Should be able to see my screen there now? Yeah perfect. Okay, thanks Luke and
welcome all. This has been, and I'd like to thank the extensionAUS people for
extending me the opportunity to do this webinar today. It's on the back, some of
you might have seen some stuff in comments and some training stuff I've
done with plant tissue in the past, this is sort of an update of that. The past
two years after being involved in the more profit from crop nutrition, and in
particular the better fertiliser decisions for cropping project, which is
aggregated all of the soil data for response surfaces, I had a couple of
years ago the thought of what what would happen if you tried to do this for grain
crops, and you did it for plant tissue. Some of the learnings along the way
probably explained to me what people were very hesitant to use plant tissue
and I would like today basically to share with you some of that in an
orderly fashion running through the whole plant tissue process. So that's the
background as to where this has come from and just sharing a bit of
information with you about it. So starting you know with the question
what's plant tissue analysis all about? In my mind it's simply put by saying
it's asking the one that really counts, and addressing the cause of the
addressing the cause of a problem as well as the symptoms. You know, with a
soil test what we're doing is inferring through our understanding of the soil
plant relationship what might happen to the plant if the root system grows the
way that we expect it will, and the extraction of the nutrients is as we
expected it to be, in an average sort of a season. Now we know averages don't take
long to break, particularly in recent years, and secondly that
plant roots can do unexpected things, particularly in relation to weather
events. So, asking the plant about some aberrant symptom that might have turned
up is probably a little bit more insightful than necessarily soil testing
after the case before the next crop. So, you know,
that's what it's about. It's it's asking the thing, and it's a akin to, you know, a
doctor going into your house and having a look at your living conditions and
trying to infer what that means about a particular health problem you're having
rather than doing a blood test. It's, it's a far stretch. So, you know, it's the same
sort of situation. So, the question is where does plant tissues testing fit in
versus soil testing. It's not a replacement for it, but it is a very
valuable tool where you have good calibrations and you understand how it
fits in and how correctly that you should use it. So, you know, the strengths
of something like plant tissue testing is we have reasonable universality of
critical ranges for crop species. You know, there's internationally
published lists and interpretation critical ranges, and by and large they
they line up fairly well, if you take some of the outliers out of it. So,
what we're saying is that good soil and and plant testing are complementary and
you know they can be used together, but generally the area of strength with
plant testing is where we can use critical ranges from a range of sources
to confirm or provide critical ranges from a range of sources both
locally and internationally, and that's very useful where we might have the
emergence of our new issue with a new nutrient - where we don't have a soil test
calibration to tell us what a high or low level is. Well, you know, plant
chemistry says that, at a certain point, whether it's in France or
Russia or somewhere else that they've been able to detect a reduction in plant
growth as a result of a low level of new we can use that reasonably to to infer
that that might be happening, and then it gives us just a heads up and a quick
start on our newly emerging issues. Test strips are the other way, but they take
time. So, yeah, it is very good in that, that area it's generally more sensitive
to nutrient changes in supply in the short term, than soil tests. So you can pick
up, um, if you leave a nutrient on, or you add one in in this year's program,
whether the actual crop is seeing it. Now, the question there is making sure you
sample at a time when the plant is actually accessing that added nutrient,
and then that's one thing I'll talk about a little bit more later, and the
other thing that plant tissue is going to give us a handle with, is it helps us
overcome issues with things like sampling stratified soil profiles and
bands or those sort of things where we don't have good sampling protocols for
soil at the moment, because we're letting the plant roots do the integration of
the soil fertility and the bands that might be placed in the soil over time. So,
this whole thing of deep application of P, waiting till the plant has access
both to soil fertility and of the band of P that's deeper in the soil
is one way of seeing whether it's providing adequacy. Another strength is
y no special sampling equipment required, it's pretty easy
sometimes, it takes a bit of legwork, but yeah most of those field jobs do, and
it's sensitive to crop growing conditions. Now that can be a positive or
a negative, if you don't take it into account. So, now the strengths I think
