Are cover crop mixtures better at suppressing weeds than cover crop monocultures?

Weed Science ◽  
2020 ◽  
Vol 68 (2) ◽  
pp. 186-194 ◽  
Author(s):  
Richard G. Smith ◽  
Nicholas D. Warren ◽  
Stéphane Cordeau
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Raphanus Sativus ◽  
Weed Suppression ◽  
Temporal Niche ◽  
Cover Cropping ◽  
Stable Mixture ◽  
Species Mixtures ◽  
Spring Planting

AbstractCover crops are increasingly being used for weed management, and planting them as diverse mixtures has become an increasingly popular strategy for their implementation. While ecological theory suggests that cover crop mixtures should be more weed suppressive than cover crop monocultures, few experiments have explicitly tested this for more than a single temporal niche. We assessed the effects of cover crop mixtures (5- or 6-species and 14-species mixtures) and monocultures on weed abundance (weed biomass) and weed suppression at the time of cover crop termination. Separate experiments were conducted in Madbury, NH, from 2014 to 2017 for each of three temporal cover-cropping niches: summer (spring planting–summer termination), fall (summer planting–fall termination), and spring (fall planting–subsequent spring termination). Regardless of temporal niche, mixtures were never more weed suppressive than the most weed-suppressive cover crop grown as a monoculture, and the more diverse mixture (14 species) never outperformed the less diverse mixture. Mean weed-suppression levels of the best-performing monocultures in each temporal niche ranged from 97% to 98% for buckwheat (Fagopyrum esculentum Moench) in the summer niche and forage radish (Raphanus sativus L. var. niger J. Kern.) in the fall niche, and 83% to 100% for triticale (×Triticosecale Wittm. ex A. Camus [Secale × Triticum]) in the winter–spring niche. In comparison, weed-suppression levels for the mixtures ranged from 66% to 97%, 70% to 90%, and 67% to 99% in the summer, fall, and spring niches, respectively. Stability of weed suppression, measured as the coefficient of variation, was two to six times greater in the best-performing monoculture compared with the most stable mixture, depending on the temporal niche. Results of this study suggest that when weed suppression is the sole objective, farmers are more likely to achieve better results planting the most weed-suppressive cover crop as a monoculture than a mixture.

scholarly journals Mustard Cover Crop Growth and Weed Suppression in Organic, Strawberry Furrows in California

HortScience ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Eric B. Brennan ◽  
Richard F. Smith
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Sinapis Alba ◽  
Weed Suppression ◽  
Shoot Biomass ◽  
Plastic Mulch ◽  
Seeding Rate ◽  
Crop Cover ◽  
Cover Cropping ◽  
Growing Seasons

Strawberry (Fragaria ×ananassa Duch.) production in California uses plastic mulch–covered beds that provide many benefits such as moisture conservation and weed control. Unfortunately, the mulch can also cause environmental problems by increasing runoff and soil erosion and reducing groundwater recharge. Planting cover crops in bare furrows between the plastic cover beds can help minimize these problems. Furrow cover cropping was evaluated during two growing seasons in organic strawberries in Salinas, CA, using a mustard (Sinapis alba L.) cover crop planted at two seeding rates (1× and 3×). Mustard was planted in November or December after strawberry transplanting and it resulted in average densities per meter of furrow of 54 and 162 mustard plants for the 1× and 3× rates, respectively. The mustard was mowed in February before it shaded the strawberry plants. Increasing the seeding rate increased mustard shoot biomass and height, and reduced the concentration of P in the mustard shoots. Compared with furrows with no cover crop, cover-cropped furrows reduced weed biomass by 29% and 40% in the 1× and 3× seeding rates, respectively, although weeds still accounted for at least 28% of the furrow biomass in the cover-cropped furrows. These results show that growing mustard cover crops in furrows without irrigating the furrows worked well even during years with relatively minimal precipitation. We conclude that 1) mustard densities of ≈150 plants/m furrow will likely provide the most benefits due to greater biomass production, N scavenging, and weed suppression; 2) mowing was an effective way to kill the mustard; and 3) high seeding rates of mustard alone are insufficient to provide adequate weed suppression in strawberry furrows.

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

Weed Science ◽  
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.

