Cover Crop Effectiveness Varies in Cover Crop-Based Rotational Tillage Organic Soybean Systems Depending on Species and Environment

Organic farming relies heavily on tillage for weed management, however, intensive soil disturbance can have detrimental impacts on soil quality. Cover crop-based rotational tillage (CCBRT), a practice that reduces the need for tillage and cultivation through the creation of cover crop mulches, has emerged as an alternative weed management practice in organic cropping systems. In this study, CCBRT systems using cereal rye and triticale grain species are evaluated with organic soybean directly seeded into a rolled cover crop. Cover crop biomass, weed biomass, and soybean yields were evaluated to assess the effects of cereal rye and winter triticale cover crops on weed suppression and yields. From 2016 to 2018, trials were conducted at six locations in Wisconsin, USA, and Southern France. While cover crop biomass did not differ among the cereal grain species tested, the use of cereal rye as the cover crop resulted in higher soybean yields (2.7 t ha−1 vs. 2.2 t ha−1) and greater weed suppression, both at soybean emergence (231 vs. 577 kg ha−1 of weed biomass) and just prior to soybean harvest (1178 vs. 1545 kg ha−1). On four out of six sites, cover crop biomass was lower than the reported optimal (<8000 kg ha−1) needed to suppress weeds throughout soybean season. Environmental conditions, in tandem with agronomic decisions (e.g., seeding dates, cultivar, planters, etc.), influenced the ability of the cover crop to suppress weeds regardless of the species used. In a changing climate, future research should focus on establishing flexible decision support tools based on multi-tactic cover crop management to ensure more consistent results with respect to cover crop growth, weed suppression, and crop yields.

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Rolled Mixtures of Barley and Cereal Rye for Weed Suppression in Cover Crop–based Organic No-Till Planted Soybean

Weed Science ◽

10.1017/wsc.2016.23 ◽

2017 ◽

Vol 65 (3) ◽

pp. 426-439 ◽

Cited By ~ 10

Author(s):

Jeffrey A. Liebert ◽

Antonio DiTommaso ◽

Matthew R. Ryan

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Block Design ◽

Weed Suppression ◽

Management Tool ◽

Weed Biomass ◽

Cereal Rye ◽

No Till ◽

Lower Cover ◽

Crop Biomass

Maximizing cereal rye biomass has been recommended for weed suppression in cover crop–based organic no-till planted soybean; however, achieving high biomass can be challenging, and thick mulch can interfere with soybean seed placement. An experiment was conducted from 2012 to 2014 in New York to test whether mixing barley and cereal rye would (1) increase weed suppression via enhanced shading prior to termination and (2) provide acceptable weed suppression at lower cover crop biomass levels compared with cereal rye alone. This experiment was also designed to assess high-residue cultivation as a supplemental weed management tool. Barley and cereal rye were seeded in a replacement series, and a split-block design with four replications was used with management treatments as main plots and cover crop seeding ratio treatments (barley:cereal rye, 0:100, 50:50, and 100:0) as subplots. Management treatments included high-residue cultivation and standard no-till management without high-residue cultivation. Despite wider leaves in barley, mixing the species did not increase shading, and cereal rye dominated cover crop biomass in the 50:50 mixtures in 2013 and 2014, representing 82 and 93% of the biomass, respectively. Across all treatments, average weed biomass (primarily common ragweed, giant foxtail, and yellow foxtail) in late summer ranged from 0.5 to 1.1 Mg ha−1in 2013 and 0.6 to 1.3 Mg ha−1in 2014, and weed biomass tended to decrease as the proportion of cereal rye, and thus total cover crop biomass, increased. However, soybean population also decreased by 29,100 plants ha−1for every 1 Mg ha−1increase in cover crop biomass in 2013 (P=0.05). There was no relationship between cover crop biomass and soybean population in 2014 (P=0.35). Soybean yield under no-till management averaged 2.9 Mg ha−1in 2013 and 2.6 Mg ha−1in 2014 and was not affected by cover crop ratio or management treatment. Partial correlation analyses demonstrated that shading from cover crops prior to termination explained more variation in weed biomass than cover crop biomass. Our results indicate that cover crop management practices that enhance shading at slightly lower cover crop biomass levels might reduce the challenges associated with excessive biomass production without sacrificing weed suppression in organic no-till planted soybean.

