Seasonal soil moisture probe network update transcript

Jemma Pearl:

Awesome. Our webinar today, in our climate webinar series, is a seasonal update from Agriculture Victoria's soil moisture monitoring network. This will include a review of the distribution of summer rain and the impact of the Autumn break, and how this season is tracking compared to last year and other years in the monitoring period for the probes.

Jemma Pearl:

Dale Boyd is a seasonal risk agronomist in the grains team with Agriculture Victoria, based out of Echuca, and he has worked with the department for 20 years, and during that time he has worked on a range of projects linked to monitoring soil moisture, irrigated cropping, and the current soil seasonal risk work.

Jemma Pearl:

As Alice passes the ball over to Dale so he can present his slides, I'll just give you an update on the network. The soil moisture probe network is a statewide technology adoption project that uses deep soil moisture probes and weather stations, so Dale, in this project, helps dryland grain farmers and advisors interpret seasonal risk information to aid decision making using soil moisture probes recording all the way down to a metre.

Jemma Pearl:

The data obtained from the moisture probes is interpreted and presented in the monthly enewsletter, which aims to educate on the use of technology and informative on the current seasonal conditions. If you just want to switch some screens over, Boydie, perfect, and the floor is yours.

Dale Boyd:

Okay. Thank you, Jemma. Can you hear me clear enough?

Jemma Pearl:

Sure can.

Dale Boyd:

Very good. Okay. Yes, well, good day. Tuning in here from Moama, where we've just received 13 mil overnight, and that's on the back of 11 mil the night before, so almost up to another inch rain event, which seem to be coming through in pretty consistent sort of timeframes in this northern Victorian environment, but I'll look to provide a bit more of an update of the seasonal conditions as measured by the moisture probes.

Dale Boyd:

Not just only central Vic, but yeah, across the whole state, and that's due to the soil moisture monitoring work that I've been doing for quite a number of years now. Initially started off as a pilot, collected some very good data, found the data was quite useful for informed decision making, and we've certainly grown a considerable network from that initial pilot in 2011.

Dale Boyd:

I'll quickly just go through the story. We've probably got some new people on, tuning in this afternoon, but in terms of where the soil moisture probes are located we've got here across the state of Victoria, the purple icons are indicating the cropping monitoring points, and we've got 16 of those now with a reasonable spread across the state, and then just recently in the last two to three years we've looked to implement more monitoring points across the state but targeting medium to high rainfall zones in pasture situations, and they're both a combination of dairy and sheep and beef systems.

Jemma Pearl:

You all right, Boydie?

Dale Boyd:

Yep. Really, how the pilot initially started up and what we were looking to achieve was just to provide some greater insights into what at soil surface in the scene of climate change and some pretty extreme seasonal variability, and I think this graph here is just a classic example of the data we've collected, and this is from a site at Normanville, just to the west of Kerang there, and starting with that data set from 2011, progressing where we are in 2020, but over that time we've certainly been able to establish these upper points indicated where the green moves to the blue and the dry points as well where the green moves into the red area.

Dale Boyd:

What we're saying with this is that the plant available water zone is the green zone. Anything below that is dry, and anything above that green moving into blue is saturation. Now, this trendline here, the black line, is an indication of all the sensors that we've got in place at the monitoring points, so with the cropping ones we're measuring from 30 centimetres down to a metre.

Dale Boyd:

But it really does clearly show that initially, in that monitoring period, we had some wetter years, and coming out of some wet summers in 2010, and '11, and '12, and they were sort of used to capitalise on those better years, and then we certainly moved into a dry stretch. A dry run of years, which are certainly very challenging, and by indication the changes in soil moisture. Very small increases in '13 and '15, indicating the challenges and really no buildup of deep soil moisture conditions.

Dale Boyd:

2016 was really the change. A really wet spring period there, and in '17, certainly presented opportunities for some high yields, despite a dry spring, and I guess that's what we're finding. Additional information about the moisture probes is that it's really these bigger crops that have the ability to deplete most of the soil moisture reserves or all of the soil moisture reserves, particularly if they're the cereals and the oil seed crops, whereas it might be surprising that in these dry years, because the crop didn't have the biomass, didn't have the vigor, the moisture changes getting down to that dry point generally don't occur.

Dale Boyd:

And this is just where we're moving across now into 2020, where at the Normanville site, we'll go into more detail, but sitting at about 50% plant available water. Just in terms of the type of equipment we're using, I'll go into a little bit of detail about that, but we're using capacitance probes. Essentially we're digging a small pilot hole in a point on a paddock on that farm that's going to be a good representative point.

Dale Boyd:

It's generally not the best or the worst soil type. It's about the average, and we're certainly looking for a soil type that covers a fair majority of the farm, and it's pretty good if it covers a fair degree of the district, as well, because then more people can relate to the data, so digging that hole, filling that hole with a slurry, and then inserting this capacitance probe in here.