going forward with plant tissue are around these areas of helping with new nutrient
issues, helping with those nutrients that aren't well calibrated, and, you know,
primarily traced things like trace elements - where we know they're very
complex in relation to toot acquisition, and soil chemistry, and soil conditions,
and all sorts of management things that interfere with
interpretation, and where we've got stratified nutrients, making sure and, and
stratified application, making sure we can pick that up in the in the plant
tissue. So, as I was saying, it's complimentary but in general we
recognize use in two major areas: one is troubleshooting - comparing good and poor
areas. That's probably the most common use of it, and the other one is to
monitor - some people use, and particularly in horticultural industries, they use it
to monitor any changes, or required changes, that they might make. So, it's
something they do every year, in particular where they've tried something
new: is it working? As I said before, it's a lot quicker to pick up the change in
in the soil nutrient availability, than necessarily soil testing will be, because
we're relying on the soil strategy, soil sampling strategy to
be able to pick up minor changes in soil chemistry, which are not necessarily
evident. So, when we're talking about problem solving this is usually at the
time when people bring in plant tissue testing, and there's a big problem:
generally that's too late. Once you see symptoms, one it makes it very very hard
to interpret what's going on, because there are knock-on effects to other
nutrients, and two, with a lot of nutrients it's too late to regain 100% of yield if
you can treat it in crop. So, you know, letting things go to that stage before,
and waiting for a problem solving situation, is not necessarily the right
way to go. It can be, as I said, too late, or very,
very hard to interpret which particular nutrient is causing the problem. So, when
we talk about speaking the language of the plant in plant tissue we have what
we call a deficient zone, marginal zone adequate zone, marginally toxic,
this one's marginally deficient, and toxic zone. Now, that's a
continuum. It's not, you know, a real cutoff, but generally, you know, what
should want to be doing as far as sampling is concerned, is trying to pick
up where there's slight changes in biomass, but before it gets to very severe
symptoms in the plant, which is, which is indicating that the
biochemistry of the plant may have been disrupted in ways that are very hard to
interpret. So, we're trying to get right on that margin of marginal to slight
deficiency, and that's the area that serves us best, really, in interpreting
plant tissue analysis. Plant tissue analysis, we've got to recognize, is part
of the toolkit that agronomists carry around, and it's part of a bigger toolkit
that I put the terminology 'differential diagnosis' around. It's the skills that
a doctor uses to take you, and a set of symptoms from you, and turn that into a
likely cause of the symptoms, and a likely action for remedying. What not
only the symptoms themselves but the cause of the symptoms and so this is a
skill that doctors learn for probably all five to seven years of their medical
degrees and you know I would ascribe to this is something that an agricultural
scientist and should be at least having exposed to them and then probably honed
I think we pick it up naturally and some are good at it and I find a lot of
people are good at plant tissue analysis I'm good at this differential diagnosis
that others not so good and a bit of formal direction in this way I probably
wouldn't hurt and what it is is is being able to have a systematic approach to
identifying the presence of a problem when there's multiple turnitin coming up
with a possible outcome and it revolves around having a detection stage
of observations measurement and then actions and it's a ski school for
problem-solving and generally plant tissue analysis soil analysis all filled
in to try to detect and head off a problem hopefully before it occurs but
afterwards is really the problem-solving so you know the sorts of thing I talked
about in detection it can come from anywhere but normally it's something
that's observed by farmers yourself someone other yeah the next-door
neighbor says oh if you see me in that letter get in the back there the tower
you've got these big patches in there yeah yeah it looks like it's a big bit
mucky affect yield probably worth having to check out so you know in this
differential diagnosis process we need the where when what symptoms are they
color density chemical analysis might come later on but certainly in the
detection phase a fighter is pretty good in this day and age to be able to record
it and possibly do the do the rounds with it to see what people might think
if you can't sort it out straight away yourself going down at detection route
and when you're in the paddock just from a person that sits back and
gets a fair to fair few of these sorts of images I would suggest what you need
to do in the observation phase if you're in the field is get a kabuki scales or
perspectives so when it comes to nutrients what I'm looking at is one the
large scale so I can understand is it happening in straight lines in which
case it's probably a management effect or is it happening in patches in which
case it is possibly something that's natural in its share in its cause
where's the symptoms on the plant as a whole so getting a perspective of the
paddock the plate as a whole or or you know a large factor and then where are
the aberrant symptoms and a close-up of what does the leaf look like or where
does it occur on what playing part in in in detail and go through my phone
instead of via the internet okay look as I was saying with the differential
diagnosis one of the steps is measurement and you know there's a whole
heap of different lots of measurement but when it comes to
plant tissue testing the more information you can get that's
absolutely measured as important and in cases of where there's large differences
in dry matter some or plant height there's you know getting some estimation
of that just even on a relative basis can be very very useful and then any
other information that we can we can apply to it such as soil analysis at the
same time may also make it easier to isolate the cause of the problem rather
than what they are necessarily treating the symptoms the next step in this whole
process is is creating an action and you're depending on the circumstances
there's many but in a set in essence the most important thing is something that's
appropriate for treating the cause and the symptoms if it's at all possible so
in treating causes frequently with plant tissue testing it's the next crop and
probably after you've done a soil test to confirm your suspicions and if it's
treating the symptoms well you've got to determine whether that's viable within
the crop that we're dealing with in a lot of annual crops it may not be viable
to do something in crop it's just to have to accept that the condition that's
there but if you're treating symptoms with fertilizer products you know it's
the AL thing use the four R's be quite specific about what we want to do with
the fertilizer
so the question I ask is why ask the crop and and yeah the crop contains
basically the integrated and accumulated plant response to saw nutrient supply so
far in the season under the seasonal conditions that have existed and a
management that's been applied to it so you know it's telling you about what's
happened so far now in that we've got to interpret it in that context because if
we try and or something changes from there forward or we try and infer
something that's not the case as can happen with soil testing as well then we
may make a wrong judgment about what needs to be done so the next step is to
gain perspective of the important variables that aid interpretation so
you've got a snapshot to date and all of these things over here in this diagram
can affect its preys weather bugs root systems nematodes fertilizer
applications if we don't interpret it in relation to those or we're not careful
when we're sampling in relation to those we can have problems with the
interpretability of the lab stuff that comes back and in particular I talked
about the four days of rootin into a root acquisition of nutrients as being
probably the prime thinking pathways of what you need to think about so when the
problem occurs getting an understanding for the depth of the root system has
reached because that's going to tell you whether it's reached nutrients that
might be available later or it has seen the best it's going to see and I can
only get worse the other one is the duration and the duration relates to the
soil moisture and the duration at various depths as we know plant a lot
most soils of stratified in their nutrient concentration for immobile
nutrients and even the mobile ones can be reversed stratified lower in the
surface and higher with depth so the duration the roots have stayed in each
can influence the concentration that's in the plant the density and
distribution of the roots within the layer give some indication as to whether
there's a problem so if you've got a system with you know pore density that
can tell you about the uptake of some nutrients and it might be related to a
condition that's not the nutrient and a typical example will be aluminium
toxicity and why a plant might be struggling to get phosphorous into it
because the pruning of the hair roots and the density of the root system is
not allowing efficient phosphorous uptake so thinking about those in
relation to the the the plant tissue analysis and even to the extent of when
you're in the field going in digging up some root systems and checking what they
look like can also be very useful in helping the interpretation process need
to identify recent significant events because they can make an effect the
chemistry of the plant and some of those are these sort of things Frost cloud
cover occurrence of rain how much and when prior to sampling temperature
humidity so having been awareness of those is very important in one choosing
your time of sampling and to interpreting samples that might come to
you where you don't necessarily have that information
soil conditions so moisture particularly extremes of moisture structural or
