The importance of soil testing

 

Swift Horticultural Enterprises, LLC
Swift Horticultural Consulting

High Altitude Lavender

Curtis Swift, Ph.D.

450 Hill Avenue, Grand Junction, CO 81501

970.778.7866

Curtis.Swift@alumni.colostate.edu

 

The importance of soil testing;

How to collect a sample, where to send it for analysis, and how to obtain a quality recommendation

 

Why is soil testing important?

·         To determine if the soil is appropriate for the trees, shrubs, flowers, herbs, lawn grasses, etc. you want to plant; not all soils can support healthy plant growth.

·         To learn what is needed to improve the health of those plants and reduce plant stress and reduce the potential for insect and disease problems.

·         To know what is needed to increase plant vigor, fruit, and flower production. 

A soil test provides the following:

·         What nutrients are deficient, the organic matter content, the pH and the soluble salt content.

·         What you need to add to the soil to correct deficiencies.

 You need the answers to the following items to realize the full potential of a soil test: 

·         Is this soil compatible with the plants you want to grow?

·         What nutrients are needed and when should they be applied and at what rate?

·         What nutrients should you avoid to prevent imbalances, excessive growth, root damage, etc.?

·         Are your plant problems the result of an improper fertilization program?

·         What nutrients are excessive and how can you avoid contributing to the problem?

·         Do you have a soluble salt problem and if so how can you correct it?

·         If the organic matter level of the soil is low how can you correct it without damaging established plants?  If this is a new planting what should you use and how much to improve the soil.

·         Is there a sodium problem and if so how do you correct it?

·         How can you enhance the growth and quality of the plants in this soil?

 

Recommendations: 

My job is to provide you the answers to the above questions.  My written recommendations will be specific to the plants you are growing or plan to grow in that soil. If you prefer the use of organic products in lieu of synthetic fertilizers I will provide you specifics on what products to use and how much of each is required for your plants and when they should be applied. 

Collecting a soil sample is simple. 

Shovel or trowel: Dig a hole in the area eight inches deep. Take a slice of soil off the side of the hole and throw it in a clean bucket, cardboard box, etc.  

Soil Auger or Probe: Twist/push the auger/probe into the soil to a depth of eight inches. Put the soil you collect in a clean pail, bag, or box.  

For more information on collecting a soil sample go to http://www.wardlab.com/SamplingInfo/ProperSampling.aspx#Soil.  Use clean tools to take samples.

 The soil testing laboratory needs about one pint of soil.  If the soil being tested is similar throughout the field or lawn take multiple samples from the area and mix them together for a composite sample.  If the soil appears or feels different in different parts of the field you should submit a separate sample for each soil type. If testing the soil around a tree, collect samples from the area half way between the trunk and the furthest reach of the branches and all the way around the circumference of the tree. 

 Air-dry the soil before sending it to the lab for analysis. Do NOT dry the sample on a newspaper or other surface where compounds can leach from the surface into the soil.  I use a plastic shoe box to dry the samples I mail to the lab. After the sample is dry, package it up in a plastic zip-lock bag. Keep the sample out of the sun after you have sealed the sample in the bag.

 

Where should you send your soil samples?

 I work with Ward Laboratories, Inc. in Kearney Nebraska (http://www.WardLab.com).  Their analytical fees are reasonable and they are quick and accurate. Their S-4 Routine analysis provides the information I need to provide quality recommendations.   Use the sample submittal sheet at http://www.wardlab.com/images/SampleForms/SoilSampleInformationSheetWithoutRecommendations.pdf .  Make a note on the form to have them email the results to Curtis.Swift@alumni.colostate.edu.  Make sure your name, address, and email address is on the form. Please send me an email to let me know you have sent a sample to the lab so I will expect it.

 Mail the dried sample(s), sample sheet, and payment of $19.25 per sample to:

 Ward Laboratories, Inc.

4007 Cherry Ave., P.O. Box 788

Kearney, Nebraska 68848-0788 

When I receive the results from Ward Lab I will contact you to obtain further information to make my recommendations fit your situation correctly.  

 My Fee: 

My fee for providing recommendations and associated literature based on the soil test results is $30 per sample.  

If you live in the Grand Junction area and want me to pick up the sample(s) at your home or office, mail them to the lab, and provide you recommendations, my fee is $40 per sample.  Please contact me at 970.778.7866 if you prefer this option.     

Now is the time to test your soil!

This past Sunday the soil in my vegetable garden had dried out sufficiently to collect a sample for this year's production season. If your garden still has snow covering it, you will need to wait a while longer to collect soil for testing.       

I dug 5 holes around my garden to the depth of 12 inches and collected a slice of soil from the side of each hole.



I placed each slice of soil into a plastic bucket and mixed them together thoroughly. The composite sample I created is what I will be submitting for testing.

Whether you have 100 acres to test or a small garden plot, this is the technique you will use.  The only exception is if your garden or field has different soil types or was managed differently the previous year.  In that case you should submit a composite sample from each area. Testing your soil will provide you a base line of nutrients which you will use to design your fertilizer applications.  Testing once every 3 to 4 years is usually adeqeuate unless you have radically changed the soil management procedure. 

