Relationships between C and N availability, substrate age, and natural abundance 13C and 15N signatures of soil microbial biomass in a semiarid climate

Microbial populations are primarily responsible for the decomposition of organic residues, the nutrients cycle, and the flow of energy inside of soil. The present study was undertaken to link soil microbiological and soil biochemical parameters with soil- and litter-quality conditions in the surface layer from 5 sites differing in plant cover, in stand age, and in land-use history. The aim was to see how strongly these differences affect the soil microbial attributes and to identify how microbiological processes and structures can be influenced by soil and litter quality. Soil and litter samples were collected from 5 sites according to different land use: preserved forest, nonpreserved forest, secondary forest, pasture, and eucalyptus plantation. Soil and litter microbial biomass and activity were analysed and DNA was extracted from soil. The DNA concentrations and soil microbial C and N correlated positively and significantly, suggesting that these are decisive nutrients for microbial growth and time required for microbial biomass renewal. The litter microbial biomass represented a source of C and N higher than soil microbial biomass and can be an important layer to contribute to tropical soil with low C and N availability. The litter quality influenced the litter and soil microbial biomass and activity and the soil bacterial diversity. The chemical and nutritional quality of the litter influenced the structure and microbial community composition in the eucalyptus plantation.

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Dynamics of carbon and nitrogen in a long-term cropping system and permanent pasture system

Australian Journal of Agricultural Research ◽

10.1071/ar9940211 ◽

1994 ◽

Vol 45 (1) ◽

pp. 211 ◽

Cited By ~ 10

Author(s):

FA Robertson ◽

RJK Myers ◽

PG Saffigna

Keyword(s):

Microbial Biomass ◽

Soil Microbial Biomass ◽

Cropping System ◽

Perennial Grasses ◽

Panicum Maximum ◽

N Availability ◽

Continuous Cropping ◽

Soil Microbial ◽

Net Mineralization ◽

C And N

On the brigalow lands of south-east Queensland, productivity of sown perennial grasses is severely limited by N availability, whereas annual crops grown on the same soil are N-sufficient. The dynamics of C and N were compared under in these soils under permanent green panic (Panicum maximum var. trichoglume cv. Petrie ) pasture and continuous cropping with grain sorghum (Sorghum bicolor). Although the sorghum system was more productive, it contained 18% less N and 29% less C. Annual flows of C and N through the soil microbial biomass were, respectively, 4500 and 240 kg ha-1 under sorghum, and 4050 and 60 kg ha-1 under pasture. Over 80% of C and N inputs to the sorghum system occurred after harvest. Under pasture, the continuous supply of residues of high C/N ratio (50-75) enabled the development of a large and active microbial biomass, which competed with the pasture plant for N, resulting in slow net mineralization of N and low levels of inorganic soil N. Under sorghum, the size of the microbial biomass was limited by C availability during the growing season. The sorghum residues had slightly lower C/N ratios (36-46), and their rapid decomposition and net mineralization of N were promoted by the fallow period and soil cultivation. Estimated annual C turnover through the soil microbial biomass was slightly faster under sorghum, and annual N turnover was around seven times faster under sorghum than under green panic. The productivity of these soils under the two management systems was controlled by the amount, quality and timing of organic matter inputs. These in turn controlled the size of the soil microbial biomass and its C and N supply, and hence the balance between immobilization and mineralization of N.

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Seasonal dynamics of soil microbial biomass C and N in different habitats in Zhalong Wetland

Acta Ecologica Sinica ◽

10.5846/stxb201211191623 ◽

2014 ◽

Vol 34 (13) ◽

Author(s):

张静 ZHANG Jing ◽

马玲 MA Ling ◽

丁新华 DING Xinhua ◽

陈旭日 CHEN Xuri ◽

马伟 MA Wei

Keyword(s):

Microbial Biomass ◽

Seasonal Dynamics ◽

Soil Microbial Biomass ◽

Microbial Biomass C ◽

Soil Microbial Biomass C ◽

Soil Microbial ◽

Zhalong Wetland ◽

C And N

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Nitrogen- and sulfur-deposition-altered soil microbial community functions and enzyme activities in a boreal mixedwood forest in western Canada

Canadian Journal of Forest Research ◽

10.1139/cjfr-2013-0049 ◽

2013 ◽

Vol 43 (9) ◽

pp. 777-784 ◽

Cited By ~ 12

Author(s):

Ya-Lin Hu ◽

Kangho Jung ◽

De-Hui Zeng ◽

Scott X. Chang

Keyword(s):

Microbial Community ◽

Microbial Biomass ◽

Soil Microbial Community ◽

Oil Sands ◽

Soil Microbial Biomass ◽

Soil Microbial ◽

C And N ◽

Boreal Mixedwood Forest ◽

The Impact ◽

S Deposition

Chronic nitrogen (N) and (or) sulfur (S) deposition to boreal forests in the Athabasca oil sands region (AOSR) in Alberta, Canada, has been caused by oil sands mining and extraction/upgrading activities. It is important that we understand the response of microbial community function to chronic N and S deposition as microbial populations mediate soil carbon (C) and N cycles and affect ecosystem resilience. To evaluate the impact of N and (or) S deposition on soil microbial community functions, we conducted a simulated N and S deposition experiment in a boreal mixedwood forest with the following four treatments: control (CK), N addition (+N, 30 kg N·ha−1 as NH4NO3), S addition (+S, 30 kg S·ha−1 as NaSO4), and N plus S addition (+NS, 30 kg N·ha−1 + 30 kg S·ha−1), from 2006 to 2010. Nitrogen and (or) S deposition did not change soil organic carbon, total N, dissolved organic C and N, or soil microbial biomass C and N. Soil microbial community-level physiological profiles, however, were strongly affected by 5 years of N and (or) S addition. Soil β-glucosidase activity in the +NS treatment was greater than that in the +S treatment, and S addition decreased soil arylsulfatase; however, urease and dehydrogenase activities were not affected by the simulated N and (or) S deposition. Our data suggested that N and (or) S deposition strongly affected soil microbial community functions and enzymatic activities without changing soil microbial biomass in the studied boreal forest.

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