Losses of phosphorus, potassium and nitrogen from horse manure left on the ground

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Taylor & Francis Group - Informa UK Limited
In this five-month Swedish field study, we examined losses of nutrients from horse manure over time, in order to examine how regularly manure should be cleared from paddocks in order to minimise the risk of nutrient leaching. Small heaps of manure (400 g) were placed in open cylinders outdoors and samples (five replicates) were taken on 12 occasions from December 2020 to May 2021. The samples were analysed for weight, dry matter content and concentrations of total nitrogen (N), ammonium N, total phosphorus (P), water-extractable P (WEP), potassium (K) and carbon (C). There was a fast decline in P and K concentrations and a strong correlation between accumulated precipitation and losses from the manure into the soil. The mean reduction in total-P was 11 mg P kg−1 manure dry weight per mm accumulated precipitation. Manure N was retained in the manure over the five-month period. In conclusion, this study demonstrated high mobility of P and K, indicating a need for strategies for rapid removal of manure from paddocks. Daily removal of manure from paddocks used year-round would, approximately, save 1.7 kg P and 5.5 kg K per horse per year, which could be recycled to replace non-renewable mineral fertilisers.
Acknowledgements: This study was enabled by financial support from the foun dation Thureus Forskarhem och Naturminne and BalticWaters2030, which we gratefully acknowledge. The authors also would like to thank Richard James Hopkins for help with installing the experimental set-up, Tom Hammarlund for providing horse manure and Christian Roman for statistical advice. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Version of Scholarly Record of this Article is published in Acta Agriculturae Scandinavica, Section B — Soil & Plant Science, 2022, available online at: http://www.tandfonline.com/10.1080/09064710.2022.2121749 . Keywords: Horse manure; nutrient losses; horse paddock; phosphorus leaching; eutrophication; nutrient cycling; water quality; Europe; Sweden; cold temperate climate.
Helena Aronsson, Sofia Nyström, Elsa Malmer, Linda Kumblad & Camilla Winqvist (2022) Losses of phosphorus, potassium and nitrogen from horse manure left on the ground, Acta Agriculturae Scandinavica, Section B — Soil & Plant Science, 72:1, 893-901, DOI: 10.1080/09064710.2022.2121749