Cellulase Accelerates Thatch-Mat Decay.

Several thatch-mat (TM) control products contain cellulase (CEL).� Testimonials for these are positive but effects have been inconsistent.� Research was done to determine if CEL accelerates decay of TM.� Its effect on CO₂-C release, percent C remaining (PTCR), and pool size (PS) and turnover time (TT) of fast-pool C (FP) and slow-pool C (SP) was studied in 2008.� Total CO₂-C released over 3 d increased from 2.95 mg g^-1 untreated TM to 4.30 or 5.84 for TM treated with 10 or 20 mg CEL g^-1.� Corresponding PTCR decreased by 3.3%, 4.3%, or 6.4%.� But at 15 d differences were insignificant for both parameters.� Cellulase at 10 mg g^-1 decreased FP TT from 3.2 d to 1.3 d and SP TT from 451.9 d to 309.2 d, but had no effect on PS.� Cellulase at 20 mg g^-1 also decreased TT for FP but increased PS from 3.96% of TM C to 6.49%; SP TT increased to 1466.8 d while PS decreased from 96.0% to 93.8%.� This implied a portion of SP converted to FP, and a larger volume of TM C decayed rapidly until recalcitrant materials remained.� At that point CEL-mediated decay was curtailed.� Treating TM with CEL accelerated decay but did not ultimately decrease PTCR.� This was likely due to an inability for CEL to hydrolyze recalcitrant SP constituents, which constituted the majority of TM C (93.8%).� Since CEL did not decrease PTCR the return on investment for products containing it may be questionable. �Enzymes that attack recalcitrant constituents may provide a better chance for enhancing SP decay.