Data/hora: 24/06/2024 05:21:13

Biblioteca(s): 	Embrapa Instrumentação.	
Data corrente: 	13/08/2004	
Data da última atualização: 	08/03/2010	
Autoria: 	SILVA, A. C.; TORRADO, P. V.; MARTIN-NETO, L.; VASQUEZ, F. M.; GONZALEZ-PEREZ, M.	
Título: 	Soil organic matter and geomorphic surface stability relationship in an Oxisol Toposequence (SE Brazil).	
Ano de publicação: 	2004	
Fonte/Imprenta: 	In: MARTIN-NETO, L.; MILORI, D.M.B.P.; SILVA, W.T.L. (Ed.). Humic substances and soil and water environment: International Meeting of IHSS, 12. São Carlos : Embrapa Instrumentação Agropecuária, 2004. p. 623-626.	
Idioma: 	Inglês	
Notas: 	CLASSIFICAÇÃO CDD: 630	
Conteúdo: 	I. INTRODUCTION 
Relieve is among soil formation factors, the one that contrais matter distribution in the soil system. The understanding of soil-landscape relations has been facilitated through utilization of topographic attributes, such as declivity, to establish relations with pedogenetic processes (Silva and Vidal Torrado, 1999). Accumulation and humification degree of organic matter, for example, can be correlated with soil declivity. In well-drained areas, the general rule is the smaller the declivity the bigger the rate of organic matter (OM) accumulation and humification degree, remaining constant the other soil formation factors (Silva and Vidal Torrado, 1999). Thus, the organic carbon content t would be higher as much as OM structure more complex at the summit of the slope than at back slope, where the carbon content would be lower and OM structure simpler. Thus, the content of  charcoal fragments found at soil surface horizons would be higher and their radiocarbon age older,  in areas with low declivity than in areas with high declivity, as the former areas suftered low influence of hydric erosion (Pessenda et al., 1996; Silva and Vidal Torrado, 1999). Riffaldi and Schnitzer (1972) report that semiquinone -type free radicais are stabilized with complex aromatic structures in humic substances. Thus, the free radical concentration of humic substances should decrease with increasing declivity and consequently the stability of geomorphic surfaces should decrease. 
Declivity is an attribute of relieve that is related to the accumulation and stability of organic matter in the soil. For this reason, in this paper were quantitatively evaluated relations among declivity, the humification degree of humic acids, the charcoal fragment content and its radiocarbon age.	
Palavras-Chave: 	C14; dectivity; EPR; humification degree; soil charcoal; Soil humic acids.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Instrumentação (CNPDIA)	
Exemplares: 	CNPDIA - (8334-1) - UMT - SP - -- - PROCI-04.00012 -  - 2004.00012 - DIS