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Agroecosystems are increasingly expected to provide multiple ecosystem services. We tested whether and how cover crop selection (identity and number of species) affects provisioning of multiple services (multifunctionality). In a 3-yr study of 10 cover crop treatments and eight ecosystem services, certain services consistently co-occurred. One such service “bundle” included cover crop biomass production, weed suppression, and nitrogen retention. Another set of bundled services included cash crop production, nitrogen supply, and profitability. We also identified trade-offs: as some services increased, other disservices arose, limiting multifunctionality. However, functionally diverse mixtures ameliorated disservices associated with certain monocultures, thereby increasing cover crop multifunctionality.
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C  are widely used to improve soil quality, weed manage-
ment, pest regulation, nutrient cycling, and crop yield (Snapp et al.,
2005; Blanco-Canqui et al., 2015; CTIC, SARE, and ASTA, 2016). is
array of ecosystem services suggests that cover crops are “multifunctional,
although current knowledge is primarily derived from studies of single or
disciplinary-focused subsets of services (Schipanski et al., 2014). Furthermore,
processes that enable cover crop multifunctionality are not well understood.
Increasing cover crop diversity, for example, can enhance multifunctional-
ity (Finney and Kaye, 2017), but not all services respond in the same manner
(Finney et al., 2016). Cover crops can also introduce disservices, leading to an
outcome worse than not planting a cover crop (Finney et al., 2016).
Managing cover crops for multifunctionality requires knowledge of how
service interactions are inuenced by species identity and diversity (Carpenter
et al., 2009). Interactions arise when the provisioning of one service leads to
changes in another or when the same factor drives a change in multiple services,
leading to co-occurring or “bundled” services (Bennett et al., 2009; Raudsepp-
Hearne et al., 2010; Storkey et al., 2015; Finney et al., 2016). As one example of
linked services, high nitrogen (N) retention in grass cover crops can lead to low
N supply (low residue mineralization) and low yields in the subsequent cash
crop (Finney et al., 2016; White et al., 2017).
Common approaches to analyzing multifunctionality do not highlight inter-
actions that lead to service synergies or trade-os. Multifunctionality is typi-
cally calculated as an average of standardized values (Maes et al., 2012; Byrnes
et al., 2014; Storkey et al., 2015; Finney and Kaye, 2017). Yet, averaging masks
how individual services respond to diversity because increases and decreases in
individual services can average each other out (Byrnes et al., 2014).
Here, we evaluate cover crop multifunctionality based on eight ecosystem
services measured for three consecutive years in 10 cover crop treatments using
Ecosystem Services and Disservices Are
Bundled in Simple and Diverse Cover
Cropping Systems
Denise M. Finney,* Ebony G. Murrell, Charles M. White, Barbara Baraibar,
Mary E. Barbercheck, Brosi A. Bradley, Sarah Cornelisse,
Mitchell C. Hunter, Jason P. Kaye, David A. Mortensen,
Christina A. Mullen, and Meagan E. Schipanski
Copyright © American Society of Agronomy, Crop
Science Society of America, and Soil Science Society of
America. 5585 Guilford Rd., Madison, WI 53711 USA.
This is an open access article distributed under the
terms of the CC BY-NC-ND license (http://creativecom-
mons.org/licenses/by-nc-nd/4.0/)
Agric. Environ. Lett. 2:170033 (2017)
doi:10.2134/ael2017.09.0033
Received 15 Sep. 2017.
Accepted 18 Oct. 2017.
*Corresponding author (dnney@ursinus.edu).
Agricultural &
Environmental
Letters
Research Letter
Abstract: Agroecosystems are increasingly expected to provide multiple ecosystem
services. We tested whether and how cover crop selection (identity and number of
species) aects provisioning of multiple services (multifunctionality). In a 3-yr study
of 10 cover crop treatments and eight ecosystem services, certain services consistently
co-occurred. One such service “bundle” included cover crop biomass production,
weed suppression, and nitrogen retention. Another set of bundled services included
cash crop production, nitrogen supply, and protability. We also identied trade-
os: as some services increased, other disservices arose, limiting multifunctionality.
However, functionally diverse mixtures ameliorated disservices associated with
certain monocultures, thereby increasing cover crop multifunctionality.
D.M. Finney, E.G. Murrell, C.M. White, B.A. Bradley,
and J.P. Kaye, Dep. of Ecosystem Science and
Management, Penn State Univ., University Park,
PA; D.M. Finney, Ursinus College, Biology Dep.,
Collegeville, PA; B. Baraibar, M.C. Hunter, and D.A.
Mortensen, Dep. of Plant Science, Penn State
Univ., University Park, PA; M.E. Barbercheck and
C.A. Mullen, Dep. of Entomology, Penn State Univ.,
University Park, PA; S. Cornelisse, Dep. of Agricultural
Economics, Sociology, and Education, Penn State
Univ., University Park, PA; M.E. Schipanski, Dep. of
Crop and Soil Sciences, Colorado State Univ., Fort
Collins, CO.
Core Ideas
• Cover crop monocultures and mixtures support
multiple ecosystem services.
• Service interactions can lead to bundling, or
co-occurrence, of certain services.
• Service interactions also create trade-os
among services and disservices.
• Cover crop mixtures can mitigate disservices to
increase multifunctionality.
Abbreviations: PCA, principal components analysis.
Published online November 9, 2017
Page 2 of 5 AGRICULTURAL & ENVIRONMENTAL LETTERS
a quantitative approach to assess multifunctionality and
service interactions. We expect that (i) interactions among
services lead to service bundles and trade-os, (ii) mixtures
provide greater multifunctionality than monocultures, and
(iii) increasing functional diversity in mixtures enhances
multifunctionality.