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

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 319 ◽  
Author(s):  
Laura Vincent-Caboud ◽  
Léa Vereecke ◽  
Erin Silva ◽  
Joséphine Peigné
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Crop Yields ◽  
Weed Suppression ◽  
Future Research ◽  
Weed Biomass ◽  
Cereal Rye ◽  
Cereal Grain ◽  
Crop Biomass

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.

scholarly journals Effects of Long-Term Cover Cropping on Weed Seedbanks

2020 ◽  
Vol 2 ◽  
Author(s):  
Virginia Nichols ◽  
Lydia English ◽  
Sarah Carlson ◽  
Stefan Gailans ◽  
Matt Liebman
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Production Systems ◽  
Early Spring ◽  
Weed Suppression ◽  
Winter Rye ◽  
Maize Crop ◽  
Cover Cropping ◽  
Crop Biomass

Cool-season cover crops have been shown to reduce soil erosion and nutrient discharge from maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] production systems. However, their effects on long-term weed dynamics are not well-understood. We utilized five long-term research trials in Iowa to quantify germinable weed seedbank densities and compositions after 10+ years of cover cropping treatments. All five trials consisted of zero-tillage maize-soybean rotations managed with and without the inclusion of a yearly winter rye (Secale cereal L.) cover crop. Seedbank sampling was conducted in the early spring before crop planting at all locations, with three of the five trials having grown a soybean crop the preceding year, and two a maize crop. Two of the trials (both previously soybean) showed significant and biologically relevant decreases (4,070 and 927 seeds m−2, respectively) in seedbank densities in cover crop treatments compared to controls. In another two trials, one previously maize and one previously soybean, no difference was detected in seedbank densities. In the fifth trial (previously maize), there was a significant, but biologically unimportant increase of 349 seeds m−2. All five trials' weed communities were dominated by common waterhemp [Amaranthus tuberculatus (Moq.)], and changes in seedbank composition from cover-cropping were driven by changes in this species. Although previous studies have shown that increases in cover crop biomass are strongly correlated with weed suppression, in our study we did not find a relationship between seedbank changes and the mean amount of cover crop biomass produced over a 10-years period (experiment means ranging from 0.5 to 2.0 Mg ha−1 yr−1), the stability of the cover crop biomass production, nor the amount produced going into the previous crop's growing season. We conclude that long-term use of a winter rye cover crop in a maize-soybean system has the potential to meaningfully reduce the size of weed seedbanks compared to winter fallows. However, identifying the mechanisms by which this occurs requires further research into processes such as seed predation and seed decay in cover cropped systems.

scholarly journals Weed suppression and early sugar beet development under different cover crop mulches

2017 ◽  
Vol 53 (No. 3) ◽  
pp. 187-193 ◽  
Author(s):  
Kunz Christoph ◽  
Sturm Dominic J ◽  
Sökefeld Markus ◽  
Gerhards Roland
Keyword(s):  
Sugar Beet ◽  
Cover Crops ◽  
Cover Crop ◽  
Raphanus Sativus ◽  
Field Experiments ◽  
Chenopodium Album ◽  
Sinapis Alba ◽  
Weed Suppression ◽  
Vicia Sativa ◽  
Stellaria Media

Field experiments were conducted at two locations in 2014–2015 and 2015–2016 to investigate the weed suppressive ability of cover crop mulches in sugar beets. Three cover crops and two cover crop mixtures were tested in all four experiments. Weed densities ranged from 2 up to 210 plants/m<sup>2</sup> in Chenopodium album L. and Stellaria media (L.) Vill. as predominant species. Sinapis alba grew significantly faster than Vicia sativa, Raphanus sativus var. niger, and both cover crop mixtures. Sinapis alba, Vicia sativa, Raphanus sativus var. niger reduced weed density by 57, 22, and 15% across all locations, respectively. A mixture of seven different cover crops reduced weed emergence by 64% compared to the control plot without cover crop mulch. Early sugar beet growth was enhanced by all mulch treatments in 2015 and decelerated in 2016.

scholarly journals Use of the Cover Crop Weed Index to Evaluate Weed Suppression by Cover Crops in Organic Citrus Orchards

HortScience ◽  
2008 ◽  
Vol 43 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Jose Linares ◽  
Johannes Scholberg ◽  
Kenneth Boote ◽  
Carlene A. Chase ◽  
James J. Ferguson ◽  
...  
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Field Experiments ◽  
Assessment Tool ◽  
Single Species ◽  
Organic Production ◽  
Weed Suppression ◽  
Initial Growth ◽  
Arachis Glabrata