drainage impediments and any soil information particularly ant
stratification of nutrients such as four deep ones like NS but boron and the
presence of sodium aluminium and an EC where you might have saw tested and
thought things were available but they're not in the plants showing that
they're not are getting access to the deeper layers of the soil where those
nutrients are occur so we're trying to find the cause not just remedy the
symptoms understanding the species of the crop variety canopy condition and
and all of those things around the crop is important pest and disease pressure
root disease can manifest themselves quite easily as nutrient deficiencies so
common ones there would be phosphorus and zinc with nematode infestations they
can look very very similar and then there's the management things pesticide
application history some say herbicide products for a number
of days up 10 days 14 days after application can affect the chemistry of
the plant so not the time you want to be sampling if you can avoid it a nutrient
amendment history nutrient placement if we're putting big bands of phosphorus in
the soil then we need to know that they're there so we can account for that
in when and where the roots might be when we sample sowing date previous
crops so there's a lot to take into account and it's no wonder people
sometimes shy away from plant analysis but ultimately what's being reflected in
the nutrients is a the plants interpretation of all of these
conditions were put on it so situations it can modify the nutrient set what
we're trying to do is make sure that we sample that it's a reflection of the
chemistry now and possibly going forward because we want to be able to treat the
crop and know that it was useful or not treated and we're not going to suffer
any of any problems in the future and that relies on the chemical status of
the crop being relatively unchanged from the point forward that you sample for
the nutrient that you're interested in so some of the things that can change
are things like plants accessing nutrient supplies as the report roots
forage deeper so I'm making sure for those types of nutrients your sample
when that layer has been accessed by the roots if that's what you're interested
in they're accessing fertilizer plans that are placed deeper or wider in the
soil or mineralization is going to occur in spring and we're not showing that up
earlier when we're looking at nitrogen management so taking a sample at the
wrong time for the wrong nutrient can be very misleading in leading you to a
better outcome from plant tissue
so you know as far as speaking the language
what deficient mean in in the literature is quite strict and and and what it
really means is there's a high risk of a 20% or more loss of yield at harvest and
generally you will find that there's deficiency symptoms present so if you
see you know that the word deficient and then you usually should be looking for
the symptoms and as I was saying when you're getting symptoms present it's
quite common for those deficiency levels in critical Rangers to be put at 40
percent potential yield loss and that's why sometimes it's hard to recover that
because the plant has declined to that extent that is hard to get that nutrient
back into the plant and normal growth resumed marginal is increased you know
it increases the risk but it's generally somewhere around up to 20% and you might
see visible symptoms as in biochemistry but you may see oh
well last year for us again Chris might be an idea perhaps to change over to the
phone if that's an option for you that will take a few seconds sorry ladies and
gentleman so we just wait for Chris just not be getting a periodic flippin the
signal it's not taking out his power point we've been losing losing your
voice Chris will last each time seem to be taking about a minute or so 30
seconds if Chris is perhaps going to the fine option that they will take about a
minute so appreciate your patience in holding on and just well well Chris is
just letting you know that this is being recorded and will edit the recording
not the one that people will get automatically but the one that goes
gotcha Chris this jebecca sitting with we'd lost you for a while
good they back up a couple slides about 45 seconds yep
you would get you're doing more speaking okay the one the the slides have yet I
thought there's one that said more speaking the language yep and you've
been into that for I don't know 20 seconds or so oh yeah okay look just to
make up some time plant tissue the language used in plant
tissue in interpretation all the statuses that are accorded based on you
know the ranges of relative yield are reasonably well defined for plant tissue
we hear about deficiencies and that usually in plant tissues speak means is
its you know greater chance or more than 20 percent your loss
marginal between 0 and 20 percent adequate sufficient generally you're
going to get you through the season with no problems with yield high up to 20
percent you lost by possibly overdoing it but generally used means that there's
been more applied that the plant can use and maybe you can cut back a little bit
