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Data extracted in October 2021
Note to the reader: This general fiche summarises all the environmental and climate impacts of organic farming systems and specifically on organic livestock systems, found in a review of 30 synthesis research papers [1]. These papers were selected from an initial number of 220 obtained through a systematic literature search strategy, according to the inclusion criteria reported in section 4.
As each synthesis research paper involves a number of primary research papers ranging from 7 to 164 (often around 50), the assessment of impacts relies on a large number of results obtained mainly from real farms, field experiments (carried out by scientists in situations close to real farming environment), and sometimes from model simulations (e.g. by life cycle analysis including accounting for all 'cradle-to-farm gate' activities).
1. DESCRIPTION OF THE FARMING PRACTICE
Description | Organic production is an overall system of farm management and food production that combines best environmental and climate action practices, a high level of biodiversity, the preservation of natural resources and the application of high animal welfare standards and high production standards in line with the demand of a growing number of consumers for products produced using natural substances and processes. [2] |
Key descriptors |
Since organic systems generally result in lower yields than conventional systems, the effects per unit of product may be different to those per unit of area. Consequently, where available, both types of results are reported in the Table 1. |
2. DESCRIPTION OF THE IMPACTS OF THE FARMING PRACTICE ON ENVIRONMENT AND CLIMATE
We reviewed the impacts of organic systems (intervention) compared to conventional systems (control) (Table 1).
The table below shows the number of synthesis papers reporting positive, negative or no effect, based on the statistical comparison of the intervention and the control. In addition, we include the number of synthesis papers reporting relevant results, but without statistical test of the effects (uncertain). The numbers between parentheses indicate the number of synthesis papers with a quality score of at least 50%. Details on quality criteria can be found in the methodology section of this WIKI.
Out of the 30 synthesis papers selected, 28 reported studies conducted in Europe and 26 have a quality score higher than 50%. Some synthesis papers reported more than one impact.
Table 1. Impacts of organic systems compared with conventional systems.
|
| Impacts per unit of agricultural land | Impacts per unit of product | |||||||
Impact | Metric | Positive | Negative | No effect | Uncertain | Positive | Negative | No effect | Uncertain | |
Organic cropping systems | ||||||||||
Increase Acidification |
|
|
|
|
| 0 | 1 (1) | 1 (1) | 1 (1) | |
Decrease Air pollutants emissions | Ammonia emission | 0 | 0 | 1 (1) | 0 | 0 | 0 | 1 (1) | 0 | |
Increase Biodiversity |
| 9 (9) | 1 (1) | 1 (1) | 1 (0) |
|
|
|
| |
Increase Carbon sequestration | 7 (6) | 0 | 0 | 2 (1) |
|
|
|
| ||
Decrease Energy use |
|
|
|
|
| 3 (3) | 2 (1) | 2 (1) | 1 (1) | |
Decrease Eutrophication |
|
|
|
|
| 0 | 1 (1) | 2 (2) | 1 (1) | |
Decrease GHG emissions | Aggregated* GHG emissions |
|
|
|
| 1 (1) | 0 | 3 (2) | 1 (1) | |
| CH4 emission | 1 (1) | 0 | 0 | 1 (1) | 1 (1) | 0 | 0 | 1 (1) | |
| N2O emission | 2 (2) | 0 | 0 | 1 (1) | 0 | 1 (1) | 1 (1) | 1 (1) | |
Decrease Nutrient leaching and run-off | Nitrogen | 2 (2) | 0 | 0 | 0 | 0 | 1 (1) | 1 (1) | 0 | |
| Phosphorous | 0 | 0 | 2 (2) | 0 |
|
|
|
| |
Decrease Pests and diseases | Increase natural enemies of pests | 2 (2) | 0 | 0 | 0 |
|
|
|
| |
| Decrease pests per unit of area | 0 | 2 (2) | 0 | 0 |
