Episode 2: Target 50 Series | Maintaining stubble in legume rotations with Michael Moodie
June 23, 2020 - 1:05 pm
TARGET 50 Podcast Series – decision making to keep ground cover in the system! Episode Two: Maintaining stubble in legume rotations with Michael Moodie, Frontier Farming Systems (MSF’s Key Research Agronomist).
Michael provides an update on:
The work he has been doing on break crops in the Mallee and the trends that he has seen in the uptake of break crops in the region.
Discussion around positives and drawbacks of growing legumes
Why we are seeing a reduction in ground cover over time when it comes to legumes
Michael’s observations on any obvious factors in maximising biomass and ground cover in legume crops
Plus much more!
We thank our Target 50 project partners, Agriculture Victoria for your support.
TEGAN BUCKLEY: - Welcome to the Target 50 decision making to keep ground cover in the system with our focus in this episode on maintaining stubble in legume rotations. This series is all about ground cover and talking through the practicalities of farming to keep the minimum recommended levels of 50% ground cover in the system. Keeping our farming systems protected from wind erosion and I soils healthy and sustainable is what we're all on about. Hi, I'm Tegan Buckley from MSF and in this episode, I'm joined by Michael Moody from Frontier Farming Systems. As many of you may already know the team from Frontier Farming Systems are our main research provider, MSF and Frontier Farming Systems are pretty close and in fact, we've actually been sharing an office in Mildura, Victoria. We've been collaborating on projects for the last 10 years and over that time, we've seen a big increase in projects looking at break crops and legumes in the rotation. Michael Moodie joins me now with a cup of coffee in hand, welcome Michael, how are you?
MICHAEL MOODIE: - Very good on this frosty morning.
TEGAN BUCKLEY: - Michael, to start with can you tell us a little bit more about the work you've been doing with legume break crops in the Mallee and the trends that you've seen in the uptake of break crops in the region?
MICHAEL MOODIE: - Yeah, well, I'm seeing over the last decade a big change in Mallee farming systems where the farmers have moved from a lot of continuous cropping with cereal crops and now, we're seeing a lot more diversity in farming rotations. That's really driven by a couple of things, one is the benefits that diversity provides such as bringing legume pulse crops into the system, provides farmers better opportunities for weed control. We're also boosting the soil nitrogen that's coming into the system and also, you know, things like conserving moisture and disease control can be some benefits. I guess the other thing that we've seen is in some seasons these alternative break crops can be very profitable in their own right, we've seen years when lentils and chickpeas have been very profitable. We've seen things like vetch hay being quite profitable enterprises for farmers and then even you know grazing vetch and other crops has also been quite profitable returns with sheep producers. So yeah, overall this increased diversity by bringing legume crops into the system has been a very positive change for most growers.
TEGAN BUCKLEY: - Fantastic, so it's been quite a rapid increase in legume area and there's many positives to growing legumes. But there are some drawbacks too, can you explain why we're seeing reduction in ground cover over time?
MICHAEL MOODIE: - Yeah, I guess that's particularly in the last two years where we've had some quite dry seasons in many parts of the Mallee, we're finding that the biggest drawback to legume crops is the reduced ground cover that they or the reduced ground protection that they're providing over that, particularly during the summer period. That’s largely a factor of the stubble residues of these break crops being so fragile and they're fragile for quite a number for reasons. One is the harvest process, so harvesting pulse crops, for example, we've got to cut them very low to the ground so we're actually taking a lot of the material through the header. Also that residues breaking up in the header and not providing the structure or the straw structure that say a cereal crop like wheat or barley would. But also particularly on deep sands as well the legume crops probably aren't performing as well as we'd like on those sandy soils. So there's reduced stubble or lower levels of stubble to start with on those soils and also particularly on the sands as well it's such a, well, I guess it's a lot of infertile environment. Those soils and the soil microbes really love that input of those highly high nitrogen stubble sources, whether it's from lentils, chickpeas, vetch, field peas those sorts of crops and therefore we see much higher rates of break down from these residues as well. So that they're turning over much faster in the soil because you know, in their own right, they're providing a food source for those microbes to actually fire up and break it down. So those factors coming together means that the legume crops are at the moment currently posing a bit of a problem particularly on those deep sandy soils and causing some low ground cover and also a lot of erosion issues. That's a big issue at the forefront of our minds is we really need to be looking and finding solutions to how we can improve that because it's becoming a bit of a problem at the moment.