Dale Boyd:

Essentially, the internals of the capacitance probe are well-illustrated with this diagram here. Essentially, they've got some plates that emit a current, and it goes into that soil medium, and it just picks up the soil water content changes, and so when it's wetter we're getting higher values, so we can plot that on the graph, and that's where you do see the spike up with the total soil water content, and as the crop uses water the values become lower, and we certainly find that the crop will use the water from its easiest source point as possible, first, so that's shallower depths, and that's where we're finding good value in having the probes go down to a metre.

Dale Boyd:

And if I had my time again, I would certainly go down deeper, because it's really these, in dry years and dry springs, it's those deep soil moisture reserves that are critical to ensure yields are maintained, particularly in the low to medium rainfall zones, so all that capacitance probe is connected we dig trenches, and connected up to the telemetry equipment, which is positioned on the fence line, and it's pretty essentially if you're looking to go down this track, to protect that telemetry gear.

Dale Boyd:

There's cables that can be potentially exposed, so you'd like to protect that from livestock, and from vermin, and pests. Yeah, just looking at the overall soil moisture conditions as measured by the probes with a background of the AWRA model there indicating the percentages of soil moisture as per the model, but what we would really like to then do is put down these specific points of measurement from the probes to indicate what the soil moisture conditions are at, and if you're subscribed to the break you'll see this come up, as Dale Grey produces this.

Dale Boyd:

And the colour indicated here in yellow is significantly wetter, so that's when he looks back historically, whether it's a month or maybe six weeks in this case. If it's 10 percent wetter than that previous point when those data sets were collected, they'll be highlighted in yellow, and anything in gray it's about the same.

Dale Boyd:

At spring times, we certainly do see some of those values going significantly dryer. We've got a few here that obviously haven't changed, but that's because they've reached their capacity with the monitoring points there. For the capacity, I'll go into the detail of the rainfall in April, but that was a fair contributing factor to it.

Dale Boyd:

We've got one irrigated site there at Kerang, so obviously it's been pre-irrigated. It's up to 100 percent. That's why that is the only one in that area there. Coonooer Bridge was in fallow last year, so we did a big carryover of moisture last year, contributing to its current value there, and we've got a few paddocks here that we were monitoring that were actually cut for hay, and we do find that when they're cut for hay it will not deplete all of those moisture reserves that a typical crop going to grain would do in October.

Dale Boyd:

And so yeah, we do find the percentage of that moisture is conserved. Just in terms of what has contributed to those soil moisture percentages, we've just got the rainfall deciles for Victoria. First of January to the end of March, so that three month period here, pretty much indicating a lot of those cropping districts.

Dale Boyd:

I have now, as per rainfall deciles, been tracking to average or above average position, and I think it's quite interesting that initially this central district in the northeast picked up rain January, the Wimmera missed, but come February that's where their rainfall come, from those storms. And then on the next month, it was a bit of a flip, and it turned back into the central Victoria, northeast, picking up the rainfall in March, whereas it wasn't so much in that Wimmera district.

Dale Boyd:

That's certainly set the scene to build up soil moisture, and probably we're observing some good summer weed control to conserve that moisture of the rainfall that fell, but really, April was the month, and when you look at sort of the state in general, a fair bit of it is above average with some of those districts very much above average, and we've got that district zone pushing out towards Bendigo.

Dale Boyd:

Sort of to the north and northwest of Bendigo, highest on record through that period in April, and when you look at those rainfall totals, there's a lot of districts there that picked up over four inches, so ticking over 100 mil, and in terms of the timing of that rain, it was in a spacing of at the start of the month and then the capacity to get back on the paddock and spray, potentially get knocked down on some wheat control, an opportunity to sow, and then more rain came at the end of the month, so some people were just saying how fantastic that break was and then the followup rain that did eventuate.

Dale Boyd:

In the background of that other model was looking at the percentages, but when we look at the Australian landscape water balance model, and then put it into the rankings, we can certainly find that there's, again, a fair portion of that state as per model that there's sitting above average, and certainly a large percentage of the cropping areas north of the divide are certainly in that position.

Dale Boyd:

And so we're starting to get quite a few data points and spacial assessments that are indicating just how the season's tracking that is better than average, and we've certainly got quite a few monitoring points sort of moving down from this line across that are certainly full point if not near saturation now, and we still yet to get to winter.

Dale Boyd:

I certainly find using the combination of multiple sources of information certainly do build a picture and increase confidence in what I'm seeing with the data, because it is quite a specific point measurement with the moisture probes. I'll just go into some of the analysis of the soil moisture graphs now, and I'll go into the Wimmera for starters and look at the total soil moisture as measured at the site there at Brim, where it's really just to the east of the Lah silos there.

Dale Boyd:

We're going back, looking at the data from this time last year, in May, and just remembering going back to that initial example from Normanville, this black line here indicates all the soil moisture values from 30 centimetres down to a metre, so effectively it's indicating how full the bucket is by this trendline. Quite a good year in the Wimmera. Very high wet profiles through winter, and a big depletion of the soil profile with a high yielding wheat crop there.