Materials and Methods
From 2012 to 2015 on land transitioning to organic certi-
cation in Rock Springs, PA (40°43¢ N, 77°55¢ W), 10 cover
crop treatments (Table 1) and a no-cover crop control (here-
aer, “control”) were planted aer wheat (Triticum aestivum
L.) and terminated prior to planting maize (Zea mays L.;
Murrell et al., 2017). We quantied eight ecosystem services
provided by cover crops for three consecutive years. e
cover crop biomass (hereaer, “biomass”) production ser-
vice was the fall plus spring aboveground biomass (kg ha-1)
sampled as in Murrell et al. (2017). e weed suppression
service was the fall plus spring weed biomass minus weed
biomass in the control (Baraibar et al., 2017). e N reten-
tion service was nitrate (NO3
-–N) accumulation on anion
exchange resin bags (169 cm2 surface area buried at 25 cm)
from cover crop planting to termination (kg NO3–N ha-1)
minus NO3–N accumulated in the control (Finney et al.,
2016). Pest suppression was indexed by infection of senti-
nel insects by Metarhizium (Order: Hypocreales; Family:
Clavicipitaceae), an entomopathogenic fungus widely
researched as a control agent against soil-inhabiting arthro-
pod pests. For 7 to 10 d prior to cover crop termination, we
placed 15 last instar greater wax moth, Galleria mellonella
(Zimmermann, 1986), in a lidded container with soil from
the plot. e pest suppression service was the percentage of
sentinel insects infected by Metarhizium in the cover crop
minus the control. e active soil carbon (C) service was cal-
culated as permanganate oxidizable C (mg C kg-1 soil; Weil
et al., 2003; Culman et al., 2012) in each cover crop treatment
minus the control. Eleven soil cores (2.5 cm diam. by 20 cm
deep) per plot were collected and composited for analysis on
two dates, before (May) and aer (July) cover crop termina-
tion. Nitrogen supply was calculated using a previously cali-
brated model that predicts the eects of cover crop residues
and N uptake on N availability to subsequent maize crops,
relative to a no-cover control (White et al., 2016). e model
inputs were fall and spring cover crop biomass N per unit
area, spring biomass C/N ratio, and spring soil NO3
- con-
centrations for each plot. e cash crop production service
(Mg ha-1) was corn silage yield (hand harvested from two
5.3-m row lengths per plot) at 65% moisture following each
cover crop minus yield in the control, both grown without
supplemental fertility inputs. Using annual enterprise bud-
gets for each treatment, the short-term protability service
was calculated as annual prot associated with each cover
crop minus the control.
e measured value of each service proxy was relativ-
ized to the control within the same year (Finney et al., 2016)
so that a higher value always indicates greater provision.
Positive values indicate that the cover crop performed better
than the control (hereaer, “service”). Negative values indi-
cate that the cover crop performed worse than the control
(hereaer, “disservice”). Service values were divided by their
standard deviation to put values on a comparable scale while
retaining directionality (positive = service; negative = dis-
service). To identify interactions among ecosystem services,
we performed principal components analysis (PCA) on stan-
dardized values (R package vegan; Oksanen et al., 2016).
To create an average multifunctionality index for each
cover crop treatment, standardized values for services exhib-
iting a signicant response to cover crop treatment (P < 0.05,
mixed-model ANOVA, R package lmer4; Bates et al., 2015)
were averaged together. Treatment dierences for aver-
age multifunctionality were determined by ANOVA with
year and block as random eects using Tukey’s adjustment
(PROC MIXED, SAS v. 9.4 [SAS Institute, 2014]). Preplanned
contrasts detected dierences between monocultures and
multispecies mixtures. e eect of species richness (S, the
number of cover crop species in aboveground biomass) on
multifunctionality for all treatments was analyzed using a
mixed model (R package lmer4; Bates et al., 2015) with block
and year as random eects. Multifunctionality and S were
log-transformed to provide the best t for the model and
marginal R2 calculated following Nakagawa and Schielzeth
(2013). Functional diversity of cover crop mixtures was
Table 1. Cover crop monoculture and mixture seeding rates planted aer wheat in a 3-yr wheat–maize silage–soybean rotation in central
Pennsylvania. Average multifunctionality value is based on seven ecosystem services. Modied from Murrell et al. (2017).
Cover crop Medium red
clover
Winter canola
‘Wichita
Forage radish
‘Tillage radish’
Cereal rye
Aroostook’
Oat
‘Jerry’
Austrian winter
pea
Average
multifunctionality
—————————————————————— p l a nt s m-2 ——————————————————————
Red clover 600 0.66de†
Canola 400 0.64de
Radish 60 0.92bcd
Rye 500 0.34e
Oat 300 0.92bcd
Pea 60 1.47a
3 species nitrogen 300 0 0 100 0 30 1.09b
3 species weed 300 0 0 250 150 0 0.77cd
4 species 300 200 0 100 0 30 1.08bc
6 species 150 100 20 100 75 15 0.94bcd
† Letters denote statistical dierences based on Tukey’s HSD (a = 0.05).
AGRICULTURAL & ENVIRONMENTAL LETTERS Page 3 of 5
estimated using relative Rao’s quadratic entropy
(rRao; Rao, 1982). Relative Rao was calculated in
FDiversity soware (Casanoves et al., 2011) based
on four cover crop characteristics: fall growth
potential, spring growth potential, peak C/N ratio,
and taxonomic family (Finney and Kaye, 2017). We
used mixed models (PROC MIXED, SAS 9.4), with
block and year as random eects, to test the rela-
tionship between rRao and (i) average multifunc-
tionality, (ii) mean service (standardized service
scores > 0), and (iii) mean disservice (standardized
service scores < 0) in cover crop mixtures.
Results
Biomass production, weed suppression, and N
retention services were provided by all treatments
(Fig. 1) and bundled in the PCA (clustered in Fig.
2). Cash crop production, N supply, and protabil-
ity formed a second bundle (clustered in Fig. 2).
ere was a trade-o between these two bundles as
they dierentiated along principle component (PC)
1, which explained 40% of the variation in cover
crop services (Fig. 2). Principle component 2, which
explained 16% of variation in services, was driven
by active soil C and pest suppression (Fig. 2).
Multifunctionality was based on seven services:
biomass production, weed suppression, N reten-
tion, pest suppression, N supply, cash crop produc-
tion, and protability. Active soil C was not dierent
among treatments (P = 0.18) and was excluded from
the index. Although mixtures on average outper-
formed monocultures (estimate = 0.15, P = 0.002),
the pea (Pisum sativum L.) monoculture exhibited
the highest multifunctionality of all treatments
(Table 1). ere was a positive relationship between
S and multifunctionality (log[multifunctionality
+ 1] = 0.22 + 0.10*log[S + 1], marginal R2 = 0.03).
