One of the primary benefits of site-specific agricultural technologies is the potential to reduce the use of polluting inputs, thereby minimizing ecological damage. Weeds are often found in patches, so site-specific (field scale) management offers a straightforward opportunity to minimize ecological effects related to wasteful broadcast use of herbicides. Beyond possible efficiencies related to accurate targeting, site-specific technologies, through a process of parameterizing management decision models for each field, may improve ecological understanding of weed populations and thus encourage ecologically based management. This hypothesis was assessed with a simple model that combined economic injury–level prediction with a single parameter (growing season precipitation) to represent environmental variability. Model simulations of crop yield in response to weed density at a virtual farm and six surrounding regional experiment stations suggested that localized (on-farm field) parameter estimation may help to circumvent the variability associated with damage function extrapolation from small-plot experiments at experiment stations and thereby improve predictive accuracy for site-specific weed management (SSWM) strategies. Thus, remote sensing and SSWM technologies may allow producers to reduce the risk associated with the reduced use of purchased inputs and greater reliance on natural weed population–regulating mechanisms. Effective ecologically based weed management may be dependent on local parameterization of models.

Crop production in the Northern Great Plains is rapidly changing because of no-till practices; producers now grow a diversity of crops with winter wheat to increase production as well as to manage weeds. With the multitude of crops available, producers are asking for guidelines to sequence crops in rotations that help weed management. We developed a planning tool that lists various choices with crops when designing a rotation; the choices are arranged by impact on weed dynamics as quantified by research in the region. The tool includes choices among crops, such as varying crops with different life cycles, planting dates, or row spacing, and choices within an individual crop, such as varying cultivar or planting date. Choices among crops impact weeds the most, whereas choices within an individual crop are less effective and usually lead to lower crop yield. For example, rotations comprised of two cool-season crops followed by two warm-season crops can reduce weed populations six- to 12-fold. In contrast, replacing a standard-height cultivar with a taller cultivar that is more competitive with weeds, is often inconsistent for weed management, whereas crop yield may be less. Producers associated with the Northern Plains Sustainable Agricultural Society felt that the planning tool would encourage long-range planning as well as help integrate weed management with the design of cropping systems. The purpose of the tool is to encourage ecologically based weed management, which can reduce herbicide inputs by 50% for Northern Great Plains producers.