Thursday, March 28, 2024

Not your average farmers

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Accurate information is very important for Emlyn and Hilary Francis, especially when it comes to getting the best value from their fertiliser spend. They told Anne Lee electromagnetic mapping and variable rate fertiliser application are making a noticeable difference on their farm.
Reading Time: 8 minutes

Culverden dairy farmers Emlyn and Hilary Francis aren’t about averages.

They want more than average performance out of their dairying business and know to get that they can’t rely on averaged information.

“Averages are misleading,” Emlyn says.

“In most cases they just don’t give you the information you need to make the best decisions.”

With fertiliser one of the big three items when it comes to farm working expenses, it makes sense to be as accurate as you can with what you’re putting on where, Emlyn says.

“Putting on half a tonne of fert where you only need 100kg or where it actually needs twice that amount is one, wasting money, and two, not really the right thing when it comes to the environmental side of things,” he says.

But that’s exactly what had been happening at Kenmare Dairies. It’s not that they weren’t using good practice – they were carrying out a standard soil testing and fertiliser regime – but they really didn’t know how variable their soils were in terms of characteristics and fertility status.

Emlyn and Hilary have been farming Kenmare for 17 years and over time have added to it, buying adjoining land so it now totals 630ha, with 450ha of that milking platform. The remaining 180ha is used as support land and during winter is home to their 1530 cows.

The milking platform area remains reasonably consistent although boundaries can be flexible depending on winter cropping rotations and pasture renewal.

Two years ago they bought a second farm of 160ha milking 600 cows. It’s run by contract milker Kane McCarthy, who previously worked with Emlyn and Hilary on the home farm for 10 years in two stints.

Emlyn says over the years on Kenmare it became obvious pasture production varied across some paddocks more than others. While he knew there was some difference in soil types and characteristics it wasn’t until he had the farm electromagnetically (EM) mapped that he realised the full extent of the variability.

“I knew the soils were probably more variable than we thought so I was interested in EM mapping and when I thought about getting it done two years ago it came down to looking at the budget.

“It was about the same price as DNA-testing the herd and I just thought that for us, given what we suspected about the different soil types, we’d get a better return from EM mapping.

“We’re not getting down to the fine detail when it comes to breeding, we’re not train-spotters when it comes to that and really I’m happy with the gains we get from using LIC bulls. They’ve got the experts making sure we’re getting the genetic gain but I thought we really needed to be a lot more accurate with fertiliser inputs.”

“We want to save money and be spending wisely but we also want to stay ahead of the game when it comes to the regulators too.”

Agri Optics did the EM mapping, which involves towing an EM machine up and down the paddock in a GPS’d linked grid.

The machine emits electromagnetic signals down into the soil, recording how far they travel.

Measurements are taken five times every second to give readings at two depths for each of the measures.

The electro-magnetic signal data is an indicator of soil conductivity, which in turn gives an indication of other soil characteristics. Elevations can also be measured during the mapping process so a 3-D image can be produced too, helpful if slope and aspect are important. While at first glance Kenmare may seem flat, there’s actually a fairly significant fall of 40m from the top of the farm to the south-eastern end, as well as undulations.

Based on the results of the EM survey Agri Optics produced a range of maps for 0-50cm and 50-125cm depths. The continuous survey results reveal where the soil characteristics change and based on that information defined soil zones can be mapped.

“I was surprised at just how variable the farm is – there are seams of different soils running right through the place.”

There are seven clear zones but they’re not all bundled together in discrete, separate areas of the farm. Instead they form what looks almost like a patchwork and even within one paddock there can be multiple zones.

Emlyn says the next step was for Ravensdown to use the zone map to create a detailed soil sampling regime. Ravensdown senior agri manager Sonya Perkin says she pin-pointed the sites where grid soil sampling should be taken based on the zone map and then used GPS technology to accurately locate the sites on the farm.

“It was a bit like orienteering – going out there with your GPS, finding the right spot and then doing a circle around that point to take the samples,” she says.

In total there were about 315 sites, each with about 20 core samples taken. Soil test results showed soil fertility was just as variable as the soil types that had been based on the EM mapping.

“A lot of Kenmare’s paddocks are quite long and there were some big differences right along the paddocks. The nutrient transfer from front to back of paddocks was also highlighted,” Sonya says.

That’s where the danger of using averages becomes apparent, even if it’s off a large number of samples.

“The average Olsen P for the farm was 34 but we had some tests that were at 11 and some that were up in the 50s in pretty close proximity,” she says.

At an average Olsen P of 34 the farm would typically receive about 450kg/ha of superphosphate but if that goes on at a blanket rate the areas testing at an Olsen P of 11 are starved of phosphate while the fertiliser is wasted on areas at an OP in the early 50s.

“There were 180ha below the target optimum Olsen P range of 30-35, 150ha in the optimum range and 129ha above that.”

For the very low testing areas Sonya recommended putting superphosphate on at a capital dressing rate, so 14.5ha received 1 tonne/ha, 13.9ha received 900kg/ha and another 47.6ha received 780kg/ha.

The high-testing areas received a very low rate – just enough to get the necessary amount of sulphur on. It was well below maintenance in terms of phosphate, allowing that to be mined from the soil’s own stores.

Sonya says she has other clients who have been mining soil phosphate for five years from paddocks with Olsen P levels in the 50s and they were still sitting at above optimum levels.

“It can take a long time for those numbers to come down,” she says.

