Compaction crisis: The unseen battle farmers face everyday

Soil becomes compacted when soil particles are compressed together, reducing porosity and increasing density. 

There are a couple of key contributors to this issue that happen on-farm, O’Neil explained. Compaction is often worsened in farm fields when heavy equipment is used on wet soils — the water acts as a lubricant, allowing particles to slide and collapse under pressure.

Small tire contact area and elevated tire pressure are also contributors to increased compaction, O’Neil continued. Farm equipment can be heavy, and small tire footprints combined with high tire pressures concentrate the weight on less surface area, leading to greater soil compression. With lower tire pressure and larger tire contact area, the weight can be distributed over a greater area, reducing the load per square inch.

The best way to mitigate compaction, as far as we know, is to prevent it by identifying the root of the problem and avoiding these practices, O’Neil said.

“The extent of compaction in New York agricultural fields is not well known,” O’Neil said. “What we do know is that compaction affects the ability of plants to penetrate the soil volume to find the nutrients and water that they need, and at that point they become less drought resistant. This is really crucial when it comes to maintaining climate resilience on our farms– the more that our farms can adapt to extreme weather conditions, the better.”

Other consequences of compaction include impeded water infiltration, drainage, and gas exchange, O’Neil stated. This can lead to increased runoff and surface flooding following heavy rains– both of which can lower crop yields, increase the amount of energy needed to till a given field and contribute to soil and nutrient losses.

“Soil compaction is a form of soil degradation that is difficult for farms to detect and evaluate, mainly because it is difficult to observe from above the soil surface,” said O’Neil. “That’s where the research comes in.”

Soon after beginning her research, O’Neil found that most soil sampling protocols do not fully account for variability in a field. In other words, they don’t illustrate the differences in compaction severity within a given farm field. She noticed that there was considerable within-field variability, due to soil type diversity and equipment travel paths, that needed to be taken into account. 

O’Neil partnered with the Cornell Nutrient Management Spear Program (NMSP), working closely with Manuel Marcaida, NMSP Data Analyst, and more recently, Issa Diaz, PhD student, to address this issue. 

“We amended the sampling protocol with Kitty,” Marcaida said. “We identified where to take the compaction readings then took measurements across the fields to see if our refined methods would illustrate the compaction throughout a field more accurately,” said Marcaida.

The researchers’ current work includes sampling of yield stability zones for seven farms across New York. The project, co-funded by Northern New York Agriculture Development Program and New York Farm Viability Institute, resulted in over 8000 penetrometer compaction readings (left photo below) collected over two sampling periods. The sampling protocol allows O’Neil and the team to evaluate the relationship between compaction severity and corn silage and grain yield. 

"A preliminary study conducted during 2021 on northern New York farms revealed a relationship not previously understood between soil compaction and historical crop yield,” said O’Neil. “This study suggested more severe compaction in the lower yielding zones within the fields. This resulted in expansion of the project to now include seven farms and 21 fields across New York State.” 

Issa Diaz is working on processing the data collected at the seven farms. She reported that analysis is still ongoing, and more results are expected to be ready for reporting later this year.

O’Neil and the team hope to see more awareness of compaction among farmers and researchers alike, and they are excited for more results to start rolling in. 

Madeline Hanscom ‘22 is a writer for the Cornell Nutrient Management Spear Program.