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Many shades of gray—The context-dependent
performance of organic agriculture
Verena Seufert
1,2
* and Navin Ramankutty
1,2
Organic agriculture is often proposed as a more sustainable alternative to current conventional agriculture. We assess
the current understanding of the costs and benefits of organic agriculture across multiple production, environmental,
producer, and consumer dimensions. Organic agriculture shows many potential benefits (including higher biodiversity
and improved soil and water quality per unit area, enhanced profitability, and higher nutritional value) as well as many
potential costs including lower yields and higher consumer prices. However, numerous important dimensions have
high uncertainty, particularly the environmental performance when controlling for lower organic yields, but also yield
stability, soil erosion, water use, and labor conditions. We identify conditions that influence the relative performance of
organic systems, highlighting areas for increased research and policy support.
Agriculture today is a leading driver of environmental degradation (1),
but despite major increases in production, one in eight people in devel-
oping countries remain malnourished (2). Organic agriculture is often
proposed as a solution to this challenge of achieving sustainable food
security. Although it only covers ~1% of global agricultural land and
only contributes ~1 to 8% of total food sales in most European and North
American countries (3), “organic”is a label that is recognized and pur-
chased by many consumers, and organic agriculture is the fastest-growing
food sector in North America and Europe (3). Given that organic ag-
riculture is a current and rather widespread farming system and is one
of the few legally regulated labels in farming, it is important to assess
its performance and identify how we can improve it.
The benefits of organic agriculture are widely debated. Although
some promote it as a solution to our sustainable food security challenges
(4–6), others condemn it as a backward and romanticized version of
agriculture that would lead to hunger and environmental devastation
(7–9). Previous reviews (4,6,10–14) have focused on the benefits of or-
ganic management, asking the question whether organic agriculture is
good or bad. Here, we address a more policy-relevant question, assessed
across a suite of different criteria and contexts: Where does organic ag-
riculture perform well, and where does it not? Unlike previous reviews,
which only assessed the average performance of organic agriculture rel-
ative to conventional agriculture, we also evaluate the range around this
central tendency, the contextual factors driving the upper and lower
range of responses, and the uncertainty in our understanding.
We assessed the benefits and costs of organic agriculture across the
following dimensions: (i) production, (ii) environment, (iii) producers,
and (iv) consumers. Rather than starting from what is known in the
literature on organic agriculture, we developed a framework that iden-
tifies important dimensions of agricultural sustainability and specific in-
dicators within each. Accordingly, we also include indicators that have
received limited attention in the organic literature to date (for example,
water use and farm wages). Often farming system assessments only ex-
amine the impact per unit area. However, given that yields vary, and that
a primary purpose of agriculture is production, it is important to also
assess the performance of farming systems per unit output (15). Per unit
output impacts are particularly relevant to the environmental dimensions
because of the strong environmental impact of land conversion (1). For
each dimension and each variable examined, we assess existing knowl-
edge based on quantitative reviews of the scientific literature, where pos-
sible, including (i) average performance per unit area and per unit output
(where relevant), (ii) uncertainty around the average performance, (iii)
factors influencing low and high performance, and (iv) knowledge gaps.
The scope of this review is limited to an examination of impacts at
the level of the farming system (including indirect impacts on consumers),
with no consideration of other aspects of the food system such as pro-
cessing and distribution, consumption, or recycling. Our assessment is
also restricted to cropping systems, excluding livestock systems (except
where integrated into mixed systems). Thus, animal welfare, in particular,
is not addressed.
Organic agriculture is defined hereasafarmingsystemthatfollows
organic certification guidelines (for example, avoidance of synthetic fertil-
izers and pesticides) and that is intentionally organic (that is, excluding
organic-by-default systems that do not apply synthetic inputs due to lack
of access). Conventional agriculture is defined as mainstream agriculture
as dominantly practiced today. This can represent both high-input and
low-input systems, depending on the region.
ORGANIC AGRICULTURE AND PRODUCTION BENEFITS
AND COSTS
Yields
Crop (and animal) production is the primary reason that humans man-
age agroecosystems. Many studies point to the need to greatly increase
food production to meet the needs of a growing human population and
the shift to more meat-intensive diets (16). Although the need for
increased food supply is still debated because of the inefficiencies and
inequities in the current system (17), yields do matter not only for farmers
whose incomes critically depend on the yield but also for many environ-
mental outcomes. Even if food production does not need to increase,
higher yields could still be environmentally beneficial because we could
take land out of production and restore natural ecosystems, which typi-
cally are better at delivering ecosystem services than production systems.
Numerous meta-analyses have concluded that yields under organic
management are, on average, 19 to 25% lower than under conventional
management (Fig. 1 and fig. S1) (18–20), and a recent analysis of com-
mercial organic crop yields in the United States reveals a similar average
yield gap of 20% (21). However, the magnitude of this yield gap varies
by crop type and depends on management practices [for example, crop
1
Liu Institute for Global Issues, University of British Columbia, 6476 North West
Marine Drive, Vancouver, British Columbia V6T 1Z2, Canada.
2
Institute for
Resources, Environment and Sustainability, University of British Columbia, 2202
Main Mall, Vancouver, British Columbia V6T 1Z4, Canada.
*Corresponding author. Email: verena.seufert@ubc.ca
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A
B
Fig. 1. Overall average performance of organic agricul ture relative to conventional agriculture. Average organic performance is indicated by the red circle.
(A) Performance per unit area and (B) performance per unit output. Figure includes production (brown petals), environmental (green petals), producer (red petals), and
consumer (blue petals) benefits (petals that extend beyond the red circle) and costs (petals inside the red circle). Dimensions assessed include (starting at the top, going
clockwise) production, biodiversity, soil quality, water quality, water quantity, climate change mitigation, farmer livelihoods, farmer and farm worker health, farm worker
livelihoods, consumer health, and consumeraccess. Larger petals represent superiororganic performance (forexample, a larger petalfor N loss means lower N loss in organic).
