AgVic Talk Season 9

Speaker 1:
Welcome to AgVic Talk, keeping you up to date with information from Agriculture Victoria.

Drew Radford:
G'day. I'm Drew Radford and welcome to season nine of AgVic Talk. This season's all about planning for the dry and to better equip you to manage the impacts of drought and our changing climate. This season will provide you with resources and a range of practices and tools that are available to help you improve your farm business. Farming's rewarding, but it can also be challenging, and no 2 stories or businesses are the same. We can all learn from each other and set a plan for success. Today's episode is a sneak peek of what's to come.

Australia has some of the oldest soils in the world. For farmers that can make it difficult to capture subsoil moisture so that they can deal better with dry times. However, one way of resolving this is through subsoil amelioration, or more commonly referred to as subsoiling.

Chris Smith runs a mixed farming enterprise at Grass Flat, around about 30 kilometres west of Horsham. He's been on a quest to improve the soils on his property. So when the opportunity came up to run a subsoiling demonstration, he keenly offered up a piece of his land for the exercise. To discuss the process, and more importantly, the results, Chris joins us in the AgVic Talk studio. Hello, Chris.

Chris Smith:
Good day, Drew. Good to catch up with you.

Drew Radford:
Chris, whereabouts do you farm? And I understand your family's been in the region for well over a hundred years.

Chris Smith:
Yeah, we farm in an area called Grass Flat, and I farm here with my wife Annette. This area is 30 kms west of Horsham, just near Mount Arapiles and getting near the edge of the Little Desert.

Drew Radford:
Right. So that would be a reasonably varied country out there then, wouldn't it, Chris, if you're between those two spots?

Chris Smith:
Yeah it is, Drew. It's a pretty spot. We get a good view of Mount Arapiles and the undulating country. So you end up with sand rises and there's an interesting run of salt lakes that run probably in a northerly direction from Mount Arapiles and we've got a number of them on our place, two of them. And on the eastern side of those salt lakes, what they have, is what they call lunettes. So they're like sand rises, and then you can end up with heavy flats. So we end up with a whole range of soil types here on our place, but it adds to the interest of trying to farm.

Drew Radford:
I think you're being fairly generous there with your description. Cropping across that landscape must be...I don't know whether challenge is the right word, but it sounds like you've got at least four different soil types. What's going on there?

Chris Smith:
Yeah, so within paddocks they do pick up different soil types. You can have limestone ridges running across your paddocks to heavy flats to sand rises, to really gutless sand. We've tried to patch out different areas at times to lift the productivity of those poorer areas. Maybe using a bit of sulphate of ammonia, gypsum and that sort of thing. But you end up with quite a colourful yield map at the end of the harvest because you can see just your different soil types dropping in and out, depending on the season.

Drew Radford:
Chris, that sounds like a fairly top-down approach for want of a better description. I understand though you've started to have a look at a slightly different approach, subsoil amelioration or otherwise known as subsoiling. For those that don't know what that is, can you describe it?

Chris Smith:
Well, subsoiling, people are probably very familiar with deep ripping and even clay delving. Deep ripping can be used to bring clay up onto your sand rises, which is not that new. People have been doing it for a long time, but subsoiling or subsoil amelioration is dropping some sort of product to improve the soil fertility, health, biological activity in the soil behind the tyne as you rip. So you're dropping it at depth so at the same time you're breaking up, maybe a compaction layer, you could be bringing clay to the top of the profile, depending what your approach is, or you could just be getting a mix of that clay and the topsoil and dropping some sort of product behind the tyne.

Drew Radford:
So it sounds like there's a bit going on there. You're not just deep ripping, you're adding something to essentially the rip, the trench, that you've dug. What's that achieve?

Chris Smith:
The idea behind subsoiling is to improve the health of the soil in a number of ways. One way is to aerate your soil. You're breaking up a compaction layer that's preventing air getting in, and without air there's not much biological activity in your soil and the roots won't be penetrating, and the water doesn't get in. So there's that side of things, and then by dropping a product in behind it, which is high in organic matter, then you're going to add all those goodies into your soil that the microbes and the bugs and the earthworms will hopefully add to the overall health of your soil.

Drew Radford:
Let's start talking about what's involved, and I understand, you offered to do a subsoiling demonstration on your property. What did you do?

Chris Smith:
It was in conjunction with Agriculture Victoria and Birchip Cropping Group and they provided the hardware, the equipment to do the job. So we allocated an area in a paddock that was going to a cereal in that rotation, and we picked a transect across the paddock that picked up a sand rise and then a gilgai heavy flat and then up onto a problem area where we get water logging. So we had all three soil types, all three areas in the one transect, which ran for about 400 metres, 350 metres, and there was a number of subsoiling products that we were dropping down the tube or just on top of the soil or just left the control. That was just to assess what is best for the soil types that we've got here and the conditions.

Drew Radford:
There's a bit going on there in terms of you're doing different soil types and you're also doing different additives for want of a better description. Did the results vary?

Chris Smith:
Yes. It was quite interesting, really. We had a pretty good winter here, so the product that we had access to was some compost pig manure, and then we had our own compost, which I made myself, made out of duck manure and straw and a few other goodies, and that was what we called our ‘home brew’, and then we had gypsum as well.