For Kenmare there were 94.2ha with high enough Olsen P levels to receive just 200kg/ha of superphosphate with 90.9ha receiving 350kg/ha. With the targeted application rates having such a wide range the overall average rate of superphosphate across the whole farm was only slightly down on previous years, at 429kg/ha.

“So even though it was being targeted to where it was needed there wasn’t a big saving to be made in that first year in the total amount used. As time goes on and the range in fertility becomes less then you will see savings,” she says.

Both Sonya and Emlyn point out that while there will be savings over time, the biggest benefit in the first year is likely to be in productivity gains from pasture.

“You get areas within a paddock that just aren’t performing – they just don’t grow like other areas. It could be because of a few things but fertility is definitely a big one,” Emlyn says.

Kenmare farm manager Emma Gibb says pasture walk records show there was about an extra tonne of drymatter (DM) grown in 2015-16 season following the variable rate fertiliser applications. While you can’t say that’s all down to the new fertiliser approach in paddocks that had a higher proportion of low Olsen P level soils, the increase in drymatter production was definitely noticeable and covers were more even.

As well as using the technology to manage variability in phosphate levels, Emlyn has tested pH levels on the farm using the same sampling regime. Those results also came back as highly variable.

Sonya says while the average pH was 5.9 and sitting within the optimum range of 5.8 to 6, the range across the farm was from 5.4 to 6.4.

Most of the farm sat within the optimum range with 85ha at a pH of 5.8 and 86ha at 5.9. Only about 10ha were at 5.4 and 5.5 but 90ha had a pH higher than 6.

“Most of the cost of lime is in the cartage and spreading so getting more accurate levels can mean a big saving,” she says.

The results following the first use of variable rate superphosphate showed the capital dressings for the low Olsen P level zones starting to rise quickly.

“The 11s shot up to the mid-20s so the range across the farm has pretty quickly begun to narrow,” Sonya says.

She selected fewer testing sites from within each zone, making sure the high, medium and low fertility areas were covered, so the fertility changes could be monitored closely without having to do the grid sampling every year.

“We’ll go back and grid sample two or three seasons down the track to get a really good look at where the farm is at but in between times we’ll base the recommendation on those monitor sites,” she says.

The high Olsen P areas will continue to receive low rates this season and a much larger proportion of the farm will receive maintenance so the overall tonnage of superphosphate will be down further this season.

Emlyn says it’s hard to totally quantify the financial benefit of the approach but ongoing fertiliser savings coupled with increased drymatter production mean a lift in productivity.

Kenmare has been able to dramatically drop its grain inputs without dropping milk production.

“We were up to close to a tonne of supplement per cow there for a while but we’ve had a refocus on pasture management and that together with the fact we’ve grown and eaten more grass has allowed us to get costs down without losing production.

“It’s meant we’re more efficient at producing milk.”

Same paddock, different rates

Because the variability in soil fertility on Kenmare can be huge even within a paddock, getting the fertiliser on at the rates needed might seem to be tricky.

But variable rate fertiliser spreading is becoming more common and thanks to accurate GPS technology with TracMap and the ability of the TracMap system to ‘talk’ to the rate controller on the truck all the driver has to do is input the right information and drive up and down the paddock as normal.

In one of Kenmare’s paddocks there are six different soil zones, each with different fertility levels and requiring a different rate of superphosphate.

“It’s pretty clever technology really – to be able to go from a rate of 200kg/ha and then increase it to 450kg/ha or even more seamlessly while the truck is driving up the paddock,” Emlyn says.

The TracMap system knows exactly where the truck is thanks to the GPS technology and with the zone maps loaded into the system along with the farm map the system knows when the truck is crossing from one zone to another and adjusts the fertiliser rates accordingly.

Peter Jones from Amuri Transport says the zone map is simply overlaid on the farm map. The zone map includes information on which rates correspond with which zones so when the driver switches the onboard TracMap system to variable rate the technology is set to go.

“We don’t have to make any changes to the truck because it’s all based on the software. We can upload the maps or the fertiliser company does it,” Peter says.

He says an increasing number of farmers are using variable rate fertiliser spreading technology because it makes sense economically and environmentally.

“We’re doing it a lot more for urea now for that reason too – so we can avoid areas where effluent’s been spread,’ he says.

It’s particularly useful if effluent is spread using a pivot irrigator, either through the irrigation system or underslung along the pivot. That’s because it might only be along a portion of the pivot length which means parts of paddocks don’t receive any effluent.

A rough reckoning on savings and benefits of variable rate fertiliser application.

Superphosphate pre variable rate 205t
• Cost @$316/t = $64,780

Year one superphosphate use 195t
• Cost @$316/t = $61,620

Year two superphosphate use 165t
• Cost = $52,140

Fertiliser savings $15,800
Additional pasture production year one extra 1 t @80% utilisation @12kg DM/kg MS and $5/kg MS = $152,000

Farm facts
Owners: Emlyn and Hilary Francis
Total area: 630ha
Milking platform: 456ha
Cows: 1500 Friesian and Jersey-cross
Supplement: 470kg DM/cow mostly wheat
Production: 700,000kg MS, 466kg MS/cow, 1535kg MS/ha
Farm working expenses: $3.73/kg MS
Staff: Eight full-time and two calf rearers
Farm dairy: 80-bail rotary
Automation: Cup removers, Protrack, EZ Heat camera

 

 

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