Effects of condensed tannins on greenhouse gas emissions and nitrogen dynamics from urine-treated grassland soil

Author(s)

Siniscalchi, Debora ; Cardoso, Abmael da Silva ; da Cruz Correa, Darlena Caroline ; Ferreira, Mariane Rodrigues ; Barbosa Andrade, Marina Elizabeth ; Gomes da Cruz, Luana Hybner ; Ruggieri, Ana Claudia ; Reis, Ricardo Andrade

• Document type: Journal article
• Source: Environmental Science and Pollution Research; v. 29, n. 56, p. 10-pg., 2022-07-05.

Abstract

Condensed tannins are a potentially important treatment option to mitigate N2O (nitrous oxide) and affect carbon dioxide (CO2) and methane (CH4) emissions; however, their effect has been poorly assessed. Here, we quantified the emissions of N2O, CH4, and CO2, soil N mineralization, and nitrification with increasing doses of condensed tannins added to the urine of cattle raised on pasture. The experiment consisted of incubation with doses of 0%, 0.5%, and 1.0% of condensed tannins added directly to the collected urine. The experimental design was completely randomized. Greenhouse gas fluxes were quantified for four weeks using static chambers and gas chromatography. The addition of condensed tannins increased N2O emissions (P < 0.05), with total emissions averaging 95.84 mg N-N2O kg(-1), 265.30 mg N-N2O kg(-1), and 199.32 mg N-N2O kg(-1) dry soil in the treatments with 0%, 0.5%, and 1% tannins, respectively. Methane emissions were reduced with the addition of tannins (P < 0.05), with total emissions of 8.84 g CH4 kg(-1), 1.87 g CH4 kg(-1), and 3.34 g CH4 kg(-1) dry soil in the treatments with 0%, 0.5%, and 1% tannins, respectively. Soil respiration increased with the addition of condensed tannins (P < 0.05), with total emissions of 3.80 g CO2 kg(-1), 6.93 g CO2 kg(-1), and 5.87 g CO2 kg(-1) in dry soil, in the treatments with 0%, 0.5%, and 1% tannins, respectively. The addition of condensed tannins reduced N mineralization and nitrification. We found evidence that the use of condensed tannins might not be a suitable option to mitigate N2O emissions. However, soil CH4 emissions can be abated. The increases in soil respiration suggest that tannins affect soil microorganisms, and the effects on CH4 and N2O could be related to the variation in the soil microbiome, which requires further clarification. (AU)

• FAPESP's process: 17/11274-5 - Decomposition of litter and greenhouse gases emission in Brachiaria grasses with increasing nitrogen fertilizer rates
• Grantee: Abmael da Silva Cardoso
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/16631-5 - Management strategies to reduce environmental impacts of beef cattle production systems
• Grantee: Ricardo Andrade Reis
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants