R&D Edition: Cover cropping converts Peter Schreurs & Sons

Vegalogue is a podcast from Australian vegetable peak industry body AUSVEG. Each episode we take a look at issues affecting the Australian vegetable, potato and onion sectors, unpacking levy-funded research and meeting some of the incredible people who make up the vegetable industry.

In the last episode we had a chat with Dr Kelvin Montagu about a project he ran a few years ago exploring the benefits of cover cropping for vegetable growers.

This episode, we speak with a grower who was part of that project, Peter Schreurs and Sons, and how it started them on a cover cropping journey that has changed the face of their farm.

You can watch a video version of this interview here.

Guests:

• Darren Schreurs, Peter Schreurs & Sons
• Mark Schreurs, Peter Schreurs & Sons

Learn more about the project discussed in this episode:

• Optimising cover cropping for the Australian vegetable industry (VG16068)

Thanks for listening to Vegalogue! You can find out more about AUSVEG and the Australian vegetable industry at ausveg.com.au. Subscribe to our newsletter, or follow us on Facebook, LinkedIn, Instagram, Tik Tok, or Twitter/X.

Transcript

But I would put it down that we've built ourselves another fairly large dam just by what we can hold in the soil.

Welcome back to the Vegalogue podcast, a dialogue about the Australian vegetable industry from AUSVEG.

I'm Tom Bicknell.

In the last episode, we had a chat with Dr. Kelvin Montagu

about a project he ran a few years ago, exploring the benefits of cover cropping for vegetable growers.

Well, this episode, I speak with a grower who is part of that project and how it started them on a cover cropping journey that's changed the face of their farm.

Peter Schreurs & Sons is a second generation vegetable grower in Devon Meadows, south of Melbourne.

Among other crops, they're one of the largest leek growers in the country.

As part of Dr. Montagu's cover cropping project

Peter Schreurs & Sons ran a trial to see if they could use a cover crop to establish mycorrhizal fungi for the benefit of their leek crops.

The trial didn't achieve what they'd hoped, but it nevertheless changed the way their farm is run for the better.

I'm Darren Schreurs from Peter Schreurs & Sons Vegetable Farm.

I'm in partnership with my two brothers, Mark and Paul.

My father established this business back in the 1960s.

In the 1980s and the 1990s, myself and my brothers became interested, so we had to expand, and we bought this property here that we're on now, 400 acres in Devon Meadows.

So my role in the business is I'm in charge of controlling insect pests.

Weeds, diseases, and the fertilisation of all our crops.

The crop we're in now, we've got a cover crop of oats and buckwheat.

Our farm mostly consists of a sandy loam.

We have some sandy blocks and some sticky clay blocks as well.

We were approached about six years ago by Kelvin Montagu about establishing mycorrhizal on our leek crops.

And I thought that would be a great way for leeks to help take up more nutrients from the soil.

A few years prior to that, I trialed my own, I'd done a few of my own trials with mycorrhizal fungi and had no luck, but that was more conventional way of growing.

So we decided to sow a cover crop down, inoculate the cover crop with mycorrhizal, and then without any soil disturbance, because mycorrhizal hates soil disturbance, it'll die off with that.

We then terminated the cover crop and planted leeks straight on that, inoculated the leeks, and then at harvest time, we got the soil tested and the leeks tested for mycorrhizal, but sadly, no mycorrhizal was found.

Did you have any ideas why the mycorrhizal fungi didn't take?

Look, some of the reasons why mycorrhizal didn't take was, it could be the high phosphorus levels in our soil.

It could be previous herbicide issues in the soil.

It could just be the soil type.

So, we have to do more testing down the track.

But what we got out of it though, was cover cropping, we find, it's energising the soil more and more.

So we've now got a philosophy that we try to keep all of our soil covered with a cover crop of some type.

My brother Mark, he looks after that, and we look at multi-species cropping all blocks, different species for different times of the year.

And yeah, we just find having the cover crops on the farm, when it rains, we get water penetration.

