Freezing can increase the emissions of carbon dioxide （CO2） and nitrous oxide （N2O） and the release of labile car- bon （C） and nitrogen （N） pools into the soil. However, there is limited knowledge about how bo...Freezing can increase the emissions of carbon dioxide （CO2） and nitrous oxide （N2O） and the release of labile car- bon （C） and nitrogen （N） pools into the soil. However, there is limited knowledge about how both emissions respond differ- ently to soil freezing and their relationships to soil properties. We evaluated the effect of intensity and duration of freezing on the emissions of CO2 and N2O, net N mineralization, microbial biomass, and extractable C and N pools in soils from a mature broadleaf and Korean pine mixed forest and an adjacent secondary white birch forest in northeastern China. These soils had different contents of microbial biomass and bulk density. Intact soil cores of 0-5 cm and 5-10 cm depth sampled from the two temperate forest floors were subjected to -8, -18, and -80℃ freezing treatments for a short （10 d） and long （145 d） duration, and then respectively incubated at 10~C for 21 d. Soil cores, incubated at 10℃ for 21 d without a pretreatment of freezing, served as control. Emissions of N20 and COz after thaw varied with forest type, soil depth, and freezing treatment. The differ- ence could be induced by the soil water-filled pore space （WFPS） during incubation and availability of substrates for N20 and CO2 production, which are released by freezing. A maximum N2O emission following thawing of frozen soils was observed at approximately 80% WFPS, whereas CO2 emission from soils after thaw significantly increased with increasing WFPS. The soil dissolved organic C just after freezing treatment and CO2 emission increased with increase of freezing duration, which paralleled with a decrease in soil microbial biomass C. The cumulative net N mineralization and net ammonification after freezing treatment as well as N2O emission were significantly affected by freezing temperature. The N2O emission was nega- tively correlated to soil pH and bulk density, but positively correlated to soil KzSO4-extractable NO3 -N content and net am- monification. The CO2 emission was positively correlated to the cumulative net N mineralization and net ammonification. From the above results, it can be reasonably concluded that for a wide range of freezing temperature and freezing duration, N2O and CO2 emissions after thaw were associated mainly with the changes in soil net N mineralization and the availability of substrate liberated by freezing as well as other soil properties that influence porosity.展开更多
Nitrous oxide (N2O) fluxes from soils were measured using the closed chamber method during the snow-free seasons (middle April to early November),for three years,in a total of 11 upland crop fields in central Hokkaido...Nitrous oxide (N2O) fluxes from soils were measured using the closed chamber method during the snow-free seasons (middle April to early November),for three years,in a total of 11 upland crop fields in central Hokkaido,Japan.The annual mean N2O fluxes ranged from 2.95 to 164.17 μgN/(m2·h),with the lowest observed in a grassland and the highest in an onion field.The instantaneous N2O fluxes showed a large temporal variation with peak emissions generally occurring following fertilization and heavy rainfall eve...展开更多
Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China.Despite the popularity of this practice,our understanding o f the underlying pro...Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China.Despite the popularity of this practice,our understanding o f the underlying processes for straw and manure combined application is relatively poor.In this study,rice straw(carbon(C)/nitrogen(N)ratio of 63),green manure(hairy vetch,C/N ratio of 14),and their mixtures(C/N ratio of 25 and 35)were added into a paddy soil,and their effects on soil N availability and C or N loss under waterlogged conditions were evaluated in a 100-d incubation experiment.All plant residue treatments significantly enhanced C〇2 and CH4 emissions,but decreased N2O emission.Dissolved organic C(DOC)and N(DON)and microbial biomass C in soil and water-soluble organic C and N and mineral N in the upper aqueous layer above soil were also enhanced by all the plant residue treatments except the rice straw treatment,and soil microbial biomass N and mineral N were lower in the rice straw treatment than in the other treatments.Changes in plant residue C/N ratio,DOC/DON ratio,and cellulose content significantly affected greenhouse gas emissions and active C and N concentrations in soil.Additionally,the treatment with green manure alone yielded the largest C and N losses,and incorporation of the plant residue mixture with a C/N ratio of 35 caused the largest net global warming potential(nGWP)among the amended treatments.In conclusion,the co-incorporation of rice straw and green manure can alleviate the limitation resulting from only applying rice straw(N immobilization)or the sole application of leguminous green manure(high C and N losses),and the residue mixture with a C/N ratio of 25 is a better option because of lower nGWP.展开更多
Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an intensive agricultural and industrial region with large emissions of NHx and NOy. To quantify N deposition, total airborne N deposit...Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an intensive agricultural and industrial region with large emissions of NHx and NOy. To quantify N deposition, total airborne N deposition was determined at three agricultural sites using a manual integrated total nitrogen input (ITNI) system during growth of winter wheat (Triticum aestivum L.) and Italian ryegrass (Lolium multiflorum Lam.) from September 2005 to May 2006. Total estimated N deposition averaged 54.9 and 43.2 kg N/hm2 across the three sites when wheat was grown to flowering and maturing, respectively. The average value was 50.2 kg N/hm2 when ryegrass was the indicator plant. Both indicator species gave similar total airborne N input results. The intermediate level of N supplied resulted in the highest N deposition, and the ratio of N acquired from deposition to total N content of the whole system decreased with increasing N supply to the roots. The contribution of atmospheric N to the total N content of the wheat and ryegrass sand culture systems ranged from 10% to 24%.展开更多
It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effe...It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effects caused by the invasion of a noxious exotic plant, Kalanchoe daigrernontiana （Crassulaceae）, on C and N mineralization and enzymatic and microbial activities in the soil of a semiarid locality in Venezuela. We compared soil parameters associated with these processes （C and N mineralization time and the cumulative values, fluorescein diacetate hydrolytic activity, and activities of dehydrogenase, β-glucosidase, glucosaminidase, and urease） between invaded and adjacent non-invaded sites. In addition, correlations among these parameters and the soil physical-chemical properties were also examined to determine if a positive feedback exists between nutrient availability and K. daigremontiana invasion. Overall, our results showed that C mineralization and transformation of organic compounds to NH4^＋ were favored at sites colonized by K. daigrernontiana. With this species, we found the highest cumulative amounts of NH4^＋-N and C and the lowest mineralization time. These results could be explained by higher activities of urease and glueosaminidase in soils under the influence of K. daigremontiana. In addition, higher amounts of organic matter and moisture content in invaded soils might favor C and N mineralization. In conclusion, invasion of Neotropical semiarid zones by K. daigrernontiana may influence the chemical and biological properties of the soils covered by this species, increasing nutrient bioavailability, which, in time, can facilitate the invasion process.展开更多
Free amino acids and short peptides(FAPS)that play an important role in plant nutrition can be extracted from rapeseed meal(RSM)by microbial enzymolysis.The enzymolytic activity of one bacterial strain isolated from R...Free amino acids and short peptides(FAPS)that play an important role in plant nutrition can be extracted from rapeseed meal(RSM)by microbial enzymolysis.The enzymolytic activity of one bacterial strain isolated from RSM for the production of FAPS fertilizer(FAPSF)via solid-state fermentation,as well as its detoxification activity for isothiocyanates and oxazolidinethione,was investigated in this study.The strain NJNPD41 isolated from RSM piled-soil possessed effective proteolytic activity and was identified as Bacillus flexus on the basis of its morphological,physiological,and biochemical properties,as well as 16S rDNA analysis.Compared to the uninoculated control,inoculation with the strain NJNPD41 significantly increased the yield of total free amino acids and short peptides by 115%and decreased the content of isothiocyanates and oxazolidinethione by 53%and 60%,respectively,after solid-state fermentation.The pot and field experiments showed that FAPSF significantly promoted eggplant growth and enhanced the fruit yield and quality of eggplant compared to the control.In conclusion,this study provided a novel method for the high-value utilization of RSM to produce high-quality and low-toxicity FAPSF using the newly isolated strain B.flexus NJNPD41.展开更多
基金the National Basic Research Program of China(Grant No.2010CB950602)the National Natural Science Foundation of China(Grant Nos.41175133,21228701,41275166&41321064)
