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Episode 3: Mallee Farming AgVic Series | Soil testing data post wind erosion Sean Mason

March 18, 2020 - 11:47 pm

Dr Sean Mason from Agronomy Solutions joins Drew Radford to outline GRDC’s massive ‘Soil and plant testing for profitable fertiliser use’ project. Growers are concerned about where soil nutrients have ended up post wind erosion damage in the Mallee. In partnership with Frontier Farming Systems, soil testing was conducted in the Mallee with findings including low organic carbon levels in sands and reduced mineralisation. Tune into this episode for all the details from Dr Sean Mason.

Podcast Transcript

INTRO – Welcome to this podcast, brought to you by Mallee Sustainable Farming and Agriculture Victoria from the MSF Research Update at Lake Cullulleraine in February 2020

  • DREW RADFORD – Soil and plant testing for profitable fertilizer use. It’s a mouthful and it’s the title of a huge research project covering the Southern region. To date there are over a hundred growers involved, with soil samples taken from 342 paddocks as well as 300 fertilizer strip trials. Dr. Sean Mason from Agronomy Solutions is leading the project and he joined me in the MSF podcast studio to discuss the results so far. I started by asking him if he was surprised with the number of producers that aren’t soil testing at all?
  • SEAN MASON – Yes. I’m probably very biased, given my work’s been in soil nutrition and doing recommendations, so I just can see the value and I understand growers are under immense pressures and soil testing and plant testing, a small part of the management strategies going forward. But I can see value and especially with the varying soil types on a paddock level that yeah, we can easily get some easy wins. In terms of fertilizer input and overall gross margins with the data that’s coming out of this project.
  • DREW RADFORD – Well you’ve done some pretty extensive testing in 2019 to validate that so far haven’t you?
  • SEAN MASON – We have, so GRDC was worried about soil testing numbers, so we engaged approximately a hundred growers, and we’ve got a few more this year. Probably evenly spread across South Australia and Victoria and all across the agro ecological zones as we call them. But with that, we zoned and tested over 300 paddocks, over 350 actually and yeah, with the zone or within paddock sampling, we’re over 700 zones profile analyze with soil tests, nutrition and constraints, so yeah, a big, big data set.
  • DREW RADFORD – That’s a huge data set. Look, we’re in the Victorian Mallee, what have you been finding there in terms about, nutrient status in some of the eroded paddocks in this region?
  • SEAN MASON – Yeah, great question, one that’s very topical at the moment. So obviously a nutrient stratification has been an issue identified and with the moving paddocks, I guess there is areas of concern where those nutrients have ended up if we’ve got surface all moving about the place. So yeah, just recently, with Frontier Farming, we’ve done some extensive sampling in some eroded paddocks in the South Australian and Victorian Mallee and we split it into dune swell systems. So, dune sort of mid slope of that dune swale system and what we call the flat. So, nitrogen, no real surprises that we’ve got low organic carbon levels on our sands. so, I suppose that indicates sort of reduced mineralization potential. So, it’s going to be heavily reliant on inputs. There are some levels of nitrogen that aren’t too bad. So sort of towards the 60 to 80 kilograms of nitrogen per hectare, we just had a comment in the workshop saying that it’s some levels of sort of 20 to 30, so that’s a bit of a worry and probably needing some nitrogen inputs, hopefully with a good year this year, but on the flats are definitely some opportunities with nitrogen and with some buildup. I mean I see, I’ll get a bit high organic matter sort of 0.6%, and I’m going a little bit more mineralization, but we did identify constraints, so effectively that meant there was a big nitrogen bank because the crops weren’t using it because a lot of that nitrogen was in where the plant roots weren’t due to the constraints. Phosphorus was interesting, it’s not a bad story with P a lot of P, obviously concentrating on top soil, but, yeah, the dune mid slopes replacement P strategies I think are quite adequate and there’s a bit of a P bank there to get the crops out of the way. So, I suppose the inputs upfront are going to be key this year to get the crop out, but we should be right and nothing silly. The flats, we sort of identified some flats that are having sort of a high fixation potential. So some calcium carbonate kicking around which indicates there’s an opportunity and we’ve run down our P on some of these paddocks and definitely not all paddocks, but sort of responses last year showed that we are getting a bit of an increase in yield, which is winning in terms of gross margins on some of these flat soil. So overall not a bad story, but hopefully the guys can implement those results into fertilizer management decisions this year.
  • DREW RADFORD – You talk about PBI, phosphorus buffering fixation, what is it and how’s it going to help producers?
  • SEAN MASON – Yeah, it’s an easy test and something that does get misinterpreted, I guess, or just not interpreted in general. So, phosphorus buffering index very cheap for the lab, but essentially it just indicates the potential fixation of your soil. So, when we talk about fixation and when the fertilizer is implemented, in the soil what the chemical reactions happening to it. So, calcium carbonite is an obvious one where we’ve got calcium carbonite present it likes to fix the P source coming in and we can gauge where these parts of the paddock are with PBI. So, we’re talking anywhere from above 80, in low hundreds, in this region, that’s where we sort of indicating that we can get P responses and we’ve identified that with replicated trials and strip trials. So that’s the small window of opportunity not all parts of the paddock, but this is where variable rate and Precision Ag can come in and PBI is a one of the easy ones to sort of interpret soil test variation in your paddock in terms of P yep.
  • DREW RADFORD – Lot of this is about obviously saving money and getting an effective response and you had a graph that spelt out soil testing costs and outcomes in terms of yield and fertilizer savings. Can you just paint a bit of a picture of that? You know, when, when you see that graph, you go, Oh, that makes sense.
  • SEAN MASON – Yeah, okay, good, I’m glad I put it in. So yeah, this projects effectively putting an economic place on soil testing and the whole process of getting a soil sample. So, in terms of costs, there’s obviously some variations in soil sampling. So, I did some cost analysis based on five zones and a hundred-hectare paddock, the costs were by memory it was around the $10 to $15 per hectare. So that includes a whole labor soil analysis at the lab and profile samples, so doing simple nutrient plus constraint analysis. So that equated to probably only about 15 kilograms per Hector of grain increase in yield and, or a fertilizer saving every about 20 kilograms per hectare of either MAP, DAP or urea combined. So, it does sort of put it into perspective and we can definitely get some wins there in, I suppose, generally putting a place of soil testing pricing.
  • DREW RADFORD – It seems like a good and logical message to get out there.
  • SEAN MASON – Yes. Yeah. Like I said before growers have got a lot of other things, so they are probably relying on a soil testing service and I suppose accessibility to soil testing services being one of the barrier and the whole price of engaging someone. So it’d be good to put that in a place of economics, but yeah, we could probably benefit from more source testing services and that service actually knowing what they’re doing and ground-truthing these paddocks and knowing the soil types that the growers are dealing with is key I think.
  • DREW RADFORD – This must build into the longer-term strategy though, in terms of, we’re seeing a lot of topsoil movement as well. You know, this must be about building a bigger picture and putting paddocks in a better place to deal with dry times.
  • SEAN MASON – Absolutely, yeah, I suppose ground cover is key at the moment and I suppose the message coming out of the dry forums is that the growers have been implementing good practice and it’s just happened. So I think on the growers behalf that they’ve done nothing incorrectly, it’s just happened with, we have to deal with it now, I guess, and learning into the future, I suppose, pulses that come onto the market. So, yeah, limited stubble sort of recovery from standing stubble in the next year, so potential soil movement. So, I mean, we’re starting to generate new zones with soil movement and analyzing paddocks on soil zones is key and we might’ve shifted them, so I suppose monitoring of them is interesting. So yeah, there’s some learnings we don’t have, unfortunately, we don’t have very few because we don’t expect our paddocks for a erode or don’t want it to happen. We don’t have a lot of control, soil testing controls before the movement and after, but we’re hopefully tapping into some sort of GPS located points left from last year that we can tap into again this year and see what’s actually happened with the nutrient profile.
  • DREW RADFORD – You’re working on a massive project, you’re trying to get across a lot of information, what would be the key takeaway point that you’d really like producers to go away from all of this with?
  • SEAN MASON – A very good question. The message is soil testing is part of the whole package, if you’re ignoring it, you’re possibly ignoring an important part of a fertilizer input decision and potentially missing out on yield. So yeah, putting that in place and obviously it’s got to be a place with the whole system, but yeah, sampling strategies and looking at zonal and the best way to get the maximize or maximizing information from your sampling within a paddock and building that into a fertilizer decision would be a key message. And yeah, it’s sampling and even looking at trends past, from past years and is huge especially at the moment I’ve got eroding paddocks and things of the like, so, big advocate, obviously for soil testing, but yeah, getting that message across and obviously getting some evidence around the benefits of it is probably the key message for growers
  • DREW RADFORD – Dr. Sean Mason, thank you for joining me in the Mallee Sustainable Farming studio today.
  • SEAN MASON – No problem at all, it’s been good to be here.