Authors: BODDEY, ROBERT M.¹; JANTALIA, CLAUDIA P.¹; CONCEIÇÃO, PAULO C.²; ZANATTA, JOSILEIA A.²; BAYER, CIMÉLIO²; MIELNICZUK, JOÃO²; DIECKOW, JEFERSON³; DOS SANTOS, HENRIQUE P.⁴; DENARDIN, JOSÉ E.⁴; AITA, CELSO⁵; GIACOMINI, SANDRO J.⁵; ALVES, BRUNO J.R.¹; URQUIAGA, SEGUNDO¹

Source: Global Change Biology, Volume 16, Number 2, February 2010 , pp. 784-795(12)

Publisher: Wiley-Blackwell

Abstract:

Conservation agriculture can provide a low-cost competitive option to mitigate global warming with reduction or elimination of soil tillage and increase soil organic carbon (SOC). Most studies have evaluated the impact of zero till (ZT) only on surface soil layers (down to 30 cm), and few studies have been performed on the potential for C accumulation in deeper layers (0-100 cm) of tropical and subtropical soils. In order to determine whether the change from conventional tillage (CT) to ZT has induced a net gain in SOC, three long-term experiments (15-26 years) on free-draining Ferralsols in the subtropical region of South Brazil were sampled and the SOC stocks to 30 and 100 cm calculated on an equivalent soil mass basis. In rotations containing intercropped or cover-crop legumes, there were significant accumulations of SOC in ZT soils varying from 5 to 8 Mg ha⁻¹ in comparison with CT management, equivalent to annual soil C accumulation rates of between 0.04 and 0.88 Mg ha⁻¹. However, the potential for soil C accumulation was considerably increased (varying from 0.48 to 1.53 Mg ha⁻¹ yr⁻¹) when considering the soil profile down to 100 cm depth. On average the estimate of soil C accumulation to 100 cm depth was 59% greater than that for soil C accumulated to 30 cm. These findings suggest that increasing sampling depth from 30 cm (as presently recommended by the IPCC) to 100 cm, may increase substantially the estimates of potential CO₂ mitigation induced by the change from CT to ZT on the free-draining Ferralsols of the tropics and subtropics. It was evident that that legumes which contributed a net input of biologically fixed N played an important role in promoting soil C accumulation in these soils under ZT, perhaps due to a slow-release of N from decaying surface residues/roots which favored maize root growth.

Keywords: carbon sequestration; conventional tillage; crop rotations; Ferralsol; legume cover crops; maize; soil depth; soybean; zero tillage

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2486.2009.02020.x

Affiliations: 1: Embrapa Agrobiologia, km 47, Antiga Rodovia Rio - São Paulo, Seropédica, 23890-000, RJ, Brazil 2: Department of Soil Science, Federal University of Rio Grande do Sul, PO Box 15100, 91.501-970 Porto Alegre, RS, Brazil 3: Department of Soil Science and Agricultural Engineering, Federal University of Paraná, 80.035-050 Curitiba, PR, Brazil 4: Embrapa Wheat Research Centre, Caixa Postal 569, Passo Fundo, 99001-970, RS, Brazil 5: Department of Soil Science, Federal University of Santa Maria, Faixa de Camobi, km 9, 97105-900, Santa Maria, RS, Brazil

Publication date: 2010-02-01

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• By this author: BODDEY, ROBERT M. ;  JANTALIA, CLAUDIA P. ;  CONCEIÇÃO, PAULO C. ;  ZANATTA, JOSILEIA A. ;  BAYER, CIMÉLIO ;  MIELNICZUK, JOÃO ;  DIECKOW, JEFERSON ;  DOS SANTOS, HENRIQUE P. ;  DENARDIN, JOSÉ E. ;  AITA, CELSO ;  GIACOMINI, SANDRO J. ;  ALVES, BRUNO J.R. ;  URQUIAGA, SEGUNDO

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