Victorian farmer John Dowling: ‘Cross Slot struck a chord with me’

A 12-metre Cross Slot with 36 openers on a 333 m spacing, a system that is owned by John Downling’s friend Alan Wragge. Cross Slot mimics nature, Dowling says. “In one pass, it puts the seeds underneath the residue or dry or green material.” – Photo: John Dowling

Fourth-generation farmer John Dowling in Victoria, Australia, has a deep-rooted commitment to enhancing soil health. Using the Cross Slot system, Dowling minimises soil disturbance and optimises seed planting, resulting in significant improvements in soil moisture retention and crop germination.

Dowling is a certified organic no-till farmer in two different locations in Victoria. He grows barley, oats, rye, sorghum, sunflowers, and hempseed on 1,500 hectares. To minimise soil compaction, he utilises a John Deere rubber track tractor.

He first became intrigued by organic farming as a young man. “When I was a young chap of 18 or 19, riding the tractor planting some seed, I was contemplating ‘if I was a seed, would I like to be placed in the soil as it is?’. So, I set out on a path of discovery, trying to create the ultimate conditions for planting seed.”

After extensive research, Dowling adopted methods that emphasised minimal soil disruption. “I was initially aerating the soil, which is not necessarily advisable, but the machine I was using created very little disturbance. I was always planting in a blanket of residue or armor. It was very difficult to tell that you had actually planted the paddock. That was already very similar to what Dr John Baker and Cross Slot are doing.“

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John Dowling is a fourth-generation farmer in Victoria, Australia. Photo: John Dowling

Planting accuracy

“When I first heard of Cross Slot, many years ago, it struck a chord with me. Reading and studying all the information and the peer reviewed research, my conclusion was that there was nothing else available anywhere that addressed all the issues that farmers deal with on a daily basis. Although there currently is a French copy of the system.”

Cross Slot mimics nature, Dowling says. “In one pass, it puts the seeds underneath the residue or dry or green material. When the next rain comes, the seed is sitting in an almost perfect situation. The Cross Slot places it 25 to 30 millimetre under the surface. The planting accuracy is second to none. It has the ability to plant over undulated terrain, and always plant the seed at exactly the same depth.”

Key points

Adoption of Cross Slot: John Dowling adopted the Cross Slot system after extensive research, finding it uniquely effective in addressing common farming issues. He appreciates its ability to mimic natural processes and its planting accuracy.
Benefits of Cross Slot system: The system plants seeds at a depth of 25 to 30 millimetres under the surface, providing ideal conditions for germination and allowing for planting on undulating terrain.
Efficiency and soil health: The Cross Slot system reduces the number of passes needed, cutting emissions and diesel use, while promoting improved soil friability and carbon levels over time.
Enhanced soil conditions: The system protects soil by planting under a residue blanket, which helps maintain cooler soil temperatures and improves water retention.
High germination rates: Dowling reports close to 80% germination rates due to the optimal soil humidity maintained by the residue blanket, even in dry conditions.

Less emissions and diesel use

Because the Cross Slot system reduces the number of passes required, it cuts emissions and diesel use while allowing for the use of smaller tractors. Over time, as the soil’s bulk density is reduced and carbon levels increase, the soil becomes more friable.

“Initially, when you first use a Cross Slot system, you’re punching into hard soil, and you might need more horsepower. But once you break that bulk density, and lift the carbon in the soil, the soil become a lot more friable, like chocolate cake”, Dowling says.

The system’s ability to plant under a residue blanket offers significant advantages, because the soil is protected. “On a hot summer’s day, when it’s 45 degrees Celsius, the soil underneath the residue, can stay lower, at 30 degrees Celsius or even less. And there’s an enormous retention of water. Once you’ve got the system going, the infiltration rates from precipitation are just extraordinary.”

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Wheat drilled into soybean stubble with 9m Cross Slot drill (310mm (12") row-spacing) in Victoria. – Photo: Cross Slot — Wheat drilled into soybean stubble with 9m Cross Slot drill (310mm (12″) row-spacing) in Victoria. – Photo: Cross Slot

Close to 80% germination

“Probably, as a farmer, I think the most critical thing from the Cross Slot research is that the soil humidity under that blanket of residue is always optimal, even if it appears to be dry. Because of that vapour in the soil, you can always get close to 80% germination. As soon a farmer cultivates the soil, the humidity in the soil starts evaporating. Then you’re relying on external rain or irrigation to germinate the seed.”