Dale Boyd:

Generally, limited rain in the Wimmera over summer. Picked up that rain in February, as I indicated previously, and then just rainfall events that have been quite timely and set this site up for a pretty good current position, that I would currently rate it as about 40 percent. Everyone's got sort of different methodologies of how to come up with their estimation of a moisture percentage, but when you look at this graph, it's broken into five increments, so if you just work on 20 percent, 40 percent, and that's where we're currently positioned, but 60, 80, and 100.

Dale Boyd:

Where we were this time last year was about 80 percent, and then they had that top up in winter. The individual sensor tracers showing the same date sequence as previous, with the summed line, these individual sensors are just stacked as they're found in the soil profile, so the red line there is indicating the 30 centimetre sensor and progressing down to 40, 50, down to the deepest sensor that we've got there at a metre.

Dale Boyd:

Last year, the high yielding wheat crop certainly acquired the shallowest soil moisture for starters, and then once it was getting near depletion, it certainly dipped into those deeper soil moisture levels at the sensor levels down to a metre, and this is where if I had my time again we've got crops that are high yielding or extend their root system down further than a metre, and I'd certainly have longer probes if I had my time again.

Dale Boyd:

Just in terms of where we're tracking in terms of moisture changes, this season, so we've got January starting off there. Initially, we had and improvement in that shallow soil moisture at 30 centimetres, and at 40 progressing into the end of April, some moisture changes at 50 centimetres with this yellow line there. I think that's fairly marginal, that improvement, but that's sort of where I'm rating the moisture to be at the moment, pretty clearly, to 50 centimetres, and probably moving its way down to 60.

Dale Boyd:

But everything else is sort of charged up, so further rain on top of this current scenario would see infiltration down to those deeper depths. It gets quite interesting with a bit of a network around that Sheep Hills, Lah, Bangerang type area, and that's supported by the local cropping group there, the Warracknabeal East Group.

Dale Boyd:

I think just what's interesting with this graph, we're going back into 2018, into '19, to where we are now, but this Paddock is interesting being cut for hay, and this is the example that I like to pick up that when the crop is actually using water, we see this depletion in that spring period, so this is in September, but as soon as the crop is cut for hay, you take off that leaf area, you stop the photosynthesis, you stop the water use, and you pretty much get a flat line after that period, so if you were growing this crop for grain you'd see the depletion for another month, but this is the effect of hay.

Dale Boyd:

And obviously '18 was a pretty challenging year. Probably the trigger for cutting that crop to make the most of that biomass. Potentially, weed issues, but you know, there's a whole list of agronomic issues that might arise for why a crop is cut for hay, and I guess soil moisture data can contribute to that, if you're looking at data and it's quite dry and the outlook's poor.

Dale Boyd:

But in 2019, we had a bit of a break in the data, but by cutting that crop for hay, again, stopped that water use, and that's why it is slightly higher in terms of its moisture percentage to the site pretty close next door there at Lah. But when you look at the individual sensor tracers, and we've still got an issue with the rain gauge there, but in terms of moisture changes, following a similar pattern to Brim, Lah site, the initial spike up with the February and early March rain, and then the later April rain, we saw the infiltration pretty clearly to 50 centimetres and probably more shown at 60 centimetres.

Dale Boyd:

But I think that's sort of about the mark that we're starting to see those Wimmera sites, particularly in that district, so they're not full at this stage. And just in terms of validating the data, because we always like to do at all points of looking at the datasets. This is just the site there at Sheep Hills, Bangerang. The soil core, that's an example of what the soil type is like there.

Dale Boyd:

The speedos give an indication of what the current soil moisture conditions are, so currently they're about 75 percent and that's on a small improvement, probably less than 10 percent in the previous month. One tool that I'm going to look to utilise in the future is having a breakdown of the soil moisture percentages sensor by sensor, so every 10 centimetres we'll get an indication of what the moisture percentages are, and as per the data it's sort of showing that the moisture improvements have been pretty sound down to 50 centimetres, some at 60, and this is probably the deep soil moisture that was left over from previous years because the previous two crops have been cut for hay, so that's still residual moisture down deep.

Dale Boyd:

We'll see if that gets connected up this season. In terms of the Mallee, Speed's been a pretty good representative site that we've had. Again, looking at that date sequence, from this time last year since 2011, we've certainly established the upper limits and the lower limit, so this is the plant available water zone.

Dale Boyd:

A wheat crop grown last year, wasn't the silo buster but was still quite a sound crop, and I think that's just why its moisture depletion was just pretty steady, really, through that spring period, but when we look at this season's summer rainfall and progressing into the autumn rainfall events, certainly February was fairly beneficial in terms of improving the moisture conditions and then the breaking rains early April, followed up by late April rains, sort of puts this site in quite a wet position and almost to 90 percent.