That's fantastic.

We don't get the runoff, we don't get erosion.

Those windy days, we're not getting dust blowing around everywhere.

Our carbon levels are increasing dramatically on a farm.

And the biodiversity, every cover crop has got a flowering plant in it.

And those flowering plants, they bring on pests as well as beneficials.

And because these crops don't get sprayed, we get a huge number of beneficials to build up in those crops so that when our cash crops are grown, especially right next to the cover crop, but anywhere on our farm, it takes no time at all for beneficials to move in, as long as we're using soft chemistry to control the pests.

What are some of the unique challenges you get with leeks that maybe some other vegetables don't face?

Leeks, they sit in the ground for a long time and they don't smother the ground.

So weeds are always an issue in the leeks.

With the cover crops too, we have to be careful that we don't let the cover crop seed.

We've learnt that in the past there, we've had some go to seed and it becomes a bit of an issue in the leek crop, the following leek crop.

If we have crops that can smother the ground, yeah, you can control the weeds a lot easier.

So yeah, biggest challenge is weed control in the leeks.

Insect pressure is not an issue.

Disease, if the crop gets too old, we might start seeing some leaf diseases in our crops.

But overall, it's mostly just the weeds that are the biggest issue.

And what's the kind of groundwork you need to do with leeks?

After a cover crop and the right fertilisers put in, we then just plough the soil under, bedform it, and then punch the holes.

There's only probably two passes.

In the past, we would probably have eight passes or so, and now we've cut it down to two.

Fertilisers, we've cut in half because of the cover cropping, and insect pressure has dropped dramatically, too.

Is it machine harvested?

All machine harvested, yeah.

So the machine, when that goes through the soil, that breaks up the soil, and that's the only downside of when we're harvesting leeks, is that we've got an open trench left on the bed, and the bed then has to be ploughed up and reformed again.

Water retention is a huge thing.

The last summer we've had nearly 10 weeks of no rain.

We didn't have to water for very long on our crops, whereas other growers, I know they have to water nearly double the amount that we do, and our soil just tend to hold the water a lot better than what it has in the past.

Our crops didn't suffer at all.

I mean, kohlrabi is one that'll really suffer in the hot, dry conditions, but they went a little bit limp, but they recover so quick, because we've got such good water retention in the soil.

So building up those carbon levels in the soil has made a big difference.

Stuff breaking up on top of the ground.

Well, my name's Mark Schreurs.

I'm in charge of operations here at Peter Schreurs & Sons.

So I look after mainly things from the irrigation through to the harvesting operations, and I manage the fields right back to after planting again.

So it's that in between time.

That's the main part of my role, amongst other things, of course.

So what field are we standing in here at the moment?

What are we looking at on the ground?

All right, what we're looking at here is a cover crop that has been planted in last December.

It's now mid-April.

So last December, we had a crop of leeks come out.

We don't like to leave the soil bare over the summer months.

We don't have a schedule till here till for another three weeks before we plant again.

So over the summer, we planted a warm multi-species mix.

There's 10 different species in there.

And over that time, we've let it grow up.

Once the dominant species started to get close to seeding, we go through with a crimp roller, roll the larger species flat.

We usually do that another two weeks again later to really terminate that first lot.

And then the second voluntary lot of plants come through.

Once again, it's just we're keeping these living roots growing in the field for as long as possible.

That's one of the main goals, and also holding our soil, keeping armour on the soil, so it's not sitting there bleaching under the sun.

So that's the way we've managed.

We've crimp rolled it.

We've had to top it once or twice when certain species come up trying to shoot the seed.

And this will be probably terminated in...

This will be knocked under and planted within three weeks from here.

So what do you see as the primary benefits of cover cropping?

The main...

Oh, there's just multiple benefits.

You can list them off as long as you want.

I mean, the biodiversity is what we're after because the more biodiversity we have, the stronger the farming system, the more resilient...

Basically, the more that's going on biologically, the harder it is for a nasty to take hold and dominate, basically, because it's got too much competition.