“As a long term organic farmer, the ability to plant my seed into dry soil, and get a germination before rain germinates the weeds, is an enormous benefit. It has a lot of value for a farmer. And in water logged soil, where it is too wet, Cross Slot actually creates a zone around the seed, where it has been planted which is less saturated. So, it also enhances the germination in overly wet conditions.”

Dowling also points to improved weed control as a benefit. He notes a conventional farmer who adopted the Cross Slot system saw remarkable weed control “As he was harvesting his cash crop, he would run behind the contract harvester, and plant his cover crop three minutes after the harvester. He was getting a phenomenal weed control, and was able to virtually stop his use of glyphosate. But unfortunately, this is not widely known.”

A long-term investment

Dowling explains that the upfront price of the Cross Slot system might seem relatively high, but argues that the Cross Slot system is a long-term investment. “You have to take into consideration that it can last for twenty to almost thirty years, if you look after it. That’s a generation. If you spread the costs over thirty years, it becomes cheap. And through concentrating on soil health, farmers can save on synthetic and organic fertilisers, herbicides, insecticides…”

Dowling has seen dramatic improvements in soil health. “The highest reading I’ve heard of is 7% organic carbon right down to 1.5 metres deep. And when that farm started with this system, it was maybe 1.5%. But it took over 20 years.“

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To minimise soil compaction, John utilises a John Deere rubber track tractor. – Photo: John Dowling

Highly uniform germination

Dowling says he uses the Cross Slot system for all his crops. “It sort of self regulates with its automatic downforce, whatever the soil conditions are. You don’t have to set it up each time, when you go to a new location. That saves a lot of of time. And it has the ability to plant into an enormous amount of residue as well.”

“I consistently observe highly uniform germination, and some farmers have reported needing to lower their seed planting rates due to excessively high germination rates, resulting in too many plants per square meter.”

In addition to its agricultural benefits, Dowling emphasises the system’s environmental advantages. “With increasing pressure to manage emissions, the Cross Slot system’s efficiency in reducing fuel usage and soil compaction will become increasingly valuable.”

The power of soil microbes and water vapour

Dr. C John Baker in New Zealand, the inventor of the Cross Slot system, highlights the significant benefits of harnessing soil water vapour. He explains that many people fail to recognise that soil aeration not only releases water vapour from pore spaces into the atmosphere but also disrupts the habitat for the 6 billion soil microbes present in every cup of healthy, undisturbed topsoil.

These microbes produce binding substances that help aggregate soil particles. “At the same time, repeat tillage of arable soils also oxidises the carbon content of soil organic matter (SOM) into CO₂ which is discharged into the atmosphere and accounts for 20% of the total CO₂ in that atmosphere at any one time”, Dr Baker says.

Dr. Baker points out that advancements in low-disturbance no-tillage tools have provided new opportunities. In the 1980s, researchers began developing no-tillage openers that created inverted-T-shaped seed slots, limiting physical disruption to a sub-surface layer while preserving a minimally disturbed surface mulch of dead or dying vegetation.

Advancements in low-disturbance no-tillage tools have provided new opportunities. – Photo: Cross Slot

“This approach maintains the soil’s water vapour in the pore spaces where newly sown seeds are placed, mimicking conditions as if the soil had never been disturbed,” Dr. Baker says. This retained water vapour not only supports seed germination and seedling growth but also energises soil microbes and minimises the oxidation of SOM. Once seeds germinate, their roots rely on natural root exploration of the untilled soil to access nutrients and water, extending beyond the seeded rows.

A diverse array of beneficial soil microbes, including bacteria, protozoa, fungi, and viruses, thrive and interact in this high-humidity rhizosphere, contributing to the regenerative capacity of undisturbed soils, along with macro-soil fauna like earthworms, nematodes and insects.

A 14-metre tool bar with the Cross Slot system. Photo: Cross Slot

Dr. Baker also notes that understanding the role of water vapour in soils opens the possibility of introducing specially bred or selected microbes that act as predators of soil pathogens and pests, similar to how medical antibiotics combat animal diseases. Additionally, some microbes can release nutrients from soil minerals, potentially reducing the need for synthetic fertilizers and pesticides.

He emphasises that a new generation of seed drills designed for low-disturbance no-tillage, which preserve rather than disrupt the soil’s rhizosphere, will enable farmers to maximise the benefits of soil water vapour and microbial activity.