Categories: Organic Gardening

Biosol or Bust

By Published On: November 9, 2010
Biosol or Bust

With fall comes the rush on local supplies of Biosol.  We went to get our share.  Each visit to the nursery they were out, expecting a shipment that very afternoon….

I was discussing materials and fertilizers with folks at a sustainable landscaping event down in Sonoma County this last spring.  I must say, these people are a little spoiled (or I’m a little jealous).  For one, they had never heard of Biosol, something we mountain dwellers live by spring and fall.  And two, they have choices far beyond the understanding and scope anyone around here could imagine.  Much of it locally produced and supplied by companies such as Sonoma Compost and Grab N’ Grow.

“What is Biosol?” they asked.  “I’ve never heard of it.”

“Well, that’s a good question,” I thought to myself.  But responded, “It’s an organic fertilizer often used in restoration projects.”

Biosol is an organic, slow release nitrogen fertilizer derived from fermented soybean and cottonseed meal.  It’s high in organic content, mostly comprised of the fungal biomass (dry mycelium) created during the fermentation process, is considered humus building, aiding poor quality and disturbed soils, and is high in insoluble nitrogen, a more stable form of nitrogen.  Unlike many other fertilizers, it has shown to produce very little seepage outside the intended area, reducing pollution.  (See Biosol Forte studies.)  It is one of the only fertilizers landscape installers and companies in the Lake Tahoe area use for this very reason.  Lake clarity is rapidly declining due to contamination from factors such as run-off, development and the need for greater erosion control.

But here’s the deal.  Organic doesn’t necessarily mean “ORGANIC” in the no pesticide, hormone free sense.  The USDA might call it Bio Preferred.  This is good.  Products made from “renewable agricultural materials” rather than chemically derived.  Then there’s 3rd party certification from organizations such as OMRI, the Organic Materials Review Institute.  If you’d like to be sure it’s “ORGANIC” look for the OMRI seal of approval or search the OMRI product list.

Busting out the Biosol

Biosol (for all of you visual folk, sold in a yellow bag) is approved by the California Certified Organic Farmers and OMRI.  It has an NPK ratio of 6-1-3.

Biosol Mix now known as Biosol Forte (once sold in a white bag and now sold in a bright blue bag) is a USDA Bio Preferred product.  It’s designed for quicker nitrogen release and has an NPK ratio of 7-2-1.

Research has shown Biosol to not only aid with humus growth but to also reduce plant disease, rally root growth, increase canopy growth in trees and shrubs, improve strength and health of turf, control soil nematodes, jump start revegetation projects and much more.  One of my favorites, though not scientifically proven, are it’s anti-vole super powers.  The general observation: lawns and other areas treated with Biosol tend to see less to no vole foraging.  Amazing.

I’m a compost queen, no make-up kind of girl.  I appreciate gardens and landscapes that mimic natural systems and the necessary soil care that comes along with it.  This means mulching and tending the soil you have for the purpose and environment at hand.  While native plants are critical to any garden and go hand-in-hand with native soils, I also love my hollyhocks, apple orchard, meadow and wildflowers.  Fertilizers are often essential, especially in a high elevation, low humidity area like mine.  It is virtually one continuous restoration project.  Biosol is a good choice.  The right fertilizer in the right place?  I’ll just do my best to ignore the line that reads, “Product of Austria” and forget to mention it to my Sonoma Compost friends.

The Hollyhocks Made Me Do It
Garden Design: Taking Cues From Nature


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About the Author: Emily Murphy

I’ve learned there’s something wonderfully powerful in the simple act of growing. Here, in our gardens, we can repair ourselves and our plots of earth with our own two hands. GROW WHAT YOU LOVE and GROW NOW!


  1. Lizet March 29, 2017 at 8:02 am - Reply


    We are a landscape company in hopes of selling this product Biosol. We have noticed that there is a bit of a smell. Does this last long?

    Please advise.

    Thank you,

    • Emily Murphy March 29, 2017 at 9:32 am - Reply

      Hi Lizet, thanks for writing! It does have a strong odor at first. It mellows out and disappears over the course of a few days. I often spread Biosol right before our first snow cycle and sometimes again in spring. Watering and mulch help the smell dissipate faster. Hope this helps! Emily