Appl Biochem Biotechnol (2011) 165:270–278 DOI 10.1007/s12010-011-9249-4 Turnover of Carbohydrate-Rich Vegetal Matter During Microaerobic Composting and After Amendment in Soil Terrence R. Green & Radu Popa Received: 6 October 2010 / Accepted: 4 April 2011 / Published online: 3 May 2011 # The Author(s) 2011. This article is published with open access at Springerlink.com Abstract We propose that microaerobic composting (MC) can be used to decompose vegetal matter with a short turnover time and large carbon (C) recycling potential. We used a novel method for measuring the degree of fragmentation of water-insoluble acid-soluble (WIAS) polysaccharides as a proxy in tracking their relative degree of degradation (i.e., fragmentation endpoint index). Oak leaves and food scrap processed by MC reached a fragmentation end point within 2 weeks. After amending the MC products into soil, the half-life of the polysaccharide residues was ~6–7 times longer (~100–110 days) than that measured during MC. The main products given up during MC were volatile organic acids (VOAs), alcohols and soluble carbohydrates in the compost tea, and CO2. These products accounted for about 2% of the initial carbon in the feedstock. Very small amounts of VOAs, particularly butyric acid, were formed in the amended soil. Based on a residence time of materials in fermentors of 2 weeks, a ~100-m3 capacity MC facility could process 2,000– 4,000 metric tons of vegetable matter amended in ten hectares of arable land per year. Keywords Microaerobic composting . Carbon recycling . Carbon sequestration . EPF index . Polysaccharide turnover . Soil Introduction Historically, the concentration of CO2 in the atmosphere has risen from a baseline value of ~260 to ~380 ppm [1–4]. Even though the exchange of carbon (C) between arable lands and the atmosphere is the most dynamic component of the global C cycle (~120 Gt year−1) [5, 6], and there is a positive correlation between atmospheric CO2 concentration and C- fixation in plants [7, 8], since the beginning of mechanized agriculture, arable land has lost T. R. Green TGA LLC, 13851 Verte Court, Lake Oswego, OR 97034, USA e-mail: greent@spiretech.com R. Popa (*) Biology Department, Portland State University, P.O. Box 751, Portland, OR 97207, USA e-mail: rpopa@pdx.edu