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Grains Research Updates 2015 | Goondiwindi | Spray tank chemistry to avoid problems – R. Buttimor

October 5, 2019


Now, I know it’s after lunch and everyone
is not a big fan of chemistry, so I’m going to keep his light and simple, and I’m going
to associate chemistry with partying. Right. Nobody likes chemistry; everyone likes partying,
so I’m going to make that analogy throughout the presentation. So I’ll keep you guys awake
for the after lunch session. Fallow management: I’m not here to tell you
how important it is to spray for fallow management and water conservation, nitrogen and your
economics returns. There’s a lot more people more experienced in this room that can tell
you a lot more about this subject. But I’m going to use the fallow spray as where to
hang your hat on for spray tank management. And so if you don’t manage what’s going on
in your spray tank, you’re not going to get those economic returns. And your spray tank will look something like
this. You’re either going to get congealed gelatinous material, cottage cheese like material,
crystals, and all sorts of other things happening in the spray tank. Now I’m going to try
to help explain this all to you, and to understand this, you really have to go back to the chemistry
of how you made these formulations. So I’m going to go over, first through spray
volume; water hardness; water conditioners; pH; tank mix order; something called the jar
test, which you might be familiar with; and then how it all ends, how it ends up on the
leaf. So I worked for a group called Actives to
Products. So we took actives from a discovery group and put them into products at the end
where you sell it in the drum. So it’s also a nerdy take-off on H2O, Actives 2 Products,
and all the products end up in water so it kind of works. And we like equations in chemistry,
so you’ve got a science guy working with chemistry to get a new product out there.
I’m kind of like the science guy, and I’m kind of like the surfer guy, and you mix surfing
with guy with chemistry. It might help explain the rest of my presentation. So let’s talk about the party in your spray
tank. Now, the problem with ECs and SLs is they’re the biggest worry in the spray tank,
and they’re the most likely to cause the party in your spray tank to crash. And you do not
want the party in your spray tank to crash. You end up cleaning out filters and pumps
and the like. So I’m going to teach you how to ensure that your party doesn’t crash in
your spray tank. The first thing we’re going to talk about
is why you can’t take the discovery molecules and just use them as a product. Because, acid
herbicides, SLs, they don’t like to party. The reason they don’t like to party is they
don’t mix with water. The reason they don’t mix with water is water is partially positive
and partially negative, and they have to interact with that partial positive and partial negativity
of the water in order to dissolve into the spray tank and become the SL formulation.
So if you take someone who doesn’t like to go to a party, a chemist will give them an
attitude adjustment and change their physical properties by changing their chemical properties
so that they can party in the spray tank. So we looked at the carboxylic acid group
on most acid herbicides; the phosphate group on glyphosate, which is a little odd – glyphosate
is an odd molecule – but Picloram and Clopyralid – it’s all the same thing. You’re going to
alter the carboxylic acid group, so it can party in the spray tank. This is going to be the only equation I’m
going to go through, but it’s an important one. This is for SLs. When you’re creating
a soluble liquid formulation, what you’re going to do is you’re going to take an amine
and you could read this on drum labels when they say a glyphosate or a 2,4-D is an IPA
or a DMA. So what we do, as a chemist, we take the solid active; we react it with an
amine; and you get a salt – something that’s partially positive and partially negative.
Kind of like table salt. You take solid table salt; you can dissolve it in water; it breaks
up into its ions; and is now a soluble liquid. And so what we’re, in fact, doing is selling
a drum full of salt. And this reaction allows the negative ion of the active to interact
with the positive part of the water, and the positive part of the amine to react with the
other. So it allows it to dissolve into water. The problem is, is the reaction can go the
other way, and what you’ll do is get crystals in your spray tank. So this is what we’re
trying to avoid with soluble liquids in your spray tank. So if you’re going to throw a party, the first
thing you’ve got to think about is the venue. The venue of where you’re going to hold the
party. Now, when you’re choosing your water that goes into your spray tank, you have very
little choice of what water you’re choosing. You’re usually using bore water, and in some
other area you’re using rain water, or maybe a combination of both, or maybe from a stream.
