General Sampling Instructions
- Collect a representative sample in a clean, 12 oz plastic bottle. Plastic water or soda bottles may be used, but rinse the bottle thoroughly before filling. Do not use soap. Do not submit samples in glass containers.
- Fill the bottle, leaving 1-2 inches of head space, and cap tightly.
- Samples should be refrigerated until transferred to the lab.
Important: Concentrated fertilizer solutions are not accepted. These nutrient solutions must be diluted to the concentration used in fertigation.
When: Water quality should be tested every 2-3 years or whenever a problem arises
How: Collect water directly from the tap or emitter allowing water to run for at least 5 to 10 minutes before collecting a sample.
Important: For new wells that recently have been chemically treated, allow the water to run for 1 to 2 hours before sampling.
When: At least annually. Biannual water testing during summer and winter is recommended
How: Sample from as close to the middle of the pond or stream as possible and at least six feet from the edge. Avoid surface or bottom residues.
Sampling Tip: One way to collect a pond sample is to tape a plastic bottle or cup to the end of a long pole. Dunk the bottle upside down into the water down to about one foot. Turn the bottle up and let it fill.
When: Nutrient solutions should be tested routinely throughout the growing season and whenever there is a problem. It is strongly recommended to test source water before mixing nutrient solutions. For diagnostic (troubleshooting samples), include a sample of the source water.
How: Collect nutrient solutions directly from the emitters, flushing 5-10 minutes before sampling. Do NOT sample the stock tank. The sample should have the same concentration as the solution being fed to the plants.
Important: Concentrated fertilizer solutions are not accepted. These nutrient solutions must be diluted to the concentration used in fertigation.
- Collect 30 minutes to 2 hours after irrigation/fertigation. Media moisture should be at “container capacity.”
Using a saucer or tray as a collection device, pour water gently and evenly over the surface media surface. See below for water volume and suggested number of subsamples.
Pot Size Water Volume 1-gallon pot 1/2 cup 3-gallon pot 1 1/2 cups Block Size Number of Subsamples Small 3-5 pots Large 5-15 pots - Allow water to drain through the bottom and collect in a saucer or tray.
Use a funnel to pour the collected leachate into a clean, plastic bottle. Combine multiple subsamples for each sample area into the bottle.
See the NCSU Pour-Through Leachate Procedure for detailed information.
Tobacco Float bed Source Water:
- Submit samples of float bed source water for solution analysis annually, well before beds are filled.
- Before sample collection, run the water 5 to 10 minutes and collect sample from the tap or emitter.
- Write the solution code for tobacco float bed source water, ST, on the sample submission form.
Tobacco Float bed Nutrient Solutions: Do not mix fertilizer into float-bed water until after seedlings emerge. There is already enough fertilizer in transplant media to get seedlings through the first week or so of growth.
- Submit samples of nutrient solutions for analysis every time fertilizer is added to beds to verify the nutrient concentrations present.
- After the fertilizer is thoroughly mixed and dissolved, collect a portion of solution from several areas in the bed to make one composite sample.
- Sample each bed separately.
- Write the solution code for tobacco float bed nutrient solution, NT, on the sample submission form.
When: Annually (around the same time each year) or whenever a suspected fertility problem arises
How: Collect water directly from the tap or emitter allowing water to run for at least 5 to 10 minutes before collecting a sample.
| Irrigation Type | Irrigation Code |
|---|---|
| General | IW |
| Overhead | IO |
| Trickle | IT |
| Irrigation Pond | AP |
This page was last modified on 02/26/2026