Weeds in Cover Crops: Context and Management Considerations

Barbara Baraibar,David A. Mortensen,Mitchell C. Hunter,Denise M. Finney,Charles M. White,Mary E. Barbercheck,Jess Bunchek,William S. Curran,Jason P. Kaye

doi:10.3390/agriculture11030193

Barbara Baraibar, David A. Mortensen + Show 7 more

Open Access

https://doi.org/10.3390/agriculture11030193

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Abstract

Cover crops are increasingly being adopted to provide multiple ecosystem services such as improving soil health, managing nutrients, and decreasing soil erosion. It is not uncommon for weeds to emerge in and become a part of a cover crop plant community. Since the role of cover cropping is to supplement ecosystem service provisioning, we were interested in assessing the impacts of weeds on such provisioning. To our knowledge, no research has examined how weeds in cover crops may impact the provision of ecosystem services and disservices. Here, we review services and disservices associated with weeds in annual agroecosystems and present two case studies from the United States to illustrate how weeds growing in fall-planted cover crops can provide ground cover, decrease potential soil losses, and effectively manage nitrogen. We argue that in certain circumstances, weeds in cover crops can enhance ecosystem service provisioning. In other circumstances, such as in the case of herbicide-resistant weeds, cover crops should be managed to limit weed biomass and fecundity. Based on our case studies and review of the current literature, we conclude that the extent to which weeds should be allowed to grow in a cover crop is largely context-dependent.

Highlights

As our understanding of ecological processes in agroecosystems improves, cropping systems are increasingly viewed as comprising interdependent component parts that interact to shape ecosystem processes that can be beneficial, neutral, or detrimental to human interests [1]
The mean soil cover provided by cover crops was 85.5%, and the potential for modelled relative soil losses was lower in November than in October for all treatments
Nitrate leaching under legume cover crops declined as N uptake by weed species growing in the cover crop increased (Figure 3)

Summary

Introduction

As our understanding of ecological processes in agroecosystems improves, cropping systems are increasingly viewed as comprising interdependent component parts (i.e., soil, crops, weeds, water, etc.) that interact to shape ecosystem processes that can be beneficial, neutral, or detrimental to human interests [1]. When a component of the ecosystem contributes to beneficial processes, it conveys an ecosystem service [2]. Sometimes a component or process contributes to an undesirable outcome and contributes to an ecosystem disservice. Examples of ecosystem services can be found in abundance in the literature, while examples of disservices are not as common [3,4]. Food provisioning from a crop is widely recognized as an ecosystem service, while an insect pest outbreak would be seen as a disservice. There are many cases where the role of a component of the ecosystem is ambiguous. Intraguild predation is an example of such ambiguity, where beneficial insects (e.g., predators) consume insect pests and other predators [5]

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