CAB Reviews 2012 7, No. 062 Review Anticipating impacts of climate change on organic

Abdullah A. Jaradat*

Address: United States Department of Agriculture, Agricultural Research Service, and Department of Agronomy and Plant Genetics, University of Minnesota, 803 Iowa Avenue, Morris, MN 56267, USA.

*Correspondence: Email: [email protected], [email protected]

Received: 28 August 2012 Accepted: 24 September 2012 doi: 10.1079/PAVSNNR20127062

The electronic version of this article is the definitive one. It is located here: http://www.cabi.org/cabreviews g CAB International 2012 (Online ISSN 1749-8848)

Abstract

Both conventional agriculture (CA) and organic agriculture (OA) are inextricably linked to climate and will impact and be impacted by climate change (CC). OA, unlike CA, encompasses hetero- geneous agricultural management methods and practices, given its multiple origins around the world. Although it represents < 1% of the world’s agricultural production and about 9% of total agricultural area, OA is a globally growing, low-input, dynamic and knowledge-intensive production system. It provides a larger flow of multiple ecosystems services than, and differs fundamentally from, CA in the conceptual approaches that frame crop, animal and natural resources-manage- ment strategies. Organic farmers have fewer means to manage their production systems and they need greater expertise and more time to optimize the management of OA in the face of CC. The diverse OA-based agroecological systems (AESs), compared with CA, provide more regulatory functions that enable OA to adjust to changing environmental conditions; however, OA may experience larger inter-annual variability which is attributed to fewer short-term possibilities for controlling biotic and abiotic stresses. Nevertheless, small-scale organic farmers and communities are seemingly able to cope with weather fluctuations and climate extremes because of the self-regulating ability of OA and the enormous variability in internal adaptation strategies they have developed over time. However, vulnerability of OA to CC will eventually depend on the level of exposure and sensitivity to multiple biotic and abiotic stresses, and on its intrinsic buffering capacity for adaptation and mitigation. Long-term of OA in the face of CC is intractably linked to ecological sustainability. CC and ecological disturbances may force OA to undergo structural changes or adjustments as to land area; farm size and land tenure; farming complexity, crop–livestock integration, sustainable intensification and specialization; environ- mental ; and labour intensity. Conventionalization, to the extent that it does not undermine its core principles, may become the only economically viable structural change option to adapt large-scale OA to CC. In order to minimize the impact of CC, OA needs to function within the broader context of multidisciplinary agro-ecological principles, while adopting scienti- fically based, resource-efficient and semi-closed AESs’ approach. The challenge facing OA is to develop measurable and reliable biophysical vulnerability indicators to prioritize adaptation and mitigation efforts at the farm and local levels.

Keywords: Abiotic stress, , Climate change, Conventionalization, Ecosystem services, Indigenous knowledge, Genetic diversity

Review Methodology: I searched the USDA-National Agricultural Library ‘Navigator’ with access to nine databases including AGRICOLA, AGRIS, BIOSIS, CAB Abstracts, among others, and contained > 44 million records. I used the listed keywords above and selected the most relevant and up-to-date references on the topic.

http://www.cabi.org/cabreviews 2 CAB Reviews Introduction One of the major differences between conventional agriculture (CA) and OA is the degree to which the farmer After almost a century of development, organic agri- can control biotic and abiotic stresses, especially under culture (OA), a product of the organic movement climate change (CC) [21, 22]. OA can be more practical originally concerned with healthy soils, food and people in more difficult environments, where resources are [1, 2], has been embraced by the mainstream [3, 4] and scarce and cultivation is problematic [20]. OA started as a shows great commercial [5, 6], social [7–10] and envir- heterogeneous agricultural management method of crop onmental [4, 11] promise. However, the modern organic and livestock production owing to its multiple origins movement that has its roots in a ‘philosophy of life’ and around the world [18, 23]. It may have a higher resilience to not in the agricultural sciences [2] is radically different CC because it is more diversified than CA [24, 25] and can from its original form, with environmental sustainability potentially contribute to long-term resilience and stability now as its core [6, 12]. Its alignment with the wider of production under CC [26–28]. However, vulnerability environmental movement has resulted in principles that of OA to CC will eventually depend on the level of have a stronger environmental focus than those from the exposure and sensitivity to multiple biotic and abiotic first half of the 20th century [6, 13]. The publication of stresses [29, 30], and on its intrinsic buffering capacity ‘’ in 1962 was a key turning point for, and the for adaptation and mitigation [31–33]. This paper presents start of, both the modern organic and environmental a critical review assessing the state of knowledge and movements. During its formative years [3, 4] the organic anticipating the impact of CC on OA, offers research-based movement lacked confrontational tactics of many other guidelines as to where future efforts should be placed to social movements but worked on exemplars of alternative adapt OA to CC and outlines strategies that can be used agricultural practices and increasingly on providing organic by farmers to adapt OA to, and mitigate CC impact at the products. OA was destined to attain ecological balance farm level. through the design of farming systems, establishment of habitats and maintenance of genetic and agricultural Climate Change diversity [2]. The formation of a formal global network (i.e. The International Federation of Organic Agriculture Global change refers to interactions of the Earth’s Movements (IFOAM)) in 1972 is one of the landmarks in biogeophysical systems with human activities, involving the history of the organic movement. A range of radical land-use, climate, water and nutrient changes [29, 34]. environmental thinkers and activists clustered around it, The climate is changing and, for the foreseeable future, it ranging from eco-socialists to conservatives. Recently, will continue to have significant positive or negative however, the movement found itself a mover within, effects on agriculture and natural resources, including and tribune for, the protests against genetically modified water, soil, biodiversity, pests and pathogens [35–38]. organisms (GMOs), especially in North America [13], Changes in climate, as manifested by higher temperatures where it became dominated by corporate interests, and and heat waves, changes in precipitation patterns, somehow soon realized that trade-offs between envi- increased greenhouse gases (GHG) and their interactions ronmental benefits and social goods are difficult. with other environmental stresses are already affecting The global organic market for and drinks the sustainability of agroecological systems (AESs) and was estimated at US$23 billion in 2006 [6] and at US$55 disrupting production [29, 39, 40]. Current knowledge billion in 2009 [14] of which North America and Europe suggests that CC will affect both biotic and abiotic factors collect almost equal portion of 97% of revenues, while in cropping systems, threatening crops’ sustainability only 3% are shared between 120 countries where OA and production [41]. Future CC could become a major is being practiced. Historically, increased cost of inputs and source of food insecurity to millions [42, 43], especially in fear over declining soil fertility were the main factors developing countries where different forms of resource- in converting to OA in developing countries, while envir- limited, low-input and OA are being practiced [18–21]. In onmental health and food quality concerns were pre- the predominantly arid AESs of the developing countries, dominant factors in converting in developed countries [15]. many crop plants and farm animals are near their phy- If it was not for the environmental movement, the siological limits for tolerating global warming and drought, organic movement was in decline during the 1950s, after and even small, let alone extreme, changes in abiotic losing the post-Second World War argument over the stress levels may have significant consequences on AES direction of agriculture [6]. Nevertheless, OA is develop- sustainability, ecosystem services and peoples’ livelihoods ing rapidly and is being increasingly practiced in many [26, 33, 39, 44–46]. countries in the developed [13, 16, 17] as well as in the developing world [18–21], with modest, but important contributions to feeding the world, especially in developing Certainty, uncertainty and CC countries [17]. The organically managed 31 million hec- tares represent less than 1% of the world’s agricultural A critical knowledge gap exists where the role of AESs production and about 9% of total agricultural area [17, 18]. [26, 27, 47–50] as well as other potential synergies and

