Miss Hana Kobayashi1, Mr Soh Sugihara1, Mrs Kozue Sawada1, Mr Method Kilasara2, Mr Haruo Tanaka1, Mr Jun Murase3, Mr Chol Gyu Lee1, Mr Koki Toyota1, Mr Takashi Kosaki4
1Tokyo University of Agriculture and Technology, Fuchu-shi, Japan, 2Sokoine University of Agriculture, Chuo Kikuu , Tanzania, 3Nagoya University, Nagoya-shi, Japan, 4Aichi University, Nagoya-shi, Japan
Microbial carbon use efficiency (CUE) is an important factor to predict the carbon dynamics and future climate change, but its controlling factors are not fully understood. Although soil microbial diversity is considered to affect CUE, there are only a few studies evaluating the relationship between the microbial diversity and CUE. Thus, the objective of this study was to test the hypothesis that “the higher soil microbial diversity, the higher CUE”. We collected the surface soils from cropland and forest (F1) with neutral soil pH (6.6-6.8), and also from grassland and forest (F2) with relatively low soil pH (5.7-6.1) in the dry tropical Tanzania, with five replications. We measured soil physico-chemical properties, microbial biomass, and fungi to bacteria ratio (F/B ratio), and conducted the amplicon sequence analysis to know bacterial composition and α-diversity (Shannon index). To evaluate the CUE, we measured hourly microbial respiration rate for 12 hours after glucose application. The microbial biomass was significantly high in F1 and F2, while F/B ratio was not different among the treatments. The bacterial compositions of grassland and F2 were clearly different from that of cropland and F1, and soil pH mainly contributed its difference. The Shannon index of F1 (6.37), F2 (6.32) and grassland (6.33) were significantly higher than that of cropland (5.98). For cropland and F1, the bacterial composition and soil pH were similar, while the bacterial diversity was different. Thus, we compared CUE only for cropland and F1, and CUE was clearly higher in F1 than in cropland, supporting our hypothesis. These results indicate that there was a close relationship between the soil microbial diversity and its CUE in Tanzania.
The first year of master’s course student of Tokyo University of Agriculture and Technology. Theme of graduation theses was “Effect of microbial diversity on carbon use efficiency in dry tropical ecosystem”.