Is allelopathy from winter cover crops affecting row crops?

Koehler‐Cole, Katja; Everhart, Sydney E.; Gu, Yan; Proctor, Christopher A.; Marroquin-Guzman, Margarita; Redfearn, Daren D.; Elmore, Roger W.

doi:10.1002/ael2.20015

Cited by 18 publications

(14 citation statements)

References 33 publications

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“…Earlier planting and later terminating allow cover crops to achieve larger biomass, which directly benefits SOC but has the risk of reducing maize yield and maize residue (Qin et al, 2021). In addition to the competition for resources (e.g., N, water, and oxygen), the allelopathy effects of winter cover crops may also negatively affect cash crop growth (Koehler‐Cole et al, 2020). Allelopathy effects suggest that chemicals released by cover crops into the soil may inhibit the growth of following cash crops (Zhang et al, 2021), which could be another reason for the trade‐off between cover crop biomass and cash crop yield.…”

Section: Resultsmentioning

confidence: 99%

Assessing long‐term impacts of cover crops on soil organic carbon in the central US Midwestern agroecosystems

Qin

Guan

Zhou

et al. 2023

Global Change Biology

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Cover crops have been reported as one of the most effective practices to increase soil organic carbon (SOC) for agroecosystems. Impacts of cover crops on SOC change vary depending on soil properties, climate, and management practices, but it remains unclear how these control factors affect SOC benefits from cover crops, as well as which management practices can maximize SOC benefits. To address these questions, we used an advanced process-based agroecosystem model, ecosys, to assess the impacts of winter cover cropping on SOC accumulation under different environmental and management conditions. We aimed to answer the following questions: (1) To what extent do cover crops benefit SOC accumulation, and how do SOC benefits from cover crops vary with different factors (i.e., initial soil properties, cover crop types, climate during the cover crop growth period, and cover crop planting and terminating time)? (2) How can we enhance SOC benefits from cover crops under different cover crop management options? Specifically, we first calibrated and validated the ecosys model at two long-term field experiment sites with SOC measurements in Illinois.We then applied the ecosys model to six cover crop field experiment sites spanning across Illinois to assess the impacts of different factors on SOC accumulation. Our modeling results revealed the following findings: (1) Growing cover crops can bring SOC benefits by 0.33 ± 0.06 MgC ha −1 year −1 in six cover crop field experiment sites across Illinois, and the SOC benefits are species specific to legume and non-legume cover crops. (2) Initial SOC stocks and clay contents had overall small influences on SOC benefits from cover crops. During the cover crop growth period (i.e., winter and spring in the US Midwest), high temperature increased SOC benefits from cover crops, while the impacts from larger precipitation on SOC benefits varied field by field. (3) The SOC benefits from cover crops can be maximized by optimizing cover crop management practices (e.g., selecting cover crop types and controlling cover crop growth period) for the US Midwestern maize-soybean rotation system. Finally, we discussed the economic and policy implications of adopting cover crops in the US Midwest, including that current economic incentives to grow cover crops may not be sufficient to cover costs. This study systematically assessed cover crop impacts for SOC change in the US Midwest context, while also demonstrating that the ecosys | 2573 QIN et al.

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Section: Resultsmentioning

confidence: 99%

Assessing long‐term impacts of cover crops on soil organic carbon in the central US Midwestern agroecosystems

Qin

Guan

Zhou

et al. 2023

Global Change Biology

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“…Disease occurrence may be mitigated by placing corn rows at greater distance from cover crop residue (Kurtz et al., 2021) and delaying corn planting by 10–14 d after cover crop termination (Acharya et al., 2017). Allelopathic chemicals secreted by cover crops have stunted corn seedling growth in laboratory experiments, but allelopathic reactions are likely transient and have rarely been confirmed in the field (Koehler‐Cole, Everhart, et al., 2020). Cover crop water use can have negative effects on subsequent crops (Rosa et al., 2021), but soil water measurements during the first 3 yr of this study revealed no deficits due to cover crops (Barker et al., 2018).…”