|
|
|
| |
Improve Soil biological quality | 1 (1) | 0 | 0 | 1 (0) |
|
|
|
| ||
Increase Soil nutrients |
| 0 | 0 | 0 | 1 (0) |
|
|
|
| |
Increase Crop yield | Main cash crop yield ** | 0 | 9 (9) | 2 (2) | 1 (1) |
|
|
|
| |
| Crop yield stability along years | 0 | 1 (1) | 2 (2) | 0 |
|
|
|
| |
Decrease land use (per unit of product)*** |
|
|
|
| 0 | 3 (3) | 0 | 1 (1) | ||
Organic livestock systems | ||||||||||
Decrease Acidification |
|
|
|
|
| 0 | 1 (1) | 1 (1) | 1 (1) | |
Increase Carbon sequestration | 2 (2) | 0 | 1 (1) | 0 |
|
|
|
| ||
Decrease Energy use |
|
|
|
|
| 1 (1) | 0 | 2 (1) | 1 (1) | |
Decrease Eutrophication |
|
|
|
|
| 0 | 1 (1) | 1 (1) | 1 (1) | |
Decrease GHG emissions | Aggregated GHG emissions | 1 (1) | 0 | 0 | 0 | 0 | 1 (0) | 3 (2) | 1 (1) | |
| CH4 emission | 1 (1) | 0 | 0 | 0 |
|
|
|
| |
| N2O emission | 1 (1) | 0 | 0 | 0 |
|
|
|
| |
Decrease Nutrients loss | Nitrogen | 0 | 0 | 1 (1) | 0 |
|
|
|
| |
Decrease land use (per unit of product)*** |
|
|
|
| 0 | 2 (2) | 0 | 1 (1) | ||
* Emissions (including contributions of all GHG emissions sources, as CO2-equivalents) are typically accounted for all 'cradle-to-farm gate' activities, using life cycle analysis (LCA), to assess the performance of organic systems in comparison to conventional systems.
** Crop yield is typically measured for cash crops only, as total biomass or target crop produce harvested per hectare per year. Research studies typically do not account for co-productions of fodder/forage through crop diversification techniques (rotations, multicropping, cover crops), which were found to be significantly more frequent in organic farming systems (Alvarez, 2021, ref. 30). One study (Ponisio et al, 2015, ref. 13) reports that yield gaps of organic versus conventional farming drop from -25% to -8%, when considering full productivity of diversification techniques (multi-cropping and crop rotations, respectively).
*** Agricultural land use per unit of product (also called Agricultural land use efficiency) is calculated (typically by LCA approaches) as the ratio between the total land used and the total amount of target food products obtained along the whole production chain. For crops production systems only, this impact is nearly equivalent to crop yield.
3. DESCRIPTION OF THE KEY FACTORS INFLUENCING THE SIZE OF THE EFFECT
Only the factors explicitly studied in the reviewed synthesis papers are reported below. Details regarding the factors can be found in the summaries of the meta-analyses.
IMPACTS | FACTORS |
Increase biodiversity | Landscape structure and heterogeneity (ref 28 ),Taxon (ref 20 ),Pest management strategies (ref 2 ),Herbicide application (ref 2 ),Addition of compost (ref 2 ),Diversity of cover crops (ref 2 ),Experiment scale (ref 14 ),Crop field size (ref 1 ),Organism group (ref 16 ),Proportion of arable land in the surrounding landscape (ref 16 ),Crop type (ref 16 ). |
Increase carbon sequestration | C input (ref 18 ),Soil disturbance (ref 18 ),Fertilisation intensity (ref 5 ),Climate (ref 5 ),External C input (ref 22 ),Clay concentrations in soils (ref 22 ),Mean annual temperature (ref 22 ),Mean annual precipitation (ref 22 ),External C inputs (ref 22 ),Crop rotation (ref 22 ),External N input (ref 22 ),Legume forages (ref 22 ),Plough depth (ref 27 ),Organic input (ref 27 ),Crop residues incorporation (ref 27 ),Land use type (ref 27 ),Region (or certification guidelines) (ref 4 ),Crop type (ref 4 ),Input of organic matter (ref 24 ),Presence of leys in the rotation (ref 24 ) |
Decrease eutrophication | Quantity and type of fertilizer (ref1) |
Reduction of energy use | Type of product (ref 12 ),Cropping pattern (ref 12 ),Data sample size (ref 12 ),Production of mineral fertilisers (ref 24 ) |
