Pedosphere 22(5): 726--735, 2012
ISSN 1002-0160/CN 32-1315/P
©2012 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Effects of Epigeic Earthworms on Decomposition of Wheat Straw and Nutrient Cycling in Agricultural Soils in a Reclaimed Salinity Area:A Microcosm Study
PANG Jun-Zhu1,2, QIAO Yu-Hui1, SUN Zhen-Jun1, ZHANG Shuo-Xin2, LI Yun-Le1,3, ZHANG Rui-Qing1,4
1.Department of Ecology and Environment Science, China Agricultural University, Beijing 100193, China2.College of Forestry, Northwest A&F University, Yangling 712100, China3.Beijing University of Agriculture, Beijing 102206, China4.Yantai Academy of Agricultural Sciences, Yantai 265500, China
ABSTRACT
      Earthworms,one of the most important macroinvertebrates in terrestrial ecosystems of temperate zones,exert important influences on soil functions.A laboratory microcosm study was conducted to evaluate the influence of the earthworm Eisenia fetida on wheat straw decomposition and nutrient cycling in an agricultural soil in a reclaimed salinity area of the North China Plain.Each microcosm was simulated by thoroughly mixing wheat straw into the soil and incubated for 120 d with earthworms added at 3 different densities as treatments:control with no earthworms,regular density(RD)with two earthworms,and increased density(ID)with six earthworms.The results showed that there was no depletion of carbon and nitrogen pools in the presence of the earthworms.Basal soil respiration rates and metabolic quotient increased with the increase in earthworm density during the initial and middle part of the incubation period.In contrast,concentrations of microbial biomass carbon and microbial biomass quotient decreased in the presence of earthworms.Earthworm activity stimulated the transfer of microbial biomass carbon to dissolved organic carbon and could lead to a smaller,but more metabolically active microbial biomass.Concentrations of inorganic nitrogen and NO3--N increased significantly with the increase in earthworm density at the end of the incubation(P<0.05),resulting in a large pool of inorganic nitrogen available for plant uptake.Cumulative net nitrogen mineralization rates were three times higher in the ID treatment than the RD treatment.
Key Words:  carbon,microbial biomass,nitrogen,plant uptake,soil respiration
Citation: Pang, J. Z., Qiao, Y. H., Sun, Z. J., Zhang, S. X., Li, Y. L. and Zhang, R. Q. 2012. Effects of Epigeic Earthworms on Decomposition of Wheat Straw and Nutrient Cycling in Agricultural Soils in a Reclaimed Salinity Area:A Microcosm Study. Pedosphere. 22(5): 726-735.
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