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Integration of cover crops and fertilizer rates for weed management in celery

Weed Science ◽

10.1614/ws-05-078r.1 ◽

2006 ◽

Vol 54 (02) ◽

pp. 326-334 ◽

Cited By ~ 9

Author(s):

Kevin S. Charles ◽

Mathieu Ngouajio ◽

Darryl D. Warncke ◽

Kenneth L. Poff ◽

Mary K. Hausbeck

Keyword(s):

Soil Fertility ◽

Cover Crops ◽

Weed Management ◽

Weed Suppression ◽

Fertility Level ◽

Hairy Vetch ◽

Bare Ground ◽

Weed Biomass ◽

Cereal Rye ◽

Oilseed Radish

Field studies were carried out in Laingsburg, MI, from 2002 to 2004 on Houghton muck soil to assess the impacts of cover crops and soil fertility regimes on weed populations and celery yield. The cover crops were oilseed radish, cereal rye, hairy vetch, and a bare ground control. The fertility rates were full (180, 90, and 450 kg ha−1nitrogen [N], phosphorus pentoxide [P2O5], and potassium oxide [K2O], respectively), half (90, 45, and 225 kg ha−1N, P2O5, and K2O, respectively), and low (90 kg ha−1N). Each cover crop treatment was combined with the low or half rate of fertilizer. An additional treatment with bare ground plus the full rate of fertilizer was added as standard practice. Treatments were maintained in the same location for the duration of the study. Major weed species were common chickweed, prostrate pigweed, shepherd's-purse, common purslane, and yellow nutsedge. Each year, oilseed radish consistently produced the greatest biomass and provided over 98% early season weed biomass suppression. Hairy vetch and cereal rye provided about 70% weed suppression in early spring. Soil fertility level affected weed populations during the 2004 growing season. In 2004, weed biomass in treatments without cover crops or with vetch increased when greater amounts of fertilizer were applied. Within individual fertility levels, higher celery yields were recorded in the oilseed radish plots. For example, in the low fertility rate, celery yield was 34.8, 29.2, 23.9, and 24.4 ton ha−1in the oilseed radish, cereal rye, hairy vetch, and control plots, respectively in 2003. Overall, the results of this experiment indicate that when included in a system where hoeing and hand-weeding are the only weed control methods, cover crops can successfully improve weed management and celery yield on muck soils, allowing reduced fertilizer inputs.

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Strategies to terminate summer cover crops for weed management in no-tillage vegetable production in southeast Brazil

Weed Science ◽

10.1017/wsc.2021.58 ◽

2021 ◽

pp. 1-26

Author(s):

Roberto Botelho Ferraz Branco ◽

Fernando de Carvalho ◽

João Paulo de Oliveira ◽

Pedro Luis da Costa Alves

Keyword(s):

