Research HighlightsExploring Autonomy and Minimizing Soil Compaction at Planting
In this article, you’ll find details on:
- On-farm research trials compare planting practices like seeding rates, dates and residue management while also testing and evaluating the feasibility of using small autonomous machines for planting.
- The lightweight autonomous toolbar seeks to support soil health by minimizing compaction.
- These trials demonstrated the value of this approach to equipment and the opportunities to improve the concept to better serve farmers.
By Laura Temple
Soil compaction describes what happens when an outside force — like farm equipment — squeezes soil particles together. Compaction degrades soil health by reducing water infiltration, changing or slowing microbial processes, and making plant roots work harder to grow.
David Krog, co-founder and CEO of Salin 247, focused on avoiding soil compaction as his team envisioned a different way to do fieldwork.
“We want to replace large, heavy equipment with small, lightweight equipment,” he explains. “We’ve developed what we call a smart, autonomous toolbar with a modular approach that runs on electricity. We can attach implements for a variety of operations, with an in-field docking station to refill it.”
After developing an initial prototype and demonstrating the concept in the fall of 2021, the Iowa Soybean Association invested in on-farm research and evaluation of the concept. Krog and his team have learned more about their planter, while supporting other Iowa Soybean Association research.
“During our first year of on-farm testing, we identified where our mechanics and software needed to improve, and addressed those issues,” he says. “That allowed us to actually plant on-farm research trials in 2023.”
Dual-Purpose Trials
Krog’s team used their autonomous toolbar to plant eight on-farm soybean trials in 2023 and 2024. Their machine eased the hassle for cooperating farmers, while also providing data and experience for Krog to improve the machine.
In 2023, the autonomous planter created plots for a soybean population rate trial. It planted four repetitions of four different seeding rates: 80,000, 110,000, 140,000 and 170,000 seeds per acre. Each on-farm plot was about 32 rows wide and 150 feet long.
In 2024, the autonomous machine planted similar plots for a soybean planting date trial looking at the relationship between planting timing and carbon intensity of crop production. This research included a residue management component, as well. On-farm trials compared two soybean plantings about three weeks apart and no residue management to removing about half the corn residue before planting. Krog’s team started planting soybeans in central Iowa on April 5 and finished late plantings for the trial by May 19.
Other researchers defined some trial goals. The 2023 trial Krog helped with compared soybean populations for yield and cost efficiency. The 2024 trial focused on the relationship between management practices and carbon intensity.
But in both cases, Krog’s goal was to demonstrate and refine the capabilities of a lightweight planter.
“We demonstrated that smaller equipment could get into fields and plant early,” Krog says. “When we started early planting for the 2024 trials, no one else was in the field.”
They also proved that the machine created minimal compaction by taking penetrometer measurements up to 18 inches deep. They took 10 samples in each of four to five locations in each field they planted. Two samples in each location came from inside the vehicle tracks. The results showed no more than 20 to 30 psi (pounds per square inch) of pressure in just the top few inches of soil, well below the 300-psi point where roots can’t penetrate the compaction. When compared to areas planted by farmers using their own equipment, the lightweight planter usually caused less compaction in the top several inches of soil.
“When planting in fields that had previously compacted soils, we actually had to add weight to our unit to provide enough downforce to plant the seeds,” Krog adds. “To me, that reinforces the need to address soil compaction.”
Evaluating the Approach
Though these in-field trials, Krog and his team have identified ways to make their approach work well for more than just planting trials. While their prototype planter covers four rows, they are determining the optimal size for the platform, which is more likely to be eight or even 12 rows.
“We are aiming for a size that remains lightweight to prevent compaction, but that improves downforce and provide better economics by spreading costs and passes over more rows,” he says.
The team also learned that their batteries needed to be changed or recharged more often than anticipated. To address this challenge, they added a small generator to continuously charge the battery.
“We are monitoring energy use in the field,” Krog explains. “Based on what we’ve observed in these trials, we plan to create a diesel-electric machine that runs on B100, or 100% biodiesel. With this approach, we won’t need to keep a battery charged, and we also eliminate the need for fossil fuel.”
In addition to planting, the team has created attachments for dry application of fertilizer or cover crop seed, post-emerge liquid applications of crop protection products and a sidedress nitrogen applicator.
As he compares this approach with others, he has heard from farmers that they like the idea of “teams” of just a few autonomous machines in a field, or four or five machines working simultaneously in different fields.
Farmers then want to know how the machines will be monitored. With rapid advances in artificial intelligence, Krog expects that technology to play a key role in monitoring these machines and the data they collect to continuously improve.
“Producing commodity crops is a challenge, but we are excited about the opportunities technology and innovation are bringing,” Krog says. “The support from the soy checkoff has helped us make great progress in contributing to this innovation.”
Additional Resources:
Testing Soil Health Tests – SRIN article
Published: Sep 26, 2024
The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.