文摘Freezing can increase the emissions of carbon dioxide （CO2） and nitrous oxide （N2O） and the release of labile car- bon （C） and nitrogen （N） pools into the soil. However, there is limited knowledge about how both emissions respond differ- ently to soil freezing and their relationships to soil properties. We evaluated the effect of intensity and duration of freezing on the emissions of CO2 and N2O, net N mineralization, microbial biomass, and extractable C and N pools in soils from a mature broadleaf and Korean pine mixed forest and an adjacent secondary white birch forest in northeastern China. These soils had different contents of microbial biomass and bulk density. Intact soil cores of 0-5 cm and 5-10 cm depth sampled from the two temperate forest floors were subjected to -8, -18, and -80℃ freezing treatments for a short （10 d） and long （145 d） duration, and then respectively incubated at 10~C for 21 d. Soil cores, incubated at 10℃ for 21 d without a pretreatment of freezing, served as control. Emissions of N20 and COz after thaw varied with forest type, soil depth, and freezing treatment. The differ- ence could be induced by the soil water-filled pore space （WFPS） during incubation and availability of substrates for N20 and CO2 production, which are released by freezing. A maximum N2O emission following thawing of frozen soils was observed at approximately 80% WFPS, whereas CO2 emission from soils after thaw significantly increased with increasing WFPS. The soil dissolved organic C just after freezing treatment and CO2 emission increased with increase of freezing duration, which paralleled with a decrease in soil microbial biomass C. The cumulative net N mineralization and net ammonification after freezing treatment as well as N2O emission were significantly affected by freezing temperature. The N2O emission was nega- tively correlated to soil pH and bulk density, but positively correlated to soil KzSO4-extractable NO3 -N content and net am- monification. The CO2 emission was positively correlated to the cumulative net N mineralization and net ammonification. From the above results, it can be reasonably concluded that for a wide range of freezing temperature and freezing duration, N2O and CO2 emissions after thaw were associated mainly with the changes in soil net N mineralization and the availability of substrate liberated by freezing as well as other soil properties that influence porosity.
基金the Global Environmental Research Program of the Ministry of the Environment of Japan (No.S-2).
文摘Nitrous oxide (N2O) fluxes from soils were measured using the closed chamber method during the snow-free seasons (middle April to early November),for three years,in a total of 11 upland crop fields in central Hokkaido,Japan.The annual mean N2O fluxes ranged from 2.95 to 164.17 μgN/(m2·h),with the lowest observed in a grassland and the highest in an onion field.The instantaneous N2O fluxes showed a large temporal variation with peak emissions generally occurring following fertilization and heavy rainfall eve...
基金This work was supported by the China Agriculture Research System-Green Manure,the Virtual Joint Nitrogen Centre(N-Circle)(No.B B/N 013484/1)the Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences(2013-2017)the Chinese Outstanding Talents Program in Agricultural Science.
文摘Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China.Despite the popularity of this practice,our understanding o f the underlying processes for straw and manure combined application is relatively poor.In this study,rice straw(carbon(C)/nitrogen(N)ratio of 63),green manure(hairy vetch,C/N ratio of 14),and their mixtures(C/N ratio of 25 and 35)were added into a paddy soil,and their effects on soil N availability and C or N loss under waterlogged conditions were evaluated in a 100-d incubation experiment.All plant residue treatments significantly enhanced C〇2 and CH4 emissions,but decreased N2O emission.Dissolved organic C(DOC)and N(DON)and microbial biomass C in soil and water-soluble organic C and N and mineral N in the upper aqueous layer above soil were also enhanced by all the plant residue treatments except the rice straw treatment,and soil microbial biomass N and mineral N were lower in the rice straw treatment than in the other treatments.Changes in plant residue C/N ratio,DOC/DON ratio,and cellulose content significantly affected greenhouse gas emissions and active C and N concentrations in soil.Additionally,the treatment with green manure alone yielded the largest C and N losses,and incorporation of the plant residue mixture with a C/N ratio of 35 caused the largest net global warming potential(nGWP)among the amended treatments.In conclusion,the co-incorporation of rice straw and green manure can alleviate the limitation resulting from only applying rice straw(N immobilization)or the sole application of leguminous green manure(high C and N losses),and the residue mixture with a C/N ratio of 25 is a better option because of lower nGWP.