Pearl Millet ◽

Cover Crops ◽

Weed Management ◽

Cover Crop ◽

Weed Suppression ◽

No Tillage ◽

Weed Biomass ◽

Jack Bean ◽

Organic Mulch ◽

Sunn Hemp

Abstract Cover crop residue left on the soil surface as organic mulch in no-tillage crop production provides several environmental benefits, including weed suppression. Thus, many farmers who use cover crops attempt to reduce the use of agricultural inputs, especially herbicides. Therefore, our objectives were to study the potential of different cover crop species to suppress weeds and produce an in situ organic mulch, and evaluate the effect of the organic mulch with and without spraying glyphosate on weed suppression for vegetable (tomato (Solanum lycopersicum L. and broccoli (Brassica oleracea L. var. botrytis) growth and yield. Five cover crop treatments (sunn hemp (Crotalaria juncea L.), jack bean [Canavalia ensiformis (L.) DC.], pearl millet [Pennisetum glaucum (L.) R. Br.], grain sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] and a no-cover crop (control)) were used in the main plots; and spraying or no spraying glyphosate on the flattened cover crop in the sub plots of split-plot experimental design. Organic mulch from pearl millet, sorghum and sunn hemp resulted in lower weed biomass during the early season of both tomato and broccoli than jack bean and no-cover crop (control). Spraying glyphosate after roller crimping reduced weed biomass by 103 g m−2 and 20 g m−2 by 45 and 60 days after transplanting (DAT) of tomato, respectively and resulted in a better tomato yield compared to non spraying. Glyphosate reduced weed biomass by 110 g m−2 in the early season of broccoli (30 DAT), but did not affect yield. Terminating high biomass cover crops with a roller crimper is a promising technique for weed management in vegetable crops, which has the potential to reduce or even eliminate the need for herbicide.

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Timing of Cover-Crop Management Effects on Weed Suppression in No-Till Planted Soybean using a Roller-Crimper

Weed Science ◽

10.1614/ws-d-10-00101.1 ◽

2011 ◽

Vol 59 (3) ◽

pp. 380-389 ◽

Cited By ~ 98

Author(s):

S. B. Mirsky ◽

W. S. Curran ◽

D. M. Mortenseny ◽

M. R. Ryany ◽

D. L. Shumway

Keyword(s):

Weed Management ◽

Cover Crop ◽

Crop Management ◽

Biomass Accumulation ◽

Weed Suppression ◽

Hairy Vetch ◽

Cereal Rye ◽

No Till ◽

Termination Date ◽

Crop Biomass

Integrated weed management tactics are necessary to develop cropping systems that enhance soil quality using conservation tillage and reduced herbicide or organic weed management. In this study, we varied planting and termination date of two cereal rye cultivars (‘Aroostook’ and ‘Wheeler’) and a rye/hairy vetch mixture to evaluate cover-crop biomass production and subsequent weed suppression in no-till planted soybean. Cover crops were killed with a burn-down herbicide and roller-crimper and the weed-suppressive effects of the remaining mulch were studied. Cover-crop biomass increased approximately 2,000 kg ha−1from latest to earliest fall planting dates (August 25–October 15) and for each 10-d incremental delay in spring termination date (May 1–June 1). Biomass accumulation for cereal rye was best estimated using a thermal-based model that separated the effects of fall and spring heat units. Cultivars differed in their total biomass accumulation; however, once established, their growth rates were similar, suggesting the difference was mainly due to the earlier emergence of Aroostook rye. The earlier emergence of Aroostook rye may have explained its greater weed suppression than Wheeler, whereas the rye/hairy vetch mixture was intermediate between the two rye cultivars. Delaying cover-crop termination reduced weed density, especially for early- and late-emerging summer annual weeds in 2006. Yellow nutsedge was not influenced by cover-crop type or the timing of cover-crop management. We found that the degree of synchrony between weed species emergence and accumulated cover-crop biomass played an important role in defining the extent of weed suppression.

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Effects of Management Type and Timing on Weed Suppression in Soybean No-Till Planted into Rolled-Crimped Cereal Rye

Weed Science ◽

10.1614/ws-d-12-00024.1 ◽

2012 ◽

Vol 60 (4) ◽

pp. 624-633 ◽

Cited By ~ 25

Author(s):

Eric A. Nord ◽

Matthew R. Ryan ◽

William S. Curran ◽

David A. Mortensen ◽

Steven B. Mirsky

Keyword(s):

