Organic Phosphorus Fertilizers

Organic phosphorus fertilizers come primarily from mineral sources, like rock dust or colloidal phosphate (also called “soft phosphate”), or from bone sources, such as steamed bone meal or fish bone meal.

Mineral phosphorus sources are cheaper and last longer in the soil. Bone sources are more readily absorbed by plants.

Phosphorus is needed for root development, stem formation, and fruiting in summer vegetables like tomatoes, peppers, eggplants, squash, melons, and cucumbers.

Phosphorus tends to be widely disbursed in soil, so it’s hard for these plants to get enough of it within their limited root zones. To get enough phosphorus to produce fruit, fruiting plants evolved symbiotic relationships with myccorhizal fungi. Almost all plants that bear fruit form myccorhizal associations.

Fungi are creatures of the soil. Their hyphae can spread for hundreds of feet underground (the largest living organisms are fungi), and they can transport nutrients anywhere in the hyphal system. Myccorhizal fungi concentrate phosphorus and other minerals at the roots of plants, and the plants provide the fungi with sugars, starches, and amino acids in exchange.

Gardeners and farmers usually add supplemental organic phosphorus fertilizers to the soil to accommodate crop needs. Inoculating seedling roots with Endo-Myccorhizae increases their ability to absorb soil phosphorus.

Dr. Earth Life (Probiotic) Fertilizer contains both endo- and ecto-mycorrhizae, as well as beneficial bacteria, and is a great soil amendment for summer vegetables. It’s especially useful for growing vegetables in containers, where sterile potting mixes limit plant growth.

The table below lists organic phosphorus fertilizers. Colloidal phosphate is more biologically available than rock dust, but not as readily assimilated by plants as bone sources of organic phosphorus.

Organic Phosphorus Fertilizers (P)—Links Go to Offsite Affiliates to
Purchase Organic Soil Amendments
 Soil Amendment  N-P-K  Description  Lasts  Application Rate
Soft Rock Phosphate 0-18-0   Colloidal Phosphate has a clay base that makes it easier for plants to assimilate than phosphate rock. Releases over months and years in acidic and neutral soils, but breaks down poorly in alkaline soils (pH higher than 7). Peak availability in 2nd year.  2-3 Years  Up to 6lbs/100 sq ft
Bat Guano (High-P) 3-10-1  High-Phosphate guano from fruit-eating bats. Excellent P source for container vegetables and gardens.  2-3 Years  2-3lbs/100 sq ft
Steamed Bone Meal 3-15-0  Made from ground cattle bones. P in bone meal is highly plant-available. Great mixed into the planting hole with bulbs. Good amendment for allium family plants (onions, garlic). May attract raccoons. P in bone meal not released in alkaline (pH greater than 7) soils.  1-4 Months  10lbs/100 sq ft
Fish Bone Meal 3-18-0   Phosphorus from fish bone meal is readily assimilated by microorganisms and plant roots in the soil.  1-2 Years  1-2lbs/100 sq ft
Rock Phosphate 0-33-0  Very slow release P source. Releases over several years in acidic and neutral soils, but won’t break down in alkaline soils (pH higher than 7).  3-5 Years  Up to 6lbs/100 sq ft.
Rock Dust (Crushed Granite) 0—3-5—0,
trace minerals
 Granite fines, the dust from rock grinding and sorting operations. Very slow releasing P source, good source of trace minerals for plant immunity and tolerance of temperature extremes.  5-10 Years  Up to 8.5lbs/100 sq ft
Chicken Manure 1.1-0.8-0.5  Good manure source for P and some K.  3-12 Months  1/2-1” layer

(5-10 5-gal buckets/100 sq ft)
Pig Manure 0.8-0.7-0.5  Good, balanced manure source of N, P, and K. Because some pig parasites and pathogens can infect humans, pig manure is not allowed in many organic protocols. If it is used, it must be hot-composted prior to use.  3-12 Months  1” layer

(10 5-gal buckets/100 sq ft)

Top of Organic Phosphorus Fertilizers Page

Organic NPK Fertilizer
(N)itrogen  |   (P)hosphorus  |   (K) Potassium  |   Calcium

New! Comments

Have a question or comment about what you just read? Leave me a comment in the box below.

Subscribe to my e-zine
to learn about additions to the site.

E-mail Address 

Your First Name


Your e-mail address is totally secure.
I promise to use it only to send you
The GiO Newsline.

