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Edited by Hans Herren, Millennium Institute, Washington, DC, and approved December 19, 2019 (received for review April 23, 2019)
Significance
Organic agriculture promotes environmental and socioeconomic sustainability to a greater degree than conventional agriculture. However, it is unknown whether effects of organic agriculture on sustainability metrics such as biodiversity, crop yields, and profitability vary across the diverse landscapes where organic farming is practiced. We addressed this using a global meta-analysis spanning 60 crops. Organic sites had greater biodiversity than conventional ones, with the largest benefits in landscapes with large field sizes. In contrast, while organic sites also had greater profits, the largest benefits occurred in landscapes with small fields. The ecological sustainability benefits of organic agriculture are most pronounced in landscapes typified by more intensive agriculture, while economic benefits are likely influenced by socioeconomic factors and yields.
Abstract
Organic agriculture promotes sustainability compared to conventional agriculture. However, the multifunctional sustainability benefits of organic farms might be mediated by landscape context. Assessing how landscape context affects sustainability may aid in targeting organic production to landscapes that promote high biodiversity, crop yields, and profitability. We addressed this using a meta-analysis spanning 60 crop types on six continents that assessed whether landscape context affected biodiversity, yield, and profitability of organic vs. conventional agroecosystems. We considered landscape metrics reflecting landscape composition (percent cropland), compositional heterogeneity (number and diversity of cover types), and configurational heterogeneity (spatial arrangement of cover types) across our study systems. Organic sites had greater biodiversity (34%) and profits (50%) than conventional sites, despite lower yields (18%). Biodiversity gains increased as average crop field size in the landscape increased, suggesting organic farms provide a “refuge” in intensive landscapes. In contrast, as crop field size increased, yield gaps between organic and conventional farms increased and profitability benefits of organic farming decreased. Profitability of organic systems, which we were only able to measure for studies conducted in the United States, varied across landscapes in conjunction with production costs and price premiums, suggesting socioeconomic factors mediated profitability. Our results show biodiversity benefits of organic farming respond differently to landscape context compared to yield and profitability benefits, suggesting these sustainability metrics are decoupled. More broadly, our results show that the ecological, but not the economic, sustainability benefits of organic agriculture are most pronounced in more intensive agricultural landscapes.
Footnotes
- ↵1To whom correspondence may be addressed. Email: olivia.m.smith{at}wsu.edu.
Author contributions: O.M.S., A.L.C., J.P.R., M.S.J., R.J.O., J.M.T., J.H.T., K.A.C., R.L.O., Y.G., C.M.K., and D.W.C. designed research; O.M.S., A.L.C., M.S.J., R.J.O., J.M.T., J.H.T., K.A.C., R.L.O., Y.G., and D.W.C. performed research; O.M.S. and D.W.C. analyzed data; and O.M.S., J.P.R., and D.W.C. wrote the paper.
The authors declare no competing interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1906909117/-/DCSupplemental.
Published under the PNAS license.
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Landscape context affects the sustainability of organic farming systems
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