Sugar and density is up with soil restoration

October 1, 2022
"WE HAD to do something. We were going backwards. We were putting more and more fertiliser on, working harder and not going anywhere- getting bigger tractors, bigger implements, spending a lot of money"

It was a switching point over a decade ago for Allan McLean and son Scott, who, with three generations of their family, farm a beautiful 526 hectare property alongside Jolimont Creek north of Kuttabul. They crop 200ha of cane and run 100 head of cattle. The farm has been in McLean family stewardship for 90 years.

"We had always used a green manure cover crop, right back from my Dad's day - poona peas, lablab bean and what have you. Our fallow, we have always looked after as best we could."

The growers were battling marked yield decline, and pest and disease pressures. A far cry from the past.

The growers first worked with agronomist Phil Jones to address soil health. Early ideas trialled on the farm, following an information session at CANEGROWERS Mackay, also included use of micronutrient-rich chicken manure. Reef Catchments assisted with the conversion of a belt spreader to a three row delivery system to put a B-Double truckload of the manure onto rows.

"That implement has proved beneficial for everything we've done down the track," Allan said. "We got some really good results with chicken manure, but freight eventually put the kibosh on that."

There were also some consistency issues with the fresh manure, but there was still a 10 tonne to the hectare yield response.

"We thought: there's something in these micronutrients."

Productivity trials with MAPS on-farm showed that while there were good results for plant cane and early ratoons, there was a decline by the third ratoon.

Over the years as soil health developed on farm, friend and agronomist Alan Royal has been an invaluable sounding board for ideas and a great source of knowledge on nutrients and soil health.

Moving forward, Scott McLean was developing an aerial spraying business. Still in the process of gaining his own licence, Scott hired a New Zealand pilot. The pair were yarning in the shed one day after wash up,

"Scotty was talking about what we were trying to do here with soil, and the pilot said, 'you gotta meet a mate of mine- Corey, a Kiwi agronomist - he's really into this.' ''

Although the agronomist had not worked with sugarcane previously, he was keen to hear results from soil testing.

"After he heard the first four results, he rattled off all the rest. Nobody's ever done that in my experience," Allan said.

Impressed, they flew Corey Martin over and took him on a tour of the farm,

"As we're driving along, he's saying 'that's lacking phosphorus', and 'there's aluminium toxicity here'. It was the first I'd heard of aluminium toxicity. He obviously knew what he was talking about."

New Zealand has much tighter environmental laws than had been experienced here, with producers accountable for all inputs. Corey had also watched Salisbury Plains cattle producers put more and more nitrogen to pastures and get less and less results.

"He knew what we were up against. You sat up and paid attention to everything he said."

It was through these discussions that Allan and Scott came to a clear understanding.

"He said the soil here was virtually dead. It had very little life in it."

They brought Corey back for another visit, accurately measuring microbial life.Microbial life was indicated at levels around 1/6 of that of healthy soil. His instruments also revealed the level of aluminium toxicity (occurring where aluminium is present in strongly acidic soils, which pH an excess use of nitrogen can trigger). When activated in acidic soil, aluminium is able to bind up important elements such as sulphur, magnesium and calcium. It manifests in poor root development.

Without first addressing the mineral balance in-soil, you could not generate the kind of soil life - like nitrogen fixing microbes, etc - that would help build healthy soil structures and make a crop thrive.

"We've had a few conversations with microbiologists, that with the microbes, you are wasting your time putting a microbial product on the soil if you haven't done anything to give those microbes a place to live," Allan said.

Soil amendments began, addressing pH and starting with micronutrients, which the agronomist supplied from his New Zealand firm, iFert.

"He initially told us there would be a drop in productivity. 'From putting this on, you won't see anything for 12 months.' Which is exactly what happened. Holy hell, it was fairly expensive."

A soil amendment blend of micronutrients, fertiliser and biostimulants was especially crafted for the McLean farm, and they imported four tonne. Initially, a small amount of micronutrient was applied each year for five years, gradually ramping up area and application rate to 1T/ha to restore optimum trace element levels. It is important not to hit the soil with too much too fast.

"Our microbial count had been so low, that if you had just given it one big boost, it would be like one of those high-energy drinks - it would just send the system into shock."

Father and son worked through some early issues with the consistency of the micronutrient pellet - initially too soft for their spreading implement - and were able to get a consistent spread. More recently, they've been getting the blend in powder form.

"But you could actually see a result the second year, and from there on, the rest is history!" Allan said.

The result was a more dense, heavier cane, with over a 10 per cent yield gain.