So the same with a party. You throw a party, you might have these attractive ions – kind
of like those attractive ions in your water – the calcium and magnesium. So these calcium
and magnesiums carry a very positive charge, and they can interact with your 2,4-D in this
situation, and create a half salt. Half salts of 2,4-D aren’t very soluble. They’ll drop
out of the spray tank and start blocking your filters. Now, water can start absorbing some
of these ions. The negative part of the water can interact with the positive part of the
calcium magnesium ion, and suck up a bit of that. So with soft water it’s not such a problem.
If you’re dealing with something under 200 or 100 PPM, it’s relatively soft. As you start
getting harder and harder water, around 350 PPM, it starts becoming a problem, and it
can create these half salts. Glyphosate, clopyralid and all those soluble liquids can have this
problem, and they crash out. So what we do, in quality formulations they add something
called chelators. Chelators cover up those attractive ions so they don’t interact with
your acid herbicides. And they kind of mop them up; cover them up so that charge is no
longer interfering. So if you think of throwing your party again,
you throw a party on Manly Beach. There’s all these uncovered half-naked ions floating
around. People are going to hook up and crash out of your party. So you want to cover them
up. So this is what we do in Canada, so you look like this, and no one’s going to interact
or crash that party. So you want to cover up those attractive ions with chelating agents
or water conditioners. Now you’re going to party. You need a wingman.
And this is another type of chelating agent: AMS, ammonium sulphate. It’s glyphosate’s
wingman in your spray tank. So what happens, is the ammonium sulphate breaks up into a
sulphate ion and an ammonium ion. The sulphate ion attracts the magnesium calcium ions so
it doesn’t hook up with the glyphosate. Glyphosate wants to hook up with the ammonium ion so
it penetrates the leaf better. And so you get no problems with your hard water, and
then the proper hook-up, so it can penetrate the leaf better. Now, if you add too many
wingmen to the party, too much AMS, you can cause problems as well. It’ll start interacting
with the wrong parts of your different acid herbicides, and it’ll crash out the party.
So if you’re using soft water, I recommend, like, 1% AMS; if you’re using harder water,
2% AMS. Any more than that, you might start having problems in your spray tank. So you see this at the party. You have Mr
Sulphate distracting the calcium ion in the background, and Mr Ammonium hooking up with
Ms Glyphosate, so at the end of the party the bright people are crashing out. So that’s
your glyphosate. Crowd control: you don’t want to mix too many
chemicals in your spray tank or you’re going to have problems. It’s the same with a party.
If you invite everyone: the punks, the bikers, the uni students, the college students, and
you invite them all into the same party, you’re going to have problems. So you want to control
the crowd. If you’re mixing pure glyphosate, you can go as high concentration as you want
in a spray tank without any problems. If you start adding everything else, especially fertilisers
and other things like that, you’re adding up all these attractive ions. They’re going
to hook up and they’re going to crash. This is kind of a little cartoon of what’s going
on there. Different ions will actually be attracted to each other. Others will be repulsed
from each other. And it’s a very complex system in the spray tank when you add more and more
ions. So you want to keep it as simple as possible. The ions that the formulation comes in are
almost brother and sister ions. The reason we formulate with those ions is because they
want nothing to do with each other. They’re just like brother and sisters; they go to
a party; they don’t want anything to do with each other. They want to see each other at
the end of the night maybe and go home or something, but they’re not going to hang out
with each other at a party. Same with the chemistry you use to develop a formulation.
They’ll never hook up together in the formulation and crash out, so you’ll never have to worry
about that. So if you’re going to invite people to a party,
you want them very similar, very regimented, and they will not cause any crashing in the
party. Now, pH: pH is like the alcohol of the party.