TEGAN BUCKLEY: - Hmm, for sure, so you measure biomass and ground cover as part of your trial work. Have you observed any obvious factors in maximizing biomass and ground cover in legume crops and is there a difference in the quality or longevity of legume residue?
MICHAEL MOODIE: - Yeah, so probably want to tackle those issues sort of separately. Biomass I guess is trying to, you know, basically grow as much as we can and with the theory that the more that we produce, the more stubble that we have there to sort of protect the soil surface. I guess one of the things that we're seeing recently is particularly on sandy soils when they're not obviously growing so well, things like sowing earlier helps produce extra biomass, crop type selection will change the level of biomass that you grow, something like early sown peas or vetch is going to grow significantly more biomass than say a lentil or a chickpea crop sown a bit later. But also soil amelioration techniques have really helped to increase biomass and we've sort of got some results from trials in the last couple of years that have sort of shown you know, more than a doubling of biomass production through actions such as deep ripping for example. So, they're things that we're looking at to increase the biomass side of it, the tricky thing with increasing biomass is also is that sometimes that's going to come at the expense of, yeah, one of the tricky things with increasing biomass is also optimizing grain yield as well. You know, if you produce too much biomass, that can have a detrimental effect on grain yield and also the other thing about increasing biomass is, you know there's always the temptation there to actually do something with it as well. So, rather than just leaving it as a soil protectant, there's also opportunities to make money out of that biomass as well. So the other part of the equation, yeah, how much of that biomass becomes soil cover and our target is 50% ground cover to be maintained at all times. So I think that's a bit of an area that needs quite a significant amount of work, I think that the challenge is going to be overcome by what can we do to not just rely on the legume component as ground cover going forward, but we need solutions to actually try and keep more of that previous cereal crop residues in the system and maintaining some sort of ground cover past the legume phase. So the two working cohesively together to protect the soil over that sort of summer period. So there's a few options there that could be looked at, seeding system stuff, so, you know, what seeding systems, edge row sowing, maybe looking at this seeding systems, you know, it could be of benefit to try and you know seed the legume crop but maintain as much of that cereal crop standing, as possible. Also trying to come up with some solutions that could potentially reduce how much ground cover is lost or how much stubble is disintegrated during the harvest process. So, yeah, I haven't got the answers yet, but there are some techniques that I think we could be looking at to try and promote that residue from the previous crops, flowing through the legume phase and helping provide that ground cover protection over the summer after the legume crop.
TEGAN BUCKLEY: - So Micheal is there any research work going on that will help address the legume ground cover issue?
MICHAEL MOODIE: - So, across the Mallee we've got quite a number of locations where we're really honing in and focusing our attention on better growing legumes on those vulnerable soil types. So particularly the deep sands, but also looking at options for improving crop growth and ground cover and reducing the sort of risks associated with that. So, some of the deep sand sites this year where we're looking, I've mentioned earlier about the huge benefits we got from soil amelioration, last year we saw some really big increases of both legume growth and yield following deep ripping at a number of sites last year and we're continuing that work on this year to relook at that. This year we've probably expanded our focus though to look at not just the impact of the deep ripping on a particular crop, but we're also looking at variety selections within each of those crops. So we're trialing sort of 8 to 12 varieties with and without ripping at number of locations in the Mallee this year for a range of crops, including chickpeas, lentils, faba beans, field peas, vetch and lupins. So quite a wide selection of different crops that we're trialing there. We're also interested in traits such as herbicide tolerance of the different crops, because that's one of the big risk factors in sowing into both sandy soils, but also, soils that might've had soil amelioration. So, rather than just omitting the herbicide all together, we're looking at different levels of herbicide tolerance that might be within different crops to actually make that safer and make sure that we're not having a negative impact on that germinating crop. And the other piece of work we're looking at this year, is some seeding system stuff, so looking at comparing, this is vetch at where we're looking at different row spacing, configurations also whether sowing with a disc rather than a tine, gives us any benefits in terms of ground cover and also crop growth as well. So, there's a range of things there that we're looking at and these trials are located right across the Mallee region in 2020.
TEGAN BUCKLEY: - That was Michael Moodie from Frontier Farming Systems, chatting all things, maintaining stubble in legume rotations and giving us an update on the trial work that's happening around the place to address this ground cover issue. Thanks Michael, for joining us and we've actually got another episode coming up soon featuring Michael chatting more about how to maintain ground cover on sand, so stay tuned for that. Don't forget to share this episode with a mate, if you took some value away from it and be sure to subscribe, rate and review our podcast. Thanks for tuning in and we'll catch you in the next episode.