"It was heavier, although looked the same, and the sugar content was up, too," he said. "Then, what we found as it got to older ratoons, there was a marked difference between what was treated and the control strip. It's held in there longer. You get your plant cane, and then it tapers off on the third and fourth ratoon. Well, this didn't do that. The angle of decline was significantly less."

This year, those first blocks to be treated have gone through their first full crop cycle, with fresh plant cane now showing. Some of those blocks ran for seven ratoons. And this year, also, paddocks are averaging over 95,000 TPH.

The learning curve of that cycle has taught lessons about critical placement of micronutrients, and the McLeans are confident that they have the system ironed out. With the whole farm now treated, the growers plan to extend the number of ratoons.

Allan and Scott have been pleased to observe changes beyond their cane quality.

"One thing, now that we've done the whole farm, is the soil's water-holding capacity. It is at least one full watering over the whole farm less. When we irrigate, the water doesn't beat the irrigator out of the row anymore.Or puddle."

That's come about with the redevelopment of good, spongy humus structure in the soil. In some soil types on the farm, colour is deepening.

"It's easier to work, less tillage" Allan said."The biggest tractor we have here, we have knocked off 100 hours a year. That's not just a fuel saving, that's a full oil change over a few years, also."

All implements are designed to not turn the soil over.

"When we got to optimum trace element levels, we cut back on nitrogen. It's back to about 130 units, or sometimes less than that. We use a quarter less nitrogen."

Weeds are now substantially fewer on farm, although vine and some pest grasses are still present, so only very selective spraying occurs.

Another sign of restored soil health and beneficial microbial activity is the pH, now mostly above 6 farmwide. Ultrafine lime assists with calcium. Biodunder is N source, at times blended with sulphate to address sulphur levels. Allan has noted this second cycle, soil has required only a small portion of the iFert blend.

"It's taken very little to get the soil back up to speed. To the point where sometimes you don't put any. You keep an eye on it in the fallow, but it just doesn't deplete that much. But In the 90 years that we - the McLeans - have been here, we haven't replaced that stuff before. We've replaced all the other bits, but not the micronutrients."

Allan said the family had always been unafraid to try new ideas.

"We're always one of the first to do most things. We were one of the first to go mechanical harvesting in this area, we were one of the first to go green cane harvesting; we introduced shielded sprayers to the district, and probably we are the first to do this sort of thing."

Allan McLean is keen to see more money directed to growers to take on projects like this, that have benefits for soil health as well as run-off water quality.

"We need to see money on the ground, going to growers."

The family business has ultimately invested $250,000 in these soil health projects, and engaged with extensive trialling, without receiving incentives or major grants. It was achieved purely from the persective of wanting to make  the McLean property healthy and profitable for generations going forward.

"With smarter farming, this will have benefits for many years. And we are already making a lot of that investment back."

Allan's thankful for strong agronomy support.

"But it's pretty strict: you've got to stick with it and do everything right. It's a balance.People say you can just Google it, but there's 16 or 17 elements needed for healthy plant growth. There's five - the N-P-K, and sulphur and calcium - that are the ones farmers do use. So you've got 11 or 12 micronutrients that you've got to get right. Good luck with that! Mr Google's not going to to tell you that! The thing with soil health, you need good help and proper advice."

Story by Kirili Lamb, The Billet, CANEGROWERS Mackay, October 2022. Reproduced here with permission.


  • The McLean family recognized a problem with their farming methods a decade ago: Despite increasing fertilizer use and investment in larger equipment, their yields were not improving. This prompted a switch to more sustainable and health-focused practices on their 526-hectare property.
  • They experimented with green manure cover crops and nutrient-rich chicken manure to address soil health. However, they found challenges with consistency and cost. They also observed an initial yield response to micronutrient input, suggesting their soil was deficient in these vital elements.
  • They collaborated with New Zealand agronomist Corey Martin, who helped them understand their soil was virtually dead due to a lack of microbial life and presence of aluminum toxicity. They started soil amendments to adjust pH and add micronutrients to their soil.
  • The results of their amended farming practice didn't appear until the second year, but then they saw a marked increase in the density of their cane and a 10% increase in yield, along with improved sugar content. Notably, the yield decline in older ratoons was significantly less.
  • Beyond improved yield, they observed benefits such as increased water-holding capacity in their soil, easier workability, less tillage needed, reduced nitrogen use, and fewer weeds. They also noted improved soil color and structure, indicating a healthier ecosystem.
  • The McLean family spent $250,000 on these soil health projects, with no major grants or incentives. The changes were made from a desire to make their property healthier and more profitable for future generations. They believe more funding should be directed to growers for similar projects, emphasizing the importance of expert advice for soil health.