Weed Control ◽

Community Composition ◽

Weed Management ◽

Cover Crop ◽

Weed Suppression ◽

Planting Dates ◽

Weed Biomass ◽

Cereal Rye ◽

No Till ◽

Weed Emergence

Knowledge of weed emergence periodicity can inform the timing and choice of weed management tactics. We tested the effects of weed management system (conventional [CNV] and herbicide-free [HF]), timing of rye sowing (two dates), timing of soybean planting (5 planting dates, 3 in each system), and supplemental control (with and without) on weed suppression and weed community composition in soybean no-till planted into a cereal rye cover crop. Cereal rye was terminated with a roller-crimper and herbicide (CNV) or with a roller-crimper alone (HF), and supplemental weed control was achieved with a postemergence glyphosate application (CNV) or with interrow high-residue cultivation (HF). Supplemental control with glyphosate in CNV was more effective than high-residue cultivation in HF. When soybean was planted on the same date, CNV resulted in less weed biomass and a more even community composition, whereas HF resulted in greater weed biomass, dominated by common ragweed. When we controlled for cereal rye biomass and compared the effects of cereal rye sowing and termination timing within each system, earlier management reduced weed biomass in HF, but tended to increase weed biomass in CNV. Our results suggest the ability to control emerged weeds prior to soybean planting is an important factor that influences the optimal cereal rye cover crop management timing for weed suppression.

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Evaluating cereal rye and crimson clover for weed suppression within buffer areas in dicamba-resistant soybean

Weed Technology ◽

10.1017/wet.2020.121 ◽

2020 ◽

pp. 1-29

Author(s):

Connor L. Hodgskiss ◽

Bryan G. Young ◽

Shalamar D. Armstrong ◽

William G. Johnson

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Early Summer ◽

Weed Suppression ◽

Weed Species ◽

Cereal Rye ◽

Herbicide Resistant ◽

Crimson Clover ◽

Emergence Patterns ◽

Crop Biomass

Abstract As herbicide-resistant weeds become more problematic, producers will consider the use of cover crops to suppress weeds. Weed suppression from cover crops may be especially in the label-mandated buffer areas of dicamba-resistant soybean where dicamba use is not allowed. Three cover crops terminated at three timings with three herbicide strategies were evaluated for their effect on weed suppression in dicamba-resistant soybean. Delaying termination to at soybean planting, or after, and using a cereal rye or cereal rye + crimson clover increased cover crop biomass by at least 40% compared to terminating early or using a crimson clover only cover crop. Densities of problematic weed species were evaluated in early-summer prior to a blanket POST application. Plots with cereal rye had 75% less horseweed compared to crimson clover at two of four site-years. Cereal rye or the mix cover crop terminated at, or after soybean planting reduced waterhemp densities by 87% compared to early termination timings of crimson clover and the earliest termination timing of the mix at one of two site-years. Cover crops were not as effective in reducing waterhemp densities as they were in reducing horseweed densities. This difference is due to a divergence in emergence patterns; waterhemp emergence generally peaks after termination of the cover crop while horseweed emergence coincides with establishment and rapid vegetative growth of cereal rye. Cover crops alone were generally not as effective as using a high biomass cover crop combined with herbicide strategy that contained dicamba and residual herbicides. However, within label-mandated buffer areas where dicamba cannot be used, a cover crop containing cereal rye with delayed termination to at soybean planting combined with residual herbicides could be utilized to improve suppression of horseweed and waterhemp.

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Cover crops and topography differentially influence weeds at a watershed scale

Weed Technology ◽

10.1017/wet.2019.83 ◽

2019 ◽

Vol 34 (1) ◽

pp. 73-81 ◽

Cited By ~ 3

Author(s):

Gurbir Singh ◽

Gurpreet Kaur ◽

Karl W. Williard ◽

Kelly A. Nelson ◽

Jon E. Schoonover

Keyword(s):

