publication. And remember: "free" soil tests may be the most expensive kind you can get -- unless (1) your sample was carefully gathered -- just like this bulletin shows and (2) the right test methods are used by a reliable lab.

What About Plant Tissue Tests?

Plant tissue tests can help you tell if you've applied the right amounts of fertilizer. ¹ They also help you plan a better fertilizer program for next year's crop, making next year's soil tests even more useful. And sometimes you can use tissue tests to correct a nutrient deficiency -- fast. But tissue tests can be hard to interpret -- be sure to check with your University of California Cooperative Extension farm advisor before using them.

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¹ Tissue tests are not commonly used in strawberries at this time.

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