You know, you want to have a few drinks around the party, get the party moving, but if people
start playing drinking games or if you see the funnel coming out, then you know you’re
going to have a problem. If you start lowering the pH too much, the acid herbicide will actually
revert back to its acid form and crash out of the party. Or, just like at other parties
with too much alcohol, it’ll find another ion attractive and crash out as well, and
start blocking up your spray tank. Now, it is true, a lot of people talk about glyphosate
and the proper pH. If you want the proper pH for glyphosate, you have to hit that 4.5
to 5.8 range. This gives it the proper charge, so that it can enter the leaf surface for
penetration in the leaf. Now, glyphosate is formulated in such a fashion that it’s a liquid,
and when you pour it into the spray tank it automatically hits that pH. A lot of people
are like “Yes, but I’ve really hard water and it’s really alkaline, it’s like pH 9”.
In fact, water has very little in it. If you have the hardest water at 1000 PPM calcium
carbonate, you’ve got your calcium bound up with your chelating agent, so the carbonate
changes it to an alkalinity. Now, 1000 PPM of that is not going to have any influence
on the 60,000 PPM of glyphosate you’re going to add to your spray tank. It’ll dictate the
pH and the pH will fall right to it. I can’t show this here; they won’t let me take chemicals
on a plane for some reason, so I did this in the lab. And here I’ve got water that’s pH9 you can
see here. And I’m adding 1% glyphosate, so this is 1 litre per hectare in a 100 litres
per hectare spray volume. So it’s very low. It’s lower than anyone would spray with glyphosate.
And you’ll notice that the pH goes right down to where it’s supposed to be after you add
the glyphosate. And it is true that if the pH isn’t in the right area, then you will
have problems. So what you want to do is, if you’re concerned about your pH, check your
pH after you add your chemicals. Make sure the pH is correct at the end. A lot of these
acidifiers are just causing more problems in the spray tank. As a formulation chemist,
I used to get a lot of these quality complaints, and you’d hear about people adding acidifiers
to their spray tank and they’re only causing problems. So unless you check your pH after
your glyphosate is added, don’t bother adding products that are going to lower the pH. Things
like LI700 lower the pH. If you’re adding it for other reasons other than an acidifier,
then that’s fine. But if you’re using it as an acidifier, it’s not actually needed a lot
of the times. And then with 2,4-D, it becomes even a bigger
problem. 2,4-D has also got great buffering capacity, and if you add your glyphosate it’ll
go down around – just under 5. You start adding the 2,4-D it’ll bring it up around 5 and it
naturally buffers it. You start taking it lower and lower, and these things are going
to start crashing out. Crowd Control: you want to have crowd control.
If you go to a party and it’s all crammed in, mosh pit, people are going to hook up
and crash out in the party. But it’s not only in the spray tank that the party can crash;
it’s the line-up to get into the party. If you’re using a granny pot and pouring 2,4-D
on the back of glyphosate; throwing in your AMS and dissolving it in there, you’re going
to have problems in the granny pot before it even gets into the bulk of the spray tank.
You want to give these ions lots of room to party so they don’t interact; they don’t hook
up; crash up and fill your filters. I did a lot of work with Statesman, glyphosate and
AMS. So we look at the worst case scenarios and create these charts. So if you want to
go 1 litre per hectare, 1 litre per hectare of Statesman, 2% glyphosate, you can go around
60 litres per hectare, and that’s the most conservative figure going. A lot of people
are like, “I’ve mixed it way higher than that and it was no problem”. They might have had
softer water. The water conditions might have been warmer. They might have other things
in the tank. There’s a whole lot of things that can go wrong, and when we do these charts,
we look at the worst case scenario. I’ve went to look at a few instances where farmers were
like, “I’ve done the same mix over and over again, and for some reason it crashed out.
Something’s wrong with your product”. And I’m like, “Okay, walk me through what happened”.