if that maintains itself across the season in some cases that high can
decline over time as the roots grow into deepest or layers and I may not be
picking up that same concentration of nutrient across the season from a well
supported layer and excessive well this is sometimes called toxic that's where
nutrient supply is excess to requirement and may restrict yield
sometimes you see low being used well it's usually on the basis there's been
no ability to discriminate between deficient and marginal
and anything that's less than the adequate range people will just say it
slow so there's some chance but we're not really giving it any probability or
type of loss that we can ascribe to it
the next thing you know in selecting a plant tissue we've really got to have
confidence in the interpreted reality of it and you know that's around making
sure the plant part really reflects the ability to predict relative yield and
this is a study on zinc that was done some years ago by Yash staying at that
stage that Queensland Research Institute and it just shows all the different
plant parts that were actually sampled and their relationship to relative yield
and what we're looking for in any plant tissue part to be able to be sampled and
used as a criteria is a clear demarcation between adequate and not
adequate and secondly a large concentration or a high concentration
range at which that occurs because that allows this lab error and sampling error
to have some fluctuation that doesn't mean that the interpretation it critical
range is overtaken by any errors that we might have so you can see in this case
you know we do have confidence in whole tops youngest mature blades because we
have relatively high concentrations and there is a reasonable discrimination you
can see from the responsive to the non-responsive so that's the sort of
thing we're looking for is critical levels and that's why there are
particular plant parts you can see the oldest level for zinc and there's too
many numbers down in here or studies are down in there that suggests that we've
got some some levels that are low but they're the plants were reaching
adequacy for yield so in looking at the plant parts just some strengths and
weaknesses generally we're going to be talking about hole tops and yips and
generally we're you've had whole tops unadjusted and
youngest expanded blades across Australia but there are instances such
as Western Australia where they basically use whole tops and adjust for
biomass differences to come up with nutrolution curves which is I suppose
classically called a nutrient index applied approach and some of the others
that there is interpretive criteria around for things like a flag leaves
grain SAP pretty old basil stems particularly these ones for nitrogen
more so than that the full range of nutrients but yeah they've all got their
strengths and weaknesses you know you know about line them here so hole tops
easy to collect good for a full scan of nutrients early reasonable volume of
interpretation data are available can be used to calculate nutrient uptake or
because you if you've got a idea of the actual amount of biomass but its
weakness is the sample intensity restricts the plant as the biomass
increases so the more susceptible to biomass differences and only I'll show
you that later or phonology differences very rapid change in critical range with
phenology and biomass critical range is very dependent on that on the crop stage
and it's misleading if you've got big biomass differences when you're using
problem solving so yeah in contrast youngest expanded blades most effective
method for blame mobility nutrients so when you're sampling a blade at the top
of the plant and you've got an immobile nutrient in the plant will guess where
the if the low level shows up first at the top so with the youngest expanded
blades they've got their there their strengths a lot of its around trace
element sampling or low mobility nutrient sampling and in the kids
situation where you've got large biomass differences in crop stages and you don't
have to have access to the interpretation criteria for a nutrient
index because that's one of the space of weaknesses that we have is there are
very or limited public access to
peer-reviewed interpretive data for nutrient our index type approaches when
we get down to some of these other player plant parts we started to get
very few non data and particularly very few non Australian data so we're
starting to really lean on overseas information and the longer we stretch
the band the more likely it is to break so so if there's advantage and
disadvantage but there's some clear guidelines in particular situations if
you're if you're not just going out there to take a sample for a general
look then you know by looking at the strengths and weaknesses you can
probably direct your self to the plant park that is probably most appropriate
is going to give you the biggest focus on the nutrient that might be of concern
just a highlight as part of the this sort of two-year project and journey of
mine what I've done is gone to the worldwide literature and plotted all
those different colors are different studies of different plant growth stages
