The rates of soil N mineralization at soil depths of 0-15, 15-30, 30-45 and45-60 cm and moisture regimes were measured at three sand-fixation plantations of Pinus sylvestrisvar. mongolica by laboratory aerobic incubat...The rates of soil N mineralization at soil depths of 0-15, 15-30, 30-45 and45-60 cm and moisture regimes were measured at three sand-fixation plantations of Pinus sylvestrisvar. mongolica by laboratory aerobic incubation method. The results showed that average rates ofsoil net N-mineralization across soil depth varied from 1.06 to 7.52 mg · kg^(-1)·month^(-1) atsoil depths from 0 to 60 cm. Statistical analyses indicated that the effects of different soildepths, moistures and their interactions on net N-mineralization rates were significant (P < 0.05).The net N-mineralization rates significantly decreased with increasing soil depths and at depth 0-15cm accounted for 60.52% of that at depth of 0-60 cm. There was no difference in soil netN-mineralization rates between half and fully-saturated water treatments, however these rates weresubstantially higher than that without water treatment (P < 0.05). The factors influencing Nmineralization process have to be studied further in these semiarid pine ecosystems.展开更多
Two sets of experiments were conducted to study the chemical composition, mineralization and availability of nutrients （particularly N） of Azolla biomass and cyanohacteria blooms in submerged rice soil. One set of e...Two sets of experiments were conducted to study the chemical composition, mineralization and availability of nutrients （particularly N） of Azolla biomass and cyanohacteria blooms in submerged rice soil. One set of experiment was conducted with Azolla without soil and the other with both Azolla and cyaobacteria with soil, in laboratory condition. Large samples were collected from the rice fields. The study shows that Azolla and cyanobacterial biomass contain good amounts of C, N, P and Ca. The chemical analysis of oxidizable C, total N, P and Ca showed that Azolla biomass contain 20.7% oxidizable C, which is higher than the cyanobacterial biomass （9.18%）. The N content in Azolla biomass was found to be 4.32%, than that of cyanobacterial biomass, i.e., 2.57%, however, P and Ca contents were also found to be higher in Azolla averaging to 124.83 ppm and 345.3 mg/100 g, respectively than cyanobacteria. The leachate analysis revealed that Azolla biomass release about 39.18% to 64.48% oxidizable C and about 19.23% to 33% N after 45 days of incorporation of soil dilution. Incorporation of Azolla and cyanobacterial biomass N@ 100 kg/ha significantly improved the oxidizable organic C, total as well as available N content in soil up to 75 days of incubation. Due to the incorporation of Azolla in soil, oxidizable organic C increased 25.51%, total N 4.10% and available N 47.65%. Almost similar trend of increase was also observed with the incorporation of cyanobacterial blooms.展开更多
基金This paper was supported by National Natural Science Foundation of China (30471377), the Chinese Academy of Sciences (Knowledge Innovation Project KZCX3-SW-418), and the Institute of Applied Ecology of Chinese Academy of Sciences (SLYQY0409).
文摘The rates of soil N mineralization at soil depths of 0-15, 15-30, 30-45 and45-60 cm and moisture regimes were measured at three sand-fixation plantations of Pinus sylvestrisvar. mongolica by laboratory aerobic incubation method. The results showed that average rates ofsoil net N-mineralization across soil depth varied from 1.06 to 7.52 mg · kg^(-1)·month^(-1) atsoil depths from 0 to 60 cm. Statistical analyses indicated that the effects of different soildepths, moistures and their interactions on net N-mineralization rates were significant (P < 0.05).The net N-mineralization rates significantly decreased with increasing soil depths and at depth 0-15cm accounted for 60.52% of that at depth of 0-60 cm. There was no difference in soil netN-mineralization rates between half and fully-saturated water treatments, however these rates weresubstantially higher than that without water treatment (P < 0.05). The factors influencing Nmineralization process have to be studied further in these semiarid pine ecosystems.
文摘Two sets of experiments were conducted to study the chemical composition, mineralization and availability of nutrients （particularly N） of Azolla biomass and cyanohacteria blooms in submerged rice soil. One set of experiment was conducted with Azolla without soil and the other with both Azolla and cyaobacteria with soil, in laboratory condition. Large samples were collected from the rice fields. The study shows that Azolla and cyanobacterial biomass contain good amounts of C, N, P and Ca. The chemical analysis of oxidizable C, total N, P and Ca showed that Azolla biomass contain 20.7% oxidizable C, which is higher than the cyanobacterial biomass （9.18%）. The N content in Azolla biomass was found to be 4.32%, than that of cyanobacterial biomass, i.e., 2.57%, however, P and Ca contents were also found to be higher in Azolla averaging to 124.83 ppm and 345.3 mg/100 g, respectively than cyanobacteria. The leachate analysis revealed that Azolla biomass release about 39.18% to 64.48% oxidizable C and about 19.23% to 33% N after 45 days of incorporation of soil dilution. Incorporation of Azolla and cyanobacterial biomass N@ 100 kg/ha significantly improved the oxidizable organic C, total as well as available N content in soil up to 75 days of incubation. Due to the incorporation of Azolla in soil, oxidizable organic C increased 25.51%, total N 4.10% and available N 47.65%. Almost similar trend of increase was also observed with the incorporation of cyanobacterial blooms.
