PARENT SESSION
Wednesday, August 9, 8:00-11:30 am
Symposium 12 - Beyond labeling: comparing the sustainability of conventional and certified alternative farming systems
Steamboat, Mezzanine Level, Cook Convention Center
Organized by: FD Menalled (menalled@montana.edu), AG Hulting, and KL Monsen

This symposium addresses the sustainability of conventional and certified alternative farming systems by comparing established agroecosystems on a wide array of environmental and production metrics and concludes with a panel and audience discussion on how to prioritize research efforts to increase agricultural sustainability.

Weed communities in organic and conventional cropping systems.

Menalled, Fabian ^*,1, Maxwell, Bruce¹, Smith, Richard¹, Gross, Katherine², ¹ Montana State University, Bozeman, MT² Michigan State University, Hickory Corners, MI

ABSTRACT- In modern agricultural systems, consideration of weed diversity may be counter-intuitive as most cropping practices favor a single crop species and productivity is often preferred over diversity and sustainability. Despite the fact that there is growing evidence that diversity plays an important role in ecosystem functions such as productivity and nutrient cycling, the relevance of the number and relative abundance of plant species to agricultural systems remains largely unexplored. Understanding the functional consequences of weed diversity in agroecosystems will become increasingly important as more growers shift to reduced-input and organic production systems as these systems can affect weed species diversity. We have evaluated the effect of different agricultural management systems on the aboveground and seedbank weed communities in annual row crops. Weed abundance and diversity is higher in organic compared to conventional systems, but the spatial distribution of weed diversity also differs between these systems. While weed communities in conventional systems tend to be highly patchy with low species richness and percent cover, communities in organic systems are less patchy, have high percent cover, and higher species richness. We are currently performing manipulative experiments to assess the functional role of weed diversity in cropping systems. Preliminary results suggest that weed community abundance and diversity play a role in determining yield, crop-weed interactions, and nutrient dynamics. This suggests that differences in weed communities among management systems may play an important role in the functioning of row crop agroecosystems but the exact mechanisms are elusive.

Key words: Weed diversity, Agroecosystems, Weed spatial distribution