and plotted the change in critical level according to phenological stage out of
the literature starting with the writer and robinson book which is the classical
one that was published in 96 but hasn't been upgraded today and this is the sort
of plot that you get when you throw out the outliers
so this is the critical range for nitrogen from wheat across time and with
current interpretive criteria generally we have defined critter stages say 14 to
21 21 to 31 31 - 31 or whatever the problem being with something for
nitrogen that there's the change in critical level and general we have a
critical range for that but it doesn't reflect the real change in critical
level becomes uninterpretable and that's been I think why people have had some
problems when it plantains you testing in the past is that criteria haven't
been foreign enough for hole tops and there's some other issues as well and
I'll talk about later but there's there there's a recent plot of you know
there's about 30 or 40 world wide studies and they fit
nicely once you throw out some of the issues around data that's published that
has not the dot as people that have cropped my published deficiency ranges
in other words 60% relative yield in among critical ranges for management
which is I'd say is nineteen ninety five percent you get these outliers where you
let the plant go really low before you actually say to treat it and now yeah we
don't want to be in that situation because as I said if it's in the
deficiency state then it could not be that you can't recover so this data I've
recently put in in an app called wheat PTI for wheat that really basically
publishes those curves in an app that you could put your your load test data
into this is the case with nitrogen for youngest expanded blades so you can see
one of the the advantages of having a common plant part is that the rate of
decline of or the rate of change of the critical range is a lot shallower and
not a lot less prone to prone to misinterpretation they're based on the
critical stage but given that the youngest expanded blade is a part of the
plant that can receive nitrogen from lower in the plant of its deficient it
can be problematic doing young as expanded blades for mobile news just
like NPK because the younger plant is getting nutrients that are sacrificed in
the lower part of the plant in a very mobile oil situation so there's the you
know they've all got their do you know there are attractions and attractions
and this is a you know the signal for zinc this is right across the case so
youngest expanded blade for zinc for you know the major points that I've indicate
on there has a pretty tight relationship and is is pretty good over time as the
interpretive criteria
for those who want to know a little bit about the bata the nutrient index and as
I said this is probably best used when you've got big biomass differences what
it does is uses our trade-off dilution curve and it comes up with a standard
dilution curve that says if I biomass is this then my critical level changes
according to the biomass so in this case we've got a sample over here they're
just looking at the nutrient you might say is three percent you know is three
percent is adequately you know is from a neutral nutrient concentration is
adequate from a biomass point of view you know is a bit on the low side and
this one is there any difference this one's you know even higher and yet you
know there is a difference in the biomass between them between the plants
well in fact if you apply that dilution curve to a standard nutrient index what
it says is this one is no either marginal and this one with a lower
nitrogen is actually adequate because of dilution so you know that is a you know
a very very good way particularly where these large differences in biomass to
sort out whether if that dilution is causing a problem or you're getting a
true reflection just through the plant tissue concentration alone so I suppose
in summary with hole tops or yams as a as a recommendation it's horses for
courses yeah it's generally better for immobile
nutrients hole tops better for mobile nutrients where there's large data but
no large biomass differences and you can adjust for the penological stage hole
tops they allow our take of nutrients particularly if you are doing biomass
cuts as well and you can relate them to biomass sensing models for the future
Gibbs are good because the plant materials of the same age so you don't
get the same impact of plant development so you've got a shallower more stable we
are curved over time yes are easier to sample particularly
the old parts are dead and diseased you don't want disease plant parts in sample
so if the top of the plant is still healthy then you can use it it's easy to
get a representative sample of years late in the season because one of the
things we can't do it or shouldn't be done is subsampling whole tops unless
you're willing to go through and pick out the tillers of the same age to go in
the sub sample so picking out the primary tiller and only putting it in
there in the hole tops rather than the youngest expanding the blades and
youngest expander blades can be a pain the sample early when the plants are