Decrease of GHG emissions | Product/area unit (ref 12 ),Per unit of field area: Positive; Per unit of product: Negative. (ref 15 ) |
Decrease nutrient loss | Fertilisation regime (ref 27 ),Crop diversification strategies (ref 27 ),C/N ratio of fertilisers (ref 27 ),Livestock density (ref 27 ),Nitrogen input (ref 24 ) |
Decrease pests and diseases | Pests type (ref 25 ),Crop type (ref 25 7 ),Presence of pest management (ref 25 ),Experiment scale (ref 25 ),Study type (ref 7 ) |
Improve soil biological quality | Fertilisation (ref 29 ),Diversification strategies (ref 29 ),Pesticides use (ref 29 ),Tillage (ref 29 ) |
Increase crop yield | Fertilisation regime (ref 6 ),Crop diversification strategies (ref 13 ),Multicropping, crop rotations and the use of cover crops reduce the yield gaps of organic farming. (ref 13 ),Nitrogen input (ref 23 ),Water management (ref 23 ),Type of crop (ref 23 ),Soil pH (ref 23 ),Best practices (ref 23 ),Negative effect (ref 1 ),Fertilisation (ref 30 ) |
4. SYSTEMATIC REVIEW SEARCH STRATEGY
Keywords | TS=("grazing*" OR "grassland*" OR "pasture*" OR "rangeland")) AND TS=(("meta-analy*" OR "systematic* review*" OR "evidence map" OR "global synthesis" OR "evidence synthesis" OR "research synthesis") or TITLE-ABS-KEY: ( "grazing*" OR "grassland*" OR "pasture*" OR "rangeland") AND TITLE-ABS-KEY ( "meta-analy*" OR "systematic* review*" OR "evidence map" OR "global synthesis" OR "evidence synthesis" OR "research synthesis") |
Search dates | No time restrictions |
Databases | Web of Science and Scopus, run in September 2021 |
Selection criteria | The main criteria that led to the exclusion of a synthesis paper were when the paper: 1) did not deal with terrestrial grasslands or the effects on grasslands could not be disentangled from other land uses; 2) did not deal with grazing management; 3) was either a non-systematic review, a non-quantitative systematic review, or a meta-regression without mean effect sizes; 4) was not written in English. Due to the high number of potentially valid synthesis papers, we applied additional exclusion criteria: [5]) the paper did not include studies conducted in Europe; 6) the paper only reported impacts on grassland or animal production, but any environmental impacts. Synthesis papers that passed the relevance criteria were subject to critical appraisal carried out on a paper-by-paper basis. The search returned 1022 synthesis papers potentially relevant for the practice object of our fiche. From the 1022 potentially relevant synthesis papers, 661 were excluded after reading the title and abstract, and 330 after reading the full text according to the above-mentioned criteria. Finally, 31 synthesis papers were selected for grazing. |
5. LIST OF SYNTHESIS PAPERS INCLUDED IN THE REVIEW
Ref. Num | Authors | Year | Title | Reference | DOI |
1 | Crowder, DW; Northfield, TD; Gomulkiewicz, R; Snyder, WE. | 2012 | Conserving and promoting evenness: organic farming and fire-based wildland management as case studies. | Ecology 93: 2001–2007. | 10.1890/12-0110.1 |
2 | Garcia-Palacios, P; Gattinger, A; Bracht-Jorgensen, H; Brussaard, L; Carvalho, F; Castro, H; Clement, JC; De Deyn, G; D'Hertefeldt, T; Foulquier, A; Hedlund, K; Lavorel, S; Legay, N; Lori, M; Mader, P; Martinez-Garcia, LB; da Silva, P; Muller, A; Nascimento, E; Reis, F; Symanczik, S; Sousa, J; Milla, R. | 2018 | Crop traits drive soil carbon sequestration under organic farming | Journal of Applied Ecology 30, 1–10. | 10.1111/1365-2664.13113 |
3 | Gattinger A; Muller A; Haeni M; Skinner C; Fliessbach A; Buchmann N; Mäder P; Stolze M; Smith P; El-Hage Scialabba N; Niggli U. | 2012 | Enhanced top soil carbon stocks under organic farming | PNAS 109 (44), 18226-18231. | 10.1073/pnas.1209429109 |
