火山灰草地土壌の微生物バイオマス窒素の無機化に及ぼす石灰施用の影響

Effect of liming on the mineralization of microbial biomass nitrogen in volcanic grassland soil

Creators Marumoto Takuya

Creators Okano Seigo

Creators Nishio Michinori

The pH of volcanic grassland soils (3.8 and 4.9) was adjusted to 6.5 and 7.0 by liming with calcium carbonate, respectively. 1) Mineralization of C and N from the treated soils was accelerated after liming and the degree of mineralization during 20 days was larger in the soil with adequate application of lime (pH7.0) than in the soil adjusted to pH6.5. 2) Soil microbial biomass C decreased during the 2 day period after liming and then gradually reached the level of the control soil within the following 2 weeks. 3) Fungal biomass C which was determined by a microscopic method decreased significantly immediately after liming in spite of the constant level of fungal biomass C in the control soil. On the other hand, bacterial biomass C in the control soil increased from the early stage of incubation in treated and control soils. 4) On the basis of these results, it is concluded that (a) a considerable portion of fungal biomass was destroyed by liming and (b) soil respiration and nitrogen mineralization were promoted due to the subsequent decomposition of the cytoplasm and cell walls of the dead fungi by the bacteria.

[ISSN]0912-2184

[NCID]AN00352796