Non-Chemical Methods for Terminating Cover Crops

June 3, 2026

Non-Chemical Methods for Terminating Cover Crops

By Ankit Yadav - Graduate Research Assistant, Department of Agronomy and Horticulture, Sam Wortman - Professor and Environmental Horticulturist, Agronomy and Horticulture, Amit Jhala - Professor and Associate Department Head, Department of Agronomy and Horticulture

Tractor with sprayer attachment in a field under a cloudy sky.

Not all cover crop termination methods deliver the same results. Learn how common non-chemical approaches affect weed suppression, soil health and crop performance. 

Luka Milosevic/University of Nebraska-Lincoln
Key Takeaways

  • No one-size-fits-all solution — No single non-chemical cover crop termination method works best in every situation; effectiveness depends on species, growth stage and management goals. 

  • Termination method affects more than cover crop control — Roller crimping, mowing, disking, undercutting, flaming and electrocution each influence weed suppression, soil health and nutrient management differently. 

  • Timing is critical — Successful termination often depends on terminating cover crops at the proper growth stage, particularly for cereal rye and other grasses. 

  • Combining methods may improve results — Research suggests that integrating two termination methods can increase control and reduce the risk of cover crop regrowth.

Cover crops are valuable tools for weed suppression, building soil health, and managing nutrients. To fully realize the benefits of cover crops, careful management is essential, including species selection, seeding rate, planting time, termination timing and termination method. For organic growers, chemical termination is generally not an option (except for approved non-synthetic herbicides, which are currently not cost effective), so alternative termination strategies must be considered. This article discusses several non-chemical termination methods, their effectiveness, and their influence on the expected benefits of cover crops.

Disking

Disking is a traditional method commonly used in tillage-based systems for initial bed preparation and weed control (Figure 1). The disks vigorously disturb the topsoil as they cut vertically through it. This method is highly effective at all cover crops growth stages, increases the availability of inorganic soil N when used to terminate legume cover crops (Jani et al. 2016), and can increase potentially soil mineralizable carbon (Bloszies et al. 2022). However, several studies have documented limitations of disking that may reduce some of the intended benefits of cover crops, such as soil aggregation (Bloszies et al. 2022), weed suppression (Bavougian et al. 2019), reductions in soil organic carbon over time, surface soil moisture, and positive impacts on subsequent cash crop yield (Wortman et al. 2012).

Large agricultural disc harrow with metal blades, set against a clear blue sky.
Figure 1. Disk equipment. (Alex Chmielewski/University of Nebraska-Lincoln)

Sweep Plow Undercutter

A sweep plow undercutter is a mechanical termination implement consisting of horizontal V-shaped blades that sever cover crop roots while leaving surface residue intact and causing minimal soil inversion. It has been shown to be highly effective in controlling cereal rye, crimson clover and hairy vetch when used at mid- to late bloom or beyond growth stages (Creamer et al. 1995). Compared to disking, this method has been shown to increase surface soil moisture, soil nitrogen (NO3-N), crop yields, and profitability (Wortman et al. 2012). However, sweep plow efficacy is best in sandy, coarse-textured soils and requires significant horsepower to pull through heavier clay soils.

Propane Flaming

Propane flaming has been investigated as a mechanical cover crop termination method (Figure 2). This method exploits heat-induced disruption of the cell membrane to desiccate aboveground tissue. The propane rate used in previous studies is 54 lb per acre, and in some cases, LPG is used as a heat source at 60 lb per acre. Propane flaming has been discussed as one of the more expensive methods compared with other mechanical methods, given the fuel cost in addition to the machinery. Cover crop species respond differently to propane flaming. Bavougian et al. (2019) reported that hairy vetch, triticale and winter rye were more effectively suppressed than clovers. However, regrowth of all species is possible later in the season. Therefore, a follow-up treatment may be needed. In one study, combining flaming with roller crimping achieved up to 90% control of a fall-planted winter pea and barley mix that was approximately 1 meter tall (Frasconi et al. 2019). 

