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Molecular techniques for studying soil microorganisms allow to quantify the presence of specific functional groups from the total soil DNA and thus to assess their dynamic in response to the land use. Using this approach, a study was carried out to assess the increase the soil organic carbon (C) of arable land in the central Po Valley with three woody species (white willow, black locust, hybrid poplar) in short rotation forestry. Being fungi the most involved microorganisms in the C-cycle and representing the larger part of microbial biomass in volume, total fungi e the two most widespread main fungal degraders in the upper soil layer (Ascomycetes and Basidiomycetes) were used as indicators of the effectiveness of land use in increasing soil organic C. An innovative molecular technique (SYBR® Green I dye on the QuantStudio™ 3D digital PCR system) which allows to overcome the critical issues associated with the relatively low concentration of fungal DNA compared to that of bacteria was used. Compared to the ploughed soil, total organic carbon (TOC), microbial biomass and enzyme activities increased significantly in the woody plantations. However, TOC increased to different degrees among the woody species. White willow and black locust showed a greater increase in soil TOC than arable (+30 and 20% respectively), followed by hybrid poplar with a smaller increase of +12%. The increases in soil TOC in the three plantations were not correlated with the total woody mass, assessed 15 years after abandonment. Total fungi and Ascomycetes were highly correlated with microbial biomass and TOC, while Basidiomycetes were not. Ascomycetes, which commonly prevail in agricultural soils, were still the most abundant even after a short rotation forest cycle of 15 years and can be taken as good indicator of C sequestration activities into the soil. Soil tillage strongly reduced the content of Basidiomycetes and short rotation forestry managed to increase it at least 4-5 times over a 15-year cycle of short rotation forestry, suggesting that it can act as a qualitative indicator of C sequestration. Since Basidiomycetes have different biological and morphological characteristics than Ascomycetes, combining them (i.e., as Ascomicetes:Basidiomycetes ratio) seems to be a good option for choosing the most suitable woody species for carbon accumulation in agricultural soils. [ABSTRACT FROM AUTHOR]

Characterisation and evaluation of soil bacteria were conducted in order to select the most potent strains that participate in the degradation of cellulose in unique agroecosystem and climatic conditions. Cellulolytic activity of soil bacteria was estimated using qualitative assays such as growth on selective media followed by screening with Congo red, Gram's iodine solution, confirmation test on Congo red agar, determination of enzyme production, and sugar utilisation pattern. A total of 159 soil cellulolytic bacterial strains were selected based on shape, size, and colony characteristics. According to the results of all three screening assays, sixty-four, thirty-eight and fifty-one isolates were able to degrade at some level of cellulose, respectively. Partial sequencing of the 16S rRNA gene of 64 bacterial strains obtained using sequences retrieved from the databases indicated the presence of cellulolytic bacteria represented by members of the phyla Actinobacteria (48.44%), followed by Firmicutes (32.81%), Proteobacteria (15.62%) and Bacteroidetes (3.13%). Determination of enzyme production showed that fifteen strains possess endoglucanases activity which ranged from 9.09 to 942.41 nanomoles of MUF (4-methylumbelliferone) mL. Likewise, β-glucosidase enzyme activity was determined in 23.4 % of all isolates. The sugar utilisation pattern of soil bacterial strains displayed the different capabilities of growth and utilisation on various carbon sources, which occur in lignocellulosic materials (cellulose, starch) or their hydrolysates (glucose, galactose, fructose, cellobiose, maltose, lactose, sucrose, trehalose). [ABSTRACT FROM AUTHOR]

This study sought to quantify the influence of 'carbon fanning' practices on soil carbon stocks, in comparison with conventional grazing and cropping, in northern New South Wales. The study had two components: assessment of impacts of organic amendments on soil carbon and biological indicators in croplands on Vertosols of the Liverpool Plains; and assessment of the impact of grazing management on soil carbon in Chromosols of the Northern Tablelands. The organic amendment sites identified for the survey had been treated with manures, composts, or microbial treatments, while the conventional management sites had received only chemical fertilisers. The rotational grazing sites had been managed so that grazing was restricted to short periods of several days, followed by long rest periods (generally several months) governed by pasture growth. These were compared with sites that were grazed continuously. No differences in total soil carbon stock, or soil carbon fractions, were observed between sites treated with organic amendments and those treated with chemical fertiliser. There was some evidence of increased soil carbon stock under rotational compared with continuous grazing, but the difference was not statistically significant. Similarly, double-stranded DNA (dsDNA) stocks were not significantly different in either of the management contrasts, but tended to show higher values in organic treatments and rotational grazing. The enzymatic activities of β-glucosidase and leucine- aminopeptidase were significantly higher in rotational than continuous grazing but statistically similar for the cropping site treatments. Relative abundance and community structure, measured on a subset of the cropping sites, showed a higher bacteria : fungi ratio and provided evidence that microbial process rates were significantly higher in chemically fertilised sites than organic amendment sites, suggesting enhanced mineralisation of organic matter under conventional management. The higher enzyme activity and indication of greater efficiency of microbial populations on carbon farming sites suggests a greater potential to build soil carbon under these practices. Further research is required to investigate whether the indicative trends observed reflect real effects of management. Additional keywords: organic amendment, rotational grazing, soil carbon stock, soil microorganisms., Introduction Soil organic matter contains a large fraction of the global terrestrial carbon stocks (Batjes 1996). In recent years, the importance of soil organic matter as a significant carbon sink [...]