Within mixtures, average multifunctionality
increased (P = 0.01) with increasing functional diversity
(rRao) because disservices (scores < 0 in Fig. 1) decreased
as rRao increased (P < 0.001). In contrast, services (scores
> 0 in Fig. 1) were not related to changes in rRao (P = 0.71).
Discussion
e temporal and spatial co-occurrence, or bundling,
of ecosystem services is typically evaluated at landscape
scales, frequently with dierentiation among land uses
(Raudsepp-Hearne et al., 2010; Maes et al., 2012). Within
our eld-based study, ecosystem services provided by cover
crops were bundled into groups linked to aboveground
biomass production and those linked to N supply. In gen-
eral, we found few cover crop treatments that provided all
ecosystem services because of a central trade-o between
the biomass (biomass production, N retention, and weed
suppression) and nutrient (N supply, cash crop production,
and protability) service bundles (PC1, Fig. 2). In legume
monocultures, both bundles were supported, but there was
large variation between species, as pea exhibited the high-
est multifunctionality index across all treatments whereas
red clover (Trifolium pretense L.) was among the lowest. e
high multifunctionality of pea was due to adequate provi-
sioning of many services with no signicant disservices.
Red clover also provided many services and only one dis-
service, but the magnitude of individual services was low,
leading to low multifunctionality (Fig. 1).
Overwintering nonlegume monocultures exhibited more
extreme trade-os, in which robust provisioning of the bio-
mass bundle was accompanied by disservices in the nutrient
bundle. is is consistent with disciplinary studies showing
that legume cover crops that supply N retain less N than non-
legume cover crops (Tonitto et al., 2006). Conversely, cover
crops with high N retention potential (e.g., cereal rye [Secale
cereale L.]) are oen associated with N immobilization lead-
ing to cash crop provision disservices (Wagger, 1989; Finney
et al., 2016). An important implication of our results is that
managing a trade-o like that between N supply and N
retention by manipulating the cover crop C/N ratio (Finney
Fig. 1. Ecosystem services (values > 0) and disservices (values < 0) provided
by 10 cover crop treatments incorporated in a wheat–maize silage–soybean
rotation in a 3-yr eld study in central Pennsylvania. See Table 1 for species
included in each cover crop mixture.
Page 4 of 5 AGRICULTURAL & ENVIRONMENTAL LETTERS
et al., 2016) may have implications for other nontar-
get services in the bundle.
Although increasing species richness had a posi-
tive eect on multifunctionality, it explained only
3% of the variation in multifunctionality. is out-
come, coupled with the variable performance of
monocultures, suggests that species number is less
important to multifunctionality than the variety of
traits present in a cover crop mixture. Functional
diversity measures like rRao are commonly used
to quantify trait variation (Cadotte et al., 2011).
Consistent with previous research on the eects of
pre-maize cover crop diversity on multifunctional-
ity (Finney and Kaye, 2017), increasing functional
diversity increased multifunctionality of cover crop
mixtures. e fact that rRao reects both the diver-
sity of species traits and their relative abundance in
a mixture indicates that multifunctionality was not
based solely on the presence or absence of a par-
ticular species (Gagic et al., 2015). Notably, more
functionally diverse mixtures increased multifunc-
tionality by ameliorating disservices associated with
component species, not by enhancing services. In
this study, cereal rye was included in all mixtures
and comprised 20 to 40% of fall and 70 to 90% of
spring aboveground biomass (Murrell et al., 2017).
Rye was exceptional in providing services in the
biomass bundle, but it had high disservice scores
for the nutrient bundle. Multispecies mixtures
were an eective tool for managing these trade-os because
mixing rye with other species ameliorated the strong nutri-
ent bundle disservices.
Awareness of common service bundles and trade-os
among them can help farmers and agronomists design
multifunctional cover crop treatments that avoid damag-
ing disservices. Our study demonstrates that while cover
crop mixtures tend to have greater multifunctionality than
monocultures, certain monocultures may provide simi-
lar (oat [Avena sativa L.], radish [Raphanus sativus L.])
or greater (pea) multifunctionality than diverse mixtures.
Selecting a monoculture cover crop to support a single
management goal will likely lead to provision of additional,
bundled services but may also introduce disservices. is
research demonstrates that mitigation of such trade-os
can be achieved with the use of functionally diverse cover
crop mixtures.
Acknowledgments
We thank Dayton Spackman, James LaChance, Alan Cook, and
the sta of the Russell E. Larson Agricultural Research Center
for planting, managing, and assisting in data collection in our
experimental plots, D. Wilson of King’s Agriseed and our Farmer
Advisory Committee for their recommendations on seeding rates
and planting practices for cover crop treatments, and numerous
undergraduate assistants for assistance with data collection. is
project was primarily funded by a grant from the USDA National
Institute of Food and Agriculture Organic Agriculture Research
and Extension Initiative (2011-51300-30638). Additional funding
was provided by USDA NIFA grant 2012-67012-22889. is
material is based on work supported by the National Science
Foundation under Grant no. DGE1255832. Any opinions, ndings,
and conclusions or recommendations expressed in this material are
those of the authors and do not necessarily reect the views of the
National Science Foundation.
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... The integration of non-commercial cover crop species into annual crop rotations to increase sustainability in agricultural practices and pest regulation has gained significant interest among farmers as well as stakeholders (Schipanski et al., 2014). Cover crop rotation provides a wide range of ecosystem services that includes nutrient recycling, increase soil health, suppression of weeds, etc. (Finney et al., 2017). Cover crops also benefit agroecosystems when plants, such as the leguminous cover crop pea (Pisum sativum L. ssp. ...
... Post-hoc means separation was done using Tukey test at p < 0.05 and treatments that are significantly different from each other are denoted by different letters (details of ANOVA results in table S1). implicated in increasing numerous edaphic properties, nutrient cycling and weed suppression in organic agricultural systems that may add towards sustainable intensification of agriculture (Chapagain et al., 2020;Finney et al., 2017). However, the indirect benefits of cover crops and their soil legacy in altering agroecosystems with emphasis on pest and pathogen suppression is relatively understudied. ...