4 | Katayama, N; Bouam, I; Koshida, C; Baba, YG | 2019 | Biodiversity and yield under different land-use types in orchard/vineyard landscapes: A meta-analysis. | BIOLOGICAL CONSERVATION 229, 125-133 | 10.1016/j.biocon.2018.11.020 |
5 | Lichtenberg, EM; Kennedy, CM; Kremen, C; Batary, P; Berendse, F; Bommarco, R; Bosque-Perez, NA; Carvalheiro, LG; Snyder, WE; Williams, NM; Winfree, R; Klatt, BK; Astrom, S; Benjamin, F; Brittain, C; Chaplin-Kramer, R; Clough, Y; Danforth, B; Diekotter, T; Eigenbrode, SD; Ekroos, J; Elle, E; Freitas, BM; Fukuda, Y; Gaines-Day, HR; Grab, H; Gratton, C; Holzschuh, A; Isaacs, R; Isaia, M; Jha, S; Jonason, D; Jones, VP; Klein, AM; Krauss, J; Letourneau, DK; Macfadyen, S; Mallinger, RE; Martin, EA; Martinez, E; Memmott, J; Morandin, L; Neame, L; Otieno, M; Park, MG; Pfiffner, L; Pocock, MJO; Ponce, C; Potts, SG; Poveda, K; Ramos, M; Rosenheim, JA; Rundlof, M; Sardinas, H; Saunders, ME; Schon, NL; Sciligo, AR; Sidhu, CS; Steffan-Dewenter, I; Tscharntke, T; Vesely, M; Weisser, WW; Wilson, JK; Crowder, DW. | 2017 | A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes. | 23, 11, 4946-4957. | 10.1111/gcb.13714 |
6 | Smith, OM; Cohen, AL; Reganold, JP; Jones, MS; Orpet, RJ; Taylor, JM; Thurman, JH; Cornell, KA; Olsson, RL; Ge, Y; Kennedy, CM; Crowder, DW | 2020 | Landscape context affects the sustainability of organic farming systems | PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 117 6, 2870-2878 | 10.1073/pnas.1906909117 |
7 | Smith, OM; Cohen, AL; Rieser, CJ; Davis, AG; Taylor, JM; Adesanya, AW; Jones, MS; Meier, AR; Reganold, JP; Orpet, RJ; Northfield, TD; Crowder, DW | 2019 | Organic Farming Provides Reliable Environmental Benefits but Increases Variability in Crop Yields: A Global Meta-Analysis | FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 3 | 10.3389/fsufs.2019.00082 |
8 | Tuomisto HL; Hodge ID; Riordana P; Macdonald DW | 2012 | Does organic farming reduce environmental impacts? – A meta-analysis of European research | Journal of Environmental Management 112, 309-320 | 10.1016/j.jenvman.2012.08.018 |
9 | Ugarte, CM; Kwon, H; Andrews, SS; Wander, MM. | 2014 | A meta-analysis of soil organic matter response to soil management practices: An approach to evaluate conservation indicators | Journal of soil and water conservation 69, 422-430 | 10.2489/jswc.69.5.422 |
10 | Knapp, S; van der Heijden, MGA. | 2018 | A global meta-analysis of yield stability in organic and conservation agriculture. | NATURE COMMUNICATIONS 9, 3632 | 10.1038/s41467-018-05956-1 |
11 | Ponisio, LC; M'Gonigle, LK; Mace, KC; Palomino, J; de Valpine, P; Kremen, C | 2015 | Diversification practices reduce organic to conventional yield gap | Proc. R. Soc. B 282, 20141396 | 10.1098/rspb.2014.1396 |
12 | Muneret, L; Mitchell, M; Seufert, V; Aviron, S; Djoudi, E; Petillon, J; Plantegenest, M; Thiery, D; Rusch, A. | 2018 | Evidence that organic farming promotes pest control | Nature Sustainability 1, 361-368 | 10.1038/s41893-018-0102-4 |
13 | Seufert, V; Ramankutty, N; Foley, JA | 2012 | Comparing the yields of organic and conventional agriculture | NATURE 485, 229–232. | 10.1038/nature11069 |
14 | Wilcox, JC; Barbottin, A; Durant, D; Tichit, M; Makowski, D. | 2013 | Farmland Birds and Arable Farming, a Meta-Analysis. | Sustainable Agriculture Reviews 13: 35-63. | 10.1007/978-3-319-00915-5_3 |
15 | Doring, J; Collins, C; Frisch, M; Kauer, R | 2019 | Organic and Biodynamic Viticulture Affect Biodiversity and Properties of Vine and Wine: A Systematic Quantitative Review | AMERICAN JOURNAL OF ENOLOGY AND VITICULTURE 70 3, 221-242 | 10.5344/ajev.2019.18047 |
16 | de Ponti T., Rijk B., van Ittersum M.K. | 2012 | The crop yield gap between organic and conventional agriculture. | AGRICULTURAL SYSTEMS 108, 1–9 | 10.1016/j.agsy.2011.12.004 |