In addition, note that per unit output performance isonly relevant for environmental variables; other petals are unchanged relative to per unit area performance. Shading of
petals represents level of uncertaintyfor each variable, with uncertainty determinedby the number of primary studiesincluded in each assessment and thelevel of agreement
between different quantitative reviews (see fig. S6 for details). Variables that could not be quantified are in gray. Length of gray petals also varies slightly depending on
whether the qualitative assessment of each dimension (see Table 2) is uncertain or suggests no difference (that is, petal is on the red circle) or shows higher (that is, petal
extends beyondthe red circle) or lower (that is, petalis inside the red circle) performance. Means used to quantifyeach variable (also known as petallength) were calculatedas
weighted means (weighted by the sample size, typically the number of observations in each quantitative review) across estimates of response ratios (organic/conventional)
from different quantitative reviews (see table S1for sources and figs. S1, S2, and S5 for values used) and are represented ona log scale to treatchanges in the numerator and
denominatorthe same [with the red circle indicating no change, that is, log(org/conv) = 0]. Note that this approach doesnot account for double-counting of primary studies
included in multiple quantitative reviews or meta-analyses. This double-counting might affect petal size but would not alter qualitative size relationships among petals.
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rotations, amount of fertilizer inputs (Table 1) (18–20)]. The yield gap
can be as low as 5 to 9% under some conditions, but as high as 30 to 40%
under other conditions (18,19). Many cereals show, for example, a
higher yield gap (18,21), while forage crops, such as hay, tend to have
smaller yield gaps (20)orevenhigheryieldsunderorganicmanagement
(21). However, studies disagree on some of the factors that influence the
yield gap (table S2), possibly because of the small sample sizes when
individual factors are considered. An importantcaveatisthatexisting
analyses are mostly limited to data from high-income countries (Fig. 2),
which prevents a verdict on the relative yield performance of organic
agriculture compared to different types of high-input and low-input
conventional systems in low-income countries.
Studies have typically examined the annual output (in terms of dry
matter) of single crop species per unit area of cultivated land (18–20).
However, given the diversity of temporal dynamics (for example, fallow
periods and multicropping) and the diversity of land uses (including
nonedible crops and livestock), a more useful comparison would be
of the total energy, caloric, or protein yield across an entire crop rotation
available for human consumption [that is, whole system output per unit
area-time (9,20)].
Yield stability
Most assessments of the productivity of agricultural systems focus on ef-
ficiency of production (that is, how much can be produced per unit area of
land in a single year?) but ignore the resilience of production (that is, can
thesameproductionbeachievedoverlonger time frames?). Yield stability,
one measure of the resilience of food production, matters not only for
farmer livelihoods but also for food production under a changing climate.
Organicagricultureisoftensaidtobemoreresilientandhavehigher
yield stability (11,22). A possible mechanism may be the use of organic
amendments leading to higher soil organic matter, resulting in higher
yields under drought conditions (23). In addition, more diverse crop
rotations can increase yield stability (24). However, organic systems
are sometimes more prone to pest outbreaks (25), can experience high
weed pressure (26), or be characterized by highly variable N availability
(25), which all can lead to higher yield variability. The relatively few
comparisons of yield stability in organic versus conventional systems
conducted to date have therefore shown both higher (23,24)andlower
yield stability under organic management (Table 1) (25–27).
ORGANIC AGRICULTURE AND ENVIRONMENTAL BENEFITS
AND COSTS
Biodiversity
Not only is agricultural land use one of the leading drivers of biodiversity
loss (28), but food production also depends on many regulating and
supporting ecosystem services (such as pest regulation, crop pollination,
and soil nutrient cycling) from biodiversity (29). The benefits of organic
management for biodiversity of wildlife on farmland are clear, with a typ-
ical increase in organism abundance of 40 to 50% across different taxa
(30,31). The influence on species richness is less clear (ranging from
1to34%;seeFig.3andfig.S2)becausesomehavearguedthattheoften-
observed species richness effect (31,32) might be driven by an underlying
sampling effect at higher organism densities (30).
Generally, it appears that plants (32)andbees(33) benefit the most
from organic management, although other arthropods and birds benefit
to a smaller degree (Table 1 and table S3). Landscape context is an impor-
tant factor, and higher benefits of organic management are found in sim-
plified landscapes with high agricultural land cover (32) and lower habitat
quality (33) and in regions with intensive agriculture (34). Some evidence
also suggests that organic agriculture has a stronger effect on biodiversity
in arable systems (for example, cereal) than in grassland systems (32,34),
and a stronger impact within individual fields than at the farm scale (34).
Because of the importance of habitat conversion for biodiversity loss,
an assessment of the impact of farming systems on biodiversity has to con-
trol for yields, which few studies have carried out to date (Fig. 1B) (35,36).
Both Gabriel et al. (35)andSchneideret al.(34) suggested that there are
trade-offs between the biodiversity benefits of organic management and
yields. Gabriel et al. (35) further argued that although earlier studies had
shown higher organic benefits for biodiversity per unit area in simplified
landscapes (see Table 1), biodiversity per unit output might benefit most
from organic management in mixed and low-productivity landscapes be-
causeofasmalleryielddifferencebetween organic and conventional farms.
Soil quality
Soil health has always been at the core of organic philosophy (37). The
formation of soil and soil nutrient cycling are important supporting
services for food production (29). Soil degradation and soil erosion,
which affect large areas of land today because of the intensive use of
croplands and rangelands, threaten current and future food production
and are a key sustainability challenge for agriculture (38).
Several meta-analyses and quantitative reviews have found that soils
managed with organic practices have higher organic carbon content
(Fig. 1A) (39–42). Studies have also typically found reduced soil erosion
from organic farms due to improved soil structure (Table 2) (43–45),
but more studies are needed to quantify this variable (Fig. 1A). Primary
studies have also often shown improvements in other soil health and
fertility parameters (such as soil nutrient status or soil physical proper-
ties) under organic management (46–48). Despite these generally pos-
itive impacts of organic management on soil parameters, the soil fauna
does not appear to be more species-rich (31,32),butitismoreabundant
in organically managed soils (31).
One of the most important factors influencing the impact of organic
management on soil organic carbon content is the amount of organic
matter inputs; the higher the organic inputs such as composts or animal
manure, the higher the organic matter content in organically managed
soils (Table 1) (39,40,42). However, we have a poor understanding of
other potential important drivers, such as the presence of legumes in the
crop rotation (39), or of the impact of organic agriculture on soil quality
per unit output (Fig. 1B).
