A method for mechanically killing cover crops to optimize weed suppression

Abstract

Residues of dead cover crops can suppress weeds by providing a mulch on the soil surface. The cover crop usually is killed with herbicides, but a mechanical method is desirable in systems intended to reduce chemical use. We designed and built an undercutter to kill cover crops by severing their roots while flattening the intact aboveground biomass on the surface of raised beds. We studied which cover crop species could be killed with the undercutter and compared the weed control potential of cover crop residues after flail mowing, sicklebar mowing, and undercutting.Whether a species was killed by the undercutter depended primarily on growth stage. Species that were in mid- to late bloom or beyond, including rye, hairy vetch, bigflower vetch, crimson clover, barley, and subterranean clover, were easily killed by undercutting. There were no differences in dry weights of broadleaf weeds between the undercut and simulated sicklebar mowed treatments, both of which had less weed biomass than the clean-tilled or flail-mowed plots.

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

“…Rollers received the greatest attention. Creamer et al [28] reported better results when cover crops were killed using a roller compared with a flail mower, but a blade plow was attached to the roller and shallow soil disturbance occurred. Ashford and Reeves [29] were perhaps the first North American researchers to consider terminating cover crops mechanically but without tillage using a roller-crimper, borrowing an idea first developed and used in South America following the introduction of conventional ZT.…”

Conservation Tillage and Weed Management

“…Cover crops can be grown and then undercut and left on the same beds to form organic mulch (Lanini et al, 1989;Creamer, 1995). Plants that are used to produce this type of organic mulch include various cereals, clovers, vetches, and fava beans (Abdul-Baki andTeasdale, 1993 and.…”

Guest Editorial: Conservation Tillage for Organic Farming

“…This reliance on tillage has led some to openly criticize organic farming proponents as advocating for an agro-ecological system that is not sustainable [11,12]. Recognizing the negative impacts that tillage can have on soil quality, Creamer et al [13] and others [14,15] worked on alternative weed control systems that did not rely on tillage or herbicides, beginning in the 1990s. Cover crops were a key component in these no-tillage (no-till) systems because of the vegetative mulch that could be produced when these crops were killed.…”

“…Cover crops were a key component in these no-tillage (no-till) systems because of the vegetative mulch that could be produced when these crops were killed. This vegetative mulch proved effective at suppressing weeds when retained on the soil surface, as long as amounts of dry matter exceeded 5000 to 6000 kg·ha −1 [16].Different kill methods for terminating cover crops were compared in early organic no-till research, but most involved rolling or mowing [13][14][15]. Over time, interest focused on rollers with blunt blades welded or otherwise connected to the rollers in various configurations [17].…”

“…Different kill methods for terminating cover crops were compared in early organic no-till research, but most involved rolling or mowing [13][14][15]. Over time, interest focused on rollers with blunt blades welded or otherwise connected to the rollers in various configurations [17].…”