Seasonal variability of microbial biomass associated with aggregates in a rice-based ecosystem

• Published in: European journal of soil biology Vol. 56; pp. 84 - 88
• Main Authors: Jiang, Xianjun, Shi, Xiuli, Wright, Alan L.
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 01.05.2013; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Anthrosols; autumn; Biochemistry and biology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; clay; clay fraction; climate change; Conservation tillage; conventional tillage; Cropping systems. Cultivation. Soil tillage; ecosystems; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; microbial biomass; Microbiology; no-tillage; Nutrient cycling; Physical properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Rice soil; seasonal variation; silt; soil aggregates; Soil erosion, conservation, land management and development; soil heterogeneity; soil microorganisms; Soil science; Soil structure; spring; Structure, texture, density, mechanical behavior. Heat and gas exchanges; summer; winter; China; Soil structure; Nutrient cycling; Rice soil; Conservation tillage; Translocation; Monocotyledones; Cultivated soil; Biogeochemical cycle; Microbial biomass; Inorganic element; Paddy soil; Oryza; Gramineae; Seasonal variation; Ecosystem; Angiospermae; Nutrient; Herbaceous plant; Spermatophyta; Soil science; Aggregate
• ISSN: 1164-5563
• DOI: 10.1016/j.ejsobi.2013.03.004

Temporal variability of soil microbial biomass shows contradictory trends for different ecosystems. Since soils are comprised of many sizes of aggregates and soil particles, we hypothesized that the microbial biomass response to seasonal variation is more sensitive at the aggregate scale than for whole soil. Tillage impacts on seasonal variation of microbial biomass were determined for a hydargric Anthrosol in China from 2008 to 2009. No significant seasonal changes occurred for soil total organic C (TOC), but microbial biomass C (MBC) exhibited distinct seasonal variation. However, seasonal variation patterns of MBC associated with aggregates coincided with patterns for whole soil, regardless of tillage regimes. The MBC in whole soil was significantly higher in spring (272 mg kg−1) than autumn (186 mg kg−1) and winter (165 mg kg−1) under CT (conventional tillage), while MBC was higher in spring and autumn than winter and summer for RNT (ridge with no-till). Microorganisms associated with different sizes of aggregates responded similarly to environmental changes, but the degree of response for different sizes of aggregates varied. The CV (coefficient of variation) for seasonal change was lowest for macroaggregates, while the highest CVs occurred for the silt + clay fraction. The results indicated that soil microorganisms associated with macroaggregates were more stable than with silt + clay fractions to resist seasonal changes in climate and soil properties, and therefore more likely to play a role in enhancing nutrient conservation in the soil. Seasonal variation patterns of microbial biomass associated with aggregates coincided with patterns for whole soil, suggesting that microorganisms associated with different size fractions of aggregates respond to macro- and micro-environmental changes in a similar way. •Seasonal patterns of microbial biomass within aggregates were consistent with the whole soil.•Microorganisms associated with macro-aggregates were more resistant to seasonal changes.•Tillage did not increase the seasonal variability of microbial biomass.