Fertilization using manure minimizes the trade-offs between biodiversity and forage production in agri-environment scheme grasslands

RESEARCH ARTICLE Fertilization using manure minimizes the trade-offs between biodiversity and forage production in agri-environment scheme grasslands Edith Villa-GalavizID1¤*, Simon M. Smart2, Susan E. Ward3, Mariecia D. Fraser4, Jane Memmott1 1 School of Biological Sciences, University of Bristol, Life Sciences Building, Bristol, United Kingdom, 2 NERC Centre for Ecology & Hydrology, Library Avenue, Bailrigg, Lancaster, United Kingdom, 3 Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom, 4 Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Pwllpeiran, Cwmystwyth, Aberystwyth, United Kingdom ¤ Current address: Ecological Network lab, Technical University of Darmstadt, Darmstadt, Germany * edith.villagalaviz@bristol.ac.uk Abstract A common practice used to restore and maintain biodiversity in grasslands is to stop or decrease the use of fertilizers as they are a major cause of biodiversity loss. This practice is problematic for farmers who need fertilizers to increase forage and meet the nutritional needs of livestock. Evidence is needed that helps identify optimal fertilizer regimes that could benefit biodiversity and livestock production simultaneously over the long-term. Here, we evaluated the impact of different fertilizer regimes on indicators related to both biodiver- sity (plant, pollinator, leaf miners and parasitoid Shannon-Weiner diversity, bumblebee abundance, nectar productivity and forb species richness), and forage production (ash,

crude protein, ruminant metabolizable energy and dry matter). To this end, we used data from a grassland restoration experiment managed under four nutrient inputs schemes for 27 years: farmyard manure (FYM; 72 kg N ha-1 yr-1), artificial nitrogen-phosphorus and potas- sium (NPK; 25 kg N ha-1 yr-1), FYM + NPK (97 kg N ha-1 yr-1) and no-fertilizer. Results showed strong trade-offs between biodiversity and forage production under all treatments even in applications lower than the critical load in the EU. Overall, farmyard manure was the fertilizer that optimized production and biodiversity while 97 kg N ha-1 yr-1 of fertilizer addition (FYM+NPK) had the most negative impact on biodiversity. Finally, forage from places where no fertilizer has been added for 27 years did not meet the nutritional requirements of cattle, but it did for sheep. Rethinking typical approaches of nutrient addition could lead to land management solutions suitable for biological conservation and agriculture. PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0290843 October 4, 2023 1 / 18 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Villa-Galaviz E, Smart SM, Ward SE, Fraser MD, Memmott J (2023) Fertilization using manure minimizes the trade-offs between biodiversity and forage production in agri- environment scheme grasslands. PLoS ONE 18(10): e0290843. https://doi.org/10.1371/journal. pone.0290843 Editor: Paulo H. Pagliari, University of Minnesota, UNITED STATES Received: March 31, 2023 Accepted: August 16, 2023 Published: October 4, 2023

Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal.pone.0290843 Copyright: © 2023 Villa-Galaviz et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: The plant-insect data has been previously published and is in the public domain (https://datadryad.org/stash/dataset/