small because your mite defoliate the crop all the time you get sufficient
sample which is about 2 to 500 grams to go to the lab so just from a sampling
and interpretation these are the classic books that are
around to help you and you know this is probably the newest one an American one
that's been published in the last two years but certainly not as comprehensive
as the old Reuter and Robinson the problem with Reuter and Robinson people
find is that it publishes the critical ranges of all the studies and you've got
to study the notes very carefully that are on the side of it to understand
which plant part what the plant stage was and the relative yield and also what
it is giving you the critical range for is it biomass or is it grade and I see a
lot of mistakes when I was doing my study over the two years where critical
range is quoted in other summer in places such as websites and you know
third-party publications and have misinterpreted what's been in here and
published data that is not really representative of the 90 to 95%
confidence for a relative yield that's what's in this weed PGI it's been that
data clean as in the bfdc and and it is standardized so
you know some of the issues I came across and you need to be on the lookout
for is whether the data type that's in the interpretation is plant response in
other words established from plot and field experiments and provides a true
critical range or is as a result of a big data survey in other words you know
someone with a lot of lab samples has gone through and provided a normal room
so they fitted a curve through wall of their data and come up with a 95%
confidence interval and said that's the normal range well in this case you know
the normal range is but it does it is what it is but it doesn't necessarily
reflect respond respond civ 'no syn a crop if it's below that because there's
no definition necessarily of what had the to the response or the relationship
to relative yield look out for inconsistencies in there Emily
referenced relative yield and there is certainly a lot of deficiency rangers
quoted as sufficiency rangers and that's sixty percent relative yield not 90
there's an interchange of biomass and grain yield critical rangers so people
have looked up looked at a number in the likes of water and robinson and haven't
looked across to the side to see the sufficiency range or the deficiency
range is related to biomass growth not grain yield and sometimes even having to
go back into the the original literature and find that whole tops as been
someone's quoted something as whole tops but they've they've used data that
relates to the top of the plant in other words top three to five leaves
not just the whole the whole tops of the plant above ground level and the same
with youngest expanded blades there are descriptions called youngest blades
which means again they've sampled the top three to five leaves not the
youngest expanded blade as we're looking for so pretty careful of the
interpretation data and get it from a reputable source or if it doesn't line
up you get a couple of sources that they like
line up be very careful or check them so yeah yeah if we've got deficiency
zone versus marginal zone we're trying to interpret in the marginal zone not
deficiency zone down here yeah we want our critical levels to where we haven't
suffered too much yield damage by the time we detect a problem as far as
guidelines on where and what the sample these sorts of guides are available from
most labs and a pretty standardized these days
based on what Reuter and Robinson would say about about sampling and you can
also get the required number of plant parts out of there as well so anyone
that's interested in that I can now I can send it out or we'll post it as a
PDF in some way just a quick word about sampling hole tops basically pull the
plant out cut it at the point where it goes from photosynthetic to known so
photosynthetic and discard the roots Young has expanded blades you don't have
to pull the plants out but certainly try and be consistent with what plant part
in this case I'm showing the youngest expanded blade normally it's the one
between where it's not fully unfilled and not fully the same color as this one
it's a lighter color but it's there's one below it that's even more mature and
this one's and be consistent in sampling and when it comes to later stages make
sure you take it from the primary tiller which is the oldest tiller if you start
getting it from younger tillers then we will have higher concentrations relative
the primary tiller so all of the calibrations are based on primary tiller
youngest expanded made not subsequent tiller and you can see the difference in
sample volume of getting a young is expanded via blade versus a whole top if
we want to account the field variability we should be doing the same number of
sub samples in a peg as we do for soil so at the end of tillering or halfway
through to flag leaf if you go ahead and get hole tops you're going to have far
too much sample to send to the lab and one of the practicalities is being able
their plant tissues through yips which will give you a lower amount some of the
