Most fertilizers are labeled with a sequence of numbers detailing the percentage of nitrogen (N), phosphate (P2O5) and potash (K2O) they contain. For example, a complete inorganic fertilizer containing all three may be labeled 16-16-8, meaning it contains 16% nitrogen, 16% phosphate and 8% potash.
Not all fertilizers are considered equal, especially when comparing inorganic and organic options. Some major things to remember when picking out an organic fertilizer are:
- Organic fertilizers are not typically synthesized and available for immediate uptake by plants.
- Organic fertilizers are usually dependent on microorganisms to break them down, so soil health and preparation are important.
- Manure alone will not provide plants all the nutrients they need. Sometimes it takes an entire season before the nutrients in manure are available for plant uptake. Plus manures are often high in salts!
- Most organic fertilizers have much lower analysis than the inorganic options so direct substitution is challenging. The amount of fertilizer you apply and how often you apply it will need to be correctly calculated!
For more information on:
- How to pick out an ORGANIC fertilizer
- How to correctly calculate the application rate
- Average nutrient concentrations in organic materials
Please visit this USU Extension FACTSHEET
For information on organic product availability and certification visit WWW.OMRI.ORG
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