Dale Boyd:

It's actually a touch over 90 percent. And then when we look at the individual sensor traces, last year we are seeing the moisture depletion occurring shallowest initially then moving down to these deeper sensors, those deeper depths, and when we look at the moisture accumulation for this season really occurring at the start of February, because that first sensor is at 30 centimetres.

Dale Boyd:

We can have rainfall, but it takes a while for that top horizon to wet up and then allow that infiltration to move down deeper, which we certainly saw with rain events, and then April was really where it all started to happen in terms of that deeper infiltration. 60 centimetres, 70, 80, and now we're seeing it at 90, and probably a bit of a kick up at a metre as well, so for a low to medium rainfall zone, it's filling the profile quite early in the season.

Dale Boyd:

North Central, so a pretty reliable performer over the years. Certainly wasn't as wet as some other environments, districts, last year. Didn't quite get the big December rains in 2018, but nevertheless it still started off with a pretty handy profile, being about half full, but smaller rain events never did a heck of a lot.

Dale Boyd:

This is a barley crop depleting that, but yeah, it really has been a real change in the moisture conditions as measured by the probes at this site, with initially good rains, second half of January, followed up by February, and then just a real sequence of rain events.

Dale Boyd:

And when we're seeing rain events over that inch mark, they've really got some punch and some penetration to move down deeper into the profile. We're looking at probably 250 mil plus for this year. There's probably no reason why we've got profiles that are getting to that saturation point, and I've just thought I would change tacks, so instead of looking at the individual sensors with this graph or with this site, because a lot of them are going to show that they're full to capacity, I just thought I would bring up another tool that I use in my tool bag.

Dale Boyd:

And that's by using an app, and it's the Soilwater app on my phone. I've got that site loaded in with its soil type. It's got a canola crop assigned to it this year. I've put into the model, and I guess that's the beauty of the moisture profile, is you can actually give a fairly accurate starting point for when to start the soil moisture, but as per the model it's just picking up BoM and recognised rain gauges as they plot those.

Dale Boyd:

You can see the buildup in soil moisture to the point where, by the model, Soilwater app, it's above saturation. I'd certainly recommend you to get on and at least have a look at it, and just see if it works for you. I find it is very handy tool to show, initially, the buildup of soil water up until that sort of midwinter period, and I've got a whole array of sites and a lot of these are actually monitoring sites and that's what I use to cross reference the Ag Vic or other moisture probe sites with data.

Dale Boyd:

The other feature that I do see as an improvement with its update is season, you can actually go in and provide your own localised rainfall totals, which is pretty important because of the nature of the thunderstorms that we've had this season, probably not all the rain gauges and the rainfall totals are reflected on the BoM site, because they've been isolated in their nature.

Dale Boyd:

If you have got the ability to put in your actual rainfall totals, you're going to get a better result. Moving over to the northeast, over there at Youanmite, near Tungamah, this time last year we're sitting in quite a wet position, but when we look at where we are now it's pretty much to a full point, and we can see with the sum line here the responses to rainfall once that initial zero to 30 was let up, which would've happened with the January rain event, as there was no change, the next rain, because there was obviously weed control there, allowed the infiltration and to move deeper into the profile, which has gradually been stepped up with each substantial rain event that we've had there in the northeast.

Dale Boyd:

And probably to the point where entering winter a full profile, we're probably looking at some water logging conditions, just in an average winter, particularly in those lower lying areas. The individual traces certainly do show the buildup of moisture. Initially, with these deeps here at 30, 40, and 50 centimetres, the next rain event progressed down to 60 and 70, moving to 80, and now we're certainly seeing moisture moving down at 90 and the buildup at a metre, so it certainly is wet up over there in the northeast.

Dale Boyd:

Even though we've only got that one cropping point over there, there's a number of networks that are over there. The Riverine Plains have got a fantastic one, so I can tap into that and it's also telling a similar story of moisture accumulation down to those depths of a metre, and probably a good strategic move of the Riverine Plains is that they've got longer probes, so that'll pick up moisture down to metre 20 and metre 40, so I'll be closely watching that over winter to see how deep the moisture is moving down.

Dale Boyd:

That's an assessment of those monitoring points. All of this information is freely and publicly available, and there's a webpage that the host farmers get in and have a look at the data, and obviously anyone else that's got an interest in soil moisture can also do so. It's as simple as going into your web browser, putting in intelliweb.mait.com.au, and you'll come up with some prompts here for username and password.

Dale Boyd:

To look at the cropping sites, it's DPI, with the password DPI, will get you in to look at this view here, and you'll see all the cropping sites. To acquire the pasture dataset, it's a change in the username and password, so it's AgVic, AgVic. And in terms of what all these icons indicate, the bottom icon is the separate tracers where you can actually look at the individual sensors and how those trends are occurring at that monitoring point.