Tractor with sprayer attachment in a field under a cloudy sky.
Figure 2. Propane flaming equipment. (Luka Milosevic/University of Nebraska-Lincoln)

Roller Crimping

Roller crimpers are cylindrical implements with protruding tines that roll behind a tractor, crushing and flattening cover crops while leaving a mat-like residue layer on the soil surface (Davis et al. 2010; Figure 3).

The effectiveness of roller crimping depends heavily on the crop growth stage at termination. Research by Mirsky et al. (2009) found that cereal rye control improved when terminated at or after anthesis (flowering stage). Among legumes, hairy vetch (Bavougian et al. 2019) is more suited to roller crimping than clovers. Roller-crimped cover crops generally provide greater weed suppression than flaming or disking (Bavougian et al. 2019).

Green tractor with rusted farm equipment on a grassy field under a bright blue sky.
Figure 3. Roller crimper. (Gourav Chahal/Auburn University)

Mowing

There are different types of mowers that can be used with cover crops — most are attached to a tractor and powered by a power take-off (PTO) shaft, such as sickle-bar, rotary, and flail mowers. All three mow cover crops in different ways, resulting in mulch of different sizes and degrees of uniformity. Common mowing equipment includes:

Sickle Bar Mowers

A reciprocating knife cuts near the soil surface and leaves the cover crop residue intact, producing a thick mulch that decomposes more slowly than finely chopped residue (Creamer et al. 1995). The sickle bar may not perform well on legume species because of cover crop entanglement with the cutter blade.

Rotary Mowers (Brush Hogs)

The implement consists of one or more horizontal blades or knives mounted on a vertical rotating shaft (Figure 4). The shaft spins the blades parallel to the ground at high speed, and cutting occurs when the blade tips strike standing stems. Rotary-mown residue persists on the soil surface for a shorter period than roller-crimped residue, shortening the weed-suppression window (Dhakal et al. 2024).

Rusty mower deck in a grassy field with farm buildings and tanks in the background.
Figure 4. Rotary mower. (Alex Chmielewski/University of Nebraska-Lincoln)

Flail Mowers

Knives mounted on a rotating horizontal shaft finely chop residue and distribute it evenly across the soil surface (Creamer et al. 1995; Figure 5). The resulting small residue pieces maintain close contact with the soil, which promotes rapid decomposition by microorganisms. Consequently, this thin mulch layer may not persist long enough to provide season-long weed suppression (Creamer et al. 1995). 

In contrast, flail-mowed plots exhibited greater broadleaf weed biomass compared with undercut or sickle-bar–terminated plots, and were similar to the clean-tilled weedy check. This suggests that residue is more effective for weed suppression when left intact rather than finely chopped (Creamer et al. 1995).

Rusty red agricultural equipment in a field, surrounded by weeds and dry grass.
Figure 5. Flail mower. (Alex Chmielewski/University of Nebraska-Lincoln)

Electrocution

Electrocution is an emerging option for non-chemical cover crop termination (Figure 6). Moisture in plants is necessary for conductivity, but excess soil moisture can overload the machine and redirect electricity into the soil. 

In Texas, researchers found that one pass with the Zasso EH60 effectively terminated flowering brown mustard and winter pea monocultures, whereas cereal rye and hairy vetch required four passes of electrocution (Zasso EH60) to reach 90% termination, with some regrowth (3–5%) observed in cereal rye. 

In Oregon, one pass of the Zasso EH30 over a flowering oat–crimson clover mixture achieved 80% termination, and mowing prior to electrocution increased termination to over 90%. Researchers hypothesize that brassicas, with a single taproot, were terminated more effectively than cover crops with extensive root systems, which may survive in part after electrocution (Sullivan 2025).

Green tractor with yellow rims operating in a grassy field under a cloudy sky.
Figure 6. Electrocution machine. (Sougata Roy and Ryan Hamberg/Texas A&M University)

Take-Home Message

Organic growers face distinct challenges when terminating cover crops, as they lack access to conventional inorganic herbicides and organic alternatives tend to be costly and less effective. In terms of mechanical termination, no single method is universally suitable; each has its own advantages and limitations. Cover crop species and termination timing become increasingly important when relying on mechanical approaches. Management objectives also influence the selection of the termination method, whether prioritizing weed control, soil health, nutrient cycling, or facilitating the planting of the subsequent cash crop. 