So we're creating competition for our pests.

We're basically sequestering a lot of carbohydrates into the soil.

So while it's sitting there doing nothing, it may as well be sitting in, like, just using the sunshine.

The carbon dioxide in the atmosphere, turning all that into carbohydrates for the soil, encourages more biology and everything like that.

And we try to do that in amongst as little disturbance as possible.

We still use tillage because it's a high intensity of horticulture, so tillage comes into it.

But one of our main goals is to leave the ground alone, untouched for six months of the year.

That's what we're trying to work towards, is keeping things undisturbed and allowing that time for recovery, really, for biology and diversity to recover again.

So that's one of the main goals.

There is also the nutrients you could get from different types of species.

To get ground ready for planting is a breeze, because the ground just one or two passes, it's broken up, ready to go.

So the water holding capacity of the soil, so with all the extra organic carbon that we're building, and we've gone from 0.5% when we started, we're now averaging up close to 4%, we're aiming for 5%, but we've been managing to get there, and we're noticing that with the drainage of the soil is so much better, plus the water holding capacity in the farm is just, it's been outstanding the last few years.

Looking forward to the next drought, because then it'll really prove whether we're on the right track or not, but I would put it down that we've built ourselves another fairly large dam just by what we can hold in the soil.

So in a crop like this, if we get, like the rain event we had a few weeks ago, 60 mil of rain overnight, there's almost no runoff at all.

That water is going in where it's wanted, and it's not taking soil and nutrients away from it, it's staying here, so it's a way to just preserve your soil and build it up.

So it's kind of about regeneration, really, is that the cover crops are just part of a way of keeping life happening and regenerating our soil.

So our aim is to make sure the farm, and it's sort of so far working, we want the farm to be better the day we leave it than when we found it, and we just want to constantly improve it and making the whole system more resilient, and so far it's been working very well.

Are there any trade-offs or challenges introduced by cover cropping?

There's always trade-offs, there's always challenges.

The trade-off is, and some people balk at that because they think, oh boy, I'm putting energy into a crop that I'm just turning back into the soil again when I could have been having a cash crop in there.

Yes and no.

The thing about cover cropping is, you've got to look at it, it's going to lower your inputs long term.

Okay, you might be able to get an extra cash crop off there, but all the inputs you've got to put in there to keep that constant cash cropping going is going to, anyway, it's going to shrink your bottom line, whereas this, okay, the soil is sitting there without a cash crop for a certain few months, but that's making less reliant on other outside inputs and synthetic inputs.

I know that's one of our aims too, is to eventually, we want to cut all synthetics out altogether.

That's the ultimate aim, so, and we've certainly used very little now.

We don't need it so much, so.

Would you encourage other growers to explore cover cropping and to get involved in some of the research trials that the operation here has tried?

Oh, yeah, yeah.

Just have a go.

That's my thing, is I know a lot of, in the regenerative space, you hear a lot of people talking and some, especially some of our friends across the other side of the Pacific, they really get adamant about, and they're not wrong, but they get adamant about critical timing and all this sort of stuff.

And that is true when you want to get really nuanced about it.

But to get a start, have a go.

It's just, nothing too bad can go wrong.

Put it that way.

You can't stuff it up that much.

So have a crack.

I mean, a great start if you're not sure, especially like this part of South East Australia, a good starting point is just get a mix of ricorn and vetch.

Great starting mix.

Sow that down.

Just keep an eye on it.

Let the vetch flower.

The ryecorn just start to head, then terminate that.

See how that works in for your system.

But every system is different, and every farmer has got to find their own way.

So what works for us works for us, and we've really made cover cropping an integral part of our operation.

Other people, it may not suit them quite as well, but they have to find their way.

But have a go.

That's all I say is just have a go.

That's the thing.

You can't go wrong.

Not too much anyway.

This project was funded by Hort Innovation using the Vegetable Industry Research and Development Levy and contributions from the Australian Government under project code VG16068.

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