Biochar Simultaneously Reduces Nutrient Leaching and Greenhouse Gas Emissions in Restored Wetland Soils
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APPLIED WETLAND SCIENCE
Biochar Simultaneously Reduces Nutrient Leaching and Greenhouse Gas Emissions in Restored Wetland Soils Rachel L. Rubin 1
&
Todd R. Anderson 1,2 & Kate A. Ballantine 1
Received: 4 February 2020 / Revised: 7 July 2020 / Accepted: 8 September 2020 # Society of Wetland Scientists 2020
Abstract Organic soil amendments such as biochar and compost are thought to improve soil development, but it is unclear whether they affect nutrient leaching and greenhouse gas emissions. Using mesocosms, we investigated the effects of biochar and compost on nutrient leaching and greenhouse gas emissions across varying hydrologic regimes. Increased biochar decreased nutrient leaching and greenhouse gas emissions: the highest application rate (10% wt/wt) decreased cumulative phosphate leaching by 63% (SE 1.4), ammonium leaching by 65% (SE 0.8) and nitrate leaching by 92% (SE 0.3). Likewise, 10% biochar application decreased cumulative methane emissions by 92% (SE 3.7), carbon dioxide emissions by 48% (SE 7.0), and nitrous oxide emissions by 89% (SE 4.1). Biochar effects varied with hydrology for each greenhouse gas: stronger reductions in methane and nitrous oxide emissions were observed under waterlogged conditions, whereas stronger reductions in carbon dioxide emissions were observed at field capacity. In contrast with biochar, compost was the largest contributor to nutrient leaching and greenhouse gas emissions. These results suggest that biochar is most effective in soils with episodic flooding and drying rather than continuous flooding, and that compost should be avoided. We conclude that biochar can promote desirable functions simultaneously in restored wetland soils. Keywords Wetland restoration . Soil amendments . Methane . Carbon dioxide . Nitrous oxide . Nitrate . Agricultural retirement
Introduction A central goal of wetland restoration is to increase carbon sequestration and nutrient retention. This goal is challenging to achieve in practice, however, because soil structure and function often develops slowly in restored wetlands. Organic soil amendments such as straw, wood, and compost may accelerate soil organic matter development (Ballantine et al. 2014), a prerequisite for long-term nutrient and carbon sequestration. Soil amendments can stabilize eroding soils, nourish microbial communities, and facilitate plant Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13157-020-01380-8) contains supplementary material, which is available to authorized users. * Kate A. Ballantine [email protected] 1
Present address: Department of Environmental Studies, Mount Holyoke College, 50 College St, South Hadley, MA 01075, USA
2
Division of Natural Sciences and Mathematics, Keuka College, Keuka Park, NY, USA
regeneration (Sutton-Grier et al. 2009). However, they may also increase greenhouse gas emissions, a negative tradeoff (Troy et al. 2013; Ballantine et al. 2015). It is therefore essential to gain an integrated understanding of organic amendments, because
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