Dale Boyd:

The next icon above is the summed line, 30 to 100 centimetres. We're also measuring soil temperature at these sites, and then we've got a weather station associated with all sites, so we've got some coverage there across the state. Some gaps in particular areas, but it's good to know there are other networks out there, and yeah, we'll work on aggregating the data in the near future, because I think that'll be a real benefit, to get that real, good spacial assessment across the state.

Dale Boyd:

I indicated that there's some pasture monitoring sites occurring across the state. I just thought I'd bring up some information about those sites, and this particular site is the point over at the northeast, over at Greta, which is over near Wangaratta. We've got three monitoring points there and I still think we've got a great data collection and trendline analysis of soil moisture changes, but we're still trying to exactly work out what this data can be used for in terms of informed decision making, so what I looked at doing last year was to ... I guess we've got a long data set here, going back 2018 and examining 2019.

Dale Boyd:

And the real difference with the pasture sites is that we're looking to examine more of the shallow moisture, and we're not picking up as much of the deep moisture, so the first sensor is actually just below the soil surface at 10 centimetres and we're measuring down to 80 centimetres. 2018, the trendline analysis of the soil moisture just shows how challenging it was, without getting up to any great heights in terms of deep soil moisture accumulation, whereas we look at last year.

Dale Boyd:

We see this buildup, which is great to see, to the point where we've got full point in winter, and then a dry spring and a dry matter being produced with this pasture to the point that it's depleting the moisture reserves pretty quickly, so what I was looking to get to the point is where is the point where, without further rain, there's going to be limited pasture recovery, and so after the rain, early November, I went out and did some pasture cuts, because I could see it's on a pretty steep line of decline, and when I looked at the individual sensors, most of that shallow moisture had been depleted, and really the pasture was now starting to survive, really, on that deeper moisture.

Dale Boyd:

I went out and did some pasture cuts, and it was really just to remove the dry matter residue, because it was still quite green and driving past you'd say, "Well, that paddock is still producing pretty good dry matter." And the clover was just hanging in there, maybe an indicator that the dryness was coming in, but yeah, when I come back and assessed where we'd done the pasture cuts, there'd been no regrowth, so I think that's where now we've got some good analysis with the soil moisture that it's about 20 percent left that, without further rain, pasture regrowth has got to be pretty low to nonexistent after grazing.

Dale Boyd:

We're starting to piece all of that information together, which is good, and then just in terms of how our pasture sites are now tracking in terms of the rain we've had through that late summer period over in the northeast, and the fantastic break they've had. As I said, we've got three sites over there, all in very close proximity to each other, but the two sites that I'm just showing here, they're all showing very similar moisture trends.

Dale Boyd:

A pretty positive responsive to the rainfall in March, and further buildup and infiltration of moisture in that early April period, and then becoming pretty bloody wet in that late April into early May, to the point where these two points are showing a full profile, and the other site is showing that as well.

Dale Boyd:

The individual sensors are showing the individual totals that make up that summed line, so I think this is what's going to be interesting. We've already got periods of flat lining when they're getting to this full saturation point, so last season we did get to that full point. The farmer probably thought he's seen wetter years, and water running, and that's how he's got the association of what a really wet year is.

Dale Boyd:

But we could show from the data that moisture was down to 80 centimetres, and that was an ample depth for that pasture to draw upon that moisture in that drish spring period last year. I'd imagine the way we've got ourselves established with these moisture trend lines at this stage, we're going to see a fair portion in winter now with these individual sensors being to that point of saturation and not really being able to take on anymore water, so they'll stay in that point of saturation or flat line, and that'll move the ... low lying areas will hold water and probably see runoff, with substantial rain events.

Dale Boyd:

Just coming to the conclusion now, but I just thought I'd just put a few more positives about having a monitoring point on your farm. I know a lot of farmers now are covering quite a few number of acres and out blocks and a fair distribution and spread of farms, and so this is what I'm looking to do on, now, the monitoring points, is put up a camera that'll take a still shot of the paddock so I can actually pick up not only remotely what the moisture trend changes are, but the development of the crop, and when it's being sown, and the stage of growth it's at.

Dale Boyd:

And also the period it's harvested. Even with Canola, I can pick up 10 percent flowers, so the point of when crops the flowering, and how long they're flowering for, and what the moisture used is at that point, and duration, so just there at Raywood that group there, with the Raywood Regen Ag Group, with the CMA, they've done a fantastic job of installing a very good network of moisture probes, supported by the weather station.

Dale Boyd:

We can pick up what the recent rain event has been at that site there, and the canola starting to emerge at that point, and I thought it was quite interesting that with all these storm cells floating around at different points during summer, I was looking at the data there and it was just to the west of Raywood, and I was looking, and I was just going, "Oh."

Dale Boyd:

On the sixth of February, there was a storm event, and for starters I didn't think it was quite right because we can pick up humidity, temperature, wind speed, but in terms of rainfall it's plotted by the hour as well, and I'm starting to see these totals that I've probably never seen before in an hourly rainfall distribution. 31 mil, 25 the next.

