Key Information

  1. Collect a representative sample in a clean, 12 oz plastic bottle. Do not use soap. Do not submit samples in glass containers.
  2. Fill the bottle, leaving 1-2 inches of head space, and cap tightly.
  3. Samples should be refrigerated until transferred to the lab.
  4. Concentrated fertilizer solutions are not accepted.  These nutrient solutions must be diluted to the concentration used in fertigation. 

Minimum Sample Volume: 

No matter how precise and accurate an analytical method is, meaningful results are only as good as the sample itself.  The most significant cause of poor statistical results in solution analysis is due to imprecise sample collection and preparation rather than analytical measurement. To obtain a representative sample, NCDA&CS strongly recommends a sample volume of 8-16 oz (~500 mL).  Where this is not possible, please note the minimum sample volume required to perform each analysis (Table 1). Researchers that fail to submit the minimum of 75 mL will not receive the full standard analysis--pH, EC and alkalinity will be automatically omitted.

Analytical TestMinimum Volume (mL)
NO3-N, NH4-N, and Cl15
All other elements (P, K, Ca, etc.)15
pH, EC, and alkalinity50

Sample Collection from Different Sources

Tab/Accordion Items

  • Collect water directly from the tap or emitter. 
  • Allow water to run for at least 5 minutes before collecting a sample.
  • For new wells that recently have been chemically treated, allow the water to run for 1 to 2 hours before sampling. 

  • 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.  

  • One way to collect a pond sample is to tape a plastic bottle or cup to the end of a long pole. If using a plastic bottle, the bottle is then dunked upside down into the water down to about one foot. Turn the bottle up and let it fill. 

     

  • Collect nutrient solutions directly from the emitters, NOT the stock tank. The sample should have the same concentration as the solution being fed to the plants. Do not submit concentrated fertilizer solutions.

  • Flush emitter lines sufficiently to ensure that the sample is representative of the supply solution.  

     

  1. Collect 30 min to 2 hrs after irrigation/fertigation. Media moisture should be at “container capacity.”
  2. Use a saucer or tray as a collection device. 
  3. Pour ½ cup of water gently and evenly over the surface of a 1-gallon pot; for a 3-gallon pot, use 1½ cups of water, etc. 
    For a small block, use 3–5 pots. For a larger block, use 5–15 pots. 
  4. Allow water to drain through the bottom and collect in a saucer or tray.
  5. Use a funnel to pour the collected leachate into a clean soda or water bottle.  Combine multiple subsamples for each sample area into the bottle.
  6. Collect 8–12 oz.  of leachate, leaving a 1-2 inch head space in the bottle.
  7. See the NCSU Pour-Through Leachate Procedure for detailed information.

     
Solution Pour-through

 

 

Tobacco Float bed Source Water:  

  1. Before sample collection, run the water 5 to 10 minutes and collect sample from the tap or emitter.  
  2. Write the solution code for tobacco float bed source water, ST, on the sample submission form.
Tobacco floatbed source water

 

Tobacco Float bed Nutrient Solutions:  

  1. After fertilizer is thoroughly mixed and dissolved, collect a portion of solution from several areas in the bed to make one composite sample. 
  2. Sample each bed separately.
  3. Write the solution code for tobacco float bed nutrient solution, NT, on the sample submission form.
Tobacco floatbed nutrient solution
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This page was last modified on 06/05/2026