PARENT SESSION
Oral Session #52: Carbon and Nitrogen Cycling: Soil processes and patterns. Presiding: F. Gilliam.
Wednesday, August 8, 2001. 1:00 PM to 5:00 PM. Hall of Ideas E.
The effects of compost and crop rotations on carbon turnover in particulate organic matter.
FORTUNA, ANN-MARIE1, HARWOOD, RICHARD1, PAUL, ELDOR1,2, 1 2
ABSTRACT- Agronomic systems that utilize organic resources including crop rotations, and/or compost to provide plant nutrition and maintain soil quality can increase C sequestration but require intensive management of soil C. The effect of crop rotations and compost applications on carbon sequestration, soil-C decomposition, and the turnover rate of C4-derived C was assessed via changes in the C content and 13C values of particulate organic matter (POM). Increases in C inputs were equated to changes in the quantity and 13C values of POM-C and total soil-C (TOC). Intensive cropping including continuous corn elevated TOC by 17% in 5 y. Compost applications increased TOC by an additional 17%. The POM fraction was an indicator of increased TOC in the integrated-compost management. Measurements of POM C were 45% higher after 5 y of compost applications. Eighty-five percent of compost material was initially associated with the POM fraction. The turnover rate of C4- and C3--derived C in the POM fraction ranged from 4 to 12 y. The presence of compost C had no affect on the turnover rate of corn derived C. Compost application, high cropping intensity, and chisel plow management (CP) increased C sequestration and maintained soil fertility.
KEY WORDS: particulate organic matter, 13C natural abundance, compost, carbon sequestration