Section: Resultsmentioning

confidence: 99%

Cover crop planting practices determine their performance in the U.S. Corn Belt

et al. 2023

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Cover crop growing periods in the western U.S. Corn Belt could be extended by planting earlier. We evaluated both pre-harvest broadcast interseeding and post-harvest drilling of the following cover crops: (a) cereal rye (Secale cereale L.) [RYE]; (b) a mix of rye + legumes + brassicas [MIX1], (c) a mix of rye + oat [Avena sativa L.] + legumes + brassicas (MIX2), (d) legumes [LEGU]) and (e) a no cover crop control. These were tested in continuous corn (Zea mays L.) [corn-corn] and soybean [Glycine max (L.) Merr.]-corn systems [soybean-corn] at three sites in Nebraska for their effect on cover crop productivity, soil nutrients, and subsequent corn performance. At the sites with wet fall weather, pre-harvest broadcasting increased cover crop biomass by 90%, to 1.29 Mg ha −1 for RYE and 0.87 Mg ha −1 for MIX1 in soybean-corn, and to 0.56 Mg ha −1 and 0.39 Mg ha −1 in corn-corn, respectively. At the drier site, post-harvest drilling increased biomass of RYE and MIX1 by 95% to 0.80 Mg ha −1 in soybean-corn. Biomass N uptake was highest in pre-harvest RYE and MIX1 at two sites in soybean-corn (35 kg ha −1 ). RYE and sometimes mixes reduced soil N, but effects on P, K, and soil organic C were inconsistent. In soybean-corn, corn yields decreased by 4% after RYE, and in corn-corn, by 4% after pre-harvest cover crops. Site-specific selection of cover crops and planting practices can increase their performance while minimizing impacts on corn.Abbreviations: CON, control without cover crops; GDD, growing degree days; LEGU, legume cover crop blend consisting of hairy vetch and winter pea; MIX1, cover crop mix consisting of cereal rye, hairy vetch, winter pea, and radish; MIX2, cover crop mix consisting of cereal rye, hairy vetch, winter pea, radish, oat, collard, clover; RYE, cereal rye cover crop.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…Some studies have reported allelopathic effects of the cover crops on the following cash crop [ 85 ]. Koehler-Cole et al [ 86 ] published a review on the allelopathic effect of winter cover crops on several row cash crops. Legumes, such as velvet bean ( Mucuna pruriens ), have also been reported to have suppressive effects on weeds in a field experiment in Mexico with corn [ 87 ], which perhaps is an example of physical rather than allelopathic suppression.…”

Section: Mechanisms Of Weed Suppression By Cover Cropsmentioning

confidence: 99%

The Potential of Cover Crops for Weed Management: A Sole Tool or Component of an Integrated Weed Management System?

Fernando

Shrestha

2023

Plants

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Cover crops are an important component of integrated weed management programs in annual and perennial cropping systems because of their weed suppressive abilities. They influence weed populations using different mechanisms of plant interaction which can be facilitative or suppressive. However, the question often arises if cover crops can be solely relied upon for weed management or not. In this review we have tried to provide examples to answer this question. The most common methods of weed suppression by an actively growing cover crop include competition for limited plant growth resources that result in reduced weed biomass, seed production, and hence reductions in the addition of seeds to the soil seedbank. Cover crop mulches suppress weeds by reducing weed seedling emergence through allelopathic effects or physical effects of shading. However, there is a great degree of variability in the success or failure of cover crops in suppressing weeds that are influenced by the cover crop species, time of planting, cover crop densities and biomass, time of cover crop termination, the cash crop following in the rotation, and the season associated with several climatic variables. Several studies demonstrated that planting date was important to achieve maximum cover crop biomass, and a mixture of cover crop species was better than single cover crop species to achieve good weed suppression. Most of the studies that have demonstrated success in weed suppression have only shown partial success and not total success in weed suppression. Therefore, cover crops as a sole tool may not be sufficient to reduce weeds and need to be supplemented with other weed management tools. Nevertheless, cover crops are an important component of the toolbox for integrated weed management.

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Is allelopathy from winter cover crops affecting row crops?

Cited by 18 publications

References 33 publications

Assessing long‐term impacts of cover crops on soil organic carbon in the central US Midwestern agroecosystems

Assessing long‐term impacts of cover crops on soil organic carbon in the central US Midwestern agroecosystems

Cover crop planting practices determine their performance in the U.S. Corn Belt

The Potential of Cover Crops for Weed Management: A Sole Tool or Component of an Integrated Weed Management System?

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