http://www.cabi.org/cabreviews Abdullah A. Jaradat 3 trade-offs with CC mitigation and adaptation (i.e. the integrate crop and livestock production [56, 65] or adopt adjustment in natural or human systems to actual or a new production system [21, 35, 76–78]. Therefore, expected climate stimuli or their effects) is uncertain discussing the risk and uncertainty of CC is especially [9, 42, 51]. Nevertheless, the Intergovernmental Panel on critical [40, 42, 46, 73, 74], as sound climate science is Climate Change (IPCC) [29] routinely discusses and required to implement rational and useful adaptation and provides consensus judgments about the nature and mitigation strategies [59, 63, 79–81]. Organic farmers’ extent of scientific uncertainty about factors causing CC; awareness of change in climate attributes such as tem- however, if CC is a real issue [33], then it needs to be perature and precipitation is important for adaptation made real to people on the ground, including farmers decision-making [82, 83]; however, they may have realized practicing OA. Although there is uncertainty about the that adaptation options become fewer as climate varia- absolute magnitude of CC over the next 50 years [36, 52, bility increases [10, 21, 68, 84]; the cost and complexity of 53], there is general agreement that carbon dioxide (CO2) adaptation will increase [41, 85, 86], yet the benefits of levels will increase to near 450 ppm, temperature will adaptation will increase as well [23, 27, 54, 87]. increase by 1.0–2.0C and precipitation will become more variable as defined in the IPCC AR4 analysis [54, 55]. Organic farmers may be able to manage this variation through investment, management and indigenous knowl- Organic Agriculture edge (IK) [32, 33, 56]; however, there will be some inherent uncertainty in expected responses depending The multitude of names encountered in the literature for on the intrinsic buffering capacity of OA for adaptation OA [66], may represent different production ‘ideologies.’ and mitigation [33, 57–59]. Adaptation of crop pests Nevertheless, OA can be defined as any system of food and pathogens to environmental stresses is an important production that seeks to minimize the flow of inputs and aspect that adds to the uncertainty of CC impact on OA outputs; which sequesters non-renewable resources because of its specific pest- and pathogen-control stra- across the boundaries of the production area while at the tegies [60–62]. same time maintains or increases the internal flows of mass, nutrients and energy within the system’s bound- aries; or alternatively [88] a system aimed at producing Farmers’ perception of CC food with minimal harm to ecosystems, animals or humans. Others [89] consider OA as an aggregate of Farmers are generally aware of the overall effects of CC regulations ensuring efficient use of resources, and as on agriculture, but usually are not aware that it could be such, is no different from integrated farm management. exacerbated by some agricultural practices [39]. Organic Whereas, in a developing country context [83, 90], OA farmers acknowledge that extreme weather events and represents a broad set of practices that emphasize farming uncertainties in the onset of farming season have been on based on ecosystem management, integrated cropping the increase [1, 26, 39]. They attribute climatic variability and livestock systems, diversity of products, and reliance at intra- and inter-annual and decadal time scales to CC on natural pest and disease management without the use [24, 63, 64] and consider the practice of OA as one of the of synthetic inputs. Most farms in developing countries are most important measures for adaptation to CC [39, 40, organic by default [91]; the majority is small subsistence 56]. Farmers also realize that the capacity of OA to adapt crop–livestock family farms with no access to chemical to changing climate and weather conditions is based on its inputs owing to lack or inaccessibility of such inputs. natural resources endowment [10, 17] and associated Whether it is an ideology [92], a complex and holistic economic, social, cultural and political conditions [10, 34, production management system [2, 23], the answer to 65]. Given the enormous variability in internal adaptation sustainability [6], a solution for global [37], strategies [22, 33, 66], many organic and traditional farms, or a more resilient production and management approach despite weather fluctuations, seem able to cope with CC to CC than CA [2], OA is more than ‘avoiding chemical and climate extremes. Small-scale organic farmers are inputs and plugging in some organic practices [37].’ seemingly able to cope with weather fluctuations and Moreover, OA is considered by some [6] as the original climate extremes because of the self-regulating ability of and mainstream agriculture and CA is the one that OA [24] and the enormous variability in internal adapta- departed from the practices that agriculture has been tion strategies they developed over time [58, 67–69]. In following since its inception. Many of the practices of OA addition, farmers rely on IK to exploit different micro- were the only option for farmers before the advent of climates and to derive multiple AES services from the chemical inputs, mechanization and fossil fuels that allow genetic and species diversity among their crop plants [65, to function [13, 19]. OA is generally 70–72] and farm animals [50, 55, 56]. Production risk associated with higher levels of floral and faunal biodi- under CC influences organic farmers’ decision to adopt a versity; thus, it may have positive effects on species’ new management practice [73, 74], diversify crops [8, 69], richness and abundance [45]. The complex nature of OA alternate short- and long-cycle crop varieties [8, 9, 75], agroecosystems contrasts with the extreme simplification

http://www.cabi.org/cabreviews 4 CAB Reviews and large dependency on external inputs that characterize Structural and Temporal Diversity of OA and CC CA [2]. As an ideology, not all OA’s strategies can be applied Presumably, OA should attain ecological balance through globally and without many local adjustments; because the design of farming systems, establishment of habitats of this lack of coherence, it may aggravate agricultural and maintenance of genetic and agricultural diversity [2]; and environmental problems [92]. However, many of its its adaptive capacity stems from its ability to adjust to supporters believe that OA, besides having a strong social climate variability [84, 99] and weather extremes [10, 35], and political agenda, is more than the sum of its parts and to moderate potential damages [35, 42, 60] and cope with that the reductionist view widely used in natural science the consequences of CC [10, 68, 69]. This adaptive does not see the big picture [13, 17]; OA is a systems capacity is attributed to the high structural and temporal approach that combines a range of practices in an optimal diversity of OA and is applicable at different temporal and and synergistic manner. The organic movement used OA spatial scales [35]. OA and similar traditional AESs have as a bottom-up strategy for rural economic and social been recognized as complex dynamic co-evolutionary development. Largely driven by non-governmental orga- processes generating adaptive plant–animal–human inter- nizations (NGOs), this side of the movement seeks to use actions [34, 51, 100]. This complexity maintains a high OA to improve livelihoods and revitalize rural economies. level of variation through temporal and spatial changes in A more stable and reliable crop yield, income diversifi- selection pressure, inter-genotypic and inter-specific cation, the chance to receive higher prices for organic competition, and interaction of arable crops and farm products, minimal reliance on external inputs and the animals with pests and pathogens [101–103] and the encouragement of IK all indicate that OA has this environment [19, 61, 65]. potential [21, 23]. However, some obstacles persist, Introducing variation over time and space will stabilize including expensive certification processes, under- or OA at different spatial scales; this includes complex crop undeveloped domestic markets for organic products and rotations and growing mixtures of heterogeneous vari- the recent conventionalization of OA [28]; it was sug- eties [69, 104] and landraces with large buffering capacity gested that ‘organic movement’ is not relevant anymore [75]. Varietal mixtures, particularly of small grains, can and should be replaced with ‘organic industry’. Never- provide functional diversity that limits pathogen and pest theless, the continued existence of a major social and expansion thus stabilizing temporal crop yields under political role for OA suggests that it is more than just an disease pressures [75, 105, 106]. Complex crop rotations industry [4]. are expected to produce larger total yields and to have As a holistic production management system, which smaller temporal variances than simple rotations or promotes and enhances AES health [27], including biodi- monocultures [32, 74] and may significantly increase the versity [18, 45, 93], biological and nutrient cycles [94], and long-term retention of soil carbon (C) and nitrogen (N) soil biological activity [23, 95], OA emphasizes the use of [107], which has important implications for sustained management practices in preference to the use of exter- production over time and for better environmental nal and off-farm inputs, taking into account that regional quality [31]. Structural heterogeneity created by organic conditions require locally adapted AESs [23, 96]. This is agroforestry has an important role in biodiversity reg- accomplished by using, where possible, agronomic, bio- ulation [108]. Perennial energy crops, fruit trees [69] and logical and mechanical methods, instead of using synthetic organic agroforestry [93] add more structural diversity to inputs, to fulfil any specific function within the system the agricultural landscape and provide a high-quality [23, 42]. If OA is the answer to sustainability, it has to be matrix through which CC mitigations may occur; thus, adapted to the local farming and social norms [4]; and to counteracting the extinction rates of that geographical and climatic conditions [45]. The capacity of usually co-exist in a meta- model context. OA to influence, for example, international trade, labour Integrating trees into the agricultural landscape can reg- relations and agrichemical policy is limited [6]. As global ulate the climate at a local scale through modification food security has become a primary concern because of of the microclimate and at global scale through reductions population growth and CC [46, 56, 59, 62], the pro- in atmospheric C by sequestering, preserving and sub- ductivity of OA and thus the contribution that it can make stituting C as a stable organic matter [108]. Changes in in feeding the world is increasingly important [37, 58, 68, soil organic matter (SOM), an important AES service 93]. Recent reports [97] suggested that a rise in demand associated with OA, may need many more years or a few for organic products led to a shortage and strained decades to reach equilibrium [61] and contribute to CC organic supply chains. Increased demand for organic adaptation [83, 105, 109]. products may lead to increased involvement of large agribusinesses in an increasingly globalized organic food market and may lead to more externalization of envir- C-N- of OA onmental costs through intensification of OA; organic premiums could be reduced or eliminated with social, There is considerable interest in OA as one of the environmental and climatic ramifications [98]. potentially most C-neutral (or preferably C-negative)

http://www.cabi.org/cabreviews Abdullah A. Jaradat 5 strategies to produce food in temperate [48] as well as considerable impact on surface- and ground-water quality tropical and sub-tropical regions [83]. The C footprint, [117]. Higher soil C and N availability from cover crops, an indicator of GHG emissions and global warming [110], typical of OA, may increase CO2 and N2O emissions is much smaller in OA as compared with CA. OA has [116]. These emissions, without significant concomitant greater C-sequestration potential than CA [80]; on C-sequestration, could render OA vulnerable to CC and average, soil C content in OA may increase annually by make it a net contributor to global warming [104]. 2.2%, whereas in CA it may not change significantly [111]. Widespread adoption of OA could potentially sequester up to 1.5 Bt of C yr71, which would offset about 11% of Energy and nutrient flow in OA all anthropogenic global GHG emissions for at least the next 20 years [29]. For example, the adoption of OA In the nutrient- and energy-intensive CA, solutions to practices in the maize/soybean growing region of the USA CC are generally more technologically focused, requiring would increase soil C-sequestration by 0.13–0.30Â1014 larger investment in mitigation and adaptation over time gyr71 [45]. However, there is a high uncertainty in [33]. Such external inputs are likely to become increas- sequestration rates of C in organic pastures given the ingly inaccessible by resource-poor farmers because of typically large soil and stand spatial and temporal het- rising energy costs [17]; OA offers an alternative to CA by erogeneity [112]. implementing a series of practices that optimize nutrient Optimization of C and N cycling through SOM can and energy flows, minimize production risk [73, 104] and improve soil fertility and crop yields, while reducing is likely to impart yield stability under CC [20, 72, 117]. negative environmental or climatic impact [107]. Soil Such practices include the use of complex crop rotations, C-sequestration, as SOM and humus, through OA prac- enhanced crop diversity and cropping intensity, BNF, tices improves soil quality as a result of improved soil organic manure, crop–livestock integration, and biological structure, water-holding capacity, aggregate stability and control of pests and pathogens [17]. These practices may cationic exchange capacity; and leads to improved tilth lead to moderate (10–50%) [45] or large (50–70%) [21] and adaptation to CC [29, 61]. However, different reduction in direct and indirect energy use per unit of thresholds of soil organic C for sustainable tilth conditions production in OA as compared with CA, lower direct and may exist for different soil types [113]. The higher level of indirect GHG emissions [17], and further adapt OA to SOM in OA, compared with CA, creates greater sinks for CC and climate variability [39]. both C and water, thus addressing GHG emissions and OA is sensitive to asynchronous nutrient availability the approaching global water shortages [102]. Given the [116]; the limited availability of nutrient resources is a higher SOM produced by OA, which retains more water characteristic of OA, and it is an ongoing challenge for for longer time than soils of CA, not only organic farmers to maintain a balance between nutrient conserves water but also saves energy inputs for irrigation demands for crops [109], livestock [118] and the organic [21]. Variations in the storage, fluxes and quality of soil resources available. It is claimed [119], however, that water are invariably sensitive to CC [26]. increased diversity of soil microbial biomass contributes C and N assimilations are strongly linked and are both to more readily available nutrients in the soil profile and linked to water availability in the soil profile [72]. These eventually to larger productivity. Nutrient balance in OA linkages are important in OA which offers numerous is often close to zero, resulting in higher energy efficiency opportunities for developing more sustainable production [13]. Nutrient budgets can be used as regulatory tools to systems with higher C-sequestration capacity, no external monitor, and potentially reduce nutrient loss to the N input and lower net fossil energy consumption and environment [109]. Organic standards impose a specific GHG emissions under CC [49, 114]. Biological N fixation set of realities and restrictions on OA [2] that affects (BNF), a major N source in OA, contributes 180Â106 energy efficiency and GHG emissions. Even though OA mt yr71 globally, out of which symbiotic associations practices are compliant with existing regulations [3], they produce 80% and the rest from free-living or associative may negatively impact energy use, nutrient losses, and systems [115]. This N form is more sustainable than N , and could result in a large C footprint [7]. from industrial sources in terms of ecological integrity, Although OA, on average, is more energy-efficient than energy flows and food security [58]; and when properly CA [45, 120], it requires 10% more labour for field managed, it improves soil properties and nutrient cycling crops, and up to 90% more labour for horticultural crops [99] and often reduces GHG emissions [48, 49]. Although [45]. Energy output of OA is about one-third lower than N2O emissions from OA using biological N sources is CA, whereas energy efficiency (output energy : input usually low [80], N management in OA to reduce reactive energy) is higher in OA [120, 121]. As a result, OA can be N losses can be a key component in the mitigation of CC designed to store energy at levels similar to or even because emissions of N2O can significantly contribute to higher than CA, thus contributing to a better energetic global warming [59]. N losses via surface runoff can be efficiency and adaptation to CC [65]. relatively low in OA [116]. However, OA may leach large In a C-constrained world, it is relevant to question amounts of N, which, over the long-term, may have a whether and to what extent might energy offsets from

http://www.cabi.org/cabreviews 6 CAB Reviews bioenergy crops, crop residues and biogas production biodiversity and the provision of ecosystem services create a more favourable energy balance for OA [19, 81, under CC [132]. A large portion of agricultural pests and 122, 123]. Using crop biomass for bioenergy production diseases is usually controlled by natural enemies [85, 126, in OA would cause a large nutrient deficit that cannot be 132]. Such background suppression is a valuable ecosys- replaced using synthetic nutrient sources [81, 116, 117]. If tem service largely suppressed in CA, but of greater sig- implemented in OA, the use of biomass for bioenergy may nificance in OA to keep pest populations below economic lead to short-term reduction in GHG emissions; however, threshold levels [103]. in the long-term, it can result in reduced energy-use On-farm use and maintenance of large inter- and intra- efficiency, increased CO2 emissions and detrimental crop diversity, as a regular practice in OA, is a highly environmental impact [72]. In addition, the practice may valued component [130] whose include eventually lead to increased acidification and eutrophica- increased genetic diversity and buffering capacity to tion risk [122]. combat biotic and abiotic stresses [45], better competi- tion with weeds [133], higher pollination success rates and improved quality [87, 134] and enhanced yield stability Ecosystem services of OA under CC under CC [69]. Weed control in OA is a major technical challenge and the mechanical methods that are often used Organic agricultural production, as a dynamic social– can impact several ecosystem services, including soil ecological system based on the extraction of biological C-sequestration and nutrient mineralization [103]. By products and services from an ecosystem [4], internalizes using organic residues with low C:N ratio to maintain soil public benefits by bundling a ‘product’ and an ‘ecosystem fertility, combined with large temporal diversity in crop service’ that are paid for, often at a premium, by con- sequences in OA, significantly increases the retention of sumers [86, 124]. These premiums, however, may soil C and N [50, 107, 110]. High SOM in OA is usually become at risk if and when large-scale organic producers associated with richer food webs and higher biological or processors enter the organic food market [125]. activity that drive soil ecological services [61]. The Promotion of organic products with added environmental retention of high SOM has important implications for value enables their market penetration [96] and regional and global C and N budgets, sustained crop encourages farmers to further incorporate environmental production, enhanced environmental quality [107, 111, objectives into the production and marketing of such 135], and may contribute to macroclimate modification products [126–128], and even direct marketing [129]. For [20, 26]. On the other hand, microclimate modification example, the monetary value of ecosystem services in the can be accomplished through organic agroforestry by USA, including provisioning, regulating, supporting and changing the availability of abiotic and biotic resources to aesthetic services was estimated at about US$1074 ha71, other species in the ecosystem [108]. Perennial agrofor- of which 46 and 54% were derived from market and non- estry and horticultural trees can modify microclimate market ecosystem services, respectively [108]; ecosystem conditions, including temperature, humidity and wind services derived from OA are usually 2–3 times higher speed that can have beneficial effects on crop growth or than those derived from CA [103]. animal welfare, and eventually on multiple ecosystem Some researchers (e.g. [130]) and practitioners [2, 23] services [61, 108]. However, horticultural crops are more attribute a larger flow of ecosystem services to OA than sensitive than field crops to short-term environmental to CA; hence, the decreased vulnerability and stronger stresses that affect reproductive biology, water content link between the functioning of OA ecosystems and their and fruit quality; thus, they are likely to be more impacted role for society [124]. Ecosystem responses to CC and by CC and extreme weather events [136]. variability may have implications for sustainability, biodi- versity and ecosystem services available to society [131]. Certain CCs impact biological (i.e. crops, farm animals and Impact of CC-mediated biotic and abiotic stresses micro-organisms) systems only; others create further on OA feedbacks to the climate through GHG fluxes, eco-phy- siological changes and edaphic processes [26]. Consistent Although critical knowledge gaps in the role of OA in with evidence for higher ecosystem service provision in GHG emissions, and other potential synergies and trade- OA compared with CA [67], higher crop diversity in OA offs with CC mitigation and adaptation still exist [51], the has a stabilizing effect on the higher trophic levels that greater dependence of OA on ecological approaches to it supports; whereas, removing a trophic level can cause food production potentially offers novel ways of dealing an ecosystem to shift to a less-desired state, affecting its with CC and climate variability and reducing external capacity to generate ecosystem services, such as edaphic inputs to control or modify the production environment processes [26] and pest control [41]. Biological control of [75]. CC-mediated biotic and abiotic stresses are forcing pests and diseases is a key ecosystem service crucial OA and other AESs to function under a greater level of to OA. Maintenance of plant health is a key requirement perturbation [41]. However, because there are few for CC mitigation; it contributes to the preservation of opportunities for immediate alleviation of abiotic and

