Snapshot

Owners: Alistair and Kate Ifould
Location: Malinong, South Australia
Average annual rainfall: 400 millimetres
Soil types: rubbly red soil, clay flats, sand over clay
Soil pH: previously 4.0 to 8.0, now 5.5 to 8.0
Crops: wheat, canola, faba beans.

The pursuit of healthier, more-resilient soils is an ongoing quest for South Australian growers Alistair and Kate Ifould.

Together with their operations manager Ben Reynolds and agronomist Matt Howell from Platinum Ag Services Coorong, Alistair and Kate have put in place an ambitious soil improvement program to correct a worsening soil acidification problem.

This has involved a combination of liming and deep ripping, followed by a generous fertiliser application program, to get the most out of their newly improved soils.

“Nutrition is king,” Alistair says. “We are finding rainfall is becoming less reliable and therefore it makes sense to focus on the areas we can control, such as crop nutrition.

“A season with good rainfall can be a disguise. It is when you get a low-rainfall year that nutrition deficiencies start to show up and tell the real story.”

Correcting a potassium deficiency has been a big focus for the Ifoulds for the past eight seasons. They apply potash at seeding as well as zinc, sulfur, phosphorus and nitrogen.

Canola gets a dose of sulfate of ammonia top-dressed at the two-to-four-leaf growth stage before nitrogen is applied on wheat and canola throughout the season.

Trace elements are another big focus of the nutrition program. Copper, manganese and zinc are applied at early to mid-tillering in wheat crops, followed by manganese and copper applied at flag leaf emergence. Canola and faba bean crops receive additional applications of boron and a molybdenum-boron mix respectively.

“The more we do with soil amelioration and addressing subsoil constraints, the more gains there are to be made,” Alistair says. “Amelioration gives the soil more productive potential, which means it needs more nutrition. The more nutrients we remove through grain production, the more we have to replace.

“We cannot afford to be splashing too much applied fertiliser around given the current high prices, so it is a matter of balance – we chase yield potential as much as we can while being smart about it with the budget.”

Deep-ripping investment

The Ifoulds’ approach to soil amelioration has evolved over time – from dabbling with clay delving 25 years ago to, more recently, investing in amelioration equipment such as Plozza Plow discs fitted to two old John Shearer one-way plough frames.

“We purchased the Plozza Plow discs about seven years ago after reading an article in GroundCover™ with its developer Ben Plozza,” Alistair recalls.

“I actually ended up ringing Ben to find out more information, which was very helpful. We are finding the ground we have treated with Plozza ploughing has had lasting results. Areas we treated six years ago are still showing benefits, particularly improved soil moisture holding capacity and crop germination.

“Our aim with the Plozza ploughing is to bury non-wetting soil and weed seeds, break up the hardpan and incorporate lime below the soil surface. We still use the Plozza Plow when we cannot get clay close to the soil surface.”

But it was the purchase of a Bednar Terraland deep ripper two years ago that has Alistair the most excited about soil improvement. He was instantly sold on the ripper after witnessing it in action at a local demonstration day. “I ordered one that same day,” he says.

“It is a perfect fit for our soil types. Where there is clay within 400 millimetres of the soil surface we will use the Bednar ripper, which pulls subsurface clay up into the topsoil and mixes it with a spiky roller in one pass.

“It also busts up the hardpan at 180 to 220mm below the soil surface, mixes the phosphorus-rich topsoil with the subsoil and helps us incorporate lime.”

Taming acidity

Tied to the Ifoulds’ focus on nutrition are their efforts to address subsurface soilacidity.

About one-quarter of the farm is sown to faba beans every year and, about five years ago, Alistair noticed those crops were starting to struggle, particularly on sandier soil types.

“Something was clearly wrong, and it turned out the problem was subsoil acidity,” he says. “Acidification is a by-product of pushing the crop rotation harder with more nutrition and trying to achieve better yields. It became a real issue for us in the top 20 centimetres of the soil.”

To examine the extent of the problem, the Ifoulds and Matt have mapped the whole property using a Veris pH mapping machine and examined acidity deep in the soil at selected sites.

That approach has enabled them to spread lime at variable rates across the property – ranging from one to nine tonnes per hectare, depending on the acidity of different soil types.

We are turning our B-grade soils into A-grade soils through our liming and amelioration program.

Soil pH ranged from 4 to 7.8 on the soil surface, which correlated strongly with the subsurface soil layer to a depth of 20cm. With pH mapping and applying lime that is incorporated with tillage, they are now targeting a soil pH of 6.0.

“We are seeing dramatic improvements in our faba bean crops after liming and deep ripping. I estimate that we have seen a 40 per cent increase in faba bean yields since we started addressing subsurface soil acidity.

“Faba bean roots are going deeper into the soil profile, they are nodulating well and fixing more nitrogen, and grain yields have also improved significantly. These benefits are making us re-evaluate how much farm area we sow to faba beans.

“I have always described our rubbly red soils as our ‘A-grade’ soil type and our sandier soils as ‘B grade’. The red soils are where we have mostly sown our faba bean crops, and in sandier areas our legume options were limited to lupins because the faba beans did not perform.

“However, we are now finding that by applying lime and incorporating clay into the topsoil, we can grow faba beans in those sandy areas where we previously could not. In fact, faba beans are now performing better in some of those treated sandy areas than on the red soils.

“That is because we are turning our B-grade soils into A-grade soils through our liming and amelioration program.”

Farm business bottom line

The Ifoulds’ investment in soil improvement over the years has been considerable. The whole farm area was pH-mapped at a cost of $16/ha, and liming costs varied from $50/ha to $450/ha, depending on the application rate.

The cost of deep ripping includes machinery, fuel and time, which together cost up to $150/ha at contract rates, he says.

However, Alistair says those costs pay off once soils start performing at their full potential.

Plus, it has become a real passion for the Ifoulds.

“We really like mucking about with our soils to improve our farm business bottom line. There are benefits there to be had, otherwise we would not be doing it. The price of land is only increasing, so we want to make sure the land we do have is performing at its best.

“We pay council rates on every hectare we own, so we have to make every hectare count. Nutrition, liming and amelioration are the main drivers in making the whole system work for us.”

More information: Alistair Ifould, magicdirtfarming@gmail.com; Matt Howell, 0458 277 546, mhowell@platinumops.com.au