Spectroscopic characteristics of humic acids extracted from soils under different integrated agricultural production systems in tropical regions

Author(s)

Tadini, Amanda M. ^[1] ; Bernardi, Alberto C. C. ^[2] ; Milori, Debora M. B. P. ^[1] ; Oliveira, Patricia P. A. ^[2] ; Pezzopane, Jose R. M. ^[2] ; Martin-Neto, Ladislau ^[1]

Affiliation

^[1] Embrapa Instrumentacao, Rua 15 Novembro 1452, BR-13560970 Sao Carlos, SP - Brazil

^[2] Embrapa Pecuaria Sudeste, Rd Washington Luiz, Km 234 Fazenda Canchim, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: GEODERMA REGIONAL; v. 28, MAR 2022.
• Web of Science Citations: 0

Abstract

Soil Organic Matter (SOM) plays an important in many ecosystems on the planet. Therefore, we employed elemental analysis (CHN), fluorescence spectroscopy (EEM-CP/PARAFAC), and electron paramagnetic resonance (EPR) to characterize the humic acids (HA) extracted from soils under integrated agricultural production systems (e.g. agroforestry systems (AFS)). These systems (S) included Crop (C), Livestock (L), Forest (F), and different combinations of them (CLFS, LFS, and CLS), which were compared with pastures (intensive (INT) and extensive (EXT)) and native forest (NF). For this purpose, we collected samples of a dystrophic Red-Yellow Latosol from experimental field areas which it is located at the Embrapa Pecu ` aria Sudeste in Sao Carlos, Sao Paulo state, Brazil. Results showed that the HA humification index increased with soil depth, which is identified by complex structures more affluent in semiquinone-type free radical (SFR) and higher fluorescence intensity, especially in the AFS. Therefore, the HA from the CLFS systems had a higher aromaticity profile than HA from pastures and native forest areas, suggesting a longer lifetime to Carbon compounds. These significant findings are important for developing climate change mitigation strategies. (AU)

• FAPESP's process: 17/22950-1 - Dynamics, reactivity and structural aspects of soil organic matter under integration crop-livestock-forest systems
• Grantee: Amanda Maria Tadini
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/20084-5 - Strategic practices for mitigating greenhouse gas emissions in grassland systems of the Brazilian Southeast
• Grantee: Paulo Henrique Mazza Rodrigues
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants