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Huddell A, Neill C, Palm CA, Nunes D, Menge DNL. Anion Exchange Capacity Explains Deep Soil Nitrate Accumulation in Brazilian Amazon Croplands. Ecosystems 2022. [DOI: 10.1007/s10021-022-00747-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractDeep tropical soils with net anion exchange capacity can adsorb nitrate and might delay the eutrophication of surface waters that is often associated with many temperate croplands. We investigated anion exchange capacity and soil nitrate pools in deep soils in the Southern Brazilian Amazon, where conversion of tropical forest and Cerrado to intensive fertilized soybean and soybean-maize cropping expanded rapidly in the 2000s. We found that mean soil nitrate pools in the top 8 m increased from 143 kg N ha−1 in forest to 1,052 in soybean and 1,161 kg N ha−1 in soybean-maize croplands. This nitrate accumulation in croplands aligned with the estimated N surpluses in the croplands. Soil anion exchange capacity explained the magnitude of nitrate accumulation. High nitrate retention in soils was consistent with current low levels of streamwater nitrate exported from croplands. Soil exchange sites were far from saturation, which suggests that nitrate accumulation can continue for longer under current cropping practices, although mechanisms such as competition with other anions and preferential water flowpaths that bypass exchange sites could reduce the time to saturation.
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Moreira JCF, Brum M, de Almeida LC, Barrera-Berdugo S, de Souza AA, de Camargo PB, Oliveira RS, Alves LF, Rosado BHP, Lambais MR. Asymbiotic nitrogen fixation in the phyllosphere of the Amazon forest: Changing nitrogen cycle paradigms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 773:145066. [PMID: 33582326 DOI: 10.1016/j.scitotenv.2021.145066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/06/2021] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Biological nitrogen fixation is a key process for the maintenance of natural ecosystems productivity. In tropical forests, the contribution of asymbiotic nitrogen fixation (ANF) to the nitrogen (N) input has been underestimated, even though few studies have shown that ANF may be as important as symbiotic nitrogen fixation in such environments. The inputs and abiotic modulators of ANF in the Amazon forest are not completely understood. Here, we determined ANF rates and estimated the N inputs from ANF in the phyllosphere, litter and rhizospheric soil of nine tree species in the Amazon forest over time, including an extreme drought period induced by the El Niño-Southern Oscillation. Our data showed that ANF rates in the phyllosphere were 2.8- and 17.6-fold higher than in the litter and rhizospheric soil, respectively, and was highly dependent on tree taxon. Sampling time was the major factor modulating ANF in all forest compartments. At the driest period, ANF rates were approximately 1.8-fold and 13.1-fold higher than at periods with higher rainfall, before and after the extreme drought period, respectively. Tree species was a key modulator of ANF in the phyllosphere, as well as N and Vanadium concentrations. Carbon, molybdenum and vanadium concentrations were significant modulators of ANF in the litter. Based on ANF rates at the three sampling times, we estimated that the N input in the Amazon forest through ANF in the phyllosphere, litter and rhizospheric soil, was between 0.459 and 0.714 kg N ha-1 yr-1. Our results highlight the importance of ANF in the phyllosphere for the N input in the Amazon forest, and suggest that changes in the patterns of ANF driven by large scale climatic events may impact total N inputs and likely alter forest productivity.
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Affiliation(s)
| | - Mauro Brum
- Department of Plant Biology, Programa de Pós Graduação em Ecologia, Institute of Biology, State University of Campinas -UNICAMP, PO Box 6109, 13083-970 Campinas, SP, Brazil
| | - Lidiane Cordeiro de Almeida
- Department of Ecology, IBRAG, Rio de Janeiro State University (UERJ), R. São Francisco Xavier, 524, PHLC, Sala 220, Maracanã, Rio de Janeiro, RJ, Brazil
| | - Silvia Barrera-Berdugo
- Soil Science Department, University of São Paulo, Av. Pádua Dias 11, 13418-900 Piracicaba, SP, Brazil
| | - André Alves de Souza
- Soil Science Department, University of São Paulo, Av. Pádua Dias 11, 13418-900 Piracicaba, SP, Brazil
| | - Plínio Barbosa de Camargo
- Center for Nuclear Energy in Agriculture, University of São Paulo, 303 Centenário Avenue, Piracicaba, SP 13400-970, Brazil
| | - Rafael Silva Oliveira
- Department of Plant Biology, Programa de Pós Graduação em Ecologia, Institute of Biology, State University of Campinas -UNICAMP, PO Box 6109, 13083-970 Campinas, SP, Brazil
| | - Luciana Ferreira Alves
- Department of Plant Biology, Programa de Pós Graduação em Ecologia, Institute of Biology, State University of Campinas -UNICAMP, PO Box 6109, 13083-970 Campinas, SP, Brazil
| | - Bruno Henrique Pimentel Rosado
- Department of Ecology, IBRAG, Rio de Janeiro State University (UERJ), R. São Francisco Xavier, 524, PHLC, Sala 220, Maracanã, Rio de Janeiro, RJ, Brazil
| | - Marcio Rodrigues Lambais
- Soil Science Department, University of São Paulo, Av. Pádua Dias 11, 13418-900 Piracicaba, SP, Brazil.
