No tillage and bagasse mulching alter fungal biomass and community structure during decomposition of sugarcane leaf litter in Lampung Province, Sumatra, Indonesia

Soil fungi are the predominant decomposers of soil organic matter (SOM). To manage SOM in tropical agricultural soils, it is important to understand the effects of agricultural management on fungal communities and their decomposition of organic matter. Our study site was located in a sugarcane plantation in Lampung Province, Sumatra, Indonesia. The objectives of this study were to determine the following: (1) the effect of conversion from conventional tillage to no-tillage farming and the application of bagasse mulch on fungal biomass, community structure, and the relative ratio of fungal to bacterial biomass (F:B); (2) the combination effect of no-tillage with bagasse mulch on these fungal parameters; and (3) possible links between these fungal parameters and the decomposition rate of sugarcane leaf litter. We measured fungal biomass and F:B by phospholipid fatty acid (PLFA) analysis, and we evaluated fungal molecular diversity and community structure by modified terminal restriction fragment length polymorphism (T-RFLP) profiling. Fungal biomass was 2-fold greater with no-tillage and 2.5-fold greater with added bagasse mulch relative to conventional (tillage without mulch) plots. On the other hand, no-tillage also increased bacterial biomass and fungal OTU (operational taxonomic unit) richness, whereas bagasse mulch increased the F:B and inhibited a specific fungal OTU. Under a combination of no-tillage and bagasse mulch, the fungal biomass was 1.7-fold greater than in conventional plots, indicating that the combination did not have an additive effect on fungal biomass. The litter mass loss rate was negatively correlated with fungal biomass, and bagasse mulch suppressed the mass loss approximately 20% less than in the conventional plots. However, the mass loss rate in no-tillage plots did not differ from that in conventional plots. Overall, our results indicated that no-tillage and bagasse much increased litter fungal biomass and altered the fungal communities, and these changes were reflected in the litter decomposition and soil C dynamics. Further studies are needed to clarify the relationship between litter decomposition and fungal species identity.