Research Highlights Value of Integrated Weed Management with Cover Crops in Corn-Soybean Systems

Strategic Insights -

Farmers have been finding innovative ways to address the rising issue of herbicide resistance in weeds, particularly in corn and soybean cultivation. Research from the University of Nebraska-Lincoln suggests that using integrated weed management tools, such as cover crops, can be a cultural approach to reduce herbicide-driven selection pressure. Cover crops, when used over multiple years, can alter the species composition of the soil seedbank and aboveground weed density, but the outcome may vary depending on factors such as tillage practices and the specific weed species involved.

Key Takeaways:

  • The use of herbicide-tolerant crops has led to soil management with reduced tillage, resulting in the accelerated development of herbicide-resistant weed populations, particularly from the Amaranthaceae family.
  • Integrated weed management tools, such as cover crops, have the potential to reduce herbicide-driven selection pressure and help manage weed populations.
  • Research trials conducted at the University of Nebraska-Lincoln found that cover crops increased Amaranthaceae family seedbank densities by 137-355% compared to the no cover crop check at three out of six trial sites.
  • Cover crops reduced aboveground total weed density and biomass at all trial sites, but increases from the pigweed seedbank were not observed at any site.
  • The species composition of the seedbanks under cover crops was distinct from that of the check at two trial sites, indicating that cover crops may influence weed seedbank composition over time.
  • The research emphasizes the importance of exploring integrated weed management approaches, such as the multi-year use of cover crops, to better understand how they shift weed communities, particularly with respect to herbicide-resistant weeds.

Statistics:

  • The research trials were conducted over 4-7 years, with 4 on-farm and 2 university research experiments across eastern and central Nebraska.
  • Statistically significant increases in Amaranthaceae family (pigweed) seedbank densities were observed at three out of six trial sites, with an increase of 137-355%.
  • Cover crops reduced aboveground total weed density and biomass at all trial sites.
  • No differences in total weed seedbank densities were found between trial sites with and without cover crops.

Sources:

  • Exploring how multi-year cover crop use alters above and belowground weed communities in limited tillage corn-soybean systems. Frontiers in Agronomy, 2025, 7.
  • NewsRx. Studies from University of Nebraska-Lincoln Have Provided New Data on Cover Crops (Exploring how multi-year cover crop use alters above and belowground weed communities in limited tillage corn-soybean systems). Agriculture Week. June 12, 2025; p 4304.