Dale Boyd:

Yeah, but when you look at the buildup of it, it's gone from 29 percent humidity right up to an 80 percent. We've had over a 10 degree temperature drop with that storm event going through, and I think quite amazingly that this out block is really a couple of kilometres away from the home block, and the home block received about 19 mil, and this monitoring point has had over 86 mil.

Dale Boyd:

I guess you've got to treat paddocks differently in terms of their moisture profile, so it's good to know in terms of not only a weather gauge, or a rain gauge that's picking up rain events that can be vastly different to your home block, particularly in summer storm events, but also the effect you can have from rain in terms of moisture changes.

Dale Boyd:

That certainly presents opportunities with profiles that are quite full, and it sort of goes back to that example at Normanville where we had a fair spread of some good years, some average years, and some poor years, and obviously those poor years are fairly challenging, but there's certainly potential with those better years to capitalise, apply the right amount of inputs to the potential yield you're sitting on, and make the most of that year.

Dale Boyd:

There's always been the question of how useful is that data in terms of moisture probes, and just useful initially, and how long is it in that useful stage until then you can convert it into assisting with decision making. We might've got lucky here over at that Raywood site, but going back, it's been in the ground for nine months.

Dale Boyd:

It grew a fairly handy crop of Barley last year, which I'm assuming almost got to that crop lower limit. This is something that, each year, I sort of tweak and change, or closely examine anyway, but at this stage even after three or four months that's sort of where I set it, but as we've progressed through summer and into autumn I can pretty quickly establish that we're pretty close to near a full point for this site.

Dale Boyd:

In the matter of nine months, we've got our upper limit, our plant available water zone, as an initial estimate, and then we'll work out where this lower point is. The other thing that I am looking to do now is to probably not put the sensors down as deep, with that top sensor measuring 20 centimetres, I think that's probably the more preferred position to put that sensor or that probe, and then you can still safely sow and do all your paddock management activities over the top of it without damaging it, because that is still the main strength of monitoring cropping paddocks, is to have the probe in place for as long as possible undisturbed, so then you can capture not only the growing season changes but these out of season moisture changes.

Dale Boyd:

And if we're looking at their dry times, or more intense summer storms, it's the collection of data over 365 days of the year that's got to be pretty important to tell the picture and draw those comparisons to other years. Just to wrap it up with that, Leighton gave a very good talk about the principals of soil moisture monitoring two weeks ago, and I think he had a pretty good point that the moisture probe data, I think you've just got to have the right expectations.

Dale Boyd:

It'll certainly provide you with data and an indication of the seasonal conditions, but it's really up to how you interpret the data to make those informed decisions because I think I've worked with all of the host farmers, and they've all got their own little individual way of interpreting the data and how they use the data to make decisions by. I guess this technology was initially developed and utilised in irrigation environments, and I've just been working on an AgNote, and that's why it's sort of come to me that by the soil of moisture in an irrigated environment, it certainly would tell you the point where whatever the pasture species or plant species was, when it needed to be refilled, so that data would then indicate a decision.

Dale Boyd:

But in a dry land environment, it all comes into the whole agronomic and seasonal outlook mix. This guide that's been recently released is a really good guide of how farmers and agronomists in the industry are using seasonal forecasts, and there's a few of the soil moisture monitoring hosts listed in this case study booklet, and as indicated they've all got their own little specific methodologies of how they read the data.

Dale Boyd:

Essentially quite similar, but no doubt they've tailored it quite specifically to their particular enterprise and their specific soil type as well, and I think that's why we see some that are sitting on pretty good yield potentials, and they've got the ability to assess those crops at those critical times, and whether it's a benefit to take those crops to grain or to cut them from hay, and we've certainly seen quite a few of these host farmers be quite responsive to converting what was looking like a grain crop to a hay crop based on soil moisture data.

Dale Boyd:

They're certainly getting some valuable insights into what's happening underneath their soil surface. I think I can wrap it up here. I know there's been a few questions come through, so I can look to tackle those.

Jemma Pearl:

There sure have been, Boydie, so we will aim to answer as many as possible before 1:00 o'clock, but if you do, use the chat function. If you've got more questions, let us know. Just thought I'd let everyone know that we had 144 people register for today's webinar, and we've had 81 join us, so thank you all for being here. I'm going to go back to the very start, Boydie, talking about the actual putting the probes in the ground.

Jemma Pearl:

First question, can you explain what the slurry is, please, for anyone who doesn't know?