Cover Crops ◽

Weed Management ◽

Weed Suppression ◽

Watershed Scale ◽

Hairy Vetch ◽

Weed Biomass ◽

Cereal Rye ◽

Topographic Positions ◽

Winter Fallow

AbstractCover crops (CCs) play an important role in integrated weed management. Data necessary to evaluate the role of CCs in weed management at the watershed scale with topographic positions are lacking. We evaluated the effects of cereal rye and hairy vetch CCs on weed suppression at different topographic positions (shoulder, backslope, and footslope) at a watershed scale. Watersheds with a CC treatment followed a crop rotation of corn–cereal rye–soybean–hairy vetch, whereas watersheds without a CC (no-CC) had a crop rotation of corn–winter fallow–soybean–winter fallow. A negative relationship was present between CCs and weed biomass at the shoulder, backslope, and footslope topographic landscape positions, with R2 values of 0.40, 0.48, and 0.50, respectively. In 2016, a cereal rye CC reduced weed biomass 46% to 50% at footslope and shoulder positions compared to no CC. In 2018, a cereal rye CC reduced weed biomass between 52% and 85% at all topographic positions in CC treatment watersheds compared to no-CC watersheds. Hairy vetch in 2017 reduced weed biomass 62% to 72% at footslope and shoulder topographic positions in CC watersheds compared to no-CC. The C:N ratio of weed biomass in CC treatment watersheds was generally higher compared to watersheds without CCs. In this study, several significant interactions were found between the topographic positions and CC treatments. Cover crop–induced weed suppression at different topographic positions can lead to developing better site-specific weed control strategies. Therefore, CC interactions with topography, weed germination potential, and the role of soil moisture at the watershed scale should be further evaluated.

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Potential Synergistic Effects of Cereal Rye Biomass and Soybean Planting Density on Weed Suppression

Weed Science ◽

10.1614/ws-d-10-00110.1 ◽

2011 ◽

Vol 59 (2) ◽

pp. 238-246 ◽

Cited By ~ 54

Author(s):

Matthew R. Ryan ◽

Steven B. Mirsky ◽

David A. Mortensen ◽

John R. Teasdale ◽

William S. Curran

Keyword(s):

Cover Crops ◽

Weed Management ◽

Management Practice ◽

Synergistic Effects ◽

Weed Suppression ◽

Planting Density ◽

Hyperbolic Model ◽

Weed Biomass ◽

Cereal Rye ◽

Crop Density

Increasing crop density is a cultural weed management practice that can compliment the use of cover crops for weed suppression. In this research, we created a range of cover crop biomass and soybean densities to assess their weed-suppressive ability alone and in combination. The experiment was conducted in 2008 and 2009 in Maryland and Pennsylvania using five levels of cereal rye residue, representing 0, 0.5, 1.0, 1.5, and 2.0 times the ambient level, and five soybean densities ranging from 0 to 74 seeds m−2. Weed biomass decreased with increasing rye residue and weeds were completely suppressed at levels above 1,500 g m−2. Weed biomass also decreased with increasing soybean density in 2 of 4 site–years. We evaluated weed suppression by fitting an exponential decay model of weed biomass as a function of rye biomass and a hyperbolic model of weed biomass as a function of soybean density at each of the five tactic levels. We multiplied these individual tactic models and included an interaction term to test for tactic interactions. In two of the four site-years, the combination of these tactics produced a synergistic interaction that resulted in greater weed suppression than would be predicted by the efficacy of each tactic alone. Our results indicate that increasing soybean planting rate can compensate for lower cereal rye biomass levels when these tactics are combined.

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Overcoming Weed Management Challenges in Cover Crop–Based Organic Rotational No-Till Soybean Production in the Eastern United States

Weed Technology ◽

10.1614/wt-d-12-00078.1 ◽

2013 ◽

Vol 27 (1) ◽

pp. 193-203 ◽

Cited By ~ 98

Author(s):

Steven B. Mirsky ◽

Matthew R. Ryan ◽

John R. Teasdale ◽

William S. Curran ◽

Chris S. Reberg-Horton ◽

...