Citrus is one of the most important crops in Florida. During the past decade, increased international competition and urban development, diseases, and more stringent environmental regulations have greatly affected the citrus industry. Citrus growers transitioning to organic production may benefit from premium prices, but they also face many challenges, including development of effective weed management strategies. Cover crops (CC) may constitute an environmentally sound alternative for improved weed management in organic systems. Two field experiments were conducted at Citra in north central Florida from 2002 to 2005, to evaluate the effectiveness of annual and perennial CC to suppress weeds in organic citrus groves. To quantify and compare the effectiveness of CC to suppress weed growth, a new weed suppression assessment tool, the cover crop/weed index (CCWI), was developed using the ratio of biomass accumulation of CC and weeds. Annual summer CC accumulated more biomass in comparison with winter CC. Sunnhemp (Crotalaria juncea L.), hairy indigo (Indigofera hirsuta L.), cowpea (Vigna unguiculata L. Walp.), and alyceclover (Alysicarpus vaginalis L.) all provided excellent weed suppression, which was superior to tillage fallow. Single-species winter CC did not always perform consistently well. Use of winter CC mixtures resulted in more consistent overall CC performance, greater dry matter production, and more effective weed suppression than single species of CC. Initial perennial peanut (PP) growth was slow, and summer planting of PP (Arachis glabrata Benth.) was determined to be the most effective date in terms of weed suppression, which was improved gradually over time, but all planting dates resulted in slow initial growth compared with annual CC. For both PP and annual CC, weed biomass typically was inversely related to CC dry weight accumulation resulting from competition for resources. The CCWI was a suitable tool to quantify CC performance in terms of weed suppression.

scholarly journals Developing Cover Crops for Weed Control in Establishment Year for Strawberries

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 820A-820
Author(s):  
Charlotte Herman ◽  
David Larson ◽  
Emily Hoover
Keyword(s):  
Winter Wheat ◽  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Plant Material ◽  
Weed Suppression ◽  
First Year ◽  
Growing Seasons ◽  
Stage Of Development ◽  
Soil Area

The goal of our program is to learn how to effectively establish first-year strawberry plantings without using herbicides. Before strawberry transplanting, four treatments were established: winter wheat, a dwarf Brassica sp., napropamide (2.24 kg·h–1) plus hand hoeing and rototilling, and no weed management. `Honeyoye' transplants were set into plots measuring 6.1 × 7.32 m on 21 May 1993 and 10 May 1994. Weekly data was taken on the percentage of soil area covered with plant material, height, and stage of development of plants, and weeds present. Weed transects and plant dry weights were done periodically during the growing seasons. The most promising cover crop treatment was the dwarf Brassica sp. for early season weed suppression because of rapid germination and short stature. Winter wheat was very competitive with the strawberry plants. The herbicide treatment had the largest inputs; however, it did produce the largest strawberry plants at the end of the season.

scholarly journals Combined effects of cover crops and herbicide rotation as proactive weed management in pineapple (Ananas comosus L. Merr) in Huimanguillo Tabasco, Mexico.

2021 ◽  
Author(s):  
RUBEN GARCIA DE LA CRUZ ◽  
Eustolia García- López
Keyword(s):  
Vigna Unguiculata ◽  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Field Experiments ◽  
Weed Suppression ◽  
Ananas Comosus ◽  
Mucuna Pruriens ◽  
Combined Effects ◽  
Reduced Rate

Objective: to evaluate the effect of two proactive strategies for weed management in pineapple, including (1) cover crop rotation and reduced rate of herbicide (RRH) and (2) cover crop association and RRH. Design/Methodology/Approach: We conducted pineapple field experiments in Huimanguillo, Tabasco Mexico, using a complete randomized block design for both rotation and association experiments. Weed occurrence were registered and classified. The weed management effect of cover crops such as cowpea (Vigna unguiculata), sunnhemp (Crotalaria juncea), stylo (Stylozanthes guanensis) and velvet bean (Mucuna pruriens) were evaluated alone and combined with three herbicides. Data of soil ground cover and  weed suppression levels were analyzed by one-way ANOVA and the means were separated by Least Significant Differences (LSD) at P = 0.05. Results:          Synergistic interaction was detected for weed suppression in all cover crops and herbicide treatments.  Combined effects of metribuzin and pendimethalin herbicides with cover crops varied from 80%- 90 % of weed suppression until 90 days after treatment (DAT); however, when cover crops were combined with haloxifop plus diuron, 100 %   of weed control was achieved until 90 DAT.   Study limitations/implications. Irrigation, weather conditions may affect observations. Findings/Conclusions: Our results showed that all cover crops, specially Vigna unguiculata and Mucuna pruriens in a rotation system, along with reduced rate of herbicides is novel approach strategy for weed management in pineapple plantation. Cover crops such as cowpea might improve crop performance, productivity and feasibility for farmers. The reduced rates of preemergence herbicides and cover crops will be very helpful for the farmers and for protection of environment. Keywords:  Cover crops, Anananas comosus, herbicide, weed suppression, integrated weed management

scholarly journals Time of Interseeding of Lana Vetch and Winter Rye Cover Strips Determines Competitive Impact on Pumpkins Grown Using Organic Practices

