Data/hora: 12/06/2024 21:05:11

Biblioteca(s): 	Embrapa Pantanal.	
Data corrente: 	20/03/2002	
Data da última atualização: 	31/03/2017	
Autoria: 	BAYER, C.; MARTIN-NETO, L.; MIELNICZUK, J.; CERETTA, C. A.	
Título: 	Effect of no-till cropping system on soil organic matter in a sandy clay loam Acrisol from Southern Brazil monitored by electron spin resonance and nuclear magnetic resonance.	
Ano de publicação: 	2000	
Fonte/Imprenta: 	Soil & Tillage Research, v.53, p.95-104, 2000.	
Idioma: 	Inglês	
Conteúdo: 	In weathered tropical and subtropical soils organic matter is crucial for soil productivity and its quantity dependens heavily on soil management systems. This study evaluated the effect of no-till cropping systems on organic matter content and quality in a sandy clay loam Acrisol soil (Paleudult in US taxonomy) from Southern Brazil. Ten cropping systems with varying additions of C and N were contucted for 12 years (from 1983 to 1994). The addition of crop residues increased total organic carbon (TOC) and total nitrogen (TN) in the soil at 0-17.5 cm depth, and this increase was directly with C and N added or recycled by the systems. The crop residues added to the soil were associated with reduced semiquinone free radical concentration, detected by electron spin resonance (ESR), in the organo-mineral aggregates <53 um and humic acid (HA) samples, in the soil at 0-2.5 cm depth. This showed that stable organic matter originating from crop residues was less humidified than the original soil organic matter. Results obtained from organo-mineral aggregates showed a higher amplitude (highest and lowest values were 5.47 and 2.09 x 10 spin g-1 of TOC, respectively) of semiquinone free radical concentration than HA samples (highest and lowest values were 2.68 and 1.77 x 10 spings g-1 of HA, respectively). These data showed that alterations due to tillage in soil organic matter characteristics, e.g., humidification degree can be better identified throught a combination of soil physical fractionation and spectroscopic analysis. Semiquinone content in the HA samples, detected by ESR, related significantly to aromaticity, as measured by nuclear magnetic resonance (NMR) of 13C. Management systems including no-till and cropping systems with high C and N additions to the soil improved its quality in Southern Brazil.	
Palavras-Chave: 	C NMR; ESR; Humic acid; Soil tillage.	
Thesagro: 	Ácido; Colheita; Lavoura; Matéria Orgânica; Solo.	
Thesaurus Nal: 	cover crops; organic matter; soil.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Pantanal (CPAP)	
Exemplares: 	CPAP - (43918-1) - ADD - SP - PP - SP16160 -  - 16160 - DIS