Pedosphere 9(3): 275--280, 1999
ISSN 1002-0160/CN 32-1315/P
©1999 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Straw 14C decomposition and distribution in humus fractions as influenced by soil moisture regimes
WANG Zhi-Ming, ZHU Pdi-Li and HUANG Dong-Mai
Institute of Soil and Fertilizer Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China)
ABSTRACT
      14C-tracer technique and closed incubation method were used to study straw 14C decomposition and distribution in different fractions of newly formed humus under different moisture regimes. Decomposition of straw 14C was faster during the initial days, and slower thereafter. Decay rate constants of straw 14C varied from 3.29 × 10-3 d-1 to 7.06 × 10-3 d-1. After 112 d incubation, the amount of straw 14C mineralized was 1.17~1.46 times greater in submerged soils than in upland soils. Of the soil residual 14C, 9.08%~15.73% was present in humic acid (HA) and 31.01%~37.62% in fulvic acid (FA). Submerged condition favored the formation of HA, and HA/FA ratio of newly formed humus (labelled) was greater in submerged soils than in upland soils. Clay minerals affected the distribution of straw 14C in different humus fractions. Proportion of 14C present in HA to 14C remaining in soil was greater in Vertisol than in Ultisol.
Key Words:  decomposition, distribution, soil humus fractions, soil moisture regimes, straw 14C
Citation: Wang, Z. M., Zhu, P. L. and Huang, D. M. 1999. Straw 14C decomposition and distribution in humus fractions as influenced by soil moisture regimes. Pedosphere. 9(3): 275-280.
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