Hidden Truth About Commercial Phosphate Fertilizers.
When I started farming in the mid 50s, South East of San Antonio,
The Texas A&M Ag and animal experts both recommended using super
phosphate (0-20-0) or bone meal. Tests showed the soil low in phosphorus.
Their recommendations proved beneficial to the plants and the grazing
In the late 60s, on my
new farm North East of San Antonio, the use of phosphorus again proved
productive. By banding colloidal phosphate in the furrow at planting,
I could double production on my fruiting vegetables. The rate applied
was two tons per acre. I never at any time noticed micro nutrient
deficiency. The soil Ph on the vegetable farm was from 7.3 to 8.3,
depending on where and when the testing was done.
Then, some time during
the 70s lawns, shrubs, trees, vegetables and flowers in San Antonio
started yellowing from the lack of micronutrients. The problem was
found to be iron, zinc and manganese being tied up by phosphate. The
extension service started putting out bulletins telling everyone to
stop using phosphate.
I never experienced these
problems. But then, I had never used the new triple super phosphate
that was now on the market. I asked one of the agricultural extension
agents if the new 0-46-0 triple super phosphate could be causing all
the problems. He thought for a moment then mentioned that the timing
correlated perfectly but he never found anyone to agree.
On my own, I did several
tests. I used plants highly susceptible to iron colorosus. I planted
some in pure colloidal phosphate, some in pure rock phosphate and
another bunch in soil that I applied the equivalent of 10,800 lbs
per acre of the old style 0-20-0 super phosphate. All of the plants
were fertilized with bat guano, which has 10-3-1 (N-P-K) all grew
normal, showing no deficiencies. I strongly believed the problem to
be the new Triple Super Phosphate. But no one, either from A&M,
USDA or the fertilizer industry would or could give me an answer.
An elderly friend that
had worked for large fertilizer companies was visiting me one day.
I asked him for an honest answer to my suggestion that the new 0-46-0
could be causing all the yellowing?
After a long pause he answered.
You are absolutely right but you are not supposed to know that. He
explained that the fertilizer manufactures made that discovery but
they kept it a secret and all agreed to stop selling and making the
0-20-0, type of phosphate. This also prevented growers from discovering
the problem by comparison.
To make 0-20-0, rock phosphate
is treated with sulfuric acid to make calcium phosphate (0-20-0) and
calcium sulphate (gypsum); these are two natural products that seldom
caused any problems.
To make 0-46-0, rock phosphate
is treated with phosphoric acid. With this, much higher phosphate
content, much higher N-P-K fertilizer formulas can be made. Less needs
to be used. And it sells for a higher price with much better profits.
My elderly friend explained
that, when used, 0-46-0 is laying naked in the soil and looking for
something to marry up with. It bonds up with zinc, iron and manganese
then the plants can’t assimilate them.
Evidently, this knowledge
is well protected because to this day the agricultural agents are
all telling gardeners and horticulturists to stop using phosphate
fertilizers and manure for three to five years. Another problem, some
agricultural agents claim, is that the phosphate is causing lakes
and streams to grow too much algae.
I can’t understand
their reasoning. Manure has been used for centuries without causing
soil problems. However, if raw manure washes into lakes it will grow
algae because it is a complete fertilizer.
The fertilizer industry
has learned to beef up their high quality phosphate fertilizer products
with extra zinc, iron and manganese to help overcome the problems
in the landscape. Also, phosphate is not known to leach from the soil,
it only moves with the soil. It can’t get into lakes unless
placed there or from soil erosion. Phosphate alone will not grow algae;
nitrogen must also be present.
For answers I did some
research. I got virgin soil from a location that has never been plowed
or fertilized. I naturally air-dried and well homogenized this soil
so I could get identical samples to send to numerous testing labs.
I sent seven in all, two to Texas A&M soil test department and
five to other labs around the U.S.
The two A&M test results
showed excessive soil phosphate with instructions to not add any phosphate
fertilizer or manure to the soil for 3 to 4 years. The other five
labs showed soil phosphate low to medium and gave recommended application
Why are the A&M test
results so much different from the other five labs? Something is definitely
1. The algae in the lakes
should be attacked by stopping erosion and the over use of highly
soluble forms of nitrogen fertilizer.
2. The fertilizer companies
should be honest with their customers.
3. Texas A&M soil
testing department should get together with the private testing
industry to end mistrust and better serve gardeners and farmers.
4. The fertilizer salesman
should be honest and better educated.
5. More and proper research
needs to be done and shared with the farmers and gardeners.
6. The agricultural agents
should keep up with all private and public, research.
7. All educational institutions
need to teach more about Nature and how she operates.
Malcolm Beck - May 2003
As of Jan. 20 Texas A&M has admitted they were wrong in their testing and have now made the proper corrections. To read the corrections go to
Laboratory Extractant Change - http://soiltesting.tamu.edu./webpages/extractant.html