Weed Ecology and Nonchemical Management under Strip-Tillage: Implications for Northern U.S. Vegetable Cropping Systems

Abstract

In northern U.S. vegetable cropping systems, attempts at no-till (NT) production have generally failed because of poor crop establishment and delayed crop maturity. Strip tillage (ST) minimizes these problems by targeting tillage to the zone where crops are planted while maintaining untilled zones between crop rows, which foster improvements in soil quality. ST has been shown to maintain crop yields while reducing energy use and protecting soils in vegetable crops, including sweet corn, winter squash, snap bean, carrot, and cole crops. Despite potential benefits of ST, weed management remains an important obstacle to widespread adoption. Increased adoption of ST in cropping systems for which effective, low-cost herbicides are either limited (e.g., most vegetable crops) or prohibited (e.g., organic systems) will require integration of multiple cultural, biological, and mechanical approaches targeting weak points in weed life cycles. Weed population dynamics under ST are more complex than under either full-width, conventional tillage (CT) or NT because weed propagules—as well as factors influencing them—can move readily between zones. For example, the untilled zone in ST may provide a refuge for seed predators or a source of slowly mineralized nitrogen, which affects weed seed mortality and germination in the tilled zone. Greater understanding of such interzonal interactions may suggest manipulations to selectively suppress weeds while promoting crop growth in ST systems. Previous studies and recent experiences in ST vegetable cropping systems suggest a need to develop weed management strategies that target distinct zones while balancing crop and soil management tradeoffs. For example, in untilled zones, optimal management may consist of weed-suppressive cover crop mulching, combined with nitrogen exclusion and high-residue cultivation as needed. In contrast, weed management in the tilled zone may benefit from innovations in precision cultivation and flame-weeding technologies. These short-term strategies will benefit from longer-term approaches, including tillage-rotation, crop rotation, and cover cropping strategies, aimed at preventing seed production, promoting seed predation and decay, and preventing buildup of problematic perennial weeds. However, a concerted research effort focused on understanding weed populations as well as testing and refining integrated weed management strategies will be necessary before ST is likely to be widely adopted in vegetable cropping systems without increased reliance on herbicides.

Impacts of Organic Zero Tillage Systems on Crops, Weeds, and Soil Quality

“…A study conducted to determine the effect of various cover cropping systems on invertebrate seed predators found that the ground-dwelling carabid Harpalus rufipes was less abundant in plots that had been recently tilled and planted to cover crops than other comparatively non-disturbed plots [95]. Organic ZT, where the winter annual cover crop is drilled directly into crop residue with minimal disturbance, retain more weed seeds on the soil surface and provide better habitat for seed predators [99,100].…”

Nonconventional Weed Management Strategies for Modern Agriculture

“…Since the advent of mechanized farming, the trend of using tractor-mounted equipment has increased. Tractor-mounted equipment is easier to use under conventional tillage systems but more difficult in modified tillage systems, including no-till, strip tillage, and other conservation tillage systems because of retained residues (Brainard et al 2013). Residue mulches or living cover crops can be managed through mowing or use of a highresidue cultivator (Creamer and Dabney 2002).…”

“…Another potential strategy is by adjusting crop rotations in such a way that the planting geometry automatically rotates the tillage patterns. For example, in the Pacific Northwest, vegetables on wider beds are rotated with cereals on narrow ridges (Brainard et al 2013). In another study, foxtail barley (Hordeum jubatum L.) was effectively controlled through shifting from no-till to primary tillage with moldboard plow followed by disking in spring wheat (Donald 1990).…”

Expanding Red Clover (Trifolium pratense) Usage in the Corn–Soy–Wheat Rotation

“…Strip-tillage has been proposed as an intermediary between conventional and no-till systems, purportedly capturing the benefits of both extremes [2,71,92]. The undisturbed inter-row space offers the benefits associated with no-till.…”

“…Strip-tillage creates two distinct zones within a field; tilled and un-tilled. The zones differ in their biotic and abiotic characteristics, making them prone to different weeds and therefore responsive to different weed management strategies [92]. Their adjacency can complicate weed management.…”