Tillage has its benefits, but the list of drawbacks to soil health is long.
This poses a question: Like Integrated Pest Management, is it time for Integrated Tillage Management?
The question was posed by Aaron Breimer, manager for Veritas Farm Management, during a presentation at Elgin Compaction Day on Aug. 8. For him, taking an integrated approach to compaction means understanding bulk density, and thinking critically about tillage activities.
Why it matters: Tillage use has been growing and the tools have become more aggressive, creating concern with soil health.
Bulk density and soil movement
According to Breimer, maintaining lighter (less) bulk density — how porous and permeable the soil is — is critical in compaction prevention. Pore size scales from macropores of over 75 microns (1 micron = 1/1000th of a millimeter), to cryptopores of less than .1 microns.
Breimer says increases in bulk density result from two sources. The first is “brittle or loosening” action from the upward movement of soil caused by equipment like cultivators, chisel ploughs, and rippers; this primarily reduces the number of larger pores.
The second is “compressive,” caused by the downwards and sideways movement of soil; this is often a result of discs, moldboard ploughs, and coulters. Like the impact of wheels, compression from these sources reduces both macro and micro pores.
“They’re technically called failures because the soil structure is failing,” he says.
But tillage does have its uses when it comes to residue management, fertilizer and pesticide incorporation, seed bed preparation, and ground levelling. However, Breimer says those employing tillage for these purposes need to understand the risks and adapt their management plan.
In particular, he says failing to use tillage tools properly or accurately, using them in less-than-ideal conditions (e.g. during a wet spring) and without additional amendments (such as cover crops), invariably increases soil bulk density.
“You are destroying the pore space in the soil, and about 50 per cent of soil is made of pore space either air or water,” says Breimer. “If that’s destroyed it becomes more compacted.”
He also highlights the compaction potential of coulters and discs, which cause compression by moving soil sideways. The amount of compression in such cases, however, is impacted by many factors like soil moisture and type, the angle and design of the tool, the number of passes, and speed.
“If you’re discing in the spring, that’s instant compaction,” he says. “There’s not always a better solution to dry things out, but don’t lie to yourself and say you’re not compacting the soil.”
Overall, he reiterates vertical tillage also ultimately reduces porosity and increases bulk density, primarily by destroying the larger pore types. He encourages producers to use it sparingly.
Quantifying compaction-related loss
“I tell people 2019 was a great year for studying soil compaction because of the wet and challenging planting conditions,” says Breimer, the statement referring to a study he and his Veritas colleagues are conducting to measure compaction using bulk density data.
This internal study focused on similar soil types – in same field with different amounts of potential compaction – that had been worked with tillage equipment. The number of equipment passes were also changed and accounted for.
Currently, he says 15 to 20 per cent increases in bulk density have been found at nine different sites with different soil types – each where vertical tillage equipment had made two passes this past spring. Further analysis and comparison with other field data, he says, should help determine the exact economic impact that compaction caused.
Breimer says his company is also working on quantifying the economic loss of compaction on a large scale, not just small plot research. This includes quantifying the damage of tire compaction by using GIS (geographical and spatial data analysis) software to overlay bulk density data with applied planting and productivity data (yield), as well as productivity zones within the field.
The idea is to provide farmers with data that can help inform their business decision, such as whether they should consider tracks, ultra-wide tires, and so on.
“We’re able to generate the economic loss in the areas that are being compacted […] looking at not just loss within an operation, but also the difference in operations with different equipment configurations,” says Breimer.
This project is still in its infancy. Despite currently working with 75 different farm operations, Breimer says the data still needs to be amalgamated before any statistically significant conclusions can be drawn.