ARTICLES https://doi.org/10.1038/s41477-022-01191-1 1 Soil & Crop Sciences Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA. 2 The Nature Conservancy, Highland, NY, USA. 3 Department of Global Development, Cornell University, Ithaca, NY, USA. 4 Horticulture Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA. 5 Cornell Agritech, Cornell University, Geneva, NY, USA. 6 Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, USA. 7 The Nature Conservancy, Arlington, VA, USA. 8 Charles H. Dyson School of Applied Economics and Management, Cornell University, Ithaca, NY, USA. 9 The Nature Conservancy, Sacramento, CA, USA. 10 Institute for Resources, Environment and Sustainability, Department of Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada. 11 Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA. ✉ e-mail: jal485@cornell.edu T ransformative changes are urgently needed to increase the sus- tainability of agri-food systems 1 . In the United States, the pre- vailing ‘conventional’ model of agriculture is input-intensive and narrowly focused on maximizing crop yield. Landscape and management simplification, product standardization and consoli- dation of farms and agribusinesses have resulted in tremendous production outputs. Yet, the practices associated with this agricul- tural paradigm have also been major drivers of biodiversity loss, soil degradation, water pollution and greenhouse gas emissions 2–6 . As a series of mutually enabling trends, synthetic fertilizer and pesticide use, mechanization and farm size have increased since the 1940s. Fewer farmers are now working larger farms, a change that was encouraged by policy, research and development. Championing this transition in the 1970s, former US Secretary of Agriculture, Earl Butz, declared that farmers should ‘get big or get out’ 7 . Since then, the average size of US farms has increased. By 2000, the major- ity of cropland had shifted from being managed by small- and medium-scale farmers to large-scale farmers on operations of at least 405 ha. As a result of market forces and policies that dispro- portionately reward economies of scale and particular commodity crops 8 , the majority of cropland is now managed on large farms, primarily at the expense of medium farms (Fig. 1). In the United States, organic farms are smaller (135 ha), on aver- age, than conventional farms (180 ha) 9,10 . Over 2.2 million hectares of farms and ranches are certified organic, with 1.4 million hect- ares dedicated to crop production. Although it comprises less than 1% of all farmland in the United States, organic agriculture has been promoted as a management approach that can help amelio- rate the deleterious effects associated with conventional agricul- ture 11,12 . Compared with conventional production, organic farming performs better across an array of sustainability metrics—such as energy use, soil quality and the provision of ecosystem services— largely through the use of practices that support biodiversity and minimize negative impacts on the environment 11,13,14 . These bene- fits reflect the focus of the United States Department of Agriculture (USDA) National Organic Program (NOP) standards, which were designed to maintain or enhance soil health and ‘promote ecologi- cal balance’ 15 . Many of the practices commonly used on organic farms are also characteristic of agroecology and other alternative approaches to agriculture. Agroecology can be described as a scien- tific discipline, suite of practices and social movement 16 . Although the focus is on practices here, we understand agroecology to inte- grate these three dimensions. Agroecological practices Agroecological practices aim to maintain the ecological integ- rity of farming systems, which in turn provide ecosystem services such as nutrient cycling, pollination and biological pest control 17–19 . Such services not only undergird the resilience of a farming sys- tem, but can also reduce the need for off-farm inputs. In this study, we focused on eight agroecological practices that range from within-field to landscape-level implementation: compost or manure application, intercropping, insectary plantings (for example, flower strips), reduced tillage (a decrease in tillage intensity or frequency), Farm size affects the use of agroecological practices on organic farms in the United States Jeffrey Liebert  1 ✉ , Rebecca Benner 2 , Rachel Bezner Kerr  3 , Thomas Björkman  4,5 , Kathryn Teigen De Master 6 , Sasha Gennet 7 , Miguel I. Gómez 8 , Abigail K. Hart 9 , Claire Kremen  6,10 , Alison G. Power 11 and Matthew R. Ryan  1 Organic agriculture outperforms conventional agriculture across several sustainability metrics due, in part, to more widespread use of agroecological practices. However, increased entry of large-scale farms into the organic sector has prompted concerns about ‘conventionalization’ through input substitution, agroecosystem simplification and other changes. We examined this shift in organic agriculture by estimating the use of agroecological practices across farm size and comparing indicators of con- ventionalization. Results from our national survey of 542 organic fruit and vegetable farmers show that fewer agroecological practices were used on large farms, which also exhibited the greatest degree of conventionalization. Intercropping, insectary plantings and border plantings were at least 1.4 times more likely to be used on small (0.4–39 cropland ha) compared with large (≥405 cropland ha) farms, whereas reduced tillage was less likely and riparian buffers were more likely on small compared with medium (40–404 cropland ha) farms. Because decisions about management practices can drive environmental sustain- ability outcomes, policy should support small and medium farms that already use agroecological practices while encouraging increased use of agroecological practices on larger farms. NATURE PLANTS | VOL 8 | AUGUST 2022 | 897–905 | www.nature.com/natureplants 897