http://www.cabi.org/cabreviews Abdullah A. Jaradat 7 biotic stress in OA, the need for complex adaptation crops [24, 106, 139] and on improving soil fertility over strategies to CC is becoming increasingly more important years [59, 111, 113]. They also can use appropriate crop [75]. In order to reliably predict the effects of CC on OA varieties, variety mixtures and crop populations which are processes, it will be necessary to determine how biotic competitive with weeds, tolerant to pests and diseases and abiotic context alters the direction and magnitude of [132], and have improved nutrient and water uptake and CC effects on numerous biotic interactions within the use efficiencies [69]. Many organic farmers are aware of soil–water–crop–atmosphere continuum [137]. In-depth the strong association between a landscape with poor understanding and proper management of these interac- biodiversity and the appearance of pests and diseases in tions will reduce the CC-mediated stresses on OA [51]; their crops. Organic farmers try to enrich such landscape upon decomposition, plant residues may have positive or with different species and even biotopes by integrating negative effects on plant-derived resources [137]. The species’ diversity into the cultivated land [70], which can C:N ratio in plant residues affects the soil micro-flora and be used to assess the biotic environment of their farms. N release during decomposition [46]; nutrient recycling is sensitive to changes in plant species composition (e.g. in a ) and their response to CC [116]. Multi-functionality and Vulnerability of OA to CC Higher-order effects among multiple CC drivers, which are expected to act simultaneously, may create challenges OA is multifunctional; it encompasses practices that in predicting future OA responses to CC [35, 84, 136]. promote environmental quality and ecosystem function- Moreover, extrapolating these complex impacts across ality using an integrated natural resources management networks of micro-organisms–crop plant (and possibly approach [140]. From an organic AES’ perspective, CC is soil fauna and farm animal) species’ interactions may result not simply an environmental problem that can be solved in unanticipated effects on OA [137]. Micro-organisms, by reducing GHG emissions, with little or no attention to particularly in OA, can influence crop plant response its interdependent and interconnected social, cultural, to abiotic stresses (e.g. drought, chilling injury, salinity, environmental, political and ethical aspects [141]. Social metal toxicity and high temperature) through different norms, as exemplified through consumer pressure, are mechanisms such as induction in plant cells of osmopro- particularly relevant to adaptation to CC. On the other tectants and heat-shock proteins [44] and nutrient cycling hand, environmental and human rights norms are of [41]. Climatic or soil characteristics often result in sec- importance not only to public actors or NGOs but also to ondary nutritive or biotic stresses, which may become customers, especially those who care about the environ- limiting factors for crop yield and quality. Therefore, mental and social implications of the products they buy nutrient uptake and use efficiencies are of particular and the brands they support [12, 14]. Although there is importance whether in breeding crops [31, 75, 101] or complexity in combining socio-economic, development, fertilizer management in OA [5, 25, 41, 45]. biodiversity conservation and CC adaptation outcomes, Crop landraces and heterogeneous populations pro- OA, being more diversified than CA, may have higher pagated on the farm are capable of adapting to changing resilience, but is more costly to sustainably function under climate and biotic pressures owing to dynamic changes in CC; the extra cost is usually met by premiums, subsidies gene frequencies and related phenotypes over time [31]. or both [35]. In general, higher levels of biological diver- Natural selection usually favours high-yielding genotypes sity [34] and increased capacity of soils to store stable C in environments with fluctuating biotic and abiotic selec- [29] potentially confer more resilience to CC. Therefore, tion pressures, a condition typical of most AESs [101]. a comprehensive understanding of the vulnerabilities of This flexibility is especially useful in OA because it does OA to CC, at different bio-physical and edaphic hier- not rely on external synthetic inputs. Crops in OA usually archies, is required to develop an effective adaptation have enough genetic plasticity to adapt to the specific response at local, regional and global scales [20]. Vul- conditions of their target environment [24]; however, nerability of OA is a result of exposure, sensitivity and new crops or crop varieties with broad adaptation to adaptive capacity to abiotic [29] and biotic stresses, annually varying climatic factors combined with acceptable especially when it is exposed to possible migrations of level of specific adaptation to ‘normal’ local climate and pests and diseases from conventional AESs [97]. The level soil conditions may become necessary. Therefore, of susceptibility to or inability to cope with adverse cli- advanced breeding and selection techniques, including matic effects largely depends on OA’s level of sensitivity, , may have to be employed to accel- resilience [36] and adaptive capacity [35]. Such vulner- erate crop plants manipulation and to develop or select ability increases in line with OA’s performance level, and more resistant crops or crop varieties to biotic and when coupled with an adverse environment, it becomes at abiotic stresses [138]. even greater risk [55, 124]. In addition, inherent genetic In OA, large inter-annual variability can be expected characteristics, including potential contamination with because of fewer short-term possibilities for controlling genetically modified crops [125], and management sce- biotic and abiotic stress; therefore, organic farmers have narios that limit OA’s ability to adapt to, or cope with, to rely on resilience and self-regulating ability of their environmental factors also puts it at risk [20, 55, 126].

http://www.cabi.org/cabreviews 8 CAB Reviews Linking adaptation to agricultural resilience constitutes [19, 89], increased intensification may render OA more a valuable multifunctional approach to develop sustainable vulnerable to CC since it depends on market conditions OA, particularly in environmentally and edaphically sen- [12, 35, 142]. Any changes in productivity, product quality sitive regions of the world such as parts of Africa [27], or production cost will have immediate consequences Latin America [34] and the Mediterranean Basin [64]. for OA’s viability [21, 77, 120]. On the other hand, land Therefore, the development of bio-physical vulnerability sharing between food production and biodiversity, within profiles and indicators to prioritize adaptation and miti- OA’s context, may render semi-natural ecosystems and gation efforts becomes necessary [27]. Vulnerability pro- biotops more vulnerable to CC because of smaller sizes, files of OA can assist in the selection and development of reduced land quality and less connectivity between habitat appropriate multifunctional adaptation measures and may patches [132]. help prevent the use of an exploitative adaptation strategy that could lead to land degradation, loss of biodiversity, inefficient use of energy and water, and, eventually, a Organic Agroecosystems: their Role in CC gradual loss of productivity [27]. Adaptation and Mitigation Mitigation and adaptation strategies, and their syner- gistic effects, are response options to decrease OA’s Agroecosystems are products of co-evolution between vulnerability to CC [136]; however, adaptation, but not farmers and nature [65], and agroecology, as a trans- mitigation, is a priority in developing countries where disciplinary field of inquiry that has both scientific and mitigation capacity is low and vulnerability is high [28]. philosophical bases for promoting sustainability [51], Historically, extensive and inexpensive mitigation and links structure and functioning of AESs, and offers basic adaptation strategies developed and implemented by principles for their design and management at the field and indigenous people in developing countries have enabled farm levels [65]. Our knowledge of the role of AESs in farmers to reduce their vulnerability to past climate reducing CC impact is still in its infancy [36], and more variability and change [68]. As a result of ‘observational research and broader databases than currently available studies,’ those farmers realized that the linkages between are still needed to quantify the mitigation potential of vulnerability, adaptive capacity and adaptation are often organic AESs [23]. However, the more diverse the circular rather than linear in nature [9]. With the advent organic AESs are, the more they are expected to provide of the ‘,’ there is a need to expand those larger and more sustained ecosystem services [130]; observational studies in developing countries and tropical organic AESs have intrinsic regulatory functions that and subtropical climates. Such studies might also broaden enable them to adjust to changing conditions, including the knowledge base on vulnerability and adaptive CC and climate variability [22, 29]. With smaller capital responses in organic, low-input and subsistence AESs. The and input investments and larger knowledge investment, presence or absence of such knowledge and adaptation along with larger ecological complexity, organic AESs, skills comprises fundamental determinants of how vul- unlike high-input, high-risk conventional AESs, have the nerable OA will be to external or internal stresses potential to be of lower risk and less vulnerable to CC including CC [10]. and climate variability over time [33, 84]. Climate-related adaptations form part of producers’ The challenge of developing and maintaining such AESs overall risk management strategy and vary according that can simultaneously adapt and mitigate CC impact to farm types and locations [10]. As different farm types while providing multiple ecosystem services is urgent in adapt differently, a larger diversity in farm types may developed as well as developing countries [27, 36]. A reduce the impact of CC and climate variability at a critical knowledge gap exists where the role of agro- regional level, but certain farm types may remain vulner- ecology and GHG emissions as well as other potential able [84]. For example, organic horticultural production synergies and trade-offs with CC mitigation and adapta- systems [25], unlike field crops [101], are most vulnerable tion is uncertain [51]. Therefore, adaptive management, to CC; they have long management response time-frames, where indicators of AES health and service delivery and and significant infrastructure and production investment. the state of climate and climate stressors are continuously However, when combined with agroforestry, horticultural monitored, was advocated [36] to ensure that AESs are production systems serve as tools in biodiversity con- adapting to changing climate conditions. At the AES level, servation, CC mitigation and overall land-use sustainability autonomous and planned adaptations to CC may involve in CA [22] and OA [68]. Similarly, small family organic changes in land use and allocation, new management farms, unlike large, conventionalized organic farms, have techniques, breeding organic crop varieties, and changes little capital to invest in expensive adaptation strategies in crop species and cultivars [35]. Nevertheless, as site- [28, 39, 51]; this could increase the vulnerability of rural specific production issues require site-specific knowledge agricultural communities to CC and a changing environ- and solutions, experience [8] has shown that identified ment [9, 41]. adaptation measures to increase the resilience of AESs Although land availability may not be as great a [99] do not necessarily translate into changes at the constraint for extensification as claimed by OA critics field or farm level because there are context-specific

http://www.cabi.org/cabreviews Abdullah A. Jaradat 9 agronomic, social, financial, cultural and even psychologi- can be subsequently engineered into crop plants to cal barriers to adaptation [8, 63]. Constraints to adapta- cope with CC-induced stresses at AES and regional tion, especially among resource-poor farmers, include scales [44]. poor financial resources, non-availability of weather information and poor access to technology necessary for adaptation and to extension services [90]. Small-scale Intensification versus extensification of OA under CC farmers, having a low resource base, are more vulnerable and less able to cope with the consequences of CC. Such Although ecological intensification of agriculture, including farmers also have less likelihood of accessing weather OA, ultimately depends on successful scientific break- information or the capacity to develop technologies on throughs in basic plant and soil sciences [78], the trans- their own [90, 104]. Adaptation of OA to CC can be formation of OA, whether through intensification or influenced and motivated, or prevented and constrained, extensification, is more about the interaction of such by the public sector through laws, regulations, incentives breakthroughs with a number of social, environmental and policies with direct or indirect affects [12, 30]. and economic concerns and outcomes [19]; these include One underlying theme in developing the scientific provisioning of nutrients other than N, biological and basis and design of organic agro-ecological practices is mechanical control of pests, diseases and weeds, product the biotic interactions within the soil–plant–atmosphere quality and safety, labour and minimizing off-site envir- continuum that largely determine functions and adapta- onmental impact [67, 85, 132, 133]. Consequently, sus- tion and mitigation potential response of organic AES to tainable intensification [42] to produce more food and CC and climate variability [51]. All mitigation options at other ecosystem services from the same land area while the AES level affect the C and N cycles; these include reducing the environmental impact of OA is an important measures to reduce soil erosion, reduce N and phos- factor in determining the actual impact of CC and climate phorus (P) leaching, increase soil moisture conservation, variability on OA [62, 84]. increase crop diversity and rotation complexity, modify If OA has the potential to mitigate the negative impact microclimate and change land use [99]. Soil management of intensification on biodiversity [143, 144], then the less- can be an effective tool for CC mitigation and adaptation intensive OA can promote species richness [145], con- [59] especially in temperate climates [23]; whereas dif- tribute less nutrient loadings, improve environmental ferences between soil types and between crop rotations performance in terms of energy use and eutrophication were singled out as major contributors to yield variability [7] and benefit both crop yield and quality via crop pol- in organic AESs in temperate [74], but not tropical and lination as an ecosystem service [87]. Pollinator commu- subtropical, climates where there is need for more data to nities inhabiting extensively managed marginal areas are consolidate these findings at a global level [23]. generally much more diverse, and provide more ecosys- The need for adaptation of crop species and varieties to tem services, than those inhabiting the more intensively varied environmental conditions is currently more managed agricultural landscapes [134]. The intensification- important in organic AESs [75]. Demand for more crop land sparing argument, which implies that there is a pro- species and new varieties with proper mix of broad and ductivity–biodiversity trade-off [66, 94], could be valid for specific adaptation and response to short- and long-term post green revolution CA [142, 146]; however, the variations in climate, weather, soil and management situation is more complicated when the more complex factors is triggered by CC and climate variation [24, 75]. organic AESs are considered [93, 147]. This combination of requirements implies that crop vari- Increased intensification of OA, if resulted in larger eties developed for organic AESs need to be better farms, simplified cropping systems and less use of labour, characterized with respect to genotypeÂenvironment may become vulnerable to CC [35]. Such large farms (GÂE) interaction than varieties for CA [24, 127]. In function on market conditions and any changes in pro- addition, organic farmers have to rely more on short-term ductivity, product quality or production cost will have resilience and self-regulating ability of their crops during immediate effects on their sustainability [58, 61, 148]. the growing season and on improving soil fertility and its A majority of global land use changes, associated with buffering capacity over years [24, 33, 36]. Genetically agricultural intensification, lead to degradation in the diverse bulk populations [101], or even genetically mod- forms of soil erosion, compaction, reduced SOM and ified crops [18], allow for adaptation to diseases through biotic simplification [25, 34]. Land-use intensification the establishment of a self-regulating plant–pathogen has consistently adverse effects on many components of evolutionary system within organic AESs. The adaptation soil decomposers [76, 113]. These arise mainly from of crop varieties to efficient nutrient use derived from enhanced disturbance, changes in the nature of organic slow nutrient-releasing organic fertilizers in organic AESs (and inorganic) inputs and altered resource levels in the is of special importance [106]. The rich and highly diverse soil. Different components of the soil food web respond microbial populations characteristic of organic AESs very differently to CC because the relative importance of provide excellent models for understanding the stress top-down and bottom-up forces differ for different tolerance, adaptation and response mechanisms that components of the soil food web [94, 137].

http://www.cabi.org/cabreviews 10 CAB Reviews Extensive organic livestock production, when based on OA can be impacted by large inter-annual climatic crop–range–livestock AES, may increase resource-use variability because of fewer short-term possibilities for efficiency and land-use intensity [149]; have a higher controlling biotic and abiotic stresses [41, 63] or mod- environmental impact in relation to water, land, and waste ifying the production environment [142]. Therefore, consumption and management, and may directly result in organic farmers mostly rely on resilient and diversified higher C footprint of livestock production [7] or indir- AESs [35], self-regulating ability of their crops [101] and ectly through land-use change, which is a driver of global on improved soil fertility [69]. This knowledge-intensive warming [149]. Replacement of mineral fertilizers by strategy [33] has the potential of providing adaptation farmyard manure as a special form of extensification may and mitigation benefits to farmers. Nevertheless, future reduce resource-use and improve soil quality, but slightly developments in OA may call for adopting technologies increase nutrient losses [146]. Improved grazing man- from the most diverse and seemingly incompatible sour- agement, including the use of legumes, and grazing inten- ces, including the products of biotechnological innovations sity and stocking rates, can be a cost-effective option that [18]. The ‘Organotransgenesis’ concept was advanced promotes substantial soil organic C gains on the extensive [150] to advocate the transformation of low-yielding OA, land areas of often degraded permanent grasslands [7]. especially in developing countries, where ‘ecological Limited livestock density on natural pastures avoids agriculture’ can benefit from biotechnological advances. overgrazing, which is considered a risk factor for land Organotransgenesis can provide smart technological and degradation and may lead to high soil C losses [47, 50]. biological solutions, for example, for efficient weed con- The limitation of livestock units per hectare and the lower trol [95]; management of agrochemical and nutrient inputs production intensity are incentives for multiuse livestock [96]; modification of livestock diets to reduce or minimize systems [17]. enteric fermentation [5, 58] and N content of manure Any future extensification of OA will increase compe- [36]; integrated crop–livestock production to minimize tition for labour, land area and organic nutrients [19]. overall GHG emissions and nutrient cycling [7, 119]; and Such competition may reduce OA’s beneficial effect on for the development of alternative choices of final animal the low-input component of agriculture in developing products to reduce environmental loadings [151]. countries owing to limited land area and organic nutrients Modern biotechnology is producing new crop varieties [116–118, 139], and may increase its disadvantage in with higher input-use efficiency [62], and tolerance to developed countries because of competition for land and biotic and abiotic stresses [152, 153]. Is it conceivable, for labour [19]. In both cases, extensification may result in example, that organic farmers will use transgenic crops as higher GHG emissions if OA is assumed to produce lower an adaptation strategy to lessen the impact of CC [18]? crop yields [51]. Generally, the overall extensification of Genetically modified crops are advocated as being rele- an intensively managed AES will reduce its environmental vant for in developing countries impacts, both per unit area and product [146]. Partial where OA is expanding [18]. Genetic engineering has extensification of OA, in order to achieve economic and already produced crop plants that are more resistant to environmental sustainability, should be considered within biotic and abiotic stresses [138], and horticultural crop the context of the whole organic AES [146]. Extensifica- varieties with improved quality and shelf life [6]. tion of organic fertilizer use and mechanical cultivation, Biofortification through genetic engineering has the for example, may only result in a general improvement in potential to improve the amount of micronutrients, vita- environmental performance of OA [116]. A reduction in mins, essential amino acids and fatty acids (e.g. Omega-3) plant protection intensity, by banning certain organic in OA [138]. Biotechnological advances leading to more , may reduce negative impacts on eco-toxicity stable soil C-sequestration (i.e. humus) through organic and biodiversity [34, 126, 143], global warming, eutro- farming practices will improve soil structure and quality phication and acidification [7]. [95]; whereas, advances leading to increased buffering capacity of organic inputs are expected to improve nutrient and water availability over time and are likely to Biotechnology, resilience of OA and CC impart yield stability in OA [80]. Alternatively, bio- technologies developed by OA to replace synthetic As global food security of a growing [43] external inputs, such as biofertilizers, symbiotic BNF, and climate risks [20] have become primary concerns, the bioenhancers (e.g. N-fixing bacteria) and biopesticides, resilience [33], productivity [37], environmental health are cost-effective, low-input options that can be adopted and optimization [142], and the contribution of OA to by CA [62, 71, 115]. feed the world are becoming increasingly important There is a growing need to breed crop varieties [24, 31, issues. Most agricultural (bio)-technologies have direct or 101, 106] and animal breeds [5, 21, 26, 36, 54, 154] indirect climate linkages [30] and may benefit OA [18]. suitable for OA. Evolutionary plant breeding [31], where However, evaluating new technologies, according to the crop populations with a high level of genetic diversity organic movement [2], can be problematic and subject to are subjected to natural selection, and marker-assisted heated debate [6]. selection based on markers that contain GÂE interaction

http://www.cabi.org/cabreviews Abdullah A. Jaradat 11 information in plant breeding [24] are technologies tar- and organic AESs is the degree to which farmers can geting organic AESs. Selection of crop varieties suited to control biotic and abiotic stresses [24] and, subsequently, OA requires a different approach to that used when reduce the resulting yield gap [37, 156], or help mitigate breeding for conventional high-input systems. Molecular CC [33, 35]. Because of the lack of historical data and markers may help predict the trait expression of a depending on what OA actually entails, it is debatable plant genotype in relation to a specific environmental whether OA as a whole is ‘conventionalizing,’ or it is being factor(s) [24]. increasingly influenced by CA [3] through, for example, There are fewer opportunities in OA to compensate the use of off-farm inputs which is a violation of for limitations to yield imposed by crop and livestock core organic principles and values [2]. Eventually, con- diseases [26], low nutrients and weed pressure [35, 117]; ventionalization of OA may be triggered by a reduction in in addition, new crop varieties and animal breeds need to its competitiveness with CA or when its relative profit- adapt to highly variable environmental conditions across ability is reduced substantially due to higher production the diversity of organic AESs [155]. The livestock popu- costs and higher prices [12]. Alternatively, new advances lation explosion, potentially a huge contributor to global in seed technology and crop breeding for OA may warming and a target of CC [54], may account for 18–51% accelerate the transition to commercial organic farming, of total GHG global emissions [7]. On the other hand, the and reduce the current yield gap [156]. Technological use of energy-saving and regenerative energy technologies innovations in CA may result in matching productivity can improve production and efficiency of OA without with environmental protection, and the latter is no longer increasing the risk of environmental pollution [57]. a specific competitive advantage for OA. However, if the OA sector desires to adhere to the core principles and values of OA [2] and promote long-term market Conventionalization of OA to combat CC perspectives as well as public support, it should develop strategies that limit conventionalization or mitigate its If OA has intrinsic adaptive advantages to combat CC negative effects on OA [3]. [136], emits lower GHG than CA per unit land area [58], augments ecological processes that foster plant nutrition and health [45, 103], produces healthier food [92], empowers women farmers [4] and generally provides IK, OA and CC more sustainable ecosystem services [130], then why conventionalize it? Changes in AES processes associated Local cultures play important roles in generating IK and with converting from CA to OA, especially processes can shape the process of adaptation to CC [39]. More- based on SOM, can take many years or even decades to over, local cultures can provide, alter or limit options for reach a new equilibrium [61]. Whether the reverse is adaptation and can determine how individuals within true is yet to be seen, especially if a more pragmatic communities respond to the prospect of changes to their and flexible move is taken to face the global problems lives and livelihoods in the face of CC [21]. Although of CC and population growth [89]. Nevertheless, con- there is sufficient knowledge and experience to adapt to ventionalization of OA may help identify its strengths and CC [33, 90], the wealth of IK, based on predicting weaknesses [6]. For example, the perceived low pro- weather and climate, is rarely taken into consideration in ductivity [94] and vulnerability of OA to CC highlights the the design and implementation of modern CC mitigation importance of generating local knowledge and integrating and adaptation strategies [68]. Historically, IK was well it with other sources of knowledge and practices in order recognized in empowering local decision-making and was to develop successful responses to CC and empower highly appreciated in developing successful responses to local decision-making [40]; improvements can be made for CC [40]. Proactive, innovative organic farmers generally OA and relevant knowledge and practices can be trans- served as role models for others in their community ferred to receptive CA farmers [6]. A few detailed [33]. Resource-poor farmers, with these aspects in mind, accounts suggest that nitrate leaching rate in OA is similar developed IK systems and implemented extensive miti- to CA and that OA may experience slow but accumulating gation and adaptation strategies that enabled them to mineral deficits, particularly of P and potassium (K); reduce their vulnerability to past CC and climate varia- therefore, OA may become dependent on products that bility [68]. are conventionally produced with inorganic minerals [89]. Our knowledge of the role of AESs in reducing CC The production and delivery of multiple ecosystem impact [36], as well as other potential synergies and trade- services depend on land-use intensity and diversity of an offs with CC mitigation and adaptation [51] is still in its AES [130]. Current practices in (certified) OA may have a infancy. However, the knowledge-intensive organic AES, negative impact on issues such as energy use, nutrient being more consistent with de-carbonizing the world, is losses and recycling, even though these practices are, for likely to become more attractive over time for a high-C the most part, compliant with existing regulation on OA world [33]. In addition, IK’s contribution in improving [2]. One of the major differences between conventional climate modelling and forecasting provides the basis for

http://www.cabi.org/cabreviews 12 CAB Reviews decision-making and implementation of adaptation stra- closing the yield gap between OA and CA would increase tegies [53]. food production and supply [37, 156], the impact on the Regarding social and gender equity in agriculture, environment and potential feedbacks that could affect OA, unlike CA, empowers women and relies on their future food production [42] might be uncertain, especially IK for decision-making on business development and if larger yields are achieved through intensification [93]. management, resource allocation, production of crops New markets for organic foods, as well as government and livestock, and marketing of products [4]; such incentives and mandates [51], no matter how small, IK-based decisions are more critical for OA under chal- temporary or permanent [157, 158] are behind the global lenging environmental and management conditions [118]. adoption of organic practices in managing biotic interac- For example, IK-based decisions about livestock diseases tions at the AES level. However, perception of risk were shown to be practical, cost-effective, sustainable and and losses because of biotic stresses influence farmers’ environmentally friendly [2, 21, 23]. There is a need to decision to adopt OA [97]. Therefore, environmental include IK in manipulating the more complex organic sustainability became the new component, in addition to AESs, breeding locally adapted crops and livestock breeds, healthy soils, food and people, at the core of the modern and on-farm production of biofertilizers and biopesticides organic movement [6]. Organic farmers are now equipped [21, 62]. with the proper mechanisms for incorporating environ- mental objectives into [96], and are able to harness natural biological and ecological processes [83] in the The OA-Food Systems-CC Interface production of sustainable and healthy food and other ecosystem services, and simultaneously mitigate and adapt CC and food security are two great challenges for to CC [22, 27, 139]. Based on these expectations, it was humanity in the 21st century [92]; however, until recently, projected [154] that OA can meet the quantitative food the scientific community could not measure, monitor and requirements of a large metropolitan region (e.g. River analyse the complex linkages between agriculture–food– Seine watershed, France) if a few structural adjustments, environment systems at a global scale [43]. Although it is especially in livestock and N management, are imple- difficult to predict the CC impacts on agricultural pro- mented at the watershed level. On the other hand, duction and food security [17, 34, 36], CC-induced advocacy of the ‘Local-Food Movement’ and ‘Eat-Local’ changes in nutrient cycling and soil moisture and fertility, philosophy, a promoter of environmentally friendly eating as well as shifts in pest incidences and plant diseases will habits and reduced food miles, may lead to limited greatly influence food production and food security [41]. exports of organic products from developing to devel- Some researchers (e.g. [42]) contend that the risk of oped country markets, reduced income of poor farmers climate-induced collapse of the food system is substantial. and lower adoption of organic farming practices [45]. Others (e.g. [139]) warn of the implications of trade-offs More recently, the ‘Know Your Farmer, Know Your between crop yield and C-sequestration for meeting Food’ advocacy in the USA [159] promotes, among other global demand for food and other ecosystem services as things, the consumption of locally grown products, well as the need to mitigate CC. If global food systems including organic food. These feedbacks may have negative are already stressed because of CC [42] or will become implications for food security and sustainable livelihoods stressed as a result of rising population pressure and under CC in developing countries [9, 13, 17]. CC [25], do we have the key information needed to efficiently and simultaneously manage climate risks and enhance food security [20]? OA at the Genotype-Management-CC Nexus OA is expected to have a strong potential for building resilient food systems in the face of uncertainties [17] Organic farmers are expected to produce food and other through farm diversification and building soil fertility with ecosystem services with fewer environmental impacts; organic matter [21], where N derived from BNF pro- they need a thorough understanding of the potential cesses is more sustainable in terms of ecological integrity, trade-offs among several management options [116], and energy flows and food security than N from industrial how to select crop species, varieties or genotypes to fit sources [45, 50, 58]. Within the African context, for their production objectives and climates [127]. OA differs example [8, 30, 83], OA enables AESs to better adjust to fundamentally from CA in the conceptual approaches the effects of CC through GHG reduction, restoration of that frame crop management strategies [60]; it depends SOM content, reduced soil erosion and improved soil on system properties that take many years to develop physical structure. In many developing countries, organic equilibriums between many interacting biotic and abiotic AESs achieve equal or even higher yields than conven- factors [37]. These properties enhance a dynamic mosaic tional ones [21, 53]. This may have positive implications structure on the landscape and benefit microbial [76], for food security and sustainable livelihoods under CC nutrients [61] plant [144] and livestock [160] diversity and [17, 36] and calls for better understanding of factors interactions. Adherents to its principles and values argue limiting crop yield in organic AESs [31, 39, 88]. Although that OA is a holistic, low-impact production management