A common criticism of organic farming is the use of increased tillage
to control weeds because of the prohibition of herbicides (7), which can
enhance organic matter loss and soil erosion (49). However, the typical-
ly higher organic matter content of organically managed soils suggests
that tillage under organic agriculture is no more intensive than under
conventional management (39). Furthermore, reduced tillage systems
seem to be feasible under organic agriculture, as evidenced, for example,
by the large number of U.S. organic farmers reporting the use of reduced
tillage [that is, 41% (50)], which is the same proportion as for con-
ventional farmers in the United States (51) and also highlighted by a
recent meta-analysis that suggested that some organic reduced tillage
systems (for example, shallow noninversion tillage) can lead to higher
soil organic matter content without incurring yield penalties relative
to intensive tillage (52).
Climate change mitigation
Agriculture, which is responsible for ~22% of global anthropogenic
greenhouse gas (GHG) emissions [including deforestation (53)], is a
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Table 1. Factors influencing the low and high performance of organic agriculture across some production (brown), environmental (green), producer
(red), and consumer (blue) dimensions. Shading represents the strength of the evidence base (that is, dark shade, based on meta-analyses and quantitative
reviews; medium shade, based on qualitative reviews or large-scale primary studies; light shade, based on primary studies or authors’opinion). Some key
references supporting the assessment of each effect are indicated. Note that numerous variables (for example, yield stability, water use, pesticide leaching,
resilience, or farm wages) could not be assessed. For the level of agreement between different studies for production and biodiversity, see tables S2 and S3. org,
organic; conv, conventional.
Low performance High performance References
Production per
unit area
Cereals Fodder crops (18, 20, 21)
Nonlegumes and annuals Legumes and perennials (18, 21)
Lower N inputs in org Higher N inputs in org (18, 19)
No rotation More rotation in org (18, 19)
Strong acidic and alkaline soils Neutral soils (18, 19)
Species richness
and abundance
Arthropods and Birds Plants (32, 34)
Predators, herbivores, and
decomposers Pollinators and producers (32, 33)
Pastures Cereal fields (32, 34)
Extensive agriculture in
region
Intensive agriculture in
region (34)
Complex landscapes Simple landscapes (32, 33)
Outside fields/at farm level Within fields (34)
Soil organic
carbon
Same organic matter inputs
in org and conv
Higher organic matter
inputs in org (39, 40, 42)
Energy use Fruits and vegetables Other field crops (58)
GHG emissions Multicropping systems Monocropping systems (58)
N loss High N inputs in org Low N inputs in org (60)
P loss Organic amendments Legume-based systems (65)
N and P loss Horticultural systems Arable systems (63)
Profitability
No access to premium prices Access to premium prices (81)
Regions with high labor
cost
Regions with low labor
costs (81)
Autonomy Reliance on export markets Participation in alternative
food networks (82, 87)
Pesticide
exposure
Crops with low pesticide use
and/or regions with strong
pesticide regulation and
enforcement
Crops with high pesticide
use and/or regions with
weak pesticide regulation
and enforcement
Rural
employment
Regions with high rural
unemployment
Pesticide residues
Crops with low pesticide use
and/or regions with strong
pesticide regulation and
enforcement
Crops with high pesticide
use and/or regions with
weak pesticide regulation
and enforcement
Nutritional
content
Regions with
micronutrient deficiencies (101)
Low-income groups (109)
Consumer prices (110)Regular wholesale CSA
—
—
—
—
—
—
Variable
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major contributor to climate change. Agricultural GHG emissions from
croplands and pasture (excluding livestock systems) are mostly in the
form of N
2
O emissions from agricultural soils (from fertilizer and ma-
nure application and crop residue management), CH
4
emissions from
paddy cultivation, and CO
2
emissions through energy use [for example,
for fertilizer production and machinery use (53)].
Overall, both N
2
O and total GHG emissions per unit area appear
to be lower under organic management for most crops (Figs. 1 and 3)
(40,54,55). Studies of organic performance for CH
4
emissions from
rice paddy are limited [the review by Skinner et al.(54) is based on a
single-field study (56)]. However, the limited evidence suggests higher
CH
4
emissions from organic paddy management (56). Organic agri-
culture generally leads to reduced energy use due to avoidance of
synthetic fertilizers (Fig. 1A) (12,40,55). Organic agriculture typical-
ly increases soil organic carbon content (39), which is often argued
to contribute to carbon sequestration (22). Because of uncertainties
about the ultimate fate of the stored carbon (that is, for how long this
sequestration will continue and whether it will be permanent) and the
counterfactual (that is, how the carbon inputs would otherwise have
been used), the potential for climate change mitigation through carbon
storage in agricultural soils is heavily debated (57). Therefore, we do not
consider soil carbon storage as a climate change mitigation option here.
Because of the importance of land conversion for GHG emissions
[that is, deforestation for agriculture represents ~7% of global anthro-
pogenic GHG emissions (53)], per unit output impacts are partic-
ularly important for climate change mitigation. Evidence on GHG
emissions per unit output mostly comes from modeling and life-cycle
analysis studies and shows high variability in outcomes (40,55). N
2
O
emissions per unit output appear to be higher under organic manage-
ment because of lower yields (54), whereas CH
4
emissions from paddy
soils per unit output might be even higher than per unit area (Fig. 1B)
(56). Energy consumption per unit output tends to remain lower, but
with high variability (Fig. 1B) (12,40,55).
Few studies to date have identified contextual factors driving GHG
emissions in organic versus conventional systems. Lee et al. (58)found
that the benefit of organic management in terms of energy consump-
tion is lowest for vegetables and fruits, whereas the benefit in terms of
GHG emissions was higher in monocropping systems (Table 1).
Water quality
Agriculture is a major threat to water quality, which affects both human
water security and freshwater (and marine) biodiversity (59). Agricultur-
al management influences water quality through losses of nitrogen (N)
and phosphorus (P) (which lead to eutrophication and hypoxia), as well
as pesticide leaching, and soil erosion leading to sediment loading (59).
The impact of organic management on water quality is one of the
environmental dimensions with greatest uncertainty (Figs. 1 and 3).
On average, N leaching per unit area in organic agriculture appears
to be lower (40,41), but variation is high (Fig. 3). Some have argued
that the variation within organic systems is as high as the difference
between organic and conventional systems and that the magnitude of
N loss depends more on the specific management practices used (60).
