Aggregate Stability in Soil with Humic and Histic Horizons in a Toposequence under Araucaria Forest

Abstract

Aggregate stability is one of the most important factors in soil conservation and maintenance of soil environmental functions. The objective of this study was to investigate the aggregate stability mechanisms related to chemical composition of organic matter in soil profiles with humic and histic horizons in a toposequence under Araucaria moist forest in southern Brazil. The soils sampled were classified as Humic Hapludox (highest position), Fluvaquentic Humaquepts (lowest slope position), and Typic Haplosaprists (floodplain). The C and N contents were determined in bulk soil samples. The chemical composition of soil organic matter was evaluated by infrared spectroscopy. Aggregate stability was determined by applying increasing levels of ultrasound energy. Carbon content increased from the top of the slope to the alluvial plain. Higher ultrasonic energy values for clay dispersion were observed in the C-rich soils in the lower landscape positions, indicating that organic compounds play an important role in the structural stabilization of these profiles. Both aliphatic and carbohydrate-like structures were pertinent to aggregate stability. In the Oxisol, organo-mineral interaction between carbohydrates and the clay mineral surface was the most important mechanism affecting aggregation. In soils with a higher C content (Humaquepts and Haplosaprists), stabilization is predominantly conferred by the aliphatic groups, which is probably due to the structural protection offered by these hydrophobic organic groups.

Soil quality indicators under management systems in a Quilombola community in the Brazilian Cerrado

“…Moreover, the greater diversity of the planted species, especially grasses, due to their higher root biomass, increases the total organic carbon (TOC) and soil aggregate stability (Pérès et al, 2013). In the case of a Rhodic Hapludox, the organicmineral interaction between carbohydrates and the mineral surface of clay is one of the most important mechanisms in the formation of soil aggregates (Hanke and Dick, 2017).…”

“…However, their size distribution did not differ within management systems. The mineralogy of tropical soils is possibly the factor that results in increased stability of aggregates via the greater organic-mineral interaction (Madari et al, 2005;Hanke and Dick, 2017). A higher ASI was expected in the sys- tem with greater species diversity (AC), including the reference area (CR), since both could promote a greater diversity of root exudates of different compositions, guaranteeing greater carbon source diversity in the soil system (Silva et al, 2016a).…”

Soil Aggregate Stability of Forest Islands and Adjacent Ecosystems in West Africa

“…Although other organo-mineral interactions have also been proposed viz. hydrophobic interactions, cation bridges; cation and anion exchange; and Van der Waals interactions, among others (Hanke et al, 2015, Hanke andDick, 2017), these have not been well investigated.…”

Machine learning approaches for the prediction of soil aggregate stability

“…This management cannot be reached without a proper understanding of the different soil characteristics and properties. Aggregate stability is one of the essential factors in soil conservation and maintenance of its environmental functions ( Hanke and Dick, 2017 ), it affects water ( Kunhikrishnan et al., 2012 ), and store and stabilize organic carbon ( Kodešová et al., 2008 ). Furthermore, an increase in soil structural stability can directly increase the resistance against erosive agents and compaction ( Chaplot and Cooper, 2015 ).…”