Dale Boyd:

Yeah, so I've always commissioned the service providers to do the installation. I think that's such a critical point to get right, and so from observing the installers, they can work on two systems, whether it's using the localised soil and grinding that down and making a paste, and then pouring that into the pilot hole and putting the probe in so you get good contact to the outside of the probe to the soil medium you're looking to measure. Most of them are actually using, it's a combination of a small percentage of bentonite, some sand, and it just provides a nice, consistent slurry, and it's a medium that is consistent all the way down, from outside each sensor, so really the slurry has no influence. It just connects up the outside of the probe to the soil medium you're looking to measure, so in terms of the actual percentages of each component, I'd have to get back to them.

Jemma Pearl:

Okay, thank you. How do you calibrate them? Is there a certain way or certain understanding that you need to do to calibrate a capacitance probe?

Dale Boyd:

Yes, so it's a matter of probably looking at the trend line data, initially, and then certainly this season it is presenting quite a few opportunities at a lot of sites, because it looks like that upper limit is going to be reached where the sensors can't get any wetter, so that's a point where you could go out and do some soil cores, and there's some methodologies around that of you never get too close to the probe, but how many you do in terms of repetition, but I've found by going within 10 metres of the probe, doing a soil core, and then examining that soil core and breaking it into the sensor increments, so every 10 centimetres, and then taking that back to the lab and doing a wet weigh of that soil, and then putting it in the oven for 48 hours at a bit over 100 degrees.

Dale Boyd:

That takes out the water, and then giving each specific sample a dry weight, and so then it's a matter of subtracting the dry weight from the wet weight, and then that leaves what the total moisture is, and then on the other side of that you can go in and sample at that dry point as well, and then by looking at the total moisture from when you sampled at the wet point to the dry point, that is a way of calibrating to find out how many mils is actually in that measured zone, and it's probably a point in a measurement that a lot of people are looking to get to.

Dale Boyd:

From that calibration, then, you're looking to compare that to the soil type characteristics and its, I guess in theory, estimated water holding ability, so we've got some clay loams that have got some, in theory, sort of 150 mil or 15 mil plant available every 10 centimetres, so down to a metre that's 150 mil. And we've done a few calibrations, particularly at that Raywood site, Youanmite quite similar soil types and the calibrations have come up pretty close to those, so yes, that is a methodology of calibration to convert it to mils.

Jemma Pearl:

You might've kind of touched on this with the fact that the Riverine Plains group have got their soil moisture probes a little bit lower than what we've got ours, but if you had your time again, what would be the deepest sensor you would want to put in?

Dale Boyd:

The capacitance probes are 80 centimetres. They come in a 1.2 metre, so that's what I'd be looking to utilise in the future, particularly in those areas that have got soil types that have got the ability to wet up down below a metre, they don't have the soil constraints, and I guess sometimes you look at the water use efficiency calculations and you know that the crops are obviously utilising deeper water, so to get a better picture of that, a 1.2 metre probe, first sensor at 20 centimetres, would move it down to 1.4 and I think that would be quite adequate.

Dale Boyd:

Yeah, there's probably other areas. There is probably no need to go down below a metre, because they've got constraints, and some restrictions, and rainfall that allows that infiltration down to those depths.

Jemma Pearl:

Yeah, so the cropping sites start at 30 centimetres, but our pasture sites start at 10.

Dale Boyd:

Yeah, pasture at 10, and that's to capture the majority of that root zone mass down to where it's 30, 40 centimetres, so you certainly want to get as clear a picture of that as possible, and the deeper measurements are certainly of interest, and as we highlighted Greta, they're full to saturation, so that's got to indicate that further rain's going to either move further down into that profile, or rainfall on a saturated profile will provide runoff, and dam fill in and moving into those low lying areas.

Jemma Pearl:

A question about extrapolating the data from a soil moisture probe from one paddock to the other, I guess just thinking about the rainfall amounts, how can we extrapolate from paddock to paddock? And I think just on another point, just maybe comment on the probes that we've got side by side in two paddocks. That would be great, too, please.

Dale Boyd:

Yeah, yeah, so that's finding that ... the telemetry's got a fair cost into it, in terms of it logs the data, holds the data, transmits the data out. The probes are probably the cheaper side of things, so I've found by investing in the telemetry, getting the benefit of moisture probes, either side of the fence line has been a great benefit.

Dale Boyd:

You'd do it in a cropping scenario because you could pick up different rotations, and every season's different, so you can examine the effect of different crops in the same rainfall year, of how they perform and where they're picking up water from. In terms of pasture, there's always a point in difference in whether they're annuals versus perennials, or they could be two different types of perennials with some slightly different growth habits.

Dale Boyd:

That's the point of differences that I'm looking to list. In terms of Greta, what we're looking to monitor there, what we are monitoring there, is some phalaris versus some annuals, and I saw the question come up there of what was being monitored there at Greta. That was a combination of both phalaris and the other graph was over annual pastures, so something that started off with the breaking rains.

Jemma Pearl:

Just talking about species' differences, pulses versus cereals and the water being held over to the second season. Any comment on that?