Lower N losses from organic systems are typically associated with
lowerNinputs(60) and higher N losses with lower nitrogen use effi-
ciency (NUE) due to the low availability of organic N to crops and
asynchronies between crop N demand and N availability from organic
sources (47,60,61), as well as the use of cover crops or leys that are not
harvested (62). However, N application rates and NUEs of organic
systems can vary widely (63), depending, for example, on whether
systems are legume-based or use external organic amendments (such
as composts or animal manures) for nutrient management. In addition,
organically managed soils often have higher organic matter content (see
discussion above), which can lead to higher N holding capacity (47,61).
Although organic farms typically have positive N budgets because
they apply more N than they remove through harvest (63,64), organic
yields are still often N-limited because of the low NUE of organic in-
puts (47,61). On average, nitrogen leaching per unit output might
therefore be higher in organic systems (Fig. 1B) (40,41).
The limited number of studies (40,41,63) and the large variation in
results do not permit reliable conclusions on P loss from organic ver-
sus conventional systems, although we can discuss factors that influence
P loss. Because of the low N:P ratios of many organic inputs, organic
farmers often overfertilize for P while trying to match crop N require-
ments (65). High-value organic horticultural systems, which often apply
large quantities of external organic matter to avoid N limitation, typi-
cally have the highest P surplus, whereas organic arable systems, which
rely more on BNF (biological N fixation) for N management, often have
aPdeficit(63–65). P surpluses in agricultural fields do not necessarily
lead to P losses (or P deficits to crop P limitation) because of the high P
buffering capacity of many soils and depend on erosion rates and the P
solubility in organic amendments (65).
Although we have reviewed the impact of organic management on
local- and regional-scale N and P loss, it is the amount of new reactive N
Fig. 2. Regional distribution of organic area, organic producers, as well as
studies included in key meta-analyses on organic agriculture. “Organic area”
represents data on total organic agricultural area (in hectares) for 2014 (3). “Or-
ganic producers”represents data for 2013 (3). “Yield studies”represents all studies
(n= 210) included in the works of Seufert et al. (18), Ponisio et al. (19), and de
Ponti et al. (20). “Profitability studies”represents all studies (n= 44) included in
the work of Crowder and Reganold (81). “Biodiversity studies”represents all stu-
dies (n= 150) included in the works of Crowder et al. (30), Bengtsson et al. (31),
and Tuck et al. (32). “SOC (soil organic carbon) studies”represents all studies (n=
75) included in the work of Gattinger et al. (39).
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A
B
Fig. 3. Uncertainty range around the average (per unit area) performance (depicted in Fig. 1A) of organic agriculture relative to conventional agriculture
(indicated by the red circle). (A)Lowerand(B) upper uncertainty range. Figure includes production (brown petals), environmental (green petals), producer (red petals), and
consumer (blue petals) benefits (petals that extend beyond the red circle) and costs (petals inside the red circle). See Fig. 1 for details on variables depicted. Shading of petals
represents the level of uncertainty for each variable (see Fig. 1 for legend and fig. S6 for details). Variables that cou ld not be quantified are shaded in gray. Upper and lower ranges
represent the lowest and highest values (typically low or high confidence intervals), represented as log response ratio (organic/conventional), from different quantitative reviews
or meta-analyses (see table S1 for sources and figs. S1, S2, and S5 for values used).
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(Nr) fixed through human activity and the amount of newly mined P that
matter at the global scale. Organic management has a clear advantage
in this regard because it more likely relies on recycled N and P inputs
(such as composts and animal manure) and less on newly fixed Nr or
mined P (66).
Many pesticides used in conventional agriculture have negative im-
pacts on nontarget aquatic organisms and can compromise the drinking
quality of surface and groundwater supplies (67). Although organic man-
agement is often assumed to reduce pesticide loads (4,13), critics argue
that some organic pesticides are more hazardous than synthetic pesticides
(7). The few assessments that were carried out find that organic pesticides
typically have lower toxicity (68) and often lower persistence in the
environment (69). However, some organic pesticides, such as sulfur
and rotenone, can have a higher total impact because of the higher dos-
ages and the higher frequency of application required, despite lower tox-
icity quotients (68). In practice, however, organic farmers typically use
integrated pest management (69,70) or use pesticides that are less harm-
ful (71,72). Therefore, it is likely that pesticide leaching from organic ag-
riculture is lower than that from conventional agriculture (Table 2).
Water quantity
Agriculture is the single biggest user of fresh water, and water shortages
pose important risks to future food production (73). Improving irriga-
tion efficiency and crop water management thus represent key strategies
for moving toward sustainable food production.
Water use in organic agriculture has received little attention [(4,13,40),
but see related studies (74–76)]. In general, organic soils show higher
water holding capacity and water infiltration rates due to higher or-
ganic matter content (23,76). This can lead to higher yields and water
use efficiency under drought and excessive rainfall conditions (23)and
to lower water limitation of organic yields (77). A farm survey in Aus-
tralia showed considerably lower water use on organic farms, potentially
due to higher grazing and cropping densities as well as environmental
motivations of farmers (74). Wheeler et al. (75)foundsimilarwateruse
Table 2. Impact of organic management on different production, environmental (per unit area), producer, and consumer variables that could not be
quantified (see Fig. 1). The direction of the arrows indicates the direction of impacts (that is, positive, up; negative, down; no change, right; uncertain, up and
down). Shading of arrows represents the level of uncertainty for each variable (dark shade, low uncertainty; medium shade, medium uncertainty; light shade,
high uncertainty), with uncertainty being determined by the number of primary studies examining each variable and the level of agreement between different
studies (see fig. S6 for more details). Some key references supporting the assessment of each effect are indicated.
Dimension Variable Direction of impact References
Yields Yield stability
(23−27)
Soil quality Low soil erosion (43−45)
Water quality Low pesticide leaching (69, 70)
Water quantity Low water use
(74, 75)
Farmer livelihood
Resilience (88)
Autonomy
(82, 83, 87)
Other benefits (84, 92)
Farmer and farm
worker health Low pesticide exposure (69, 70, 94, 95)
Farm worker
livelihood
Farm wages
(93, 96)
Labor conditions (93, 96)
Consumer access Low consumer prices (109, 111)
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per unit farm area but higher water use per unit output as a result of
lower yields on organic farms. In other words, while improved soil
quality from organic management provides some advantages for wa-
ter management, lower organic yields implies unclear impact per
unit output. An overall conclusion on the benefits of organic man-
agement for water use is not possible. This dimension, which is of
considerable importance for the sustainability of agriculture, requires
greater attention.
ORGANIC AGRICULTURE AND PRODUCER BENEFITS AND COSTS
Farmer livelihoods
Many farmers across the world have difficulty making a living from ag-
ricultureandoftenrelyonoff-farmincome(78,79). However, a farmer’s
livelihood goes beyond the income. We use the sustainable livelihoods
framework (80) to examine how organic agriculture influences farmer
livelihoods through (i) its relative profitability (determined by yields, cost
of production, and prices received), (ii) its relative resilience, (iii) the de-
gree to which it gives farmers autonomy, and (iv) its influence on other
livelihood benefits (such as access to knowledge, access to credit, access
to inputs, or access to markets).
A recent meta-analysis of studies from North America, Europe, and
India concluded that organic was more profitable than conventional
because of the higher premium prices received (Fig. 1) (81). Total man-
agement costs were similar; organic had higher labor costs but lower
input costs. Income without premium prices was lower under organic
management because of lower yields. However, premium prices
compensated for lower yields, which are typically higher than needed
to match profits from conventional agriculture.
Although organic agriculture might be more profitable, making ends
meet might still be challenging (82–85). Many authors have criticized
organic agriculture for mimicking models of conventional industrial
production, arguing that small organic and conventional producers face
similarchallenges(82,85–87).
Organic systems are often thought to have higher socioecological
resilience than conventional systems (88). Organic systems, which are often
diverse mixed farming systems (89), can minimize risk by reducing the
economic dependence on a single crop. In addition, organic price pre-
miums can sometimes buffer against low prices and price volatility [es-
pecially when coupled to Fair Trade certification (84,89)], and farming
systems following agroecological principles have sometimes been
shown to provide more stable yields and to be more resilient to extreme
weather events (23,90) (also see previous discussion on yield stability).
Three-quarters of organic farmers are located in low-income coun-
tries (Fig. 2), while 96% of organic food sales take place in European
and North American markets (3). Certified organic agriculture in low-
income countries is therefore an export-oriented farming system, typi-
cally dependent on exporting companies to access international organic
markets and associated premium prices (84,89). International organic
trade has therefore been criticized for reproducing the inequalities of
conventional north-south trade by concentrating market power in the
hands of transnational organic buyers and certifiers and by imposing
additional certification costs on producers (87). In high-income coun-
tries, instead, organic farmers are often part of alternative (local) food
networks and often sell directly to consumers, which typically has pos-
itive impacts on farmers’autonomy (82,83,91).
Finally, organic agriculture can provide other livelihood benefits, es-
pecially for farmers in low-income countries, such as the organization of
farmers in cooperatives, building of social networks, integration of tra-
ditional knowledge, providing training, and access to health and credit
programs through the certifying and exporting agency (84,92). Access
to such services as well as organization in farmer groups is sometimes
considered one of the most important benefits of organic agriculture for
smallholder farmers (92).
Farmer and farm worker health
Farm work is considered to be one of the most dangerous occupations,
and an important reason for this is the exposure to often toxic agro-
chemicals (93). Pesticide poisoning of farm workers and other people
handling pesticides causes an estimated 1 million deaths and chronic
diseases each year (67). Because of the lower use of pesticides in organic
agriculture (see discussion under “Water quality”), it is very likely that
pesticide exposure is lower on organic farms (Table 2), and this could
be one of the most important advantages of organic management for
farm workers, particularly in crops (such as fruits and vegetables) with
typically high pesticide application rates, as well as in regions with
weak pesticide regulations, such as India (Table 1) (67). Organic farm-
ers in low-income countries often report reduced health risks from
pesticide exposure as one oftheir key motivationsfor adopting organic
agriculture (94,95).
Farm worker livelihoods
The social issues concerning farm workers are numerous—both in the
Global North, where farm workers are often precariously employed,
farm wages are declining, and farm labor is increasingly dependent
on migrant workers (93), and in the Global South, where farm workers
are often among the poorest of society. Organic regulations do not
include clear labor guidelines. The limited research on farm worker
livelihoods on organic farms suggests that, for the most part, farm workers
on organic farms are faced with the same problems as those on
conventional farms.
The clearest distinction is that organic management typically re-
quires more labor (81,96), attributed not only to more labor-intensive
management practices (such as preparation of compost or weeding) but
also to a higher share of labor-intensive commodities, such as vegetables
and fruits, and often smaller farm sizes (83,96). Although this increases
employment opportunities for farm workers (Fig. 1), it can also be an
obstacle to adoption of organic farming in regions with labor shortage
(96). Because of the premium prices received (81), some studies have
concluded that organic agriculture leads to higher returns on family
and hired labor and therefore better remuneration of labor (96). How-
ever, evidence on the difference in wages of farm workers is anecdotal
and highly variable (Table 2).
Labor practices on organic farms vary widely, typically at the discre-
tion of the farmers (93), because of the lack of concrete labor guidelines
in organic regulations. Large-scale organic agriculture is often criticized for
reproducing the inequities of the conventional system (83,93). However,
there is little consistent evidence in high-income countries on differences
in labor conditions between organic and conventional farms or between
small and large farms; both can entail different types of exploitative labor
practices [for example, migrant versus voluntary labor (82,83,85,93,97)].
In low-income countries, it appears that organic certification mostly pro-
vides benefits to farm workers when coupled to Fair Trade certification of
smallholder farmers (98). Instead, large-scale organic production often
does not provide any benefit for farm workers because it is typically not
Fair Trade–certified (98). However, in general, there are even fewer studies
on labor relations in organic agriculture in low-income than in high-
income countries.
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ORGANIC AGRICULTURE AND CONSUMER BENEFITS AND COSTS
Consumer health
Consumers buy organic food predominantly because of health con-
cerns, to avoid contamination from chemical residues, and because or-
ganic food is associated with higher nutritional value (99). Accordingly,
this topic has received great attention (we identified 22 reviews, includ-
ing 11 quantitative reviews and meta-analyses), although most of the
comparisons included in these quantitative reviews are from Europe
(and a few from North America).
