The effect of ammonium fixation on the estimation of soil microbial biomass N was studied bv thestandard fumigation-incubation (FI) and fumigation-extraction (FE) methods. NO_3-N content of fumigatedsoil changed littl...The effect of ammonium fixation on the estimation of soil microbial biomass N was studied bv thestandard fumigation-incubation (FI) and fumigation-extraction (FE) methods. NO_3-N content of fumigatedsoil changed little during incubation, while the fixed NH in soils capable of fixing NH increased withthe increase of K_2SO_4-extractable NH_4-N. One day fumigation increased both extractable NH and fixedNH. However, prolonged fumigation gave no further increase. One day fumigation caused significant loss ofNO_3-N, while prolonged fumigation caused no further loss. For soils tested, the net increases of fixed NHin fumigated soil equaled to 0-94% of NH_4-N flush measured by the FI method, and 1-74% of extractable Nmeasured by the FE method, depending on different soils. It is concluded that the ammonium fixation wasone of the processes taking place in soils during fumigation as well as incubation after fumigation and shouldnot be neglected in the estimation of microbial biomass nitrogen by either FI or FE method.展开更多
he microbial biomass C, N and P of soils all over china were determined in this study to study theiraffecting factors. The results, about 100-417 mg C kg￣(-1) soil, 18.51 mg N kg￣(-1) soil and 4.4-27.3 mg Pkg￣(-1) ...he microbial biomass C, N and P of soils all over china were determined in this study to study theiraffecting factors. The results, about 100-417 mg C kg￣(-1) soil, 18.51 mg N kg￣(-1) soil and 4.4-27.3 mg Pkg￣(-1) soil, showed the biomass C, N and P in linear relationship with the soil total organic C, toal N andsoil organic P. The ratios of C: N and C: P , ranging from 5.6 to 9.6 and from 11.2 to 48.4 respectively, wereaffected by soil pH, texture, crop rotation, macrocliniatc. etc. The ratio of C:N in soil biomass increasesgradually from the north to the south in China.展开更多
文摘The effect of ammonium fixation on the estimation of soil microbial biomass N was studied bv thestandard fumigation-incubation (FI) and fumigation-extraction (FE) methods. NO_3-N content of fumigatedsoil changed little during incubation, while the fixed NH in soils capable of fixing NH increased withthe increase of K_2SO_4-extractable NH_4-N. One day fumigation increased both extractable NH and fixedNH. However, prolonged fumigation gave no further increase. One day fumigation caused significant loss ofNO_3-N, while prolonged fumigation caused no further loss. For soils tested, the net increases of fixed NHin fumigated soil equaled to 0-94% of NH_4-N flush measured by the FI method, and 1-74% of extractable Nmeasured by the FE method, depending on different soils. It is concluded that the ammonium fixation wasone of the processes taking place in soils during fumigation as well as incubation after fumigation and shouldnot be neglected in the estimation of microbial biomass nitrogen by either FI or FE method.
文摘he microbial biomass C, N and P of soils all over china were determined in this study to study theiraffecting factors. The results, about 100-417 mg C kg￣(-1) soil, 18.51 mg N kg￣(-1) soil and 4.4-27.3 mg Pkg￣(-1) soil, showed the biomass C, N and P in linear relationship with the soil total organic C, toal N andsoil organic P. The ratios of C: N and C: P , ranging from 5.6 to 9.6 and from 11.2 to 48.4 respectively, wereaffected by soil pH, texture, crop rotation, macrocliniatc. etc. The ratio of C:N in soil biomass increasesgradually from the north to the south in China.