Dale Boyd:

Yeah, yeah, definitely. I guess we've been monitoring over the period of time pulses and lentils certainly come to my mind at Normanville last year. They didn't have the aggressive root system, the aggressive moisture depletion, that we sometimes see with a higher biomass cereal crop, so I guess the crop rotation and the response for the next year after growing potentially a low water requirement crop is that it's got to be more water in the profile, potentially down deep, compared to a higher yielding cereal crop, and then I guess I listed it there over in the Wimmera, the differences of a high yielding wheat crop which pretty much depleted a whole profile pretty much within less than 60 days, compared to a paddock pretty close by, reasonably similar soil, and that was cut for hay and that conserved a range of 20 to 40 mil carryover into the next year.

Dale Boyd:

With hay being in the mix with quite a few farms these days, you can see the effect of what hay can have for the paddock the following year.

Jemma Pearl:

Awesome. Now, I have just noticed the time, so letting everyone know that I completely understand if you have to go off to your next meeting, or wherever you have to be at 1:00 o'clock. We will probably ask a few more questions of Dale but the recording will come out. Boydie, you're happy for people to email you by the email address on the screen if they've got any questions or for the ones that we might miss today?

Dale Boyd:

Yeah, email certainly for, you know, they can send questions in, but also if they want to subscribe to get more information about the data that I'm looking to report in our monthly newsletter on the cropping side of things, the latest report's just come out, but to get on that subscription list certainly send me an email and we can add you to that list.

Dale Boyd:

And the newsletters are sort of set in a format to be informative of the seasonal conditions, as measured at these points, but also educational, so if you're looking to implement some form of measuring on your own farm some of the things you could look at in interpreting the trend line data, if you had that probe on your own property.

Jemma Pearl:

A really specific question but possibly one that's a bit of a current situation for the state of Victoria. Can you comment on the Taylors Lakes probes showing a lack of soil moisture in the profile there, Boydie?

Dale Boyd:

Yep. That's a good question. I saw that pop up, and I touched base with the owner just the other day just to find out what was happening, so it's a mixed enterprise farm, so it's certainly got sheep on that farm, and with the summer rains, there was a germination of weeds but also volunteer barley from the barley crop in 2019, so it probably didn't get the opportunity to build up those soil moisture reserves like other paddocks because the weed control wasn't performed on that paddock, but it certainly provided supplying dry matter to livestock.

Dale Boyd:

And it's also, as described by the farmer, a gray, self-mulching clay, so it's quite heavy in its texture and characteristics, and what we know with those soil types are that they can hold a heck of a lot of water, but they do take a heck of a lot of rain to actually start to infiltrate and wet them up to depths, so that's just where it's good to know the insights in terms of the monitoring point, and the specific soil types, and what's being grown there, because on that particular monitoring point it's probably a bit lower than a lot of the other Wimmera sites due to weeds growing over summer, that late summer, autumn period.

Dale Boyd:

And it's gray, self-mulching, heavy clay characteristics, so we're certainly looking at a product that'll look to highlight each specific site sort of in the next two to three weeks, and that will clearly list the soils, the rotation, and what's being grown in there, so that'll certainly provide more background, and some insights into why the data is, what it is.

Jemma Pearl:

And for our last question, I think, that really works in well with your comments just then, I've got a question about the fact that mait is our current software provider, just wondering if we gather data from other telemetry networks.

Dale Boyd:

Obviously, I've made inquiries into other networks and service providers, because essentially it is transmitting capacitance values, and what would be ideal is to convert to the same dataset so it could be all represented in the same graph or speedos, and I think that'll be a great advantage for the whole state and a lot of industries.

Dale Boyd:

Because I could probably put a number of between 100 and 200 networks or moisture probes that are out there in a whole range of networks, but all sort of disconnected because they're all being presented, and shown on different webpages, so we certainly look to utilise, to bring all of those data sets in, and once we fill in one to 200, we'll identify where the gaps are or we'll probably know where there's pretty good coverage, and at this stage I could list over the north east, that's great.

Dale Boyd:

North of Bendigo is great. That Warracknabeal east group, they've got some pretty good coverage around Sheep Hill, so it gives you pretty good confidence when you can examine six to eight sites within a district and they're telling you the data, and if it's all in a consistent fashion, yeah, that's the way the season's progressing.

Jemma Pearl:

On that note I'll wrap it up here. There are a few more questions we didn't get to, so Boydie is going to receive an email for me with those, and we'll get him to answer them in a text format and we'll put that with the recording, so I'm sorry for those we've missed but we promise we'll get that to you as soon as possible.

Jemma Pearl:

On that note, thank you very much, and please, please don't forget to do the survey. We really appreciate your assistance with that one, and if you've got any further ideas or topics that you'd like for our climate webinars, please let us know. That'd be great.

Jemma Pearl:

Thank you, everyone. Have a great rest of your Thursday.

Dale Boyd:

Thank you, Jemma.

Jemma Pearl:

Thanks, Boydie.

Page last updated: 03 Aug 2021