Repeated applications of farmyard manure enhance resistance and resilience of soil biological functions against soil disinfection

Abstract

The effect of repeated application of farmyard manure (FYM) on resistance and resilience of some of soil biological functions
was compared between two soils [chemically fertilized soil (CF soil) and chemically and organically amended soil (CF+FYM-soil)].
The impact of chloropicrin and metam sodium disinfection on organic matter (glucose and chitin) decomposition activity and
number of ammonia oxidizing bacteria in the soils was measured periodically from just after disinfection to evaluate stability
of soil biological functions to soil disinfection. Glucose and chitin decomposition activity and number of ammonia oxidizing
bacteria was suppressed by soil disinfection more seriously in the CF soil than in the CF+FYM soil. The decomposition rates
recovered in the disinfected CF+FYM soil 2 to 12weeks after disinfection, but not in the CF soil during 12weeks incubation.
These results demonstrated that soil resistance and resilience of the selected biological functions may be higher in the CF+
FYM soil than in the CF soil. The ratios of fungal and bacterial contribution to glucose decomposition activity were evaluated
by the substrate-induced respiration method. Chloropicrin and metam sodium disinfection decreased fungal contribution throughout
the incubation period (12weeks) in the CF soil. A similar tendency was observed in the CF+FYM soil, but the fungal contribution
tended to recover more rapidly in the CF+FYM soil than in the CF soil. Repeated applications of FYM may be an effective way
to enhance soil functional stability.