Keyword(s):

United States ◽

Weed Management ◽

Cover Crop ◽

Ground Cover ◽

Weed Suppression ◽

Future Research ◽

Soybean Production ◽

Cereal Rye ◽

No Till ◽

Annual Weeds

Cover crop–based organic rotational no-till soybean production has attracted attention from farmers, researchers, and other agricultural professionals because of the ability of this new system to enhance soil conservation, reduce labor requirements, and decrease diesel fuel use compared to traditional organic production. This system is based on the use of cereal rye cover crops that are mechanically terminated with a roller-crimper to create in situ mulch that suppresses weeds and promotes soybean growth. In this paper, we report experiments that were conducted over the past decade in the eastern region of the United States on cover crop–based organic rotational no-till soybean production, and we outline current management strategies and future research needs. Our research has focused on maximizing cereal rye spring ground cover and biomass because of the crucial role this cover crop plays in weed suppression. Soil fertility and cereal rye sowing and termination timing affect biomass production, and these factors can be manipulated to achieve levels greater than 8,000 kg ha−1, a threshold identified for consistent suppression of annual weeds. Manipulating cereal rye seeding rate and seeding method also influences ground cover and weed suppression. In general, weed suppression is species-specific, with early emerging summer annual weeds (e.g., common ragweed), high weed seed bank densities (e.g. > 10,000 seeds m−2), and perennial weeds (e.g., yellow nutsedge) posing the greatest challenges. Due to the challenges with maximizing cereal rye weed suppression potential, we have also found high-residue cultivation to significantly improve weed control. In addition to cover crop and weed management, we have made progress with planting equipment and planting density for establishing soybean into a thick cover crop residue. Our current and future research will focus on integrated multitactic weed management, cultivar selection, insect pest suppression, and nitrogen management as part of a systems approach to advancing this new production system.

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High-Residue Cultivation Timing Impact on Organic No-Till Soybean Weed Management

Weed Technology ◽

10.1017/wet.2016.24 ◽

2017 ◽

Vol 31 (2) ◽

pp. 320-329 ◽

Cited By ~ 5

Author(s):

Gladis M. Zinati ◽

Rita Seidel ◽

Alison Grantham ◽

Jeff Moyer ◽

Victoria J. Ackroyd ◽

...

Keyword(s):

Weed Control ◽

Weed Management ◽

Cover Crop ◽

Weed Suppression ◽

Management Approach ◽

Optimal Timing ◽

Weed Biomass ◽

Cereal Rye ◽

Organic Cultivation ◽

No Till

A cereal rye cover crop mulch can suppress summer annual weeds early in the soybean growing season. However, a multi-tactic weed management approach is required when annual weed seedbanks are large or perennial weeds are present. In such situations, the weed suppression from a cereal rye mulch can be supplemented with the use of high-residue cultivators which can prolong the weed-free period during soybean growth. Research trials were conducted to determine the optimum timing of high-residue cultivation for weed control in rolled-crimped cereal rye mulches. Treatments included three cultivation timings with a high-residue cultivator: early (3-4 wk after soybean planting (WAP)), intermediate (5-6 WAP), and late (7-8 WAP), a weed-free and no-cultivation control. Crop and weed measurement included cereal rye biomass, weed biomass, soybean population and biomass, and yield. Cereal rye biomass was 50% lower and weed biomass was three times greater in 2011 than in 2010 and 2012 due to 2011 being a dry year. There was no significant effect of cultivation timing on soybean population when compared to no-cultivation or hand-weeded treatments. While cultivation reduced weed biomass by 67% compared to no-cultivation, soybean yield was only improved by 12% in early and late cultivation treatments and 22% in intermediate cultivation treatment when compared to no-cultivation. Effective strategies for improving weed management by integrating the use of a high-residue cultivator in no-till organic systems could help existing organic field crop producers to reduce tillage while also encourage adoption of organic crop production by conventional growers who prefer reduced-tillage systems. Unlike traditional organic cultivation equipment, therefore, optimal timing of cultivation should be delayed several weeks in organic cover crop-based no-till planted soybean production as compared to the typical tillage-based approach to ensure both weed control and optimal yield.

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