HortScience ◽  
2005 ◽  
Vol 40 (6) ◽  
pp. 1716-1722 ◽  
Author(s):  
Steven Vanek ◽  
H.C. Wien ◽  
Anu Rangarajan
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Soil Water Potential ◽  
Weed Suppression ◽  
Dominant Factor ◽  
Yield Reduction ◽  
Winter Rye ◽  
Soil Nitrate ◽  
Vicia Villosa

Growing a main vegetable crop for harvest and a cover crop for residue return to soil in the same growing season is a promising strategy to sustain soil quality in vegetable rotations. Our research evaluated cover crop strips interseeded between pumpkins (Cucurbita pepo L.) as a way to implement such a strategy. Cover crop types were lana vetch (Vicia villosa ssp. dasycarpa Ten.) and a lana vetch–winter rye (Secale cereale L.) mix, interseeded before, at the same time, or after pumpkins. The competitive impact of different cover crop strips was assessed using pumpkin yield, cover strip biomass, crop nitrogen status, soil nitrate status, and soil water potential. Cover strips were also assessed for competitiveness with native weeds. Seeding date affected the competitiveness of cover strips with pumpkins, while cover type did not. Cover crops seeded before pumpkins or at the same time reduced pumpkin yield in proportion to biomass produced by the cover strips early in pumpkin growth. Cover strips seeded after pumpkins did not reduce yield. Tilling in a before-seeded cover strip at 30 days after pumpkin seeding gave higher pumpkin yield than before-seeded cover strips that were not tilled. At three of four sites, after-seeded cover strips had the lowest percent weed biomass in strips, and at two sites with moderate weed pressure vetch–rye strips were more effective than vetch alone in suppressing weeds. Cover strips seeded before or at the same time as pumpkins reduced pumpkin yield by taking up resources that were otherwise available to pumpkins. At a high-rainfall site, competition for soil nitrate by cover crop strips was the dominant factor in reducing pumpkin yield. At a low-rainfall site, the dominant factor was competition for water. Because of effective weed suppression and lack of pumpkin yield reduction, interseeding vetch–rye strips after pumpkins was a promising practice, as was tilling in preexistent cover strips at an interval <30 days after pumpkin seeding. Good previous weed management and rye–vetch mixes at high seeding rates are necessary to allow interseeded cover strips to outcompete weeds.

scholarly journals Preplant Cover Crops Affect Weed and Vine Growth in First-year Vineyards

HortScience ◽  
1997 ◽  
Vol 32 (6) ◽  
pp. 1040-1043 ◽  
Author(s):  
Bruce P. Bordelon ◽  
Stephen C. Weller
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Cover Crop ◽  
Dry Mass ◽  
Weed Suppression ◽  
First Year ◽  
Hairy Vetch ◽  
Vicia Villosa ◽  
Weed Density ◽  
Vine Growth

Use of in-row cover crops for weed management in first-year vineyards was investigated in two studies. In the first study, rye (Secale cereal L. 'Wheeler') was fall-planted, overwintered, then managed by three methods before vine planting. Rye was either herbicide-desiccated with glyphosate and left on the surface as a mulch, mowed, or incorporated into the soil (cultivated). Weed density and growth of grapevines (Vitis spp.) were evaluated. Herbicide desiccation was superior to the other methods for weed suppression, with weed densities 3 to 8 times lower than for mowed or cultivated plots. Vine growth was similar among treatments, but the trend was for more shoot growth with lower weed density. In a second study, four cover crops, rye, wheat (Triticum aestivum L. 'Cardinal'), oats (Avena sativa L. 'Ogle'), and hairy vetch (Vicia villosa Roth), were compared. Wheat and rye were fall- and spring-planted, and oats and vetch were spring-planted, then desiccated with herbicides (glyphosate or sethoxydim) after vine planting and compared to weed-free and weedy control plots for weed suppression and grapevine growth. Cover crops provided 27% to 95% reduction in weed biomass compared to weedy control plots. Total vine dry mass was highest in weed-free control plots, was reduced 54% to 77% in the cover crop plots, and was reduced 81% in the weedy control. Fall-planted wheat and rye and spring-planted rye plots produced the highest vine dry mass among cover crop treatments. Spring-planted rye provided the best combination of weed suppression and vine growth. Chemical names used: N-(phosphonomethyl) glycine (glyphosate isopropylamine salt); 2-[l-(ethoxyimino)butyl]5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim).

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