Compost NPK meaning - Ask Extension
I am using compost produced by a local city from human waste and sawdust. It meets all federal standards for safety. The producer gave me the NPK anal...
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Compost NPK meaning #868228
Asked May 13, 2024, 3:02 PM EDT
I am using compost produced by a local city from human waste and sawdust. It meets all federal standards for safety. The producer gave me the NPK analysis included below - but cannot tell me if the N component is fast or slow release (or most likely, a combination) in the gardening sense. Can you help? Thanks
Below is the City’s test data for 2023. The approximate N-P-K ratio for the 2023 data is 11:6:1. If you have any questions, don’t hesitate to reach out.
NUTRIENTS
March June Sept Dec 2023
2023 2023 2023 2023 Average
Total Kjeldahl Nitrogen, % 2.34 2.53 2.31 2.48 2.42
Ammonia Nitrogen, % 1.030 0.895 0.804 0.819 0.887
Nitrate Nitrogen, % 0.003 0.004 0.002 0.010 0.005
Potassium, % 0.187 0.223 0.263 0.217 0.222
Phosphorus, % 1.07 1.28 1.48 1.70 1.38
C:N Ratio 15.5 15.8 15.0 16.0 15.6
Yamhill County Oregon
Expert Response
Hello,
It is a little confusing to follow this spreadsheet in this system since the columns don't line up. In general, the plant available nitrogen is the nitrate and ammonium. Composts and animal manures are considered natural slow release fertilizers because they need to be broken down by biological activity for the nutrients to be available.
Have you done a soil test for the area you are going to apply the compost? Keep in mind you soil could also have some nitrogen available and this would affect how much compost to apply. Here is a publication about fertilizing gardens that may be helpful, it has a section on using manures and composts:
https://extension.oregonstate.edu/catalog/pub/ec-1503-fertilizing-your-garden-vegetables-fruits-ornamentals
Thank you for using Ask Extension!
It is a little confusing to follow this spreadsheet in this system since the columns don't line up. In general, the plant available nitrogen is the nitrate and ammonium. Composts and animal manures are considered natural slow release fertilizers because they need to be broken down by biological activity for the nutrients to be available.
Have you done a soil test for the area you are going to apply the compost? Keep in mind you soil could also have some nitrogen available and this would affect how much compost to apply. Here is a publication about fertilizing gardens that may be helpful, it has a section on using manures and composts:
https://extension.oregonstate.edu/catalog/pub/ec-1503-fertilizing-your-garden-vegetables-fruits-ornamentals
Thank you for using Ask Extension!