... We also show that maize plants that were grown in soil with pea as preceding cover crop was resistant to stem rot by F. verticillioides (Fig. 3b). Maize plants grown in soil with pea as cover crop have been shown to have significantly higher nitrogen levels in their tissues (Finney et al., 2017;Murrell et al., 2019). Higher levels of nitrogen in soil has been correlated with reduced disease severity by Fusarium sp. ...
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In this study, we show the impact of cover crop legacy in soil towards susceptibility of next generation maize to the fungal pathogen Fusarium verticillioides. The use of different plant species as cover crops in organic cropping systems has been shown to provide several ecosystem services. The direct benefits of using leguminous cover crops such as pea or mycorrhizal species such as cereal rye or oats for soil fertility and cash crop yield are well known. However, the impacts of different cover crop species on subsequent cash crop pest suppression is rarely accounted for in agricultural management. Legacy of cover crop species are of importance considering recent findings that plants promoting arbuscular mycorrhizal communities, such as cereal rye and oats as cover crops, can provide increased benefits to successive maize crops against insect pests. In this study, we test whether such benefits might also include resistance against pathogens. We examined progression of rot lesions in ear, stalk and seedling blight by Fusarium verticillioides in maize plants that were grown in soil with a cover crop monoculture history of either winter pea, triticale or radish. This study shows for the first time that soil legacy of mycorrhizal monocot triticale as a cover crop renders maize plants more susceptible to ear rot and seedling blight by Fusarium verticillioides as compared to a soil legacy of radish. This suggests that although soil legacy of radish may be detrimental to management of insects, it is effective in suppressing progression of Fusarium verticillioides in maize. This work demonstrates the significance of cover crop selection to manage fungal pathogens such as Fusarium verticillioides, it further suggests trade-offs in plant resistance to various pests’ taxa at the cover crop species level.
... Biomass is commonly used indicator to quantify competition between CC and weeds because it results from resource availability and competitive outcome with neighbouring plants (ability to tolerate or suppress) (Trinder et al., 2021). Thus, most authors reporting a weed suppressive effect of CC showed a negative relationship between CC and weed biomass (Finney et al., 2017;Wittwer et al., 2017;Osipitan et al., 2019), probably because of a greater ability of CC to uptake soil resources, produce biomass and shade competing weeds. Nevertheless, a recent study from Adeux et al. (2021) showed that the relationship between weed and CC biomass was dependent on CC species, with Brassica juncea being more weed suppressive than Vicia villosa at low levels of CC biomass. ...
... In contrast, irrigation increased weed biomass whereas biomass of CC mixtures remained stable. Besides, in 5 out of 8 CC mixture:year combinations, the relationship between weed and CC biomass was negative as previously observed many times (Finney et al., 2017;Wittwer et al., 2017;Osipitan et al., 2019), but the major part of weed suppression was done at low levels of CC biomass (< 200 g DM m -2 ). In the other 3 out of 8 CC mixture:year combinations, no relationship between weed and CC biomass was found, suggesting that nitrogen fertilisation did not hastened CC canopy close, which did not limited weed growth. ...
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Cover crop (CC) mixtures appear as a promising agroecological tool for weed management. Although CC supress weed growth by competing for resources, their suppressive effect under contrasting levels of soil resource availability remains poorly documented. A two field:year experiment was conducted to investigate the weed suppressive effect of four CC mixtures. They were composed of 2 or 8 species including or not legume species and compared to a bare soil control. The experiment included two levels of irrigation and nitrogen fertilisation at CC sowing. The objectives were to assess (i) weed and CC aboveground biomass response to CC mixtures and resource availability, (ii) the weed suppressive effect of CC mixtures across a gradient of CC biomass and (iii) weed community response to CC mixtures and resource availability. CC and weed biomass were mainly influenced by interactions between CC mixtures and fertilisation and between CC mixtures and irrigation, with contrasted effects between field:years. Nitrogen fertilisation increased biomass of non-legume based CC mixtures but this only resulted into a further reduction of weed biomass of little biological relevance. Legume-based CC mixtures suppressed weeds to a greater extent without nitrogen fertilisation in year 2 but not in year 1, possibly due to contrasted initial soil nitrogen availability (lower in year 2). Weed biomass generally benefited more from irrigation than CC mixtures. Among the 33 weed species recorded, weed communities in each plot were dominated by wheat volunteers, Geranium dissectum, Veronica persica and Echinochloa crus-galli, whose biomass varied depending on the interaction between year, CC mixture and resource availability. Our results revealed that competitive outcomes between CC mixtures and weed species were driven by a complex interaction between resource availability and species traits. Further experiments focusing on plant traits should improve our understanding of weed:CC competitive outcomes under various levels of resource availability.
... Inclusion of a legume in mixture with non-legumes enhanced N cycling by maintaining N fixation via BNF and N retention of potentially leachable N in aboveground biomass of both the legume and the non-legume mixture component (Couëdel et al., 2018;Restovich et al., 2022). The use of cover crop mixtures consisting of legumes and grasses or brassicas is a common practice to provide compromise between N cycling, biomass production, and other ecosystem services across a range of environments (Christopher et al., 2021;Finney et al., 2017;Kramberger et al., 2014). This is because while legumes can provide N fixation via BNF, they often have slow growth and relatively low biomass production compared with grasses and brassicas. ...
