Carbon in soil aggregates under native vegetation, pasture and agricultural systems in the Brazilian savannah

Author(s)

Ciniro Costa Junior ^[1] ; Marisa de Cássia Píccolo ^[2] ; Marcos Siqueira Neto ^[3] ; Plínio Barbosa de Camargo ^[4] ; Carlos Clemente Cerri ^[5] ; Martial Bernoux ^[6]

Affiliation

^[1] Universidade de São Paulo. Centro de Energia Nuclear na Agricultura

^[2] USP. Laboratório de Ciclagem de Nutrientes do CENA

^[3] USP. Laboratório de Biogeoquímica Ambiental do CENA

^[4] USP. CENA

^[5] USP. Laboratório de Biogeoquímica Ambiental do CENA

^[6] UMR

• Document type: Journal article
• Source: Revista Brasileira de Ciência do Solo; v. 36, n. 4, p. 1311-1322, 2012-08-00.

Abstract

Soil organic matter (SOM) is responsible for soil fertility, nutrient cycling and structure stability and is closely related with soil aggregation. However, the relationship between aggregate size classes in the SOM dynamics is unclear, resulting in SOM accumulation or loss due to soil land use and management. This study aimed to evaluate the amount of carbon (C) in soil aggregates under four uses and management: native Cerrado (CE-savannah vegetation), no-tillage (NT), conventional tillage (SPC) and pasture (PA). The study areas are located in Rio Verde (GO) where the soil was classified as kaolinitic clayey Oxisol. The soil layers 0-5, 5-10 and 10-20 cm were sampled (n=6) in February 2007, and the amount of water-stable macroaggregates (> 2.0 mm), mesoaggregates (> 0.25 and < 2.00 mm) and microaggregates (> 0.05 and < 0.25 mm) were determined, as well as the mean weight diameter (MWD) and mean geometric diameter (MGD), and the C levels in the soil aggregate classes. Macroaggregates were predominant in the soil evaluated, with higher quantities in CE and PA compared NT and SPC soils, indicating a negative effect of soil cultivation on macroaggregate conservation. However, the soil aggregate C levels in the 0-20 cm layer were higher in CE and SPD than in PA and SPC soils, suggesting that the absence of tillage and maintenance of crop residues on the soil drives C accumulation. This shows that macroaggregates and mesoaggregates were more sensitive to soil use and management than microaggregates. The similarities of aggregation in PA and CE soils, although with lower C levels in PA suggested different aggregation dynamics, requiring further research. (AU)

• FAPESP's process: 04/15538-7 - Stocks of carbon and nitrogen in Cerrado soils aimed at agricultural sustainability
• Grantee: Marisa de Cassia Piccolo
• Support Opportunities: Regular Research Grants