Thequantitativereviewsandmeta-analyses greatly disagree; some
found a significant difference in nutrient content between organic and
conventional crops (100–103),butothersdidnot(104–106). These dis-
agreements can be traced to four factors: (i) differences in results for
individual food components (see figs. S3 and S4); (ii) whether nutrient
content was measured on a dry matter or fresh weight basis [because
organic foods are often said to have higher dry matter content, which
could lead to a dilution in nutrient contents when measured on a dry
matter basis (100,101)]; (iii) differences in interpretation of similar
results [partly due to different grouping of compounds; see, for example,
conclusions from Hunter et al. (100) and Dangour et al. (104)onmineral
nutrient contents]; and (iv) uncertainty in whether an observed difference
in composition between organic and conventional food actually provides
any health benefits [see, for example, conclusions from Barański et al.
(102)andSmith-Spangleret al. (105) on the health effect of increased
phenolic compound content]. Few studies have examined actual health
outcomes of increased consumption of organic foods to date (105,107). It
is important to note that the health benefits of different food components
can be highly context-dependent [for example, micronutrient differences
may matter more in low-income countries, while in high-income coun-
tries, the most important health benefit of plant foods is most likely re-
lated to the antioxidant activity of secondary metabolites and vitamins
(101) (Table 1)].
Overall, average effects across different quantitative reviews and
meta-analyses suggest that organic plant foods have higher amounts
of secondary metabolites, vitamins, and mineral micronutrients and
macronutrients (Fig. 1) but with high uncertainty and disagreement be-
tween studies (Fig. 3 and fig. S5). For secondary metabolites, the evi-
dence for higher amounts in organic food is strongest (figs. S3 and
S5) and only the oldest and smallest (104) of four quantitative reviews
and meta-analyses (101,102,104,105) did not find an effect. The only
entirely unequivocal benefit of organic foods is reduced contamination
from pesticide residues (Figs. 1 and 3); although this might not matter
for consumers in high-income countries, where pesticide contamination
on conventionally grown food is far below acceptable daily intake thresh-
olds (67), it could provide an important health benefit for consumers
elsewhere.
Consumer access
Organic food typically has a substantial price premium, which benefits
producers (81), but at the expense of consumers. Higher organic prices
are due to limited supply relative to demand (108), the need to main-
tain separate distribution channels (109), and lower yields and some-
times higher production costs (81). Although direct organic marketing
initiatives such as farmers markets and Community Supported Agri-
culture (CSA) aim to be more accessible to low-income consumers,
they usually mostly reach middle-class consumers (91). However,
some studies suggest that CSA shares in an organic farm can provide
considerable cost savings to consumers, even compared to conventional
produce (Table 1) (110).
A study estimated that the costs of a fully organic diet in the United
States would be ~50% higher than a conventional one (109). However,
organic retail prices vary considerably between stores, years, and
products, ranging, for example, from 7% for spinach to 60% for salad
in the United States in 2010 (111). Data on organic consumer prices
for Europe are not available (108).Itisimportanttonotethatbreakeven
premiums needed to allow organic farmers to match profits of
conventional farmers are only 5 to 7% (81), and that if the organic sector
is to increase further, and distribution costs are lowered, organic
consumer prices could potentially decrease considerably. However, to
date, no strong decrease in organic consumer prices over time has been
observed in European or U.S. markets owing to demand outstripping
supply for many products (108,111).
SCALING UP ORGANIC
So far, we have mostly discussed the impact of organic management on
a single field or farm. A system-level transition to organic farming
would potentially have different effects from those discussed until
now, both due to positive and negative feedbacks. A fair assessment
of organic versus conventional farming systems should thus be con-
ducted at the food system level and, for example, consider feedbacks
with other sectors (such as the livestock or consumer sectors), issues
of nutrient availability, and off-farm impacts (66).
Some authors have argued that the yield gap between organic and
conventional agriculture would increase if more farms were converted
to organic because of problems in nutrient availability (9,20). Organic
agriculture today often relies on nutrient inputs from conventional
farms and is highly dependent on the livestock sector (112), and it is
unclear whether there would be sufficient non-BNF organic nutrient
inputs (from animal manure, municipal solid wastes, or crop residues)
iforganicweretobescaledup(9,20). Smil (113)estimatedthat,cur-
rently, only ~11% of total N inputs to croplands are from animal manure
and ~8% are from crop residues, and that crop residues (if left in the field)
could supply the equivalent of 30% of current global synthetic N fertil-
izer. The use of sewage sludge, currently not permitted by most organic
regulations, could potentially increase nutrient availability and recy-
cling. However, it is unlikely that global food production could be
met only through recycled N because some N losses from the system
areinevitable(114). Some amount of new N will thus need to be used,
either through synthetic fertilizer inputs or through BNF.
Whether sufficient nutrients could be available through BNF is an-
other concern. Many organic systems require long fallow periods and
(nonedible) leguminous crops in the rotation to manage soil fertility.
This implies that the output of edible calories over the course of an
organic rotation might be lower than that in conventional systems
(9) (although the legumes or leys in organic rotations are often used
as fodder for livestock and can thus also contribute to calorie produc-
tion). Somestudies estimate that BNF oncropped land provides about
half of the N required to feed the current world population (113). Badg-
ley et al. (5) estimated that BNF through additional leguminous cover
crops on current cropped land could replace current synthetic fertilizers,
but their analysis was criticized as a gross overestimate (9). Whether
sufficient organic nutrient sources from recycled N and BNF would
be available to grow enough food to feed the global population into
the future without requiring considerably more land area remains an
important question (66).
In addition to the question of whether organic could be scaled up, we
also need to consider the question of how scaling up would influence the
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performance of organic agriculture. Current organic farms are often
situated on marginal lands (21,43,115). Adoption of organic management
on more fertile lands and more beneficial production climates could po-
tentially increase the productivity of organic farming. In addition, or-
ganic agriculture has received limited research to date, and modern crop
varieties bred for high-input conventional management often do not per-
form well under organic management (116) because organic crops require
different traits (116,117). It is estimated that 95% of organic production
relies on crop varieties bred for conventional systems (117). Widespread
adoption of organic management could lead to increased research and de-
velopment of crop varieties adapted to organic management, as well as
development of management practices addressing yield-limiting factors
[for example, improved organic pest control, which has also received
limited attention (69), or the use of bioeffectors such as mycorrhiza or
rhizobia], and could thus potentially reduce the organic-conventional yield
gap. On the other hand, it is argued that organic farms are currently
benefitting from pest control on neighboring conventional farms and that
pest pressure would increase under more widespread adoption of organic
management and thus further reduce yields (118). To date there is no the-
oretical, observational, or experimental evidence to support this hypothesis,
and there also could be an opposing effect: Increased crop diversity under
organic management could potentially decrease the susceptibility to pest
outbreaks, whereas increased biodiversity on organic fields could in-
crease natural pest control.