Aligning termination techniques with specific goals and field conditions is essential to optimize the long-term advantages of cover crops. Additionally, research suggests that combining two mechanical methods may be more effective than relying on a single approach, suggesting that growers may want to consider this strategy.

Table 1. Suitable growth stage and functional group of cover crops (CCs) for respective termination methods, as well as the effect of the respective method on weed suppression.
Method

Growth stage for termination

Functional-group suitability

Effect on subsequent weed growth

Disking (incorporation tillage)Size/stage-independent, gave complete (99–100%) control of all types of cover crop species regardless of stage (Bavougian et al. 2019). Effective on all groups: legumes, grasses, and broadleaf CCs (Bavougian et al. 2019).Negative for residual suppression leaves bare soil with no surface mulch; incorporation stimulated grass-weed biomass relative to no-CC control (Wortman et al. 2013), and cultivation exposed weed seed, increasing some late-season weeds relative to crimped CCs. (Bavougian et al. 2019).
Sweep-plow undercutterMid- to late-bloom or beyond favored termination for rye, hairy vetch, and crimson clover (Creamer et al. 1995); it operates by severing roots ≈ 10 cm below the surface while leaving the surface residue intact (Wortman et al. 2012; Creamer & Dabney 2002).Documented on diverse 2–8-species mixtures containing both legumes and grasses (Wortman et al. 2012, 2013; Creamer et al. 1995 ).Positive: consistently reduced early-season grass-weed biomass and increased corn and soybean yield relative to disk incorporation (Wortman et al. 2012, 2013).
Propane flaming Based on weed species response, species- and stage-specific, younger/smaller plants are generally more susceptible (Knezevic et al. 2014; Ulloa et al. 2010)Broadleaf weeds controlled better than grasses in flaming generally (Knezevic et al. 2014); for CCs, flame gave control similar to crimping on both legumes (vetch, clover) and cereals (rye, triticale) (Bavougian et al. 2019); Austrian winter pea regrew aggressively after flame, 82% to 10% control (Price et al. 2019).Positive: equaled or exceeded roller-crimping for maize/soybean yield with comparable CC/weed suppression (Bavougian et al. 2019); standing residue may persist but can burn off under dry conditions (Bavougian et al. 2019).
Roller-crimpingRequires reproductive maturity, cereal rye consistent (≥85%) control at/after anthesis; poor at vegetative/jointing/booting (Mirsky et al. 2009; Ashford & Reeves 2003; Kornecki et al. 2012). Hairy vetch is better controlled after early pod set than flowering (Mischler et al. 2010).Best on upright/determinate cereals; legumes more regrowth-prone; broadleaf/brassica poor — roller-crimping alone did not adequately terminate rapeseed/canola (43% control; Kumar et al. 2023; not terminated at planting, Kumar et al. 2025).Positive when terminated at proper maturity with sufficient biomass, persistent surface mulch, most durable from high-biomass cereal rye (Bavougian et al. 2019; Dhakal et al. 2024); incomplete kill leads to regrowth and competition.
Mowing (flail / sickle-bar / rotary)Stage-dependent for cereals: rye mowed before stem elongation regrew like uncut, killing improved sharply when mowed at anthesis (De Bruin et al. 2005).Sickle-bar mowing is as effective as roller/blade-plow for killing CCs, but clogs on vine-like CCs, e.g., hairy vetch (Creamer et al. 1995); hairy vetch mowed at 5-10 cm height when at 50-100% flowering did not result in regrowth (Brainard et al. 2012). Mixed / shorter-lived: flail mowing accelerates residue decomposition and scatters mulch, which may reduce the weed suppression relative to roller crimper (Price et al. 2019; Wayman et al. 2014); 
ElectrocutionNot availableBased on limited research, brassicas are better suited than cereal rye and hairy vetch. 80 % control of oat-crimson clover mixture achieved. (Sullivan 2025)Not available

 

