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Zhou D.-N.,Hubei Academy of Aguicultural science | Zhang F.-P.,Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River | Zhang F.-P.,Huazhong Agricultural University | Zhang F.-P.,Tibet Agriculture and Animal Husbandry College | And 8 more authors.
Journal of Food, Agriculture and Environment | Year: 2013

Soil microorganisms play central roles in soil ecosystems, which are far more sensitive to heavy metal pollution than soil animals or plants growing in the soils. Therefore, our objective was to study the effects of heavy metal pollution on microbial populations (bacteria, actinomyces, fungi, ammonifying bacteria, nitrobacteria and cellulolytic bacteria) and microbial activities (microbial biomass C (MBC), basal respiration and metabolic quotient (qCO2)) on soils of Lawu Cu-Zn-Pb mine in central Tibet, China. Five sampling sites included the mine center (Site 1), grassland near the mine center (Site 2), traffic road of the mine (Site 3), abandoned mine tailing (Site 4) and about 2 km from the mine center (Site 5, taken as the control). A composite soil sample was collected using a soil sampler with 5 cm diameter and 10 cm depth at eight random positions in each sampling site. Results indicated that compared to the control, soils in Sites 1-4 were polluted by heavy metals (Cu, Zn, Pb and Cd), resulting in decrease in culturable number of bacteria, actinomyces, ammonifying bacteria, nitrobacteria and cellulolytic bacteria, and MBC contents, but increase in basal respiration and qCO2. Principle component analysis (PCA) extracted two principal components (the first principal component (M-PC1) and the second principal component (M-PC2)) using microbial parameter data, where M-PC1 explained 53.7% of the original variances and M-PC2 accounted for 32.5% of the variances; moreover, only one principal component (H-PC) was extracted from heavy metal data, representing 92.7% of the original variances. Linear regression analysis showed that heavy metal contents were significantly related to microbial populations and activities except to fungi and M-PC2, and stronger correlation (r = 0.94) was observed between the scores of H-PC with the scores of M-PC1 than other microbial parameters, suggesting that it might be feasible to use M-PC1 as an integrated microbial index combining microbial population and activity to assess changes in soil environment polluted by heavy metals in central Tibet, China.

Cheng-Fang L.,Huazhong Agricultural University | Dan-Na Z.,Hubei Academy of Aguicultural science | Zhi-Kui K.,Huazhong Agricultural University | Zhi-Sheng Z.,Huazhong Agricultural University | And 3 more authors.
PLoS ONE | Year: 2012

Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha-1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%-66% and SOC by 21%-94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%-36% but increased CO2 emissions by 22%-40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%-48% in the 0-5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0-20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered. © 2012 Cheng-Fang et al.

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