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Conventional dryland cropping systems rely upon frequent and lengthy fallow periods to conserve soil water and mineral nitrogen to stabilize crop production. However, this is associated with depletion of soil organic matter and decreased fallow efficiency. Intensifying cropping systems by planting cover crops has been touted as a means to stem soil organic matter loss and improve fallow efficiency. We investigated whether the manipulation of cover crop functional trait diversity and sowing proportions (utilizing Poaceae, Fabaceae, and Brassicaceae) could provide complementary functions that improve soil water and mineral N management during fallow. Grass-legume mixtures represented the best compromise between biomass production (> 4000 kg DM ha − 1), N retention (142 kg N ha − 1), N supply via biological N fixation (35 kg N ha − 1) and maintained an additional 70 mm of water at the end of fallow period. Regardless of functional trait type, cover crops increased N retention but maintained similar soil mineral N content at the end of fallow period. However, soil water effects were functional trait-specific, and there were significant soil water deficits with brassica-dominated cover crops. Soil water accumulation post cover crop termination was significantly higher in cover crops compared with conventional fallows, but the overall fallow efficiency was higher in the conventional fallow. This study demonstrates that cover crops are not universally beneficial, and careful selection of cover crop functional traits in mixtures could enhance fallow soil water and N management in semi-arid subtropical drylands.
... has posited that cover cropping can improve SOC stocks and potentially contribute to climate stability and food security (Minasny et al. 2017). However, cover crops can also potentially introduce ecosystems disservices (i.e., derived negative effects), such as depletion of soil water and nutrients available for subsequent cash crops, reduction in cash crop yield, and increased management cost (Finney et al. 2017 introduction of cover crops to replace or reduce a portion of fallow periods requires management to mitigate these potential disservices in water-limited environments. This is because crop production in such regions is opportunistic, and the risks and economics associated with expected precipitation and soil water storage dictate cropping decisions. ...
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Cover crops can provide a wide range of ecosystem services including soil water conservation, improved soil nutrient supply and retention, and enhanced crop yields. However, achieving these services in dryland cropping systems can be highly challenging, and cover crops may carry a greater risk of causing ecosystem disservices. Assessment of the balance of ecosystem services vs disservices is critical for understanding the potential role of cover crops within dryland cropping systems. The objective of this meta-analysis was to assess the effects of cover cropping in drylands on soil water and soil mineral nitrogen content at sowing of subsequent cash crops and their yields compared to control fallows. A total of 38 articles were examined, for a total of 1006 cash crop yield, 539 soil water, and 516 soil mineral nitrogen independent studies, spanning the period 1994-2021. On average, cover cropping reduced cash crop yield by 7%, soil water content by 18%, and soil mineral nitrogen by 25%, with significant variation across climates, soil types, and crop management conditions. Subsequent cash crop yields changed by +15, +4, −12, and −11% following cover crops in tropical, continental, dry, and temperate dryland climates, respectively. The most significant yield benefits were proportionate to soil water content and soil mineral nitrogen at the time of cash crop sowing. This is the first meta-analysis to demonstrate that minimum annual precipitation of~700 mm represents a "break-even" point to realize significant cash crop yield benefits of cover cropping compared to control fallows in dryland environments. The successful incorporation of cover crops into dryland cropping systems requires careful planning based on context-specific biophysical conditions to minimize trade-offs between ecosystem services and disservices.
... Brassica cover crops [e.g., canola (Brassica napus L.), radish (Raphanus sativus L.)] are mostly grown to suppress pest populations and soil-borne diseases because they contain glucosinolate compounds in their residues (Snapp et al. 2005). The net positive ecosystem services (e.g., biomass production, SOC accumulation, N supply, N retention, weed and pest suppression) can be achieved by using a mixture of diverse species because one component species compensates the limitation of other species in the mixes (Chapagain et al. 2020;Finney et al. 2017). The individual species used in the mixtures may have varying rooting behavior, C to N ratio, decomposition rates, N-fixation capacity, biomass production, and water and nutrient use. ...
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Cover crops are increasingly adopted to improve soil health in arid and semiarid regions, yet their effects on soil profile organic carbon (C) and nitrogen (N) and crop yield are inconsistent. We evaluated the cover crop effect on soil organic C (SOC) and N (SON) contents and water-filled pore space to a depth of 0.8 m and crop yield in a winter wheat (Triticum aestivum L.)–sorghum (Sorghum bicolor L. Moench)–fallow rotation under limited-irrigation conditions. Cover crop treatments were fallow (no cover crop), pea (Pisum sativum L.), oat (Avena sativa L.), canola (Brassica napus L.), pea-canola mixture, oat-pea mixture, pea-oat-canola mixture, and a six-species mixture including pea, oat, canola, hairy vetch (Vicia villosa Roth), forage radish (Raphanus sativus L.), and barley (Hordeum vulgare L.). Five years of cover cropping (2016–2020) did not affect SOC storage. Soil organic N at equivalent soil mass (ESM) layer 0–2500 Mg ha−1 was 8–14% greater in fallow than other treatments, except pea and oat-pea mixture. The fallow treatment also had 54–156% and 11–72% higher inorganic N content than cover crop treatments at ESM layers of 2500–5000 and 5000–7500 Mg ha−1, respectively. Sorghum grain yield was 33–97% higher following fallow and oat as cover crop than other treatments in 2020. Although there was a variation in crop yield responses, cover cropping largely did not affect soil profile C and N contents under a limited-irrigation semiarid cropping system.
Article
Competition for resources between crops and weeds hinders the increase of production in agroecosystems. The trait‐based plant species selection of cover crops can be a useful tool to suppress competing plants in addition to providing environmental services. Here, we assessed the growth and macronutrient accumulation metrics in Diodia saponariifolia (Rubiaceae) plants, a native cover crop found in family farming systems in southeastern Brazil. Under greenhouse conditions, three viable D. saponariifolia cuttings were planted per tray. The experimental design was entirely randomized, with treatments consisting of plant sampling times, at regular intervals of 7 days between 16 and 93 days after transplanting (DAT) and 15 days between 93 and 138 DAT. Based on dry mass and chemical analysis of leaves, stems, and roots; we fitted the logistic model to explore the metrics of growth and macronutrient accumulation. Overall, the increment in plant dry mass was slow about halfway through the experimental period, being subsequently replaced by a phase of rapid growth. The stem was the plant fraction with the highest relative biomass accumulation. The total macronutrient concentration followed the descending order of K > N > Ca > Mg > P, varying along the plant ontogeny. Considering the nutrient content, the estimated 200 g m−2 of aboveground dry mass, and 0.3 m2 of leaf area, it is suggested to perform the first mechanical weeding along the third month of growth. Our results suggest that D. saponariifolia has satisfactory agronomical features for its establishment as a cover crop in different agricultural contexts.
