make it simple but efficient
Plant parasitic nematodes live in soil or plant parts that they infect. The process of taking a soil sample for nematode assay involves collecting random sub-samples in a zigzag pattern, from the area in question similar to the procedure that would be used for a soil sample for nutrient analysis.
Sampling techniques should have backing from diagnostic and identification laboratory to obtain quick and reliable nematode identification. Auger samplers are used to obtain soil cores for nematode population studies at different depths. The soil cores should be obtained from top first foot (12 inches) where most of soil inhabiting nematodes live. Second and third samples may collect by obtaining soil core 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, at least 20 cores (sub-samples) should be taken.
Soil cores should be collected in a bucket, bag or other container that is easy to carry while walking up and down the field. 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.
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 sample until it can be sent to the Nematology laboratory. Label each sample on the outside of the plastic bag with your name, address, field (or other short sample identifier) and date of collecting. Ziploc storage bags are ideal for this use. You may also contact AGNEMA to request laboratory standard soil/plant collection sampling bags.
Notes to Handling and storage of samples
- For nematode samples, fresher is better. Soil cores should be gently mixed before placing at least 1 pint (500 cc) in a plastic bag [do not use cloth or paper bags]. Sampling bags and/or plastic zip bags are proper.
- For a root test, at least 3.5 oz. (100 g) of fine feeder roots will be needed, especially include roots showing symptoms such as galling, thickening, bunching, soil adherence etc.
- Seal bags to prevent drying and protect samples from heat and/or freeze.
- Perishable plant samples especially need to be sent promptly & be refrigerated.
- Soil does not need to be refrigerated unless liable to be exposed to high temperatures or if it cannot be dispatched promptly.
- Label the bag as appropriate and complete a Sample 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 bags with the soil.
- Send the samples promptly to the laboratory.
- To ensure samples are promptly processed, pre-book tests and preferably collect and dispatch samples early in the week.
- 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