    To Follow on Facebook   Become a fan on facebook

       Follow me on Twitter   Follow me on Twitter

       Subscribe to the Grow It Organically Blog in a Reader   Subscribe in a reader

Follow Me on Pinterest

Activity on Google


Copyright © 2009-2015, by Steve Masley,
All rights reserved

Protected by Copyscape Web Copyright Protection Software

HOME  |  About Us  |  Contact Us  |  Privacy


Follow on Pinterest

Remodeling and Home Design

Remodeling and Home Design

Trending on GiO

Growing Hot Peppers—'Bulgarian Carrot' 1
Growing Hot Peppers

Pepper Varieties 'Gourmet', Hand for Scale
Growing Peppers


“Thanks for all the great info! I have been gardening over 30 yrs and still learned things from your site!”

–Verlee Deana Norris Jenkins, Clinton, Arkansas     

“Awesome site, very informative, well laid out, very user friendly!”

–Dorothy Carothers     

“I just love this site! I am on it just about everyday - just reading all the information you have posted. Thank you so much for your creative ideas, plant information and the beautiful pictures. This is My site for all my gardening questions.”

–Judy Gianetto, Wolcott, Connecticut     

“Great info and very useful. I'm starting a new garden this spring and you've given me a lot of tips. Thanks and keep it up.”

–Gardener Angie     

“This looks like a fantastic website, full of useful inform-ation on growing organically. I'll be returning to it regularly!”

–Vera Lynne, Sydney, Australia     

“I am recommending your website to my Master Gardener students. It is very informative and contains good info on growing organically.”

–John Haase, Oklahoma State University     

“Awesome site! Really going to help me in my container gardening adventures this summer!”

–Michelle Doherty     

“I found your site while looking for changing the pH info for an article I am writing. Now I will be linking to you on my blog as well, and visiting here often!”

–Pam Carter     

“Greetings from 'Down under' in Victoria, Australia. Great gardening site with lots of info. Have put you on the favourite list for all the things I keep forgetting. Beautiful photos of your tomatoes etc. Kind regards and happy gardening.”

–Liam, Victoria, Australia     

“I love your site! And, I'm lovin' my garden more because of it. Thank you for doing so, and helping folks like me get more out of my garden.”

–Will Johnson, Denver, Colorado     

“...your website is totally awesome. The single best resource I have ever found on gardening. There's so much information, love and dedication in all the pages, and the photos are great too.”

–Greg Schofield, Vancouver, British Columbia     

“I just wanted to say "Wow"! Very beautiful site and pictures. Your passion and skill shows through on each page. Very BIG Kudos to you BalconyFarmer!”

–Lorri D     

“This is seriously the BEST and most helpful gardening site I've seen!”

–Rosalie Cronin, Adelaide, Australia     

Like What You See? Let us know
or Comment on facebook.

Pinterest Logo

See What Pinners Are Pinning

Popular Pages

Tomato Varieties—‘Sweet Cluster’
Growing Tomatoes

Growing Eggplant ‘Farmer’s Long Purple’ in a Terra Cotta Pot
Growing Vegetables
in Containers

Growing Lettuce—SaladScape of Skyphos and Santoro Lettuce
Growing Lettuce

Growing Basil—‘Genovese’
Growing Basil

Starting Seeds for 2008 Garden 1
Starting a Vegetable Garden
(10 Mistakes Beginners Make)

Growing Spinach—‘Nobel’
Growing Spinach

Growing Cilantro in a Salad Table Tray
Growing Cilantro

'Georgia' Collards
Fall Vegetables

Winter Squash Varieties—‘Bonbon’ Buttercup
Growing Squash

‘Globe’ Artichoke from Page’s Garden
Growing Artichokes

Growing Broccoli 2
Growing Broccoli

‘Jade’ Green Beans Growing in a Window Box
Growing Green Beans

Growing Carrots—‘Babette’
Growing Carrots

Growing Cabbage
Growing Cabbage

Container Cucumber 'Bush Slicer' 2
Growing Cucumbers

Steve's Top 10 Holiday Gifts for Gardeners
Gifts for Gardeners

Growing Lettuce in a Salad Table
Salad Tables

More Popular Pages

Finished Compost Pile
How to Compost

Alfalfa Meal NPK
Organic NPK Fertilizer

Soil—Wonderful Stuff, but Not Exactly Photogenic
Facts About Soil

Syrphid Fly on Flowering Cilantro (Coriander)
Natural Garden
Pest Control