variables be careful of the time of day and the conditions your sample this is
an example from cotton so I'd be careful at the time of so the conditions that
you sample under be careful of just having a necklace where we get to that
time look yeah only five seconds only five seconds lost okay so the time of
day the conditions you're sampling who are important this is an example from
cotton of the effect of soil test phosphorous or test versus time of day
on nutrient availability and you can see the time of day depending on the soil
test the nutrient tested the time of day and the salt has value it's given us
some different results so you know the idea is to be consistent in when you
take it and the conditions under sampling and generally that revolves
around not you know Frost's are one in winter crops that are a problem leaving
at least 48 hours after the last frost is very is important cloud cover in the
South can be a real issue because we're wanting to get normal photosynthetic
rate and nutrient acquisition and and incorporation rate so we need probably
again 48 hours of reasonable daylight and and the time of day that the heat of
the day can be important so being consistent and in weather sometime
probably from around 10 o'clock through to about midday is probably the best to
get the best profile of nutrient uptake and fantastic rate it makes getting
through to one o'clock in summer it can be quite different because of water
problems in with the summer heat you generally need to go a little bit
earlier so just the basics of handling and
storage firstly checking and here to biosecurity and quarantine requirements
if you're sending intrastate or interstate with any doubtful issue so we
know we've got red fire ants we've got a whole heap of biosecurity issues on the
horizon and you know the the you know the Lupin issue in New South Wales is
identified last year if that you would need to be aware of that and make sure
that we're not you know we're not creating problems so I mean what we do
in the paddock wash off any and source soil adhering to the plants or dust if
it's from this next to the road the labs don't do that it's an extra charge if
you wanted to do that so if you feel it's dusty then give it a rinse three
times in gently flowing water and then just dab it dry and whack it in it
should be pretty right for from that point of view probably needs a bit more
thorough if you've applied some sort of fungicide and the key one here is
probably any other fungicide the protected among fungicides like mancozeb
inand manire but and zinnia is I never nice things that have zinc and manganese
as active ingredients in there in the molecule
if you can't wash them off then just be careful in interpreting them that you
you realize it's there and where its soil you'll see how iron and aluminium
and where it's a crop protection product most likely it'll be zinc or manganese
air-dry them if your cock in the land straightaway dry them at less than 82 or
thermal dry them at less than 80 degrees or keep them cool refrigerated between 4
and 8 degrees put them in clean paper bags and not plastic unless it's a sap
sample you're sending to a lab which in which case they do want them in plastic
bags pack of reasonably loosely and send of the the courier via courier ASAP just
some example quick samples are here where plant tissue has helped things
when things have gone wrong these symptoms existed for a number of years
no one thought to take plant tissue or and it was related to to nutrition until
we looked at this is chickpeas up in the Emerald area
and you see the poor 1.38 percent potassium and the healthy one 1.85 and
the healthy numbers actually 1.5 so even the ones that were said to be good for
okay so this was a very very clear indication of the problem and then
subsequent soil tests were able to line this up that the saltiest were actually
telling the truth but no one believed them again this is sulfur deficiency in
wheat and you know the plant tissue we're saying it's for not potassium I'll
put it in the wrong place there but yeah the poor it's saying it's it's low but
it's not very low but when you look at the end of West ratio a thirty to one in
the poor one and the okay one seventeen to one this one's marginal this one's
horrible and the other knock-on effect of this is if we potentially you know
the nitrogen even in the one okay he is it's problematic so if we've treated
this with nitrogen then we may induce salt more sulfur problems over here so
you know the approach was to to make sure we covered both nutrients so it can
be very very useful but you know as I was saying when it gets to this stage it
can be yeah sometimes the cause of the problem may not be as easily reflected
in the plant tissue so look I'll stop there that's the end of my time so
thanks for your time just like to extend acknowledge extension Ahsan and their
generosity and letting me have a bit of this time to share with you some of my
experiences in this area geodesy on the bed of fertilizers that basically
stimulated this little exercise and and back patio I work for for give me the
time to do this
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