In terms of environmental impacts, some studies suggest that an
increased density of organic farms has strong additional benefits for bio-
diversity (119,120) and for some soil quality parameters (121). However,
others observe no impact of scaled-up organic agriculture on regional
biodiversity (34). Large-scale adoption of organic agriculture could po-
tentially reduce nutrient losses at the regional or global scale because of
its enhanced use of recycled nutrient sources and its increased linkages
between crop and animal production systems (66).
An important caveat to consider when evaluating whether results
from individual studies on organic agriculture can be scaled up is the
appropriateness of study design and management practices used in
these studies. Most assessments of organic versus conventional agricul-
ture typically only examine a single factor (for example, yields or bio-
diversity) and over a limited time period. This fails to account for synergies
or trade-offs between different outcomes of organic agriculture (for ex-
ample, between yields and biodiversity), and it also fails to account for
long-term consequences (for example, land degradation, water availa-
bility, or climate change) that may affect future food production. Better
assessments of organic agriculture should conduct multidimensional
long-term studies that consider local, regional, and global feedback be-
tween different variables (66). In addition, the representativeness of
management practices used in studies requires attention. Seufert et al.
(18) have shown that relative organic yield performance is higher when
best practices (rather than typical practices) are used by both systems,
suggesting a stronger dependence of organic agriculture on the use
of best practices, probably because it is a more knowledge-intensive
system. Although this suggests that there is substantial room for im-
provement of current organic practices, it also questions how transfer-
able the results of many scientific studies are because farmers usually
do not use best practices.
Several modeling studies have simulated scenarios of large-scale con-
version to organic agriculture (122–125). However, their results depend
strongly on underlying assumptions, which are based on uncertain em-
pirical evidence (see Figs. 1 and 3). These studies mostly conclude that
wholesale conversion to organic would lead to reductions in food pro-
duction (122,124,125), which would lead to slight increases in food in-
security (122), or require changes in diet (123,125). On the other hand,
conversion to organic agriculture would decrease the eutrophication of
local waterways (124).Animportantcaveattoconsideristhatmostof
these modeling studies (122,123,125) do not consider questions of nu-
trient availability. Given the large uncertainties on many environmental
and social dimensions (Fig. 3) and our limited understanding of system-
level feedback, potential outcomes of large-scale conversion to organic
agriculture are also highly uncertain.
KNOWLEDGE GAPS
Our review of the performance of organic agriculture across multiple
dimensions has highlighted substantial knowledge gaps (Fig. 1). Some
dimensions have received considerable attention but with no consensus
to date [for example, species richness and food quality (lower right quad-
rant in fig. S6)]. For others, the direction of impact appears to be clear, but
better quantification through additional studies is needed [for example,
pesticide residues, rural employment, and N
2
O emissions per unit area
(upper left quadrant in fig. S6)]. Numerous other dimensions have re-
ceived limited attention [for example, N and P loss and CH
4
emissions
(lower left quadrant in fig. S6) or variables that could not be quantified,
for example, soil erosion, pesticide leaching, farmer resilience, and farm
wages (see Table 2 and Fig. 1)] or no attention at all (for example, calorie
production per unit area-time or global Nr creation). For those variables
that could not be quantified and included in Fig. 1, some have not yet
been examined sufficiently (for example, yield stability, soil erosion,pes-
ticide leaching, water use, farm wages, labor pesticide exposure, and
consumer prices), whereas others are difficult to quantify (for example,
farmer resilience, farmer autonomy, farmer benefits, and labor con-
ditions). Only for production per unit area, organism abundance, soil
organic matter, and profitability there seems to be ample evidence and
consensus supported by a sufficiently large number of studies (lower
right quadrant in fig. S6).
In addition to specific dimensions that require additional research,
there are other knowledge gaps to be addressed. First, more research on
organic farming systems in low-income countries is greatly needed; the
vast majority have been conducted in North America and Europe (Fig. 2).
However, three-quarters of organic producers are located in low-income
countries (Fig. 2), and sustainable food security challenges, as well as farm
management and socioeconomic and biophysical contexts, differ sub-
stantially between low- and high-income countries.
The second knowledge gap deals with the challenge of clearly iden-
tifying factors that drive the range oforganicperformance(Table1).An
improved assessment requires more studies covering a wide range of
conditions (for example, different climates or soils, different manage-
ment practices, farm sizes, and marketing channels) and also primary
studies collecting better contextual information (for example, reporting
study location and farm characteristics).
Finally, another important knowledge gap is the environmental
performance of organic agriculture per unit output (Fig. 1B). This re-
quires environmental scientists studying organic agriculture to measure
yields; and agronomists, who typically examine yields alone, to measure
environmental variables. These multidimensional studies of organic ag-
riculture (ideally including socioeconomic assessments as well) are par-
ticularly important to assess synergies and trade-offs between different
production, environmental, and socioeconomic dimensions under dif-
ferent contexts [for example, as highlighted by one of the few bio-
diversity studies that included an analysis of yields (35)].
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CONCLUSIONS
Critics and advocates of organic agriculture often seem to describe dif-
ferent realities (5,7). Although there is some evidence supporting argu-
ments from both sides, neither side is entirely right, and there is great
uncertainty in many dimensions. Organic agriculture has some clear
benefits and promising characteristics, for example, its positive influence
on local biodiversity, high productivity in some circumstances, or a live-
lihood for poor farmers in some situations. However, many unresolved
questions and concerns remain, such as N availability and the total land
area required, accessibility, and influence on N losses from the system.
It is also important to point out that the relative performance of or-
ganic agriculture compared to conventional agriculture variesconsider-
ably and is highly dependent on context and that estimates of the average
performance have limited practical use. The studies we reviewed show
superior organic performance for yields of forage crops, for biodiversity
of plants and pollinators in arable systems and simple landscapes, for
water quality in arable systems using low N inputs, for livelihoods of
farmers who participate in alternative food networks and who are located
in regions with low labor costs, for the health of consumers in regions
with micronutrient deficiencies and high pesticide residues on food,
and for consumer prices in CSA markets (Table 1). On the other hand,
organic agriculture performs less well for yields of cereal crops, for bio-
diversity of birds in pastures and extensive agricultural regions, for water
quality of horticultural systems using organic amendments, for the live-
lihood of farmers without access to premium prices, and for consumer
prices in regular wholesale markets (Table 1). Note that there can also be
trade-offs between these contextual factors. For example, yield performance
benefits from high N inputs, but water quality does not; similarly, organic
horticultural systems show particular benefits for the health of producers
due to reduced pesticide exposure, but perform poorly on energy use and
N and P loss (Table 1).
