Carbon Source Quality and Placement Effects on Soil Organic Carbon Status
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Carbon Source Quality and Placement Effects on Soil Organic Carbon Status B. J. Wienhold & G. E. Varvel & J. M. F. Johnson & W. W. Wilhelm
Published online: 1 February 2013 # Springer Science+Business Media New York (outside the USA) 2013
Abstract Improved management of agricultural soils has potential for sequestering carbon (C) and reducing the accumulation of atmospheric carbon dioxide. Development of management practices to increase C sequestration is dependent on improved understanding of soil processes influencing long-term storage of C. A field study was conducted to compare surface C source quality and above- vs. belowground addition of annual or perennial plant biomass effects on particulate organic matter (POM), total labile C (TLC), and total organic C (TOC). Since microaggregate stabilization within macroaggregates is the main mechanism for sequestering C, aggregate size distribution, expressed as mean weight diameter (MWD), and wet aggregate stability (WAS) was also measured. After 5 years, POM decreased in plots receiving surface application of readily available substrate (sucrose and alfalfa pellets) and the bare surface control. Plots receiving plant additions [wood chips, growing wheat (Triticum aestivum L.) crop, growing switchgrass (Panicum virgatum L.) crop, and fallow receiving either wheat or switchgrass residue] exhibited higher TLC and TOC content. Plots receiving plant residue maintained MWD, and those supporting live plants exhibited increasing WAS. Surface plant residue protected the soil against raindrop impact and reduced the intensity of wetting and drying cycles allowing the development of larger more stable aggregates resulting in C accrual.
USDA is an equal opportunity provider and employer. B. J. Wienhold (*) : G. E. Varvel : W. W. Wilhelm USDA-ARS, 137 Keim Hall, East Campus, UNL, Lincoln, NE 68583, USA e-mail: [email protected] J. M. F. Johnson USDA-ARS, Morris, MN, USA
Keywords Carbon sequestration . Soil structure . Plant residue . Soil aggregation
Introduction Crop residue and perennial grasses have been identified as potential feedstock for biofuel production [12] and are currently used for animal feed. Aboveground residue protects soils from potential wind and water erosion, serves as a boundary layer reducing evaporation, and serves as a substrate for soil biota. Removing plant residue raises concerns regarding soil conservation, soil organic matter, compaction, and future soil fertility [21]. Efforts have been made to determine the amount of residue that must be retained to sustain soils [22]. The effect of removing plant residue components on water erosion [19] and soil fertility [20] has also been studied. Information regarding the role of plant residue in sustaining soil biota and processes effecting carbon (C) sequestration are lacking. Plant residue is utilized by soil biota as an energy and nutrient source. The process of plant residue decomposition results in carbon dioxide emission from soils. The long-term accrual of C in soils occurs when the C becom
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