Article
In the upper U.S. Midwest, oat is a promising crop for diversifying local cropping systems and providing local consumers with a healthy food option. However, as a result of climate change, the crop is facing increasingly severe episodes of high temperature (HT) stress during reproductive development, which limit its yield potential. The goal of this 3-year field study was to identify locally-adapted HT stress-tolerant oat breeding lines, propose a parsimonious mechanistic basis for HT stress tolerance and leverage it to develop a screening method with the potential to support a breeding program. Because water supply is rarely limiting in the region, we tested the hypothesis that canopy latent cooling would be a desirable trait. To this end, we deployed “heat tents” on a core panel of 30 oat lines between booting and heading, where we measured i) grain yield and quality traits (protein, oil and beta-glucan), ii) pollen viability, percentage of filled florets, and grain number, iii) gas exchange and canopy cooling parameters (e.g., photosynthesis, transpiration rate, stomatal conductance, canopy temperature depression). Additionally, we developed a thermal imaging approach to remotely quantify canopy temperature on contrasted lines. Significant genotypic variability was detected in yield and quality trait responses to the HT stress and a physiological path model identified canopy cooling as a main process explaining superior yield performance of HT stress tolerant lines. Interestingly, pollen viability was not found to be the main driver of yield declines, suggesting a role played by other reproductive processes, including those underlying female tissue/organs sensitivity to HT stress. Finally, canopy cooling parameters correlated with geographic locations of breeding programs from which the tested germplasm originated, indicating that they are under selection. Overall, this study opens the way for a breeding program targeting the development of more climate-resilient oats adapted to northern climates.
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It is common to use mass‐based units (e.g., kg ha–1) to describe cover crop seeding rates. However, this convention obscures important information about seed size and resulting plant density in the field, which may be linked to cover crop performance and ecosystem services. Seed counts of 27 lots of commercially available winter rye (Secale cereale L.) spanned a wide range from 28,000 to 50,000 seeds kg–1. If the lots with the lowest and highest seed counts were seeded at a common mass‐based seeding rate of 125 kg ha–1, it would result in a nearly twofold difference in density‐based seeding rate, or 3.0 and 5.6 million live seeds ha–1. Including density‐based metrics such as live seeds per area and resulting in‐field plant density in research will help advance our understanding of cover crop management, and these efforts will make it easier for farmers and policymakers to tailor cover cropping practices for specific goals. Cover crops provide many ecosystem services that benefit farmers and society. Seeding rate recommendations for cover crops are typically reported in mass‐based units. Seed counts were variable across 27 lots of winter rye, ranging from 28,000 to nearly 50,000 seeds kg‐1. The same mass‐based seeding rate results in nearly twofold difference in density‐based seeding rate. Reporting density‐based seeding rates would improve future decision making and outcomes.
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Background Cover crops can be used as a habitat management strategy to enhance the natural enemies and their temporal synchronization with a target pest. We examined the effect of winter oat intercropping within organic plum orchards on the natural enemy abundance and seasonal dynamics on the biological control of plum aphids in spring in Central Chile. Methods We compared the incidence and abundance of natural enemies and aphid pests from winter to the end of spring using two treatments: (1) plum trees with an oat cover crop (OCC) and (2) plum trees without a cover crop but with spontaneous vegetation (SV). We hypothesized that cover crops allow the development of winter cereal aphids, promoting the early arrival of natural enemies in spring, resulting in an earlier control of plum aphids. Results Winter cereal aphids developed well on the OCC, and as a result, a lower plum aphid incidence in spring was observed when compared to the SV. However, the abundance of natural enemies and the parasitism rates cannot explain the positive impacts of the oat cover crop on the aphid populations as there were no differences between treatments. A potential effect of the oat due to chemical and/or physical stimuli (bottom-up effects) could help to explain these results.
Article
Intensive vegetable crop rotations can have detrimental effects on soil health, draining soil of organic matter reserves and necessitating nitrogen (N) inputs. In addition, many vegetable crop rotations leave little time or space to integrate beneficial arthropod and pollinator habitat into crop rotations; the lack of habitat may cause declines in beneficial arthropods, which can lead to insufficient pollination services and increased pest pressure. Nine treatments, each containing one to seven species of cover crops, were evaluated for flowering, aboveground biomass production and N content, soil ${\rm NO}_3^-$ -N contribution after biomass incorporation, and beneficial arthropod visitation. A seven-species mix composed of oat ( Avena sativa L.), field pea ( Pisum sativum subsp. Arvense L.) and five clover species ( Trifolium spp.) added the largest amount of biomass (8747 kg ha ⁻¹ ). Likewise, this mix contributed the most organic N (265.6 kg N ha ⁻¹ ), and increased soil ${\rm NO}_3^-$ -N after biomass incorporation (10.9 mg ${\rm NO}_3^-$ -N kg ⁻¹ of soil). Buckwheat ( Fagopyrum esculentum Moench) and phacelia ( Phacelia tanacetifolia Bendth.) monoculture produced most abundant floral resources. Beneficial arthropods observed included pollinators (native, honey and bumblebees), predators (syrphid flies and green lacewings) and parasitoids. Increased floral diversity was associated with abundance of flies in the Syrphidae family. Phacelia monoculture was most attractive for bees in the Apidae and Halictidae family, both of which may provide pollination services. These results highlight floral visitation patterns as an indicator for beneficial insect community support and conservation, especially in summer months, when greater insect reproduction occurs. Summer-planted cover crops are an underexplored rotation option for organic farming systems in the Upper Midwest, and may provide a wide range of ecosystem services including increases in available soil N and beneficial arthropod populations.