“Well, it was a cold morning and I half-filled the tank, and then I threw in the chemicals
then my wife’s car broke down. So then I spent an hour fixing that. Came back, filled it
up with the rest of the water; drove to the furthest paddock; sprayed it and the nozzles
were blocked”. The thing here is time. He was literally using half the spray it was
before because it was mixing in the spray tank with it half full. It was very cold as
well and the additional time to get to the back paddock just all gave the chance for
these crystals to form and block the spray tank. So if you are on edge, and you start
fiddling around with how long you’re doing it, or the temperatures you’re doing in it,
or maybe you go from a rain water to a bore water, this might catch you out and you might
actually get problems with your spray tank. So if you’re throwing a party and it looks
like this, I think it’s fairly safe to say that no problems are going to happen. If your party looks like this, where you’re
cramming everything in your spray tank, it looks like you got a bit of alcohol in there,
good diversity, you’re going to have problems in your spray tank. And so you want to avoid
that. ECs. Now ECs are the oil soluble part of partying,
and people are like, “Well, oil and water don’t mix, so what are you doing here?” So
2,4-D doesn’t dissolve very well in oil either. There are certain things like triclopyr that
dissolve well in oil and they’re fine, but the things like 2,4-D, you have to esterify
them. So again, you play with the carboxylic acid group. You add a long chain of carbon
and hydrogen, and it now makes it more affable to oil. So you dissolve it in oil. So you
work on that; create that; and you’re, like, “Well, oil and water don’t mix. How are they going to join the spray tank
party?” So what we do is add… I’ll say, this isn’t health class here actually, this
is an emulsifier. You want to add an emulsifier to the oil. And the emulsifier has an oil-loving
tail, and a water-loving head. And so when you take this formulation and pour it into
the water, it actually breaks up – as a formulation chemist you look at how beautifully it breaks
up because that’s how your emulsifiers are working – and it breaks up into these small
droplets. And these are like the chaperons at the party. They let the oil in but they’re
like, “Alright, no, there’s nothing to see here. That’s fine”. And they let the oil into
the water and they float around encapsulated by the water. So if you look to the party scenario, these
guys are getting into the party, and there’s your emulsification droplet. Now this is where ECs and SLs combine to cause
problems. Formulation chemists use anionic surfactants with a negative charge on it so
that they repel each other. You create two droplets; they see each other; they’re all
negative and they pull apart. So they don’t coalesce creating bigger droplets and oiling
out or dropping to the bottom of the spray tank causing problems. So you get this repulsion.
Now, the small little ions – whether it comes from the soluble liquids such as potassium
salt, DMA and IPA – will actually interact with this. And depending on the properties
of these, you’ll cause emulsions to break up. These are different sizes. So a TIPA salt
is usually very easy to mix with an EC. It’s a big molecule with the same charge in it
so it’s got low charge density. Something like a K salt is a really tiny molecule with
a high charge density – the same charge – so it can get in amongst this, and causes the
oil droplets to now interact and collapse, or cause coagulation and cause a mess. So
this is why a lot of the K salt glyphosates don’t mix as well with a lot ECs, because
you get problems with this ion getting in between there.
So at our party you have your chaperons. They get distracted by attractive ion. A load of oil escapes. They get kicked out
of the party, and the oil starts coming out. And if anyone has seen anyone get kicked out
of a party, it’s never that pretty. It looks like that. So this is what happens
typically, something like this, or cottage cheese, when an EC starts falling apart. The
cross-linking in the emulsifiers causes a gel and it’s a mess. We’re going to take our partying and apply
it to adding it to the spray tank, so you probably all see these orders of addition.
So let’s just explain why we’re doing that. First of all, you want to put lots of room
to party in there – two-thirds of the spray tank before you add the chemical. Add your
chelating agents or water conditioners to make sure you cover up all those attractive
ions at the venue of the party. Then you add your granules, flowables and wettable powders.
