Integrating cover crops for weed management in the semiarid U.S. Great Plains: opportunities and challenges

Abstract

The widespread evolution of herbicide resistance in weed populations has become an increasing concern for no-tillage (NT) growers in semiarid regions of the U.S. Great Plains. Lack of cost-effective and alternative new herbicide sites of action further exacerbates the problem of herbicide-resistant (HR) weeds and threatens the long-term sustainability of prevailing cropping systems in the region. A recent decline in commodity prices and increasing herbicide costs to manage HR weeds has spurred research efforts to build a strong rationale for developing ecologically based integrated weed management (IWM) strategies in the U.S. Great Plains. Integration of cover crops (CCs) in NT dryland production systems potentially offers several ecosystem services, including weed control, soil health improvement, decline in selective pest pressure, and overall reduction in pest management inputs. This review article aims to document the role of CCs for IWM, with emphasis on exploring emerging weed issues; ecological, economic, and agronomic benefits of growing CCs; and constraints preventing adoption of CCs in NT cropping systems in the semiarid Great Plains. We attempt to focus on changes in weed management practices, their long-term impacts on weed seedbanks, weed shifts, and herbicide-resistance evolution in the most common weed species in the region. We also highlight current knowledge gaps and propose new research priorities based on an improved understanding of CC management strategies that will ultimately aid in achieving sustainable weed management goals and preserving natural resources in water-limited environments.

Cover Crop Impacts on Water Dynamics and Yields in Dryland Wheat Systems on the Colorado Plateau

“…This is unsurprising as cover crop species (legumes in particular) were not strongly expressed in cover crop stands. Furthermore, cover crop diversity has been shown to increase ecosystem services such as weed suppression, N retention, and aboveground biomass N, but is not typically associated with effects on cash crop yield, at least in the short-term [30,31]. Differences in wheat yields following cover crops of different planting windows (planted in the spring or in the previous fall) were observed, with a wheat yield reduction averaging 78% following fall-planted cover crops and 22% following springplanted cover crops.…”

“…Spring-planted cover crops therefore may be a way to gain benefits associated with cover crops while minimizing yield penalty. Alternatively, to limit cash crop yield penalty, fall-planted cover crops could be terminated early to limit cover crop biomass [33], while still providing soil cover through the fall, thus protecting against erosion and suppressing weeds [31,34]. It is important to note, however, that restricting cover crop biomass is likely to decrease potential soil health benefits, such as building SOC, soil fertility restoration and erosion control [23].…”

Phytosociology and cover analysis in the suppression of weeds from an Amazonian agrosystem

“…There is also ample evolution of the resistance to herbicides in weed populations, resulting from their continued exposure to heavy doses of these chemical products (Booth et al, 2003;Kumar et al, 2020). Therefore, minimizing or completely avoiding altogether the use of synthetic herbicides has gained interest in researches concerning the weed management (Ulla et al, 2014).…”

Strategic Tillage Effects on Crop Yields, Soil Properties, and Weeds in Dryland No-Tillage Systems

“…and tumble windmill grass (Chloris verticillata Nutt. ), as well as kochia (Kochia scoparia L.) and Palmer amaranth (Amaranthus palmeri S. Watson) that have become a major challenge in NT crop production [17]. For example, inadequate control of invasive tumble windmill grass could cause significant competition with wheat and sorghum resulting in yield reductions.…”