Phosphate on the brain

Better soils
with Brett Petersen
Kiwi Fertiliser & Golden Bay Dolomite

 Below is a passage written by Jerry Brunetti, as part of an article titled “Cows don’t have carburetors” and was published in Acres USA, May 2012. The title seems absurd; it is extremely relevant.

Unfortunately, livestock operators, es­pecially in New Zealand, are being sold a big lie as to how to grow forages, ap­plying huge amounts of urea and super phosphate for yield while dropping the energy levels of the forages, increasing the “funny protein” (nitrogen), oblit­erating the biodiversity of forbs (forage herbs) rich in phenols, carotenoids/terpenoids, and complexing those vital elements in the soil, namely calcium, magnesium, sulfur and boron that are responsible for creat­ing quality protein and forage diversity.

Many New Zealand farms have acid­ic soils (e.g. pH of 5.5). Yet, their soil analysis showing a P2O5 “deficiency” was derived from an “Olsen Test,” to be used on alkaline soils. These soils show a continued “need” for super phosphate, even though some soil tests that I reviewed contained 4,000 pounds per acre of phosphate when they were analysed using a Mellich III extraction procedure, the appropriate method of testing acidic soil. All this excessive phosphate locks up whatever calcium and magnesium is present, denying the plant an ability to synthesize both qual­ity protein and quality forage calories in the form of pectins and hemi-cellulose.

Moreover, the excess phosphate drives the critical mycorrhizal fungi out of the rhizosphere, depriving that organism’s contribution of phosphatase enzyme, needed to extract complexed phosphate and trace elements out of the soil. Thus, over-applying phosphate ironically leads to a deficiency of plant phosphorus, needed to produce ATP (adenosine tri­phosphate), the energy currency in the Krebs cycle for both plants and animals.


What does it all mean? Neal Kinsey, of Kinsey Agricultural Services (KAS), a true adherent to the Albrecht principles of soil fertility, advises all his clients, (which include countless consultants all over the world), to use Perry Agricultural Laboratories for their soil tests. Bob Perry uses the Bray II (root acid soluble) test for soils with pHs up to 7.5. Once the pH gets to 7.6 and above, they provide an Olsen P test result. Since there are at least 12 tests to choose from, why do NZ labs use the wrong one? The Americans use it appropriately and we in NZ have been led to believe it is a true measure of our soil P when it is not.

On average, 73 per cent of acid phosphates tie up or complex with aluminium, iron, manganese, and calcium, within six weeks, sometimes within hours of application. But super’s big marketing ploy is its low cost. How cheap is a material that is only 27 per cent effective, even less than that on some soils? Remember, chemical agriculture is a self-serving, input-driven system. You are advised to apply an unbalanced fertiliser to an unbalanced soil to help sustain a state of imbalance, which will then require constant chemical intervention. Now we have an inappropriate P test and an inappropriate product. When compared to alkaline phosphate products the answer comes out very much in favour of alkaline products such as guano, RPR, dicalcic and DAP. If needed, you can quickly build soil P levels with those products without those tying-up problems.

When we add the demise of mycorrhizal fungi (VAM) into the equation, the situation becomes even clearer. There is little or no reason to use super, as the VAM increases the effectiveness of phosphate uptake of roots by 10-1000 times. Loss of VAM leads to increased soil erosion and leaching of nutrients from the soil. When the VAM is lost, some other organism will take its place. Usually, it is a pathogenic organism. Since properties I have worked with have no facial eczema, it seems a good bet that those using alternative phosphates will also not be bothered by that terrible affliction.

As for excess phosphate in the soil, on reviewing soil tests taken on flats, 90% had an excess, some being in the plus 700kg bracket. The hills were a different proposition as 86% were deficient.

Phosphate on the brain? There comes a point when some properties at least need to address other nutrients. The best way to assess that is to get a KAS soil test. However, while the public doesn’t suffer from phosphate on the brain, the high aluminium released from using super-phosphate is certainly a real threat to the health of humans particularly their brains.

Jerry Brunetti is managing director of Agri-Dynamics, which specializes in products for farm livestock and pets, and consults on a wide variety of other issues. He can be reached at Agri-Dynamics, P.O. Box 267, Martins Creek, Pennsylvania 18063, phone 877-393-4484, email, website


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