Potassium Chloride Extraction of Soil NH4-N and NO3-N:

Materials:


2.0M Potassium Chloride (KCL):

2.0M KCL is 149g of potassium chloride per liter. For a 20L carboy of KCL, that would be 2.98kg. However, it has been our practice, especially at field stations, to simply use an entire 3kg jar of KCL to make 20L.

Lab Procedure:

  1. Weigh out 5 or 10g (depending on expected N content) of field-moist soil into whatever kind of container you're using.
  2. Also weigh out 10g or more for moisture content into a bag or onto a weigh boat. Dry for at least 24 hours at ~105C, let cool and weigh.
  3. Add 50ml of KCL to the soil in the containers.
  4. Cap containers and shake for 2 hours.
  5. Pour extracts into funnels with filter paper and allow to drain into clean marked containers.
  6. Filtrate is ready for analysis. Fill Alpkem cups and cap. If you can run them on the Alpkem within the next few days, place the samples in the cold room. If it will be weeks before you run them, they need to be frozen.

 

You also might want to check the KCL extract page from the University of Georgia Institute of Ecology.

Field Procedure:

  1. Weigh out 5 or 10g (depending on expected N content) of field-moist soil into whatever kind of container you're using.
  2. Also weigh out 10g or more for moisture content into a bag. If an oven is not available on site, load the bags into a cooler for transport.
  3. Add 50ml of KCL to the soil in the containers.
  4. Cap each container as you go and shake for 2 minutes.
  5. When done with step 4, go back and reshake the samples.
  6. Allow to settle for 24 hours.
  7. Being careful not to disturb the containers, remove caps and pipet out 3ml of extract from below the surface into Alpkem cups.
  8. Extract is ready for analysis. Analyze, cool or freeze as soon as possible.

 

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