Effects of horticulture on soil organic matter properties in highly weathered tropical soils

Author(s)

Barreto, Matheus Sampaio C. ^{[1, 2]} ; Schellekens, Judith ^[1] ; Ramlogan, Marlon ^[3] ; Rouff, Ashaki A. ^[3] ; Elzinga, Evert J. ^[3] ; Vidal-Torrado, Pablo ^[1] ; Alleoni, Luis Reynaldo F. ^[1]

Affiliation

^[1] Univ Sao Paulo, Luiz de Queiroz Coll Agr ESALQ, Dept Soil Sci, Piracicaba, SP - Brazil

^[2] Mohammed VI Polytech Univ UM6P, AgroBiosci Program, Benguerir - Morocco

^[3] Rutgers State Univ, Dept Earth & Environm Sci, Newark, NJ - USA

• Document type: Journal article
• Source: SOIL & TILLAGE RESEARCH; v. 213, SEP 2021.
• Web of Science Citations: 0

Abstract

Soil organic matter (SOM) plays an important role not only for agriculture but also in the global carbon (C) balance with a potential to mitigate climate change. Land-use changes from native vegetation to intensive agricultural use enhance mineralization of SOM and thereby cause decreases in the amount of soil C. Association of SOM on soil minerals is highlighted as key stabilization mechanism of SOM. To examine the contribution of land-use change and soil mineralogy on soil C losses, soils with different soil mineralogy assemblage were studied from four areas in Brazil, all having sites with agriculture and nearby soils under native vegetation. We assessed SOM stability by thermogravimetric (TGA) and differential scanning calorimetry (DSC) and the molecular composition of functional soil C pools by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). On average, 33 % of soil C was lost in three sites after land-use change. Py-GC/MS indicates a dominance of reworked and/or microbial material (58-99 % N-containing products and carbohydrates), and low contribution from plant-derived products such as lignin phenols (from 0.1 to 7.7 %), and striking similarities in molecular composition between native vegetation and corresponding sites under agriculture. Thermal data indicate lower energy content in soils under native vegetation than agriculture, confirming microbial-derived SOM. The gibbsite content was positively correlated to N-containing products in both SOM extracted by alkaline solution (r(2) = 0.60) and SOM residual after alkaline extraction (r(2) = 0.82), while the kaolinite content showed a negative correlation with N-containing compounds (r(2) = 0.72) and a positive one with carbohydrates (r(2) = 0.48). Thus although SOM content highly decreased upon horticulture, both Py-GC/MS and thermal analyses indicate that SOM composition is mainly controlled by site instead of land-use, and the strong correlations with clay minerals suggest a mineralogical control on SOM composition. (AU)

• FAPESP's process: 16/05870-1 - SPCIATION AND KINETIC ADSORPTION AND DESORPTION OF Cd AND Zn IN SOILS OF OLERACEUS CROPS HIGHLY FERTILIZER
• Grantee: Matheus Sampaio Carneiro Barreto
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 16/22058-9 - Adsorption and desorption of Cd and Zn in highly fertilized tropical soils
• Grantee: Matheus Sampaio Carneiro Barreto
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 19/26235-0 - Formation and paleoenvironmental reconstruction of methanogenic histosols from the Campina do Encantado Peatland (Pariquera Açu, SP)
• Grantee: Pablo Vidal Torrado
• Support Opportunities: Regular Research Grants