See more from this Session: Turf Soil and Water Management
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.