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Carbon Dynamics of Surface Residue– and Root‐derived Organic Matter under Simulated No‐till
Author(s) -
Gale W. J.,
Cambardella C. A.
Publication year - 2000
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2000.641190x
Subject(s) - chemistry , residue (chemistry) , incubation , organic matter , crop residue , soil organic matter , soil carbon , soil water , total organic carbon , environmental chemistry , agronomy , soil science , environmental science , biology , organic chemistry , ecology , biochemistry , agriculture
No‐till practices have the potential to increase soil organic C, but little is known about the relative contribution of surface residue and roots to soil organic C accumulation. In a simulated no‐till experiment, we studied the fate of 14 C‐labeled surface residue and in situ roots during a 1‐yr incubation. Soil samples collected during the incubation were chemically dispersed and separated into five particle size and density fractions. The organic C, 14 C, and total N content of each fraction was determined. Alkali traps were used to measure 14 C losses due to respiration. After 360 d, 66% of the 14 C contained in the surface residue on Day 0 had been respired as 14 CO 2 , 11% remained in residue on the soil surface, and 16% was in the soil. In comparison, 56% of the root‐derived 14 C in the soil was evolved as 14 CO 2 and 42% remained in the soil. The large (500–2000 μm) and small (53–500 μm) particulate organic matter (POM) fractions together contained 11 to 16% of the initial root‐derived 14 C in the soil. In contrast, POM contained only 1 to 3% of the inital surface residue–derived 14 C. These data show clear differences in the partitioning of surface residue– and root‐derived C during decomposition and imply that the beneficial effects of no‐till on soil organic C accrual are primarily due to the increased retention of root‐derived C in the soil.