make it simple and efficient
Plant parasitic nematodes live in soil or plant parts that they infect. The process of taking a soil sample for nematode assay in a field involves collecting random sub-samples in a zigzag pattern, from the area in question. The process is almost similar to the procedure that is used for collecting a soil fertility testing sample.
Auger samplers are used to obtain soil cores for pathogens and nematode population studies at different depths. The soil cores should be obtained from top first foot (12 inches) where most of soil inhabiting pathogens and nematodes live. Second and third samples may be collected by obtaining soil cores from as deep as second foot (12-24 inches) and third foot (24-36 inches) to ascertain that the deeper-seated nematodes are also covered.
Fields should be divided into areas of 5 Acres or less for sampling and separate samples should be taken from areas with different cropping histories, soil types, treatments applied, or crop health. For uniform fields of up to 5 acres, 10 to 20 cores (sub-samples) should be taken.
Various sampling schemes such as collecting a core at regular intervals along a “W” or “zig-zag" pattern have been used. Various patterns to obtain soil samples is depicted below.
Soil cores are collected in a bucket, bag or other container that is easy to carry while walking up and down the field.
Combine the sub-samples for a particular sample as they are collected. When sub-samples are collected, mix the soil thoroughly and place approximately 1 pint (~500 cc) into a quart-sized plastic bag. Bags should be sealed to retain soil moisture and kept out of direct sunlight – placing samples into a small, insulated cooler (without ice) is a safe and convenient method for protecting the samples until they can be sent to the laboratory.
Label each sample on the outside of the sampling or plastic bag with your name, address, field ID (or other short sample identifier) and date of collecting.
Notes to Sampling, Handling and Storage of samples
For plant-parasitic nematodes and disease testing samples, fresher is better.
When sub-samples are collected, mix the soil gently and thoroughly then place approximately a quart-sized into sampling bag or a plastic bag.
Sampling bags or plastic zip bags are proper [do not use cloth or paper bags].
Seal bags to prevent drying and protect samples from heat and/or freeze, also protect samples from direct sunlight.
Placing samples into a small, insulated cooler (without ice) is a safe and convenient method for protecting the sample until it can be sent to the laboratory.
If samples are only collected for "soil DNA analysis" keeping them in a cooler with ice or into a refrigerator is recommended.
Soil nematode samples do not need to be refrigerated unless liable to be exposed to high temperatures or if they cannot be dispatched promptly.
Sample volume: 1 pint (2 cups or ~500cc) is good enough for both Nematode and soil DNA analysis.
For a root testing, at least 4 oz. (~100 grams) of fine feeder roots will be needed, especially include roots showing symptoms such as galling, thickening, bunching, soil adherence etc.
Perishable plant samples especially need to be sent promptly & be refrigerated.
Label the bag as appropriate and complete a Testing Submission Form with the test required, sample ID, depth, crop type, mailing address, phone number, email address, etc.
Do not put paper labels inside the sampling bag.
Send the samples promptly to the laboratory.
To ensure samples are promptly processed, pre-book tests, email a copy of sample submission form, and preferably collect and dispatch samples early in the week.
If you are interested in having more information, you may check the following links:
The Hows and Whys of Soil Testing [Video] - Dr. Joan Davenport, WSU Crop and Soil Sciences Dept.
A Guide to Collecting Soil Samples for Farms and Gardens [online] - Oregon State University
Soil Testing [online] - Ohio State University Extension
Comprehensive Assessment of Soil Health [pdf] - Cornell University