If you want a soil test analysis run on your soil, you can submit a sample through our office. We will need this form (http://www.coopext.colostate.edu/TRA/PLANTS/Submitting_Soil_Samples_for_analysis.pdf) along with your sample(s). I will provide you recommendations on what you need and how the nutrients should be applied based on the crop you plan on growing. Let me know if you are an organic grower and I'll provide you recommendations based on using organic fertilizer products.

Whether you are an organic gardener or use synthetic fertilizers, a soil test will get you on the proper footing and improve the health of your plants and possibly their nutritional quality. Information on organic fertilizer products can be found at http://www.coopext.colostate.edu/TRA/PLANTS/Organic_Fertilizers.pdf.

Information on the fertilizer requirements of vegetables can be found at  http://www.coopext.colostate.edu/TRA/PLANTS/07611.pdf and http://www.coopext.colostate.edu/TRA/PLANTS/Vegetable_Gardening_Nitrogen_Recommendations.pdf  .

Potato hollow heart is influenced by water, fertilizer and spacing

Hollow Heart of Potato

When potatoes grow too fast, the inside of the tuber tears apart as seen in this photo. This occurs when potatoes are improperly watered, improperly fertilized with nitrogen, or planted too far apart. Hollow heart not only results in the loss of edible flesh due to the need to cut out the discolored tissue before cooking, but can contribute to rot when hollow heart cracks to the surface of the tuber.

Fertilizer: Applying an excessive amount of organic matter high in nitrogen, or over applying an organic or synthetic nitrogen product can increase hollow heart due to an excessive amount of nitrogen being available during the tuber enlargement stage of growth. A soil test is important in determining the fertilizer needs of potatoes and your other vegetable crops.

Nitrogen products, whether organic (http://www.coopext.colostate.edu/TRA/PLANTS/Organic_Fertilizers.pdf ), or synthetic, should be applied in split applications and not all at one time. Once you know the amount of nitrogen required, one-third to two-thirds is typically applied after the plants emerge with the remaining required amount applied 60 days after planting. Smaller but more frequent applications of nitrogen are recommended.

A soil test will tell you what nutrients in addition to nitrogen are required. Other than nitrogen, these nutrients will need to be applied and worked into the soil prior to planting. If you want a soil test analysis run on your soil, you can submit a sample through our office. We will need to receive this form along with your sample(s). I will provide you recommendations on what you need and how the nutrients should be applied based on the crop you plan on growing. A soil test will also indicate if you have a salt problem you should be concerned about. We can test your soil and irrigation water for salts at no charge at our offices in Mesa, Delta, and Montrose Counties.

Watering: Potatoes should not be allowed to drop below 60-65% of available soil moisture. 75 – 85% soil moisture is preferred after the plants emerge from the soil and before they start to set tubers. When the plants start to set tubers, the soil moisture content should be maintained between 80 and 90%. The best way to determine when tubers start to set is by digging into the soil and checking the stolon tips to see if they are starting to swell. This usually occurs when the plants start to flower.

To determine the moisture content of the soil, you can use the soil ball technique (http://www.coopext.colostate.edu/TRA/PLANTS/soilmoist.pdf ) or by checking the lenticles. Lenticles become enlarged when soil moisture is excessive. See http://swiftsgardeningblog.blogspot.com/2011/02/potatoes-have-lenticles.html  for an explanation of lenticles on potatoes.

Spacing: While the spacing of potatoes varies somewhat with variety, row width is typically 30 to 36 inches. For cultivars with a tendency to develop oversized tubers or set few tubers, such as Katahdin and Kennebec, seed pieces should be spaced 6 – 9 inches apart within the row. For cultivars that produce a heavy set, such as Norchip, seed pieces should be spaced 11 – 14 inches apart in the row. Be sure to check the production characteristics of the cultivar you are planting to determine the required spacing. Your local nursery or garden center should be able to provide you guidance on spacing for the varieties of seed potatoes they sell.

A soil test can improve the health and production of your gardens.

Soil samples can be submitted through the Mesa County Extension office for $25 per samples.  This will cover the cost of having your sample analyzed by a reputable lab and recommendations from me on what to add to your soil to improve it for plant growth.  I will also provide you recommendations on what not to add and how to correct soil problems.

Samples can be dropped off at the Delta or Montrose Extension offices for delivery to the Mesa County office.  If you live in Mesa County or are driving this way, drop off your sample(s) at my office at the Mesa County Fairgrounds. Payment for this service is expected at the time you drop off your sample(s). Checks need to be made out to the Mesa Extension Fund.

It typically takes 10 days from the time the sample reaches my office for the analysis to be completed and my letter to be sent back to you. I prefer to corresponde with you via email if at all possible.

Soil samples should be taken from several spots in the area you want to have tested. Collect the samples from the soil surface to a depth of at least 8 inches. Use a clean shovel or soil probe and a clean pail, bucket or box in which to collect the sample. If multiple samples are collected that represent one area, it is best to combine them into one sample. Allow the samples to dry on a clean table before submitting them for analysis. The sample can be placed in a zip lock bag. Submit no more than one pint per sample. Please remove any rocks or large organic debris particles from the sample. Only the soil will be tested.


If you are submitting more than one sample, mark each bag with your name, the crop/plants being grown or you are planning to grow at that site and an identifying number or name so you can match the results up to the area where you collected the sample.

I will need the following information from you along with your sample(s):
Name and mailing address
e-mail address
phone number
crop or plants you intend to grow
and whether your intention is to grow this crop organically.