Carbono no solo em sistemas integrados de produção agropecuária no Cerrado e na transição Cerrado - Amazônia
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2015-06-26
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Universidade Federal de Goiás
Resumo
Integrated crop-livestock (iCL) and integrated crop-livestock-forest (iCLF)
systems are pointed out as potential soil carbon sinks. However, there are few scientific
studies that evaluated the real contribution of these production systems. This work
included two studies. The first was to evaluate soil carbon accumulation and its origin in
iCLF in the transition zone of the Cerrado-Amazon biomes; the second aimed to calibrate
and validate the CQESTR model for the Cerrado ecosystem and to evaluate the effect of
soil management practices, including iCL and various scenarios on soil organic carbon
(SOC) over time. For the first study two areas under iCLF (iCLF1 and iCLF3, with one
and three rows of Eucalyptus urograndis by hedgerow, respectively) were selected. They
were cultivated in this system since 2009 in Nova Canaã do Norte, MT. A continuous
pasture was used as reference. Soil samples were taken from eight layers (0.0 to 1.0 m) for
the evaluation of the bulk density, texture, total C and N and δ¹³C. The second study was
conducted in the Cerrado biome. The evaluated areas (Paddock 4 - P4 and Paddock 5 - P5
has been being managed in iCL since 2000. Bulk density and the organic matter content
were determined for the 0.0-0.1 and 0.1-0.3 m layers. The CQESTR is a process based
model which simulates the effect of climate, crop rotation and tillage management
practices on SOC. The model was calibrated with P5 data and validated with P4 data. Its
performance was evaluated using statistical regression analysis and the root mean square
deviation (MSD). For the first study, the soil C stocks and isotopic composition were
affected by the implementation of the iCLF system. The forest component was an
important factor for soil C accumulation for both areas under iCLF. The N can be a
limiting factor for C accumulation. We concluded that iCLF affected soil C and N stocks in
the short term, however, longer iCLF deployment time would be necessary to elucidate the
impact of iCLF in the long-term. In the second study model calibration was performed by
adjusting the basic decomposition rate coefficient. The measured and simulated values
were significantly correlated with an MSD of 2.11, indicating that the model captured
spatial-temporal dynamics of SOC in the topsoil. However, CQESTR underestimated SOC
for the 0,1-0,3 m layer, probably due to lack of site specific grass or crop root biomass and
distribution data under tropical conditions. Additional calibration is required to improve
prediction of SOC stabilization process in the subsoil layers of tropical soils. In the long
term (20 years), for the superficial (0,0-0,1 m) soil layer, the model simulated C
accumulation in iCL and C loss in soybean/corn grain production system independently of
the use of zero-tillage or conventional tillage in either of these systems under Cerrado
conditions.
Descrição
Palavras-chave
Sistema de integração lavoura-pecuária , Sistema de integração lavourapecuária- floresta , Estoque de carbono , Modelo de dinâmica de carbono CQESTR , Calibração , Validação , Integrated crop-livestock system , Integrated crop-livestock-forest system , Soil carbon stock , Soil carbon model CQESTR , Calibration , Validation
Citação
OLIVEIRA, J. M. Carbono no solo em sistemas integrados de produção agropecuária no Cerrado e na transição Cerrado - Amazônia. 2015. 90 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2015.