17 | Kaschuk, G; Alberton, O; Hungria, M. | 2010 | Three decades of soil microbial biomass studies in Brazilian ecosystems: Lessons learned about soil quality and indications for improving sustainability. | Soil Biology & Biochemistry 42: 1–13. | 10.1016/j.soilbio.2009.08.020 |
18 | Montañez, MN; Amarillo-Suárez, A. | 2014 | Impact of organic crops on the diversity of insects: a review of recent research. | Revista Colombiana de Entomología 40: 131 - 142. | NA |
19 | Aguilera, E; Lassaletta, L; Gattinger, A; Gimeno, BS. | 2013 | Managing soil carbon for climate change mitigation and adaptation in Mediterranean cropping systems: A meta-analysis | AGRICULTURE ECOSYSTEMS & ENVIRONMENT 168, 25-36. | 10.1016/j.agee.2013.02.003 |
20 | Bengtsson, J; Ahnstrom, J; Weibull, AC. | 2005 | The effects of organic agriculture on biodiversity and abundance: a meta-analysis. | Journal of Applied Ecology 42: 261-269. | 10.1111/j.1365-2664.2005.01005.x |
21 | Garratt, MPD; Wright, DJ; Leather, SR. | 2011 | The effects of farming system and fertilisers on pests and natural enemies: A synthesis of current research | AGRICULTURE ECOSYSTEMS & ENVIRONMENT 141, 261-270. | 10.1016/j.agee.2011.03.014 |
22 | Kopittke, PM; Dalal RC; Finn D; Menzies NW | 2016 | Global changes in soil stocks of carbon, nitrogen, phosphorus, and sulphur as influenced by long‐term agricultural production. | Global change biology 23, 2509-2519 | 10.1111/gcb.13513 |
23 | Lee K.S., Choe Y.C., Park S.H. | 2015 | Measuring the environmental effects of organic farming: A meta-analysis of structural variables in empirical research | JOURNAL OF ENVIRONMENTAL MANAGEMENT 162, 263-274. | 10.1016/j.jenvman.2015.07.021 |
24 | Lesur-Dumoulin, C; Malezieux, E; Ben-Ari, T; Langlais, C; Makowski, D. | 2017 | Lower average yields but similar yield variability in organic versus conventional horticulture. A meta-analysis. | Agronomy for Sustainable Development 37, 45 | 10.1007/s13593-017-0455-5 |
25 | Mondelaers, K; Aertsens, J; Van Huylenbroeck, G. | 2009 | A meta-analysis of the differences in environmental impacts between organic and conventional farming | BRITISH FOOD JOURNAL 111 10, 1098-1119 | 10.1108/00070700910992925 |
26 | Skinner, C; Gattinger, A; Muller, A; Mader, P; Fliessbach, A; Stolze, M; Ruser, R; Niggli, U. | 2014 | Greenhouse gas fluxes from agricultural soils under organic and non-organic management - A global meta-analysis | Science of the Total Environment 468–469, 553–563 | 10.1016/j.scitotenv.2013.08.098 |
27 | Tuck, SL; Winqvist, C; Mota, F; Ahnstrom, J; Turnbull, LA; Bengtsson, J. | 2014 | Land-use intensity and the effects of organic farming on biodiversity: a hierarchical meta-analysis. | Journal of Applied Ecology 51: 746-755. | 10.1111/1365-2664.12219 |
28 | Puissant, J; Villenave, C; Chauvin, C; Plassard, C; Blanchart, E; Trap, J | 2021 | Quantification of the global impact of agricultural practices on soil nematodes: A meta-analysis | SOIL BIOLOGY & BIOCHEMISTRY, 161, 108383 | 10.1016/j.soilbio.2021.108383 |
29 | Alvarez, R | 2021 | Comparing Productivity of Organic and Conventional Farming Systems: A Quantitative Review | ARCHIVES OF AGRONOMY AND SOIL SCIENCE | 10.1080/03650340.2021.1946040 |
30 | Clark, M; Tilman, D. | 2017 | Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice. | ENVIRONMENTAL RESEARCH LETTERS 12 6 | 10.1088/1748-9326/aa6cd5 |
[1] Synthesis research papers include either meta-analysis or systematic reviews with quantitative results.
[2] REGULATION (EU) 2018/848.
[3] https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32018R0848&from=EN
[4] https://doi.org/10.1016/B0-12-227050-9/00235-0 and https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/organic-farming-system
[5] https://doi.org/ 10.1080/03650340.2021.1946040