Increasing Agricultural Sustainability by Reducing Weed-Crop Competition

Matthew Ryan, Penn State

February 4, 2010 @ 12:20 pm to 01:10 pm

10 Tyson Building

Ecologically-based weed management (EBWM) strategies that reduce weed-crop competition may decrease reliance on herbicides and improve agricultural sustainability. Here we report on three recent studies that indicate crop and soil management can alter weed-crop competitive relationships. The first study examined weed biomass and crop yield data from a long-term trial comparing organic and conventionally produced corn and soybean. The two organic systems averaged 469% more weed biomass, but only 6% lower corn and soybean yields relative to the conventional system. These data suggest that organically-managed systems tolerate a higher abundance of weeds without concomitant impacts on yields. A second study tested the conclusions derived from the long-term study, and involved experimental manipulations of weed abundance to evaluate weed-crop competition in the organic and conventional systems. Results from the second study further support the observation of greater tolerance to weed-crop competition in the organically-managed systems. We attribute these results to several factors, including delayed planting and cumulative (or legacy) effects of management. In the third study we hypothesize that weed-crop competition is related to the degree to which overlap in soil resource use between weeds and crops is altered by resource pool diversification and suggest areas for future research. Our research suggests that strategic management can reduce the competitive effects of weeds (yield loss) and thus the negative consequences of weed management (herbicide pollution, soil erosion, etc.). Widespread adoption of EBWM aimed at reducing weed-crop competition also offers the possibility of retaining positive ecosystem services of weeds while minimizing competitive losses.

Contact

Kristen Granger
klg297@psu.edu