基金the One-hundred Talents Program of CAS,the Special Fund for Agricultural Profession (200803030)the Sino-German project (DFG Training Group,GK1070)
文摘Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an intensive agricultural and industrial region with large emissions of NHx and NOy. To quantify N deposition, total airborne N deposition was determined at three agricultural sites using a manual integrated total nitrogen input (ITNI) system during growth of winter wheat (Triticum aestivum L.) and Italian ryegrass (Lolium multiflorum Lam.) from September 2005 to May 2006. Total estimated N deposition averaged 54.9 and 43.2 kg N/hm2 across the three sites when wheat was grown to flowering and maturing, respectively. The average value was 50.2 kg N/hm2 when ryegrass was the indicator plant. Both indicator species gave similar total airborne N input results. The intermediate level of N supplied resulted in the highest N deposition, and the ratio of N acquired from deposition to total N content of the whole system decreased with increasing N supply to the roots. The contribution of atmospheric N to the total N content of the wheat and ryegrass sand culture systems ranged from 10% to 24%.
基金supported by the Venezuelan Institute for Scientific Research to the first author
文摘It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effects caused by the invasion of a noxious exotic plant, Kalanchoe daigrernontiana （Crassulaceae）, on C and N mineralization and enzymatic and microbial activities in the soil of a semiarid locality in Venezuela. We compared soil parameters associated with these processes （C and N mineralization time and the cumulative values, fluorescein diacetate hydrolytic activity, and activities of dehydrogenase, β-glucosidase, glucosaminidase, and urease） between invaded and adjacent non-invaded sites. In addition, correlations among these parameters and the soil physical-chemical properties were also examined to determine if a positive feedback exists between nutrient availability and K. daigremontiana invasion. Overall, our results showed that C mineralization and transformation of organic compounds to NH4^＋ were favored at sites colonized by K. daigrernontiana. With this species, we found the highest cumulative amounts of NH4^＋-N and C and the lowest mineralization time. These results could be explained by higher activities of urease and glueosaminidase in soils under the influence of K. daigremontiana. In addition, higher amounts of organic matter and moisture content in invaded soils might favor C and N mineralization. In conclusion, invasion of Neotropical semiarid zones by K. daigrernontiana may influence the chemical and biological properties of the soils covered by this species, increasing nutrient bioavailability, which, in time, can facilitate the invasion process.
基金supported by the National Key Research and Development Program of China (Nos. 2016YFE0101100 and 2016YFD0200106)the National Key Basic Research Program of China (No. 2015CB150506)+3 种基金the Fundamental Research Funds for the Central Universities of China (Nos. KYZ201519 and BK20160710)the Jiangsu Science and Technology Program of China (No. BY2016077-05)the Jiangsu Provincial Natural Science Foundation of China (Nos. BK20150059 and BK20160710)the Top-notch Academic Programs Project of Jiangsu Higher Education Institution, China (No. PPZY2015A061)
文摘Free amino acids and short peptides(FAPS)that play an important role in plant nutrition can be extracted from rapeseed meal(RSM)by microbial enzymolysis.The enzymolytic activity of one bacterial strain isolated from RSM for the production of FAPS fertilizer(FAPSF)via solid-state fermentation,as well as its detoxification activity for isothiocyanates and oxazolidinethione,was investigated in this study.The strain NJNPD41 isolated from RSM piled-soil possessed effective proteolytic activity and was identified as Bacillus flexus on the basis of its morphological,physiological,and biochemical properties,as well as 16S rDNA analysis.Compared to the uninoculated control,inoculation with the strain NJNPD41 significantly increased the yield of total free amino acids and short peptides by 115%and decreased the content of isothiocyanates and oxazolidinethione by 53%and 60%,respectively,after solid-state fermentation.The pot and field experiments showed that FAPSF significantly promoted eggplant growth and enhanced the fruit yield and quality of eggplant compared to the control.In conclusion,this study provided a novel method for the high-value utilization of RSM to produce high-quality and low-toxicity FAPSF using the newly isolated strain B.flexus NJNPD41.