References

  • Ashford, D. L., & Reeves, D. W. (2003). Use of a mechanical roller-crimper as an alternative kill method for cover crops. American Journal of Alternative Agriculture, 18(1), 37–45. doi:10.1079/AJAA200232
  • Bavougian, C. M., Sarno, E., Knezevic, S., & Shapiro, C. A. (2019). Cover crop species and termination method effects on organic maize and soybean. Biological Agriculture & Horticulture, 35(1), 1–20. https://doi.org/10.1080/01448765.2018.1455607
  • Bloszies, S., Reberg‐Horton, C., Heitman, J. L., Woodley, A., Grossman, J., & Hu, S. (2022). Legume cover crop type and termination method effects on labile soil carbon and nitrogen and aggregation. Agronomy Journal, 114(3), 1817–1832. https://doi.org/10.1002/agj2.21022
  • Brainard DC, Henshaw B, Snapp SS. 2012. Hairy vetch varieties and bi-cultures influence cover crop services in strip-tilled sweet corn. Agron J 104:629–638.  https://doi-org.libproxy.unl.edu/10.2134/agronj2011.0360
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  • Creamer, N. G., & Dabney, S. M. (2002). Killing cover crops mechanically: Review of recent literature and assessment of new research results. American Journal of Alternative Agriculture, 17(1), 32–40. doi:10.1079/AJAA20014
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  • Frasconi C, Martelloni L, Antichi D, et al. 2019. Combining roller crimpers and flaming for the termination of cover crops in herbicide-free no-till cropping systems. PLoS ONE 14(2):e0211573. doi:10.1371/journal.pone.0211573
  • Jani, A. D., Grossman, J., Smyth, T. J., & Hu, S. (2016). Winter legume cover-crop root decomposition and N release dynamics under disking and roller-crimping termination approaches. Renewable Agriculture and Food Systems, 31(3), 214–229. doi:10.1017/S1742170515000113
  • Knezevic SZ, Stepanovic S, Datta A. 2014. Growth stage affects response of selected weed species to flaming. Weed Technol 28:233–242. DOI: 10.161 4/WT-D- 13-00054. 1
  • Kornecki, Ted & Arriaga, Francisco & Price, Andrew. (2012). Roller Type and Operating Speed Effects on Rye Termination Rates, Soil Moisture, and Yield of Sweet Corn in a No-till System. HortScience. 47. 217-223. 10.21273/HORTSCI.47.2.217. 
  • Kumar, V., Singh, V., Flessner, M. L., Haymaker, J., Reiter, M. S., & Mirsky, S. B. (2023). Cover crop termination options and application of remote sensing for evaluating termination efficiency. PLOS ONE, 18(4), e0284529. https://doi.org/10.1371/journal.pone.0284529
  • Kumar, V., Singh, V., Flessner, M. L., Reiter, M. S., Kumari, A., Price, A., … Mirsky, S. B. (2025). Impact of cover crops and termination timing on weed management in corn. Weed Technology, 39, e69. doi:10.1017/wet.2025.39
  • Mirsky, S. B., Curran, W. S., Mortensen, D. A., Ryan, M. R., & Shumway, D. L. (2009). Control of cereal rye with a roller/crimper as influenced by cover crop phenology. Agronomy Journal, 101(6), 1589–1596. https://doi.org/10.2134/agronj2009.0130
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  • Sullivan, A. (2025, September 23). Could we shock cover crops for termination? Integrated Weed Management Resource Center. Available at: https://growiwm.org/could-we-shock-cover-crops-for-termination/
  • Ulloa, S. M., Datta, A., & Knežević, S. Z. (2010). Tolerance of selected weed species to broadcast flaming at different growth stages. Crop Protection, 29(12), 1381–1388. https://doi.org/10.1016/j.cropro.2010.07.017
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  • Wortman, S. E., Francis, C., Bernards, M. L., Drijber, R. A., & Lindquist, J. L. (2012). Optimizing cover crop benefits with diverse mixtures and an alternative termination method. Agronomy Journal, 104(5), 1425–1435. https://doi.org/10.2134/agronj2012.0185

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