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United States Department of Agriculture

Agricultural Research Service

Title: Landscape-Scale Weed Deomography As a Metric of Agricultural Sustainability

Authors
item Mueller Warrant, George
item Schweitzer, Lee - OREGON STATE UNIVERSITY
item Cook, Ron - OREGON STATE UNIVERSITY

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 31, 2003
Publication Date: January 31, 2004
Citation: Mueller Warrant, G.W., Schweitzer, L.R., Cook, R.L. 2004. Landscape-scale weed deomography as a metric of agricultural sustainability. Meeting Abstract.American Society for the Advancement of Science Annual Meeting. February 12-16, 2004. Seattle, WA. General Poster Session. Poster 44.

Interpretive Summary: Agricultural production dominates many landscapes, affects many ecological processes, and poses a variety of risks. Although a goal of sustainability is claimed by nearly all parties to disputes over specific management practices and production inputs, sustainability of agricultural systems can only be truly known in hindsight. Due to the importance of weeds and weed control practices in modern agriculture, one metric of sustainability would be success or failure in limiting the impact of weeds to that experienced in the past. Major challenges to adopting this approach are shortages of sufficiently detailed information on weed distribution patterns, population densities, weed control inputs, and crop losses. Oregon's grass seed industry offers a unique opportunity to assess many of these variables via its routine collection of information on production practices and weed prevalence. Grass seed production dominates agricultural land-use in the Willamette Valley, and a majority of that production is certified seed. Access to the Oregon Seed Services database was granted under the stipulation that grower confidentiality be maintained in any public releases of maps or other summaries. A total of 71 grassy weeds and 136 broadleaves, sedges, and other types were found in 10 years of pre-harvest inspections of an average of 5,801 fields per year. The primary obstacle to georeferencing data was that fields were only localized to township/range/section (TRS) coordinates, with an average of 4.2 and a maximum of 23 fields per TRS. Arbitrary latitude/longitude values were assigned to each field using procedures maximizing distances between fields within each TRS. Raster maps were then generated with Inverse Distance Weighted methods using weed abundance values of 0, 1, 10 or 100 for ratings of absent, trace, many, or excessive numbers of each species. Subtracting rasters for one year from the next identified regions in which weeds were changing in severity over time. Increasing severity of Poa annua and P. trivialis from 1994 through 1999 corresponded to phasing in of legislatively-mandated restrictions on post-harvest field burning, whereas decreasing severity from 1999 through 2002 corresponded to registration of several new herbicides in 1999. Increases in many broadleaf weeds over the past decade imply serious problems with sustainability of current production systems. Use of actual field boundaries to georeference data will enhance the value of future analyses.

Technical Abstract: Agricultural production dominates many landscapes, affects many ecological processes, and poses a variety of risks. Although a goal of sustainability is claimed by nearly all parties to disputes over specific management practices and production inputs, sustainability of agricultural systems can only be truly known in hindsight. Due to the importance of weeds and weed control practices in modern agriculture, one metric of sustainability would be success or failure in limiting the impact of weeds to that experienced in the past. Major challenges to adopting this approach are shortages of sufficiently detailed information on weed distribution patterns, population densities, weed control inputs, and crop losses. Oregon's grass seed industry offers a unique opportunity to assess many of these variables via its routine collection of information on production practices and weed prevalence. Grass seed production dominates agricultural land-use in the Willamette Valley, and a majority of that production is certified seed. Access to the Oregon Seed Services database was granted under the stipulation that grower confidentiality be maintained in any public releases of maps or other summaries. A total of 71 grassy weeds and 136 broadleaves, sedges, and other types were found in 10 years of pre-harvest inspections of an average of 5,801 fields per year. The primary obstacle to georeferencing data was that fields were only localized to township/range/section (TRS) coordinates, with an average of 4.2 and a maximum of 23 fields per TRS. Arbitrary latitude/longitude values were assigned to each field using procedures maximizing distances between fields within each TRS. Raster maps were then generated with Inverse Distance Weighted methods using weed abundance values of 0, 1, 10 or 100 for ratings of absent, trace, many, or excessive numbers of each species. Subtracting rasters for one year from the next identified regions in which weeds were changing in severity over time. Increasing severity of Poa annua and P. trivialis from 1994 through 1999 corresponded to phasing in of legislatively-mandated restrictions on post-harvest field burning, whereas decreasing severity from 1999 through 2002 corresponded to registration of several new herbicides in 1999. Increases in many broadleaf weeds over the past decade imply serious problems with sustainability of current production systems. Use of actual field boundaries to georeference data will enhance the value of future analyses.

Last Modified: 8/30/2014
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