So there was a whole series of combinations of mixing, say, putting the pig manure, compost at depth, and then my home brew at depth, and then mixing gypsum with those products and also putting them at depth and then a few controls and then just dropping the product on the top. And then we went about speed tilling that in. So we let that run through the season. We just pretty much sowed it as part of our normal rotation and that's pretty much all I did.

I just let the trial run its course. And so as the time went by in the demonstration trial that we were running, it was plain to see that where the product was drilled in, there was a yield response and where the control, the crop wasn't as good. Between the control and the compost at depth, that ranged from about 0.6 of a tonne per hectare benefit of the pig manure, which was close to 1.3 or four tonnes higher. So there was some interesting results there, and we got to dig a soil pit. And you could see this product you dropped in at depth, it was like a big sausage ripped in behind the tyne, and it was really fascinating to see actual worms in those subsoiling lines where we dropped the compost, whereas I didn't find any other worms anywhere, but they were in the subsoiling product, which was good.

Drew Radford:
Those yield results, you'd be pretty happy with that, wouldn't you?

Chris Smith:
Yeah, it was good to see that you can get a response and you get some benefit from going to the trouble of the expense, I suppose. And it'll be interesting to see how the paddock performs this year and just how it responds. We drop back to a legume this year, a pea, so it'll be interesting just to see how that establishes and whether there's improved nodulation on those areas where we did deep rip the compost in.

Drew Radford:
Chris, you raised the word there, expense. Running a tyne through a paddock and then providing the home brew or the pig manure in behind it is a bit involved?

Chris Smith:
Yes, there is, Drew and they were putting the pig manure at 20 tonnes per hectare, which you need a fair bit. And the home brew went in at about 12 tonne and the equipment was pretty substantial, unique sort of equipment. I guess people have to weigh up what are their objectives. If you are going to deep rip it or do clay delving, is there an opportunity to drop something down the tube if you're going into the paddock anyway, so those sorts of things you have to weigh up.

Drew Radford:
Well, in terms of weighing it up, what have you taken away from it for your own property?

Chris Smith:
I'm very interested in trying to improve our soils. I'm very keen to look at doing subsoiling, particularly on poorer performing areas of our paddocks on the sand rises and just targeting those and trying to lift the overall soil health and performance and hopefully yield.

Drew Radford:
They're crucial things. Do you think it'll put you in better stead for dry seasons as well, trapping subsoil moisture?

Chris Smith:
Well, yeah, I'd hope to hold on to the moisture. If you're lifting the organic matter, in particularly those sand rises, hopefully the soil can hold on to some of the moisture more readily, rather than just draining straight through or running off, because some of our sands are non-wetting, which can be a little frustrating when it comes to germination, and trapping moisture as well as not losing nutrients through the profile as well. If we can lift the soil productivity and that can hang on to the nitrogen and the different minerals that we need to grow a healthy crop, then we're going to have a win-win, I believe.

Drew Radford:
Chris, what have you taken away from it in terms of challenges and lessons learned? I understand you're a bit surprised about the quantities involved, but I can't imagine it's a quick process running a ripper through even to start with.

Chris Smith:
It is time-consuming, and I suppose that's something to consider, but for me it was a real eye-opener to see just how the soil responds and just seeing at depth what problems that we have to deal with in this area of grassland and what benefits could be achieved using deep ripping and dropping ameliorate in. So I'm interested to pursue it further and target those areas where I believe that we could lift our soil health.

Drew Radford:
Lastly, Chris, for other farmers listening to this, have you got a couple of takeaway tips that you'd suggest to them to consider if they're thinking about subsoiling?

Chris Smith:
Yeah, I'd probably evaluate what your objectives are, like what are you trying to achieve by subsoiling and what products are readily available and at what expense and availability of the equipment, and if you are going to clay delve anyway, maybe there's an opportunity to value add that procedure by incorporating some sort of ameliorant or subsoil product into the soil profile while you're doing that process. I think that you have to evaluate each of the steps. Can you do target areas when it's so expensive and try to lift the performance of those areas and leave the better performing areas just to conventional farming or maybe using other additives to improve soil health without actually going in and ripping the soil. But I guess you have to evaluate what the problems are, whether you have a drainage issue, water penetration, compaction. So I guess you have to weigh up your limitations of your soil and saying what it's going to deliver for me and the cost associated with that.

Drew Radford:
Well, Chris, it sounds like you've had a fascinating ringside seat, literally, for this demonstration that you've run on your property and gained some huge insights about potential ways of improving your soil, because that sounds very central to your future farming. I'll be fascinated to see where you get to with this over the years. For now though, Chris Smith, thank you so much for taking the time and joining us for this AgVic Talk podcast.

Chris Smith:
Thank you, Drew.

Speaker 1:
Thanks for listening to this episode of AgVic Talk. To access Farm Business Resilience Programs and information from Agriculture Victoria, check out the show notes from this podcast. The Farm Business Resilience Program is jointly funded through the Australian Government's Future Drought Fund and the Victorian Government's Future Agriculture Skills Capacity Fund.

Contact Agriculture Victoria, or your consultant before making any changes on farm. For more AgVic Talk podcasts, visit agriculture.vic.gov.au/agvictalk. This podcast was developed by Agriculture Victoria, authorised by the Victorian Government, Melbourne.

Further information

Fact sheet: Decision support for grain growers

Case study: A first experience of subsoil amelioration on Chris Smith’s farm in western Victoria

Video: Subsoil amelioration