On Farms, Tillage Intensity Shown to Affect Beneficial Insect Communities

By Nicholas Gosling and Isaac Ativor et.al

There’s growing evidence from across the world that resilient agricultural ecosystems are characterized by soils that sustain balanced populations of bacteria, viruses, fungi, plants and animals, farming practices can play a critical role in maintaining this balance. Scientists with the New Hampshire Agricultural Experiment Station (NHAES) at the University of New Hampshire recently published findings showing that soil tillage intensity and the use of pesticide-treated seeds adversely affect arthropod communities—organisms like ground beetles, ants and spiders that contribute to controlling pests, managing weed seeds and performing other essential ecological services.

The study, published in the journal Agriculture, Ecosystems & Environment, was conducted by NHAES scientist Rich Smith, professor in the UNH College of Life Sciences and Agriculture, doctoral candidate Isaac Ativor and research scientist Nick Warren. The researchers found that higher-intensity tillage—turning or disturbing soil prior to planting to loosen and aerate compacted soil, reduce weeds and incorporate fertilizer and crop residue—impacted arthropod diversity and abundance more than the use pesticide-treated seeds, which help reduce the emergence of weeds.

The impacts of pesticide-treated seeds varied, however, across arthropod groups the and the type of tillage method. For example, pesticide-treated seeds reduced the abundance of spiders, which are important predators of crop pests, but only in plots with strip tillage—a tillage practice that involves disturbing narrow strips of soil for planting and leaving the rest undisturbed.

“The tillage findings suggest that methods involving less soil disturbance, such as strip-tillage or no-tillage systems, could better support ecological benefits,” said Smith. “However, both findings highlight the importance of looking at farming systems holistically, showing that tillage and seed treatments interact with the broader ecosystem in ways that can either support or diminish the key services that arthropods provide.”

To evaluate how farming practices influenced arthropod populations, the researchers examined three tillage systems at the UNH Kingman Research Farm: strip tillage; full tillage, where soil is completely turned over to prepare for planting; and no tillage, which minimizes soil disturbance by planting seeds directly into undisturbed soil. The study also compared the effects of using pesticide-treated seeds or untreated seeds to produce corn and soybeans. Arthropod abundance, diversity and insects’ weed seed predation were monitored over three growing seasons, providing insights into how these variables interacted across different environmental conditions.

The team’s findings have practical implications for farmers in New Hampshire and similar agricultural regions, explained Ativor, lead author of the study. A key finding was that soil practices that adversely impacted overall arthropod abundance limits the insects’ ability to perform critical ecosystem functions such as preying on and eliminating weed seeds. As such, farmers could actually see reductions in weeds as a result of adopting soil management practices that limit soil disturbance.

“Maintaining arthropod populations is critical—not only for the health of farmlands but also for the broader ecological systems that sustain agriculture, such as pollination networks and nutrient cycling,” said Ativor.

Smith added, “We hope these results will provide farmers with a fuller understanding of how these agricultural practices impact ecosystem health. Ideally, by prioritizing methods that support beneficial organisms and the services they provide, we can work toward more sustainable and resilient farming systems that benefit both agricultural productivity and the environment.”