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One potential benefit of cover crops (CCs) is that N mineralization from decomposing CC residues may reduce the N fertilizer requirement of a subsequent crop, but predicting this credit remains a significant challenge. This study used a model–data fusion approach to calibrate a model of CC residue N mineralization and pre-emptive competition for soil NO3– that occurs during CC growth to predict the yield response of an unfertilized corn (Zea mays L.) crop. The model was calibrated with a data set of 199 observations from four CC experiments in central Pennsylvania. The most parsimonious model explained 82% of the variation in corn yield response. Parameters representing the C humification coefficients for decomposed residues from winterkilled (εwk = 0.00) and winter-hardy (εwh = 0.40) CCs suggest that all winterkilled CCs resulted in net N mineralization, probably due to the longer period of time for decomposition of winterkilled residues. However, the yield response per unit of potentially mineralized N was greater for winter-hardy CCs (αwh = 0.034 with tillage, αwh = 0.020 with no-till) than for winterkilled CCs (αwk = 0.0084), probably due to the improved synchrony between corn N demand and the decomposition of winter-hardy CC residues relative to winterkilled residues. Pre-emptive competition for soil NO3– led to a reduction in the corn yield response. Because the model is based on ecological processes and can be calibrated with data sets from simple field experiments, the model–data fusion approach could be widely used to guide adaptive management of CCs and N fertilizer applications in a subsequent corn crop.
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Cover crop mixtures may provide greater diversity of benefits than monocultures. To develop management principles to establish diverse cover crop mixtures, we conducted a three-year study in which monocultures and mixtures of six cover crop species [cereal rye (Secale cereale L.), oat (Avena sativa L.), common medium red clover (Trifolium pratense L.), Austrian winter pea (Pisum sativum L.), forage radish (Raphanus sativus L.), and winter canola (Brassica napus L.)] were planted in a wheat (Triticum aestivum L.)-maize (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation after wheat (AW) and after maize (AM). Post-emergence stand counts and above-ground biomass in fall and spring were measured by species for all cover crop treatments. All species planted were present in monocultures and mixtures in fall, though oat dominated and red clover, canola, and radish underperformed in mixtures. Cereal rye had the highest spring biomass in all mixtures, especially AM. Pea spring biomass was greater than expected in relation to seeding rate in the six-species mixture (6 Spp) than in monoculture when planted AW. A four-species mixture (4 Spp) planted AW retained the highest diversity after overwintering in two of the three planting years. Our study demonstrated that (1) cover crop mixtures retain higher diversity when allowed sufficient growth in fall; (2) cereal rye dominates mixtures in spring, particularly when fall planting is delayed; (3) grasses overperform in mixtures compared to their growth in monocultures; (4) brassicas underperform in mixtures versus monocultures; and (5) legume growth in mixtures depends on species and planting time.
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Increasing plant diversity in agroecosystems with cover crops has been a successful strategy to augment ecosystem services from agriculture, and increasing diversity of cover crops may provide even greater benefits. Productivity and ecosystem services from multi-species cover crop mixtures were measured in a 2-yr field study of 18 cover crop treatments preceding conventionally tilled corn in central Pennsylvania. Increasing the number of species in a stand increased cover crop biomass (R2 = 0.15). However, mixing cover crop species that were complementary in phenology or N acquisition strategy did not result in mixtures that produced more biomass than high yielding monocultures. Increasing cover crop biomass was positively correlated with several ecosystem services, namely weed suppression, prevention of nitrate leaching, and aboveground biomass N, but negatively impacted inorganic N availability and corn yield in the subsequent cropping season. The cover crop C/N ratio was another determinant of ecosystem services positively related to nitrate leaching prevention, but negatively related to inorganic N availability and corn yield. This study supports the long-held assumption that increasing biomass can enhance certain ecosystem services from cover crops; however, because the mixtures tested did not produce more biomass than high yielding monocultures, opportunities to increase biomassdriven services with mixtures may be limited. The correlation between biomass C/N ratio and ecosystem services in this study also indicates that functional traits, as opposed to biomass alone, will be important for predicting ecosystem services from cover crop mixtures.
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Cover crops (CCs) can provide multiple soil, agricultural production, and environmental benefits. However, a better understanding of such potential ecosystem services is needed. We summarized the current state of knowledge of CC effects on soil C stocks, soil erosion, physical properties, soil water, nutrients, microbial properties, weed control, crop yields, expanded uses, and economics and highlighted research needs. Our review indicates that CCs are multifunctional. Cover crops increase soil organic C stocks (0.1-1. Mg ha-1 yr-1) with the magnitude depending on biomass amount, years in CCs, and initial soil C level. Runoff loss can decrease by up to 80% and sediment loss from 40 to 96% with CCs. Wind erosion potential also decreases with CCs, but studies are few. Cover crops alleviate soil compaction, improve soil structural and hydraulic properties, moderate soil temperature, improve microbial properties, recycle nutrients, and suppress weeds. Cover crops increase or have no effect on crop yields but reduce yields in water-limited regions by reducing available water for the subsequent crops. The few available studies indicate that grazing and haying of CCs do not adversely affect soil and crop production, which suggests that CC biomass removal for livestock or biofuel production can be another benefit from CCs. Overall, CCs provide numerous ecosystem services (i.e., soil, crop-livestock systems, and environment), although the magnitude of benefits is highly site specific. More research data are needed on the (i) multi-functionality of CCs for different climates and management scenarios and (ii) short-and long-term economic return from CCs. © 2015 by the American Society of Agronomy 5585 Guilford Road, Madison, WI 53711 USA All rights reserved.
