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Is organic matter (OM) in organic fertilizer important?

Is higher OM better than lower OM? For example: NPK 3:2:2 OM 71% better than NPK 3:2:2 OM 60%?

qnguyen
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2 Answers2

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No.

It is just important for soil (soil structure), as it help to keep fertilizers (if you are in a sandy soil) and moisture. On a pot, I think it is better (in my opinion) to use good soil, and replace it from time to time (every few years).

I would care much more about what N, P, and K is in both fertilizers (e.g. if fertilizers will be released quick or slowly), and pH.

BTW high or low number are not more important then price. The important part is the ratio: if you have low number you just put more fertilizer, but if the ratio is wrong, you can never reach a good balance of nutrients for the plants.

Giacomo Catenazzi
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  • Both the organic fertilizer are in pellet form so they are slow release. You said it's important for soil, so higher OM helps soil better than lower OM? – qnguyen Feb 22 '19 at 10:26
  • Maybe. In general it is easier to have good soil before to plant, but to get into your question: it depends on the plants. On many gardening books you have the OM requirements of plants. For sure cactus and other succulent plant do no need much OM. Vegetables usually like much OM. In general I prefer more OM, but overdoing it will cause more rot. It is not an easy question. Maybe you should do a new question with an explicit plant in mind. – Giacomo Catenazzi Feb 22 '19 at 12:07
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Organic sources of NPK will decompose and release nutrients more slowly than liquid fertilizers. Plus, OM supports bacteria and fungi which do the job. Compost, for instance, is a "topsoil builder" thanks to those attributes. Chemical fertilizers, on the other hand, feed the plants directly . Over-fertilization may provide excess salts that will upset the roots. Unused salts will be washed-away. They must either be dosed correctly, or be provided as slow-release pellets (SRP). The best would be to use OM. Add just enough SRP to balance the feed to suit the demands to whatever your plant needs.

Christmas Snow
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