The stated goal of organic agriculture is “achieving optimal agroeco-
systems which are socially, ecologically and economically sustainable”
(126). Our review highlights potential policy targets to improve organic
performance to match this ambitious goal, including (i) targeted re-
search programs to develop new crop varieties for conditions specific to
organic management and development of efficient and selective organic
pesticides; (ii) an improved focus on environmental best practices in or-
ganic regulations; (iii) enhanced research and extension services on or-
ganic best practices; (iv) development of domestic organic markets and
organic certification, especially in low-income countries; (v) subsidies
for organic farmers to alleviate higher production and labor costs during
the transition period; (vi) regulation of labor rights; (vii) development of
(domestic) Fair Trade labels coupled to organic certification; and (viii)
improving accessibility of organic to low-income consumers by lowering
organic premiums through farmer or consumer subsidies. Finally, the
adoption of organic agriculture could be particularly beneficial under
those conditions and contexts where it has been shown to perform well
(Table 1).
However, organic agriculture cannot be the Holy Grail for our sus-
tainable food security challenges. First, the outcomes are uncertain (given
the ambivalence about the social and environmental benefits of current
organic practices). Second, being primarily a production system, organic
agriculture has limits in its ability to transform the food system. From an
environmental perspective, other changes to the food system (for exam-
ple, reducing food waste and changes in diet) might have greater benefits
(1). From an equity perspective, organic agriculture faces similar agricul-
tural labor, farmer livelihood, and consumer access challenges as con-
ventional agriculture, and we require more fundamental changes in the
way we produce, distribute, and consume our food to improve these
conditions. The question remains on whether organic agriculture, em-
bedded in alternative visions of the food system and conceived as a move-
ment rather than as a production practice, could contribute to a more just
food system.
From a broad policy perspective, we conclude that organic agricul-
ture offers many benefits and could be an important part of a suite of
strategies to improve the sustainability and equity of our food system. In
addition, the influence of organic agriculture extends beyond the ~1% of
agricultural land it covers at present. Many conventional farms have, in
recent years, increased the use of organic practices such as conservation
tillage, cover cropping, or composts (51). A further expansion of organic
agriculture and integrating successful organic management practices
into conventional farming are important next steps.
SUPPLEMENTARY MATERIALS
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/
content/full/3/3/e1602638/DC1
Supplementary Materials and Methods
fig. S1. Impact of organic agriculture on production, farmer livelihood, farm worker livelihood,
and consumer access (as depicted in Figs. 1A and 3), as well as water quality and climate
change mitigation variables per unit output (as depicted in Fig. 1B), as observed by different
meta-analyses and quantitative reviews [that is, de Ponti et al. (20), Ponisio et al. (19), Seufert et
al. (18), Crowder and Reganold (81), Mondelaers et al. (41), Tuomisto et al. (40), Skinner et al.
(54), and Gomiero et al. (12)].
fig. S2. Impact of organic agriculture on biodiversity, soil quality, water quality, and climate
change mitigation variables per unit area (as depicted in Figs. 1A and 3), as observed by
different meta-analyses and quantitative reviews [that is, Bengtsson et al. (31), Crowder et al.
(30), Tuck et al. (32), Tuomisto et al. (40), Mondelaers et al. (41), Gattinger et al. (39), Skinner et
al. (54), and Gomiero et al. (12)].
fig. S3. Difference in content of individual secondary metabolites, and vitamin groups in
organic versus conventional plant foods, as observed by different meta-analyses and
quantitative reviews [that is, Barański et al. (102), Brandt et al. (101), Dangour et al. (104),
Hunter et al. (100), and Worthington (103)].
fig. S4. Difference in content of individual mineral micronutrients and macronutrients in
organic versus conventional plant foods, as observed by different meta-analyses and
quantitative reviews [that is, Barański et al. (102), Dangour et al. (104), Hunter et al. (100), and
Worthington (103)].
fig. S5. Difference in content of aggregated secondary metabolites, vitamins, mineral
micronutrients and macronutrients, and pesticide residues in organic versus conventional
plant foods, as observed by different meta-analyses and quantitative reviews [that is, Barański
et al. (102), Brandt et al. (101), Dangour et al. (104), Hunter et al. (100), Smith-Spangler et al.
(105), and Worthington (103)].
fig. S6. Uncertainty in different variables (per unit area) on production benefits and costs
(brown), environmental benefits and costs (green), producer benefits and costs (red), and
consumer benefits and costs (blue), based on quantitative reviews of the organic literature.
table S1. Sources used for variables that could be quantified in Figs. 1 and 3.
table S2. Variables influencing the organic-conventional yield gap according to different meta-
analyses [that is, Seufert et al. (18), de Ponti et al. (20), and Ponisio et al. (19)] and large-scale
census data analyses [Kniss et al. (21)].
table S3. Variables influencing the difference in biodiversity between organic and
conventional agriculture according to different meta-analyses [that is, Tuck et al. (32) and
Kennedy et al. (33)] and large-scale primary studies [that is, Schneider et al. (34)].
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Acknowledgments
Funding: This research was funded by a Natural Science and Engineering Research Council
Discovery Grant (RGPIN/341935-2012) to N.R . Author contributions: V.S. and N.R. designed the
review framework; V.S. conducted the literature review; V.S. and N.R. wrote the manuscript.
Compet ing int erests : The authors declare that they have no competing interests. Data and
materials availability: All data needed to evaluate the conclusions in the paper are present in
the paper and/or the Supplementary Materials. Additional data related to this paper may be
requested from the authors.
Submitted 27 October 2016
Accepted 1 February 2017
Published 10 March 2017
10.1126/sciadv.1602638
Citation: V. Seufert, N. Ramankutty, Many shades of gray—The context-dependent
performance of organic agriculture. Sci. Adv. 3, e1602638 (2017).
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