Data/hora: 07/06/2024 09:40:32

Biblioteca(s): 	Embrapa Gado de Corte.	
Data corrente: 	16/06/2004	
Data da última atualização: 	07/12/2010	
Autoria: 	MIRANDA, C. H. B.; MACEDO, M. C. M.; KANDA, K.; NAKAMURA, T.	
Afiliação: 	Embrapa Gado de Corte (Campo Grande, MS).	
Título: 	Soil organic residues accumulation in agro-pastoral systems in the cerrados of Brazil.	
Ano de publicação: 	2004	
Fonte/Imprenta: 	In: SUENAGA, K.; OSHIBE, A.; TANIGUHI, T. (Ed.). Development of sustainable agro-pastoral systems in the subtropical zone of Brazil. Tsukuba: JIRCAS, 2004.	
Páginas: 	p. 29-33.	
Série: 	(JIRCAS. Working Report, 36).	
Idioma: 	Inglês	
Notas: 	CNPGC. Proceedings of the Workshop on the results and prospects of comprehensive studies on the development of sustainable agro-pastoral systems in the subtropical zone of Brazil, 2003.	
Conteúdo: 	Soil samples were collected in February, 2002, from  0-10, 10-20 and 20-40cm soil depth layers, in a 20x20cm randomized soil cores, within eight production systems introduced in 1993/94. Eight replicates were collected in each plot. They encompassed continuous grazing pastures, continuous soybean plots under contrasting soil preparation (conventional, minimum or zero tillage), and  their  rotation with grazing pastures. Comparisons were made with a Cerrados undisturbed plot and a degraded pasture. A physical separation of soil organic residues was made in the lab passing 5kg of dry soil throughout  sieves with 2.0mm mesh (fresh light fraction).0,25mm (light fraction), or 0,105mm (heavy fraction). Soil was also analysed for its total Carbon content and  13C natural abundance. Most of the organic residues  accumulates on the 0-10cm depth. Compared to the native Cerrados, the introduction of a B.decumbens pasture in 1978 and its consequent degradation led to a sharp decrease in soil organic residues, specially in the layers up to 20cm depth. The renewal and fertilisation of the degraded pasture  in 1993 stopped further decrease, and incrased the total amount of residues but reaching, on average, only 65% of those shown by the Cerrados. Soil  continuously ultivated with soybean under  a convencional system showed a decrease wven larger than  the degraded pasture,  while soil under minimum or zero tillage with soybean  showed total amounts close to the degraded pasture. Soil  13C allowed to estimate that after 26 years of clearing the Cerrados and introducing pasture, 67% of  the soil C from the original Cerrados was substituted by C originated from the pasture in the 0-1-cm depth layer. It decreases to 42 and 25% in the 10-20 and 20-40cm depthlayer,  respectively. In soybean  cultivated areas, however, only 21 to 30% (0-10cm depth), 11 to 17% (10-20cm depth), and less than 1% (20-40cm depth) of the original  Cerrados C was substituted by soybean originated C. A slightly increase was observed in soil under zero tillage soybean in comparison to conventional and minimum tillage systems.	
Palavras-Chave: 	Agropastoral systems; Brasil; Brazilian savannas; Integração agricultura pecuária; Soils.	
Thesagro: 	Cerrado; Resíduo Orgânico; Solo.	
Thesaurus Nal: 	Brazil; crop residues.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Gado de Corte (CNPGC)	
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