http://www.cabi.org/cabreviews Abdullah A. Jaradat 13 system [161] which promotes and enhances AES health, Organic farmers who breed or grow evolving crop including biodiversity, ecological cycles and soil biological populations have to contend with trade-offs between activity [2]. However, management and production deci- overall performance and diversity and stability under sions based only on the IFOAM’s ‘strict’ rules may lead changing climate [31, 101]. Organic crops may have to decisions with potential negative production and enough genetic plasticity to adapt to the specific condi- environmental impacts [18]. For example, the limited tions of their target environment [24] but not to combat availability of N in organic AESs, in particular, requires CC. The typically low frequency of high-yielding geno- careful and more efficient multiple and compatible types in heterogeneous populations is expected to management strategies [58], as well as crop species, increase because of natural selection in environments varieties, and genotypes with high nutrient uptake- and with fluctuating biotic and abiotic selection pressure use-efficiencies [117, 162]. Further varietal improvements [101]; a situation typical of, and especially useful in, OA in nutrient uptake and use efficiencies alone may not be an that do not rely on external inputs for crop protection efficient way to resolve the inadequate nutrient availability or enhanced soil fertility [59]. Evolutionary breeding in some organic AESs; researchers and farmers need to [101, 106] can generate such genetic plasticity with valu- improve the overall efficiency of the cropping system able redundant genotypes that may become important as well [127]. Soil nutrient management in OA can when climate changes [41]. However, evolutionary have profound implications for plant–nutrient–pathogen– breeding may eventually lead to a build-up of seed-borne weather interactions; suggesting that the consequences of diseases, particularly for pathogens against which resis- soil processes in organic AESs extends to community- tance is rare or absent in a crop population [31]. There- level mechanisms for regulating soil microbial commu- fore, organic farmers need to use proper on-farm seed nities [76], soil-borne diseases and pest populations [61] treatment measures and crop sequencing. These practices and biobased crop protection chemicals and their will require financial expenditure to ensure high organic potential environmental hazards [163]. seed quality [31, 101]. Adaptive responses to CC include the design and management of complex AESs with abundant biological and structural diversity [34]. Organic farmers have to Future of OA: Impact of Agro-politics and CC comply with large inter-annual variability and rely on crop resilience [24] because of fewer short-term possibilities OA was originally formulated as an ideology, but current available to control biotic and abiotic stresses [106]. In the and future global problems (mainly CC and population absence of external inputs, the environmental buffering growth) need agricultural pragmatism and flexibility, not capacity of an organic crop largely depends on its genetic ideology [89]. Therefore, the long-term positive envir- buffering capacity, and ability and flexibility for intra- onmental effects of OA and the potential impact of CC on genotypic compensation [75]. Organic crops may have OA are critical factors in formulating agro-policies for enough genetic plasticity to adapt and respond to the delivering its AES services to the public [29]. The public specific conditions of their target environments [24]. needs to identify and design an adequate policy frame- However, broad adaptation to temporal variation (i.e. work to support mitigation and adaptation of OA to CC long-term climate) and responsiveness to short-term [164]. The Round Table on OA and CC is spearheading climatic variation and soil conditions are prerequisites for a public initiative ‘to increase the understanding and crop varieties and populations to fit the objectives of OA quantify the role that OA can play in CC mitigation and [31]; therefore, such crops need to be better character- adaptation ... with a view to initiate policy change to ized for GÂEÂmanagement interactions [24, 110]. wider adoption and support of OA’ [23]. However, the Heterogeneous crops, varietal mixtures and crop global liberalization of agro-policies is placing more bur- populations provide organic farmers with ample variation dens of managing AESs on local farmers and farming for multiple traits needed under a changing climate [75]. communities [25]. Thus, organic farmers, depending on Increased crop genetic diversity can play a role in pest and national agro-policies, invariably need to be more self- diseases management [67], enhance pollination services reliant in the face of increasingly open and competitive [134] and improve biochemical soil processes [45]. national and international organic food markets [23–25]. A genetically diverse bulk population, particularly of Marketing issues [159] influence farmers’ decisions of field crops, allows for adaptation to disease through whether to expand or decrease their organic operations the establishment of a self-regulating plant-pathogen co- or shift to CA. Moreover, because of its small share of evolutionary system [75, 101]. Old crop varieties and global food production, OA has a limited influence on genotypes are often more competitive than modern international trade, labour relations and agro-policies [6]; varieties; their early-season and rapid ground cover, high therefore, it is challenging to identify and design adequate tillering ability and high leaf area index confer later com- policy framework for supporting CC mitigation and petitiveness against weeds [75]; whereas their well- adaptation strategies for OA [164]. developed root systems confer drought tolerance [41] While policy makers and the public increasingly and efficient water and nutrient uptake [117]. recognize the importance of diversifying agriculture for

http://www.cabi.org/cabreviews 14 CAB Reviews delivering multiple AES services, mainstream policies environmentally friendly, than synthetic counterparts in developed countries are still in favour of high-input [126] is not always valid [15, 126] and their potential and monoculture agribusiness in responding to CC and impact on pollinators, if not properly used, need to be related issues affecting agricultural production [31]. OA, evaluated [134]. CC may indirectly enhance human in the foreseeable future, may enjoy stable expansion with exposure to agricultural pathogens and chemicals; a increased public support by boosting research and hazard that can be managed, for the most part, through development; experience a policy-driven modest positive targeted research and policy changes [38]. Specialized growth as a result of a general global economic crisis farm equipment and inputs are considered as main con- and a worsening of the socio-economic climate; or it may straints facing OA farmers in developing countries [63]; lose public support, competitiveness and comparative their availability and affordability are intricately linked to advantage because of more agricultural industrialization, agro-policies and market development forces which deregulation and relaxed agro-environmental policies appear to override CC concerns [63]. [12]. Regardless of these scenarios, policy-makers and researchers should consider the sociological and eco- nomic implications when formulating agro-policies to Research and Development Needs and Priorities invest in exploring the potential of reducing the environ- mental impact on OA and improving its performance Research on more closed organic AESs has been ongoing under CC [72]. Policy-makers, in trying to get farmers since the 1940s, and data describing the benefits and to adapt to CC, should always involve those farmers problems of these systems have been generally adequate in formulating agro-policies and learn from adaptive [14]. Recently, however, researchers allied with the measures they already practice [56]. organic movement are determined to provide it with the Agro-policies should facilitate and support autonomous practical knowledge to farm organically and to argue for and planned adaptations to CC [35]; the former involves organic in policy circles [11, 57] in spite of some scepti- adjustments at the farm-level to optimize production, cism [19]. Nevertheless, research and development such as changes in crop species, cultivars, sowing date, priorities in OA are being shaped simultaneously by cli- fertilization rates and timing, and irrigation frequency [35]; matic and environmental concerns [30, 158], and by food the latter involves changes in land allocation, AES design, security and quality issues [20, 157]. Current research breeding of crop varieties and new land management embodies trans-disciplinary, holistic and reductionist techniques [35]. Public policies targeting market integra- research methods in understanding the complexities of tion, farm production, food security concerns and ecological approaches to OA [11]. OA has the potential response to CC are expected to drive OA intensification to evolve into a more vibrant and environmentally friendly through land-use change and AES transformation [12, 30, agricultural sector because of its multiple socio-economic 54]. Therefore, conducive land-use policies may assist and environmental benefits [7] even if sustainable inten- farmers and farming communities to develop CC-resilient, sification was the choice for development under CC [42]. or properly adjust current AESs within their local bio- The overriding question in this regard is how and how physical and socio-cultural contexts [25]. well organic farmers can, quantitatively and qualitatively, Rising energy costs and the need to optimize energy mitigate and adapt to CC [99], while sustainably produ- use on organic farms may require a trade-off between cing high-quality food [10, 23]? Evidently, both pro- policies and practices formulated to promote on-farm ductivity and efficiency must be increased without bioenergy production [7, 80] and strategies designed to increasing the risk of environmental pollution [112]. increase biomass recycling and enhance soil fertility and Historically, innovative on-farm agricultural practices OA sustainability [81]. C emission policies need to and technologies contributed to CC mitigation and simultaneously encourage OA farmers to recognize GHG adaptation in developing [30, 90] and, more recently, in emissions as a costly production input and create new developed countries [3, 37]. Crops and livestock, selected opportunities and incentives for on-farm mitigation [30]. from local germplasm [41] and breeds [55] or developed Therefore, it may be more cost-effective for agro-policies using advanced breeding methodologies [18, 101], when to promote reductions in GHG emissions from OA than properly managed, have lower climate loadings [42], or increase its C-sequestration under CC [48, 110, 139]. are tolerant to CC [69]. In future, not only the suitability Global warming, especially under tropical and sub-tropical of crop cultivars but also the suitability of applied tech- climates, will inevitably lead to higher decomposition rates nologies during the breeding process has to be considered of SOM, which can only partly be compensated for by when choosing cultivars for OA. The current develop- increased inputs in OA [35]. ments in global breeding (e.g. organic wheat) put further Policies guiding the selection of pesticides with small pressure on the organic movement to establish its own ecological footprints often emphasize natural products breeding programmes [101]. Current and future organic and organic-certified pesticides to increase OA’s sustain- farmers need to optimize future on-farm research in ability [85, 126]. The public perception of biofertilizers order to maximize the ability to detect true responses to and biopesticides as being uniformly safer, and thus more management and input factors [12, 32]. Organic farmers

http://www.cabi.org/cabreviews Abdullah A. Jaradat 15 need current information on better long-term weather important to gain full understanding of OA’s performance forecasting and drought planning at the organic AES level under CC [48, 165]. [10, 104] and on how to predict the capability of their There is a large variability within organic farms farming enterprises to remain sustainable [10, 92]. in nutrient-use efficiency [168]; therefore, there is a need Public funding for organic research is currently aimed to document and verify efficacy of farmers’ knowledge mostly at increasing on-farm production [11]; and modest on nutrient management practices in certified, mostly increases are projected for the foreseeable future [157]. export-oriented, OA in developing countries [162]. In- While the present system ensures agricultural pro- depth knowledge of nutrient sources and practices, ductivity, global competitiveness and food security, it and the development of innovative nutrient cycling offers few resources to support research on the organic methods and budgets, especially for the limited P farming–environment–CC complex relationships [157, resources [118], can help in developing sustainability 158]. Organic farmers need to be more aware of CC indicators of OA, especially for CC mitigation and hazards [39] and their impact on sustainability [99]; they adaptation [162] and in developing a policy instrument for need increased access to efficient inputs as effective tools environmental protection [30, 108]. Non-synchronized for CC mitigation and adaptation [10], including research timing of N mineralization and crop N demand will lead to resources for the development of publicly available seeds large gaseous N losses in OA. This calls for proper spatio- and animal breeds adapted to regional climates [12]. The temporal allocation of crops within crop rotations to sooner these farmers have access to such resources synchronize mineralization and demand for N [123]. and they can apply more mitigation measures, the less Optimal integration of green manure [95] and BNF adaptation they need in the future [28]. There is a need to using legume crops in OA and their role in N dynamics expand and document the ‘observational studies’ and needs further research [107] to minimize leakage practices in developing countries’ OA, especially those in and gaseous losses [59]. Organic AESs may reduce P tropical and subtropical climates [63]; this might increase losses to the environment [169]. P management in OA our knowledge base on vulnerability and adaptive is not simply related to the nature of the AES (i.e. responses in organic as well as other subsistence agri- crops versus crop–livestock mixed farming); therefore, cultural AESs in these countries [63]. nutrient cycling should be addressed and assessed at a Energy use for crop production is generally correlated scale beyond the farm gate (i.e. region) [170]. The with GHG emissions and depletion of natural resources potential of arbuscular mycorrhizal fungi to enhance [114]. OA, given its low energy inputs, could lead to more plant growth in organic systems needs quantifying [108], reductions in GHG emissions [114, 165] and better 2011; arbuscular mycorrhizal fungi play a crucial role in environmental protection [166, 167]. However, further nutrient acquisition, especially immobile soil nutrients research is needed to develop regenerative energy tech- such as P, they help to build-up soil fertility, and are more nologies [57], technologies capable of reducing energy effective in promoting plant growth under OA conditions inputs of mechanical weeding per unit of output [7] and [171]. the use of energy-saving technologies such as no-till or Research on organic crops and crop rotations needs reduced tillage [95]. To close this knowledge gap, further to be site-specific in order to comply with environmental research and development on reduced tillage systems and soil constraints, save inputs and reduce adverse addressing C sequestration and GHG emissions as well as environmental impacts [65]. In regions with more variable weed and nutrient management are being pursued. climate and reduced external inputs, organic crops need Although systems for the production and use of to cope with spatio-temporally heterogeneous environ- renewable energies were introduced very early in organic mental conditions [69] and with the few opportunities for farming [57], bioenergy crops and crop residues have a immediate alleviation of abiotic and biotic stresses; much more limited role in OA compared with CA [7]. therefore, crops and varieties with wide adaptation are Organic residues are normally used for nutrient recycling needed, which can be achieved through intra-specific crop and to build up soil fertility in OA [153]. Research is diversity [31, 75]. The need for crop varieties specifically needed to verify if and to what extent might energy offsets bred for OA is increasing in developing [31] and devel- from energy crops, crop residues and biogas production oped [106] countries. Plant breeding method(s), including create a more favourable energy balance for organic farms participatory and evolutionary breeding, to address the [7, 123]; whether biogas digestion of slurry had an impact specific requirements of small-scale, low-input organic on soil N and C budgets [123]; and to what extent farmers is needed [101] to develop crop varieties with removal of crop residue might impact soil fertility and proper levels of wide and specific adaptation and to productivity [167] and environmental quality [108]? The characterize germplasm for GÂE interaction [24] so that current mechanistic understanding of how SOM builds up farmers may benefit from more conscious choice of crops in soil is not consistent and needs to be refined and and varieties [100]. Farmers’ participation in all phases of aligned with the assertion of how C is being sequestered the breeding, selection and characterization process may in OA [148]. More importantly, GHG coefficients in OA address their concerns about the complexity of dealing are not very precise [7]; their refinement is particularly with large crop plant populations [31].

http://www.cabi.org/cabreviews 16 CAB Reviews Weed pressure and the need for reduced tillage to climate impacts on different components of OA enter- minimize energy inputs, two perennial challenges for OA’s prises, including the probabilities of extreme weather call for smart technological and biological solutions, events [12]. including bioherbicides [95] and eco-tillage [138]. Further research to improve and validate bioherbicides is essential before a policy can be formulated and they can be prac- Acknowledgments tically used on the farm [110]. When exposure, toxicity, environmental contamination, and the volume of bio- Thanks to Beth Burmeister for editing the manuscript. and biopesticides are considered in an overall The use of trade, firm or corporation names in this pest-management strategy, organic practices need to be publication is for information and convenience of the carefully researched and evaluated as they may pose a reader. Such use does not constitute an official greater environmental hazard than conventional ones endorsement or approval by the United States [125, 163]. Soil-borne diseases may develop in OA; Department of Agriculture or the Agricultural Research however, they need not be a problem in well-managed, Service of any product or service to the exclusion of long-term organic farms [105]. On the other hand, on- others that may be suitable. USDA is an equal provider farm organic seed saving can lead to seed-borne disease and employer. problems [31] and the need for seed processing and quality maintenance. Similarly, there is a need to develop simple and low-cost biological methods for the manage- References ment of abiotic stresses, which can be used on short-term basis in OA [44]. 1. Wezel A, Bellon S, Dore T, Francis C, Vallod D, David C. 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