Article
Biomedical research aimed at the development of therapies for chronic and late‐onset conditions increasingly concentrates on the early treatment of symptom‐less disease. This broad trend is evidenced in prominent shifts in contemporary dementia research. Revised diagnostic criteria and new approaches to clinical trials propose a focus on earlier stages of disease and prompt concerns about the implications of communicating test results associated with the risk of developing dementia when no effective treatments are available. This article examines expectations of the implications of learning test results related to dementia risk, based on focus group research conducted in the UK and Spain. It points to the extended social and temporal aspects of the dementia risk experience. Three key dimensions of this risk experience are elaborated: living ‘at risk’, represented in efforts to reduce risk and plan for the future; ‘with risk’, through vigilance towards cognitive health and earlier or prolonged contact with healthcare services; and finally, ‘beyond risk’ through a cessation of the self in its current social, legal and financial form. A virtual abstract of this paper can be viewed at: https://www.youtube.com/channel/UC_979cmCmR9rLrKuD7z0ycA
Article
Interest in planting mixtures of cover crop species has grown in recent years as farmers seek to increase the breadth of ecosystem services cover crops provide. As part of a multidisciplinary project, we quantified the degree to which monocultures and mixtures of cover crops suppress weeds during the fall-to-spring cover crop growing period. Weed-suppressive cover crop stands can limit weed seed rain from summer- and winter-annual species, reducing weed population growth and ultimately weed pressure in future cash crop stands. We established monocultures and mixtures of two legumes (medium red clover and Austrian winter pea), two grasses (cereal rye and oats), and two brassicas (forage radish and canola) in a long fall growing window following winter wheat harvest and in a shorter window following silage corn harvest. In fall of the long window, grass cover crops and mixtures were the most weed suppressive, whereas legume cover crops were the least weed suppressive. All mixtures also effectively suppressed weeds. This was likely primarily due to the presence of fast-growing grass species, which were effective even when they were seeded at only 20% of their monoculture rate. In spring, weed biomass was low in all treatments due to winter kill of summer-annual weeds and low germination of winter annuals. In the short window following silage corn, biomass accumulation by cover crops and weeds in the fall was more than an order of magnitude lower than in the longer window. However, there was substantial weed seed production in the spring in all treatments not containing cereal rye (monoculture or mixture). Our results suggest that cover crop mixtures require only low seeding rates of aggressive grass species to provide weed suppression. This creates an opportunity for other species to deliver additional ecosystem services, though careful species selection may be required to maintain mixture diversity and avoid dominance of winter-hardy cover crop grasses in the spring.
Article
The ability of cover crop mixtures to provide both nitrogen (N) retention and N supply services has been extensively studied in research station experiments, especially with grass-legume bicultures. Mixtures are often as effective as grass monocultures at N retention, but the N supply service can be compromised when non-legumes dilute the presence of legumes in a cover crop stand. To study the tradeoffs between N retention and supply when using cover crop mixtures, we measured N retention and supply in distributed on-farm experiments, developed multiple linear regression models to predict N retention and supply based on cover crop functional characteristics and environmental variables, and synthesized the regression models into a graphical analysis tool. The experiments took place on three organic farms and a research station in Pennsylvania, USA and tested 3-species and 4-species cover crop mixtures in comparison to commonly used grass and legume monocultures. Cover crop treatments were planted between a small grain crop harvested in mid-summer and a maize (Zea mays L.) crop planted the following spring. Potential nitrate (NO3⁻) leaching below 30 cm, an indicator of the N retention service, declined as the presence of non-legume species in a cover crop increased (r² = 0.72). Potential NO3⁻ leaching increased as the August soil NO3⁻-N concentration increased and as the fall biomass N content of winter-killed species or canola (Brassica napus L. ‘Wichita’) increased. Relative maize yield, an indicator of the N supply service, decreased as fall and spring cover crop biomass carbon-to-nitrogen (C:N) ratios increased and increased as total spring biomass N content and soil carbon (C) concentration increased (r² = 0.56). Synthesizing the regression models in a graphical analysis tool revealed a tradeoff between N supply and retention services for cover crop mixtures, where increasing the fractional non-legume seeding rate to reduce potential NO3⁻ leaching also reduced relative maize yield. The tradeoff could be minimized by managing environmental conditions and cover crop composition so that potential NO3⁻ leaching remains low even when the fractional non-legume seeding rate is low. The regression models suggest this could be achieved by maintaining low soil NO3⁻-N concentrations prior to cover crop planting in August, not including winter-killed legumes in the mixture, and using non-legume species that are the most efficient at N retention. Thus, with thoughtful management of cover crops and soils, farmers may be able to realize the potential of cover crop mixtures to provide high levels of both N retention and supply services.
Article
Ecological studies identifying a positive relationship between biodiversity and ecosystem services motivate projections that higher plant diversity will increase services from agroecosystems. While this idea is compelling, evidence of generalizable relationships between biodiversity and ecosystem services that could be broadly applied in agricultural systems is lacking. 2.Cover crops grown in rotation with cash crops are a realistic strategy to increase agroecosystem diversity. We evaluated the prediction that further increasing diversity with cover crop polycultures would enhance ecosystem services and multifunctionality in a two year study of eighteen cover crop treatments ranging in diversity from one to eight species. Five ecosystem services were measured in each cover crop system and regression analysis used to explore the relationship between multifunctionality and several diversity indices. 3.As expected, there was a positive relationship between species richness and multifunctionality, but it only explained a small fraction of variance in ecosystem services (marginal R2=0.05). In contrast, indices of functional diversity, particularly the distribution of trait abundances, were stronger predictors of multifunctionality (marginal R2=0.15-0.38). 4.Synthesis and application. In a corn production system, simply increasing cover crop species richness will have a small impact on agroecosystem services, but designing polycultures that maximize functional diversity may lead to agroecosystems with greater multifunctionality. This article is protected by copyright. All rights reserved.
Article
The sustainable delivery of multiple ecosystem services requires the management of functionally diverse biological communities. In an agricultural context, where conflicting services often need to be reconciled on the same parcel of land, growing species mixtures may improve multi-functionality when compared to monocultures. In this case, the optimum number and identity of species will be determined by trade-offs between ecosystem services, functional composition of the available species pool and competitive dynamics. A combination of functional trait / ecosystem service relationships and a process-based model of plant competition was used to engineer a plant community that delivered the optimal balance of services using the case study of a legume-based fertility building cover crop. An experimental species pool of 12 cultivated legume species was screened for a range of functional traits and ecosystem services at five sites across a geographical gradient in the UK. All possible species combinations were then analysed to identify the community that delivered the best balance of services at each site. In our system, low to intermediate levels of species richness (1-4 species) that exploited functional contrasts in growth habit and phenology, were identified as being optimal. The optimal solution was determined largely by the number of species and functional diversity represented by the starting species pool emphasising the importance of the initial selection of species for the screening experiments. The approach of applying functional traits / ecosystem service relationships to the design of multi-functional biological communities has the potential to inform the design of agricultural systems that better balance agronomic and environmental services and meet the current objective of European agricultural policy, to maintain viable food production in the context of the sustainable management of natural resources.