This is just a physical mixing property. If you have small granules that aren’t dissolved,
they have a high concentration, and they’re going to attract their ions, and start breaking
up other problems. So you want to just dilute them into the bulk of the spray tank and give
it time. Then you want to add your ECs. You’ll let these chaperon emulsifiers stack up, because
they are engineered to stack a certain way around the oil droplet. If you add the SLs
before that, they start interfering with the stacking, and you get problems with you don’t
get that good a small emulsion size. After that, you add your SLs, like glyphosate and
the like, and that will less interact with this. Then you add your wetters. Now, the
wetters you typically call – have surfactants. Surfactants will work on surfaces, surface
acting, and they’ll interact with that stacking of the emulsifiers on the oil droplet. Plus
they foam, and you don’t want all this foam happening while you’re putting in these other
chemicals, because then you got chemical foam coming everywhere out of the tank. And then
you top it up with water. Now, the key is to read the label, but I know
a lot of people are adding more to the tank than their label says, and you know, that
can cause problems. So it’s kind of like, again, back to the party scenario. If your daughter is going to take out a new
boy to a party, you want to meet him before you let the two of them loose. So just the
same, you want to make sure you “meet the parents”, I call it. You do a jar test. You
use the same water, same temperature and same concentration; put it in the jar; give it
a shake; leave it for as long as you think is possible for that formulation to be sitting
in your spray tank. A lot of people say, “Oh, thirty minutes”. These reactions take time.
So if you honestly think you’re going to empty that spray tank in thirty minutes, that’s
fine. I say five hours, because you never know what’s going to happen, and it might
be stuck in there for the five hours. A lot of people will do it overnight. Do the jar
test; leave it overnight; in the morning how’s that look? Crystals definitely don’t mix in
your spray tank. A little bit of cream, no problem. Oil droplets, it’s not going to
work very well. So those are things to look at, and remember small problems in the jar
test are big problems in the spray tank. Yes, I’ve got to say, you guys are probably
thinking this is really ridiculous comparing my spray tank to a house party, because, I
mean, it is a little ridiculous because your spray tank has wheels… so it’s more like
a party bus really. And so you take that party bus and you spread
the party around the neighbourhood… and it eventually crashes out on the leaf. And now you’re all thinking “Well that’s the
worst wetter adjuvant I’ve ever seen in my life”. And you’re probably right, because this is
what the emulsifiers wetters and adjuvants are designed to do, is to spread out these
droplets. They cover more surface area. They disrupt that membrane and then you can
get the actives to get driven in to the plant’s surface. And as it evaporates, it drives the
concentration gradient, so more and more gets in. Eventually it’ll crystallise out. Typically
it will crystallise as its acid form, but if you have things like AMS, you’ll get the
ammonium glyphosate complex interacting and going into the leaf. With esters and oils,
they tend to stay liquid longer and they also interact with that waxy layer quicker, so
you get better penetration. The problem with these oils is they can be very volatile and
you can get drift of the volatilised chemical and cause off-target problems, but that’s
a completely different issue that we won’t cover in this. But if all goes well, what you spray should
start looking like this. Take home messages. First of all, read the
label. Always read labels. They have a lot of good information. A lot of work goes behind
that in the lab to make sure what is said on the label is true. If you’re ever in doubt,
always go higher spray volumes. A Lot of people say “But if I just go 50 litres per hectare,
I can get that extra paddock done. Then I won’t have to fill up again”. That’s when
you’re likely to have trouble, so always err on higher spray volumes. The more variety
you add to a spray tank, the more chance of problems you’re going to have. It’s just plain
and simple. And if you are going to go for a larger variety of chemicals, increase your
spray volume. pH, glyphosate and all those chemicals that depend on pH generally hit
their target. They’re formulated that way, so they don’t need anything to adjust those.
And if you are concerned about it, take the pH after you’ve added the chemicals to the
formulation. Hardness is definitely a problem with ECs and SLs. You can use chelating agents
or water conditioners to reduce the charge on those particles, kind of mop them up, and
that’s always a good idea. You can also – typically bore water is hard; rain water is soft. If
you’re concerned about your bore water, you can get it tested and get a very good analysis
of what different species of hard water you have in there. And AMS: hard water 2%, soft
water 1%. And novel brews, do a jar test and it will always save you in the long run, because
a little problem in there is easy to deal with, as opposed to cleaning out the spray
tank. So if you follow those, hopefully you’ll keep
the party rolling on and you can have some good spraying.

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