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Soper FM, Taylor BN, Winbourne JB, Wong MY, Dynarski KA, Reis CRG, Peoples MB, Cleveland CC, Reed SC, Menge DNL, Perakis SS. A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13586] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Fiona M. Soper
- Department of Biology and Bieler School of Environment McGill University Montréal QC Canada
| | - Benton N. Taylor
- Department of Organismic and Evolutionary Biology Harvard University Cambridge MA USA
| | - Joy B. Winbourne
- Department of Earth and Environment Boston University Boston MA USA
| | | | - Katherine A. Dynarski
- Department of Ecosystem and Conservation Sciences University of Montana Missoula MT USA
| | - Carla R. G. Reis
- Department of Forest Ecosystem and Society Oregon State University Corvallis OR USA
| | - Mark B. Peoples
- Commonwealth Scientific and Industrial Research Organisation, Agriculture and Food Canberra ACT Australia
| | - Cory C. Cleveland
- Department of Ecosystem and Conservation Sciences University of Montana Missoula MT USA
| | - Sasha C. Reed
- U.S. Geological SurveySouthwest Biological Science Center Moab UT USA
| | - Duncan N. L. Menge
- Department of Ecology, Evolution and Environmental Biology Columbia University New York NY USA
| | - Steven S. Perakis
- Department of Forest Ecosystem and Society Oregon State University Corvallis OR USA
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center Corvallis OR USA
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Wong MY, Neill C, Marino R, Silvério D, Howarth RW. Molybdenum, phosphorus, and pH do not constrain nitrogen fixation in a tropical forest in the southeastern Amazon. Ecology 2020; 102:e03211. [PMID: 32981087 DOI: 10.1002/ecy.3211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 07/06/2020] [Accepted: 08/06/2020] [Indexed: 01/09/2023]
Abstract
High rates of biological nitrogen fixation (BNF) are commonly reported for tropical forests, but most studies have been conducted in regions that receive substantial inputs of molybdenum (Mo) from atmospheric dust and sea-salt aerosols. Even in these regions, the low availability of Mo can constrain free-living BNF catalyzed by heterotrophic bacteria and archaea. We hypothesized that in regions where atmospheric inputs of Mo are low and soils are highly weathered, such as the southeastern Amazon, Mo would constrain BNF. We also hypothesized that the high soil acidity, characteristic of the Amazon Basin, would further constrain Mo availability and therefore soil BNF. We conducted two field experiments across the wet and dry seasons, adding Mo, phosphorus (P), and lime alone and in combination to the forest floor in the southeastern Amazon. We sampled soils and litter immediately, and then weeks and months after the applications, and measured Mo and P availability through resin extractions and BNF with the acetylene reduction assay. The experimental additions of Mo and P increased their availability and the lime increased soil pH. While the combination of Mo and P increased BNF at some time points, BNF rates did not increase strongly or consistently across the study as a whole, suggesting that Mo, P, and soil pH are not the dominant controls over BNF. In a separate short-term laboratory experiment, BNF did not respond strongly to Mo and P even when labile carbon was added. We postulate that high nitrogen (N) availability in this area of the Amazon, as indicated by the stoichiometry of soils and vegetation and the high nitrate soil stocks, likely suppresses BNF at this site. These patterns may also extend across highly weathered soils with high N availability in other topographically stable regions of the tropics.
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Affiliation(s)
- Michelle Y Wong
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA
| | | | - Roxanne Marino
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA
| | - Divino Silvério
- Instituto de Pesquisa Ambiental da Amazônia (IPAM), Canarana, Mato Grosso, 78640-000, Brazil.,Departamento de Biologia, Universidade Federal Rural da Amazônia-UFRA, Capitão Poço, Pará, 68650-000, Brazil
| | - Robert W Howarth
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA.,Woods Hole Research Center, Falmouth, Massachusetts, 02450, USA
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