Papers by Keyword: Mean Weight Diameter

Abstract: The effects of an arbuscular mycorrhizal fungus, Glomus mosseae, on plant growth, soil aggregate stability, and rhizosphere carbon pools of young Citrus junos seedings were investigated with potted experiment in greenhouse. After three months of mycorrhizal inoculation, root colonization was 54.25%. Inoculation with G. mosseae significantly promoted plant height, stem diameter, leaf number, and shoot and root fresh weights. Colonization by G. mosseae significantly increased soil aggregate stability of the citrus rhizosphere through increase of mean weight diameter. G. mosseae could release a specific glycoprotein viz. glomalin into the rhizosphere as glomalin-related soil protein (GRSP). Meanwhile, mycorrhizal colonization was significantly positively correlated with two GRSP fractions. In stabilization of aggregate stability, in GRSP fractions only easy extractable -GRSP might contribute the role. The mycorrhizal symbiosis could increase soil organic carbon, hot-water extractable carbohydrates, and hydrolyzed carbohydrates concentrations, but the differences were not significant. Combined with the correlation analysis, it suggests that GRPS did not significantly regulate rhizospheric carbon pools, due to the short treated time (only 3 months).

Abstract: Soil aggregate stability as a key indicator of soil structure and erodibility to evaluate soil stability, is a product of interactions between soil environment, management practices, and land use patterns. The objective of this study was to analyze the distribution characteristics, characteristics of fractal features and stability of soil aggregates in tea plantations and eucalyptus plantations of Western Sichuan in China. The dry- and water-stable aggregate size distributions were determined by dry sieving and wet sieving methods. The results showed that soil structural properties in tea and eucalyptus plantations were similar. With increase in depth of soil layer, the aggregate stability of tea plantation soil became stronger. Comparative analysis of dry and wet sieving results showed that most of the aggregates in tea plantation soil were unstable. The soil aggregates >5mm and 0.5-0.25mm in size had higher stability, while those 2-1mm in size had lower stability. For tea plantation soil, the correlation coefficients between aggregate stability index and mean weight diameter, geometric mean diameter, fractal dimension were bigger under wet sieving than those under dry sieving. The results showed that aggregate stability index, mean weight diameter, geometric mean diameter, fractal dimension of water-stable aggregates could characterize soil aggregate stability in tea plantation ideally.