Rock Phosphate : A biological Game Changer

Rock Phosphate a game changer in Biological Farming

By John Moor

Phosphorus is one of the 17 essential elements required by plants, “NO PHOSPHORUS NO FOOD”

In this article I will endeavour to explain in simple terms why Acid treated Phosphorus such as MAP and DAP, although they have a place in biological and regenerative agriculture are also working against some of the basic principles and damaging soil life. I will introduce Rock Phosphate as an alternative, discuss its pros and cons and where I believe it fits perfectly into a biological programme.


  1. It is essential in the process by which plants convert sunlight into energy.
  2. It is essential for nutrient transfer in a plant
  3. P is an essential part of ATP (adenosine tri Phosphate) which is the energy currency of plants and forms part of their DNA.
  4. P stimulates root growth, pollination, seed formation and seed viability.

Many soils around the world are deficient or low in Phosphorus, this has a knock on effect that manifests in low levels of P plants and then in animals and why many graziers supplement P to their cattle at great cost.

Most commercially available sources of Phosphorus (P) are acid treated water soluble compounds like MAP and DAP. They dissolve readily when they come into contact with water and become plant available. Although this source of Phosphorus might be readily available to plants as much as 75% can quickly be locked up by soil Cations (positively charged elements in the soil) and made unavailable to plants, in particular Ca and Mg in alkaline soils and Fe and Al in more acidic soils.
A Calcium Rock Phosphate on the other hand is less water soluble and requires slight acidic conditions to mineralise (release) the Phosphate compounds so that they become plant available. So in the absence of an acidic soil, which we don’t necessarily want to promote how does this happen.
There is an invisible work force exactly placed where the plant needs it to do this job and they are called Fungi, in particular Mycorrhizal Fungi. In healthy soils these little fellas colonise the Rhizosphere or root zone, they do this because the plant, through the roots feeds them sugars which are essential to their survival, in return the Fungi go hunting for elements that the plant needs and bring these back to the root zone. The fungi exude weak Organic Acids which dissolve the Rock Phosphate and other minerals right in the root zone where uptake take place. As the plants requirements increase so does the root mass, so does the Fungi and so does the availability of dissolved nutrients like Phosphorus. If this environment can be maintained the plant will receive all it needs to grow, reproduce and seed.
BUT we keep bombing the Bridge between the soil microbes and the plant.
This we often do unknowingly using synthetic fertilizers and chemicals which kill the very things we need, fungi, bacteria, earthworms, amoeba but to name a few.
Synthetic acid based fertilizers have high salt indexes which dehydrate the soil environment making life for water loving fungi, bacteria and others impossible to live in.
Herbicides, insecticides, glyphosate and most agro chemicals kill or inhibit soil biology. So each time they are applied we again either kill those present or set back their proliferation.


Most agronomists would agree that the absence of plant available Phosphorus will end in poor germination, weak root development, poor growth and low or no yield.
I agree, BUT this phosphorus need not all be applied as Acid treated MAP, DAP etc.
Apply only that what is absolutely necessary to initiate plant growth in row crops. The balance of the required Phosphorus should be applied before planting as a natural slow release organic Phosphate in the form of Rock Phosphate. In established Orchards, pastures and other perennial crops it will be far more beneficial to build soil P levels with annual applications of Rock Phosphate allowing the soil biology to mineralize this over time and trickle feed the plants as required.
Research shows that under ideal conditions as much as 50% of a good rock phosphate can become plant available in the first year. The balance does not leach, builds soil structure, promotes soil biology, adds Calcium and other trace elements to the soil, increases its CEC (cation exchange capacity). Speak to your agronomist and see if Soft Rock Phosphate will fit into your program.

I have a reliable, high quality source locally available.

John Moor