Polymaleic acid to
control Iron in water
I'm working with a blueberry grower in South Jersey who has
an iron problem (3 ppm in well water). The iron has precipitated in the PE tubing and
clogged many emitters. Our Extension Service Small Fruit Specialist advises against
continuous chlorine injection in blueberries due to their sensitivity.
Also the grower does not want to take this risk. I discussed
this problem with Dr. Charles Burt, and he suggested polymaleic acid /polyphosphate
treatment to keep iron in solution. I also read information on this in FERTIGATION -
C.Burt, K.O'Connor, T.Ruehr.
We would like to pursue more information and possibly a small
demonstration to see if this would be most feasible on blueberries to prevent iron
clogging. There was no bacterial slime associated with the iron clogging. Soils are
naturally acidic. Recommended pH for blueberries is 4.8. No problems with water hardness.
If anyone has information or experience with the use of
polymaleic acid or polyphosphates for sequestration of iron, please let me know.
- The following information would be helpful:
Recommendations on product and suppliers in NJ (Fertilizer companies?) Injection rates and
how it should be injected Continuous injection? Can it be mixed with fertilizer
injection/compatibility with liquid fertilizer? Caution or safety concerns. Any other info
would be helpful. Also a recommendation on unclogging emitters with sulfuric acid would be
helpful (rates and procedure).
by MaryBeth Sorrentino
In the past a product called Poly-trol produced by chemist,
Dr. Dick Hornack, worked quiet well on problem wells in Florida. It was a formulation of
several polyphosphate compounds. I believe that it is now sold as Line Master through UAP,
but I don't know if the formulation is the same as in the early 90's. The usual dosage is
about 2 ppm to 5 ppm continuous feed. Be warned, there are several snake oils of similar
nature on the market, so approach with caution.
Basically the material is safe and normally pH neutral. It works well with fertilizers and
adds a little extra ortho-phosphate to the root zone once it reverts. Personally, I've
found that aeration and oxidation in ponds works best. I've designed large scale systems
for this type of approach and the results are very good. If you have any other questions,
please call or write.
by Jim Prochaska
I would like to echo Mary Beth Sorrentino's request for info
about practical experiences with polyphosphate and chlorine solutions to iron problems.
There are growers in the northeast who have solved their iron problems with constant
chlorine injection and acid cleaning where the iron concentration is less than 3 ppm.
However, I recently worked with a grower having 43 ppm of Fe and learned that
polyphosphates (at up to 100 ppm in the lab) are unable to keep this amount of iron in
solution. I have told him a realistic solution is to "move the farm" but we are
still seeking a more practical solution.
Specifically, please provide research and/or practical
experience info about chlorine injection. I would like to know the irigation water active
chlorine concentration at which plant growth or yield is affected for various
horticultural crops. Since I am talking iron removal, I am specifically interested in
cases where chlorine is injected continuously and with every irrigation. Also please
comment about your climate related to the amount of irrigation water applied.
by Craig A. Storlie
I agree with Jim's comments in general. But I would added
that the injection rate for successful sequestering of iron with polyphosphates may be
greater the 2 ppm per ppm iron. Thus, chemical treatment can be expensive and not always
successful with Fe concentrations as high as 5 ppm. This often makes the economics of pond
aeration a more attractive alternative.
by Don Pitts
Ag H2O is a California company that specializes in water
quality problems as they relate to agricultural applications. We employ a program to deal
with iron related problems that has been successful and economic for producers. If you
e-mail me direct, I would be glad to forward additional information.
by Tom Piatkowski
The removal of iron with chemical injection and also aeration
remains unpractical and expensive in irrigation. The most practical is to seep the iron in
suspension and prevent it from sticking to filters and emitters. I have results were the
problem were solved and even systems that were completely blocked opened in a very short
period.
I am not going to explain the process in detail as Frank Hartman wrote already wrote pages
on the subject. As he explained by making use of colloidal chemistry and Zeta potential
the problem can be solved very practically and economically.
I have actual case histories with photos were water was
treated with excellent results. As the files with photos are fairly long I can not sent it
to the list, but if interested contact me direct and I will make it available.
Casper du Plessis
I will try to address your concerns one by one, and hopefully it will be helpful to you.
1. 3 p.p.m. iron is considered high. Anything above 0.5
p.p.m. can cause problems. I agree with Don. Poly-P might work only on low concentrations
(~1.0-1.5 ppm.).I know cases where the injections of Poly were left wide open (~15
ppm.)and A: it did not work. B:it is very expensive. When you encounter levels of 2.0-4.0
ppm. - liquid hypochlorite works. Between 4.0-7.0 - gas chlorine works. I agree with Jim
that aeration and sedimentation Works as well and might be the only option for very high
levels (7.0 and above).
Another option that exist out there (And I'm talking only on real systems on commercial
operations that I know personally) is the use Potassium Permanganate to replace the
Chlorine as an oxidizer.Hydrogen Peroxide is another option.
2. The working concentrations on continuous injection are
10.0-15.0 ppm. active Chlorine. The concentrations that hit the ground are averaging 2.0
ppm. Once it hit the ground it all converts to Chlorides.
Chlorides are:
A- very leachable out from the root zone.
B-specially in blueberries growing areas (well drained soils
and high precipitations).
The most Chloride's sensitive woody crops
like:citrus,avocado,berries, - have a threshold of ~300.0 ppm. Cl in the soil solution. In
fact, some of the highest citrus yields are being achieved under these circumstances. The
threshold for the E.C. is 1.5 ds/m. The E.C. of your water is ~0.3-0.5. Is that correct?
Some of the most successful tropical foliage (very sensitive) growers, are using
continuous gas Chlorine injections (15.0ppm.). Do you know that by applying the very
popular pre-plant, fertilizer Murriate of Potash, you apply 47lbs./Ac. of pure Chlorine
for 100lbs. of the fertilizer !!! With 10" of total irrigation and 10.0 ppm.
Chlorine, you will end up with 22.5lbs./Ac. Chlorine. In many fertilizers which are
designated for sensitive crops the Chlorine is not more than 2% which are 20,000 ppm. Some
of them (the finest) are no more than 0.3% - 3000 ppm. Do you get the proportion of the
chlorination?. By the way, in New-Zealand they use up to 500.0 ppm. for a shock treatment.
Bottom line - if chlorination,irrigation and fertigation are done right, there is no risk
to plants. In any rate, there are very little scientific figures on the quantitative
sensitivity of blueberries and many other woody crops to Chlorine.If anybody has more
info., I would appreciate very much if it will be shared among us.
3. Fertilizers can be injected parallel and separately to the
chlorination. Fertilizers that contain ammonium might react with the Chlorine to form
Chloro-amines that might slightly reduce the effectiveness of the fertilizer.
4.I am going to attach...ooooops.NO! NO! NO!. I'll mail you
recommendations for treating drip irrigation systems with acid. Please feel free to call
me or write to me directly for references or anything else. You might also want to look
into my paper on Iron control which is posted on the MIF.
by Ilan Bar
Thank you very much for your response. I am using the
information you sent me before, and will forward your posting to Dr. Gary Pavlis our
Blueberry Specialist in NJ, (Rutgers Coop. Extension). I'll keep you posted. Thanks again
for your help.
by MaryBeth |
