Plant biofertilization involves introducing compounds containing living mi-croorganisms into the coating medium to sustainably enhance plant production and soil health. This is a complex process that undergoes multipl...Plant biofertilization involves introducing compounds containing living mi-croorganisms into the coating medium to sustainably enhance plant production and soil health. This is a complex process that undergoes multiple stages of development before yielding a final product. The final biofertilizer is used by legumes-protein-rich crops in symbiosis with rhizobia to enable biological nitrogen fixation increasing natural soil fertility. This study aims to determine the optimal formulation of a rhizobial biofertilizer to improve the performance of soybean (Glycine max L. cv. Docko). To this end, soybean seeds obtained from IRAD were coated with different formulations derived from locally sourced materials. Palm kernel oil was used as an adhesive in one group, while corn powder served as an adhesive in another. The coated seeds were then sown in the field. The results indicate that the combination of pigeon pea powder + sugarcane molasses, with palm kernel oil as an adhesive, produced the best nodulation (nitrogen fixation). This formulation also led to significant improvements in growth (+350%) and total nitrogen content (+1100%) compared to the bacterial broth inoculum control (B0) (P ≤ 0.01). These findings represent a significant advancement in improving nitrogen-fixing bacterial inoculants and enhancing soil fertility for the sustainable cultivation of soybeans in this tropical soil.展开更多
Biodiversity experiments have shown that soil organic carbon(SOC)is not only a function of plant diversity,but is also closely related to the nitrogen(N)-fixing plants.However,the effect of N-fixing trees on SOC chemi...Biodiversity experiments have shown that soil organic carbon(SOC)is not only a function of plant diversity,but is also closely related to the nitrogen(N)-fixing plants.However,the effect of N-fixing trees on SOC chemical stability is still little known,especially with the compounding effects of tree species diversity.An experimental field manipulation was established in subtropical plantations of southern China to explore the impacts of tree species richness(i.e.,one,two,four and six tree species)and with/without N-fixing trees on SOC chemical stability,as indicated by the ratio of easily oxidized organic carbon to SOC(EOC/SOC).Plant-derived C components in terms of hydrolysable plant lipids and lignin phenols were isolated from soils for evaluating their relative contributions to SOC chemical stability.The results showed that N-fixing tree species rather than tree species richness had a significant effect on EOC/SOC.Hydrolysable plant lipids and lignin phenols were negatively correlated with EOC/SOC,while hydrolysable plant lipids contributed more to EOC/SOC than lignin phenols,especially in the occurrence of N-fixing trees.The presence of N-fixing tree species led to an increase in soil N availability and a decrease in fungal abundance,promoting the selective retention of certain key components of hydrolysable plant lipids,thus enhancing SOC chemical stability.These findings underpin the crucial role of N-fixing trees in shaping SOC chemical stability,and therefore,preferential selection of N-fixing tree species in mixed plantations is an appropriate silvicultural strategy to improve SOC chemical stability in subtropical plantations.展开更多
We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation...We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation（ACp）,10-species-mixed plantation（Tp）,and 30-species-mixed plantation（THp） using the static chamber method in southern China.Four forest management treatments,including（1） understory removal（UR）;（2） C.alata addition（CA）;（3） understory removal and replacement with C.alata（UR＋CA）;and（4） control without any disturbances（CK）,were applied in the above four forest plantations with three replications for each treatment.The results showed that soil CO2 fluxes rates remained at a high level during the rainy season（from April to September）,followed by a rapid decrease after October reaching a minimum in February.Soil CO2 fluxes were significantly higher（P 〈 0.01） in EUp（132.6 mg/（m2.hr）） and ACp（139.8 mg/（m2.hr）） than in Tp（94.0 mg/（m2.hr）） and THp（102.9 mg/（m2.hr））.Soil CO2 fluxes in UR and CA were significantly higher（P 〈 0.01） among the four treatments,with values of 105.7,120.4,133.6 and 112.2 mg/（m2.hr） for UR＋CA,UR,CA and CK,respectively.Soil CO2 fluxes were positively correlated with soil temperature（P 〈 0.01）,soil moisture（P 〈 0.01）,NO3？-N（P 〈 0.05）,and litterfall（P 〈 0.01）,indicating that all these factors might be important controlling variables for soil CO2 fluxes.This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.展开更多
Rare earth element(REE)mining has wrought severe ecosystem destruction,particularly in the loss of carbon(C),nitrogen(N),and phosphorus(P).Furthermore,its effects on nutrient recovery characteristics and associated mi...Rare earth element(REE)mining has wrought severe ecosystem destruction,particularly in the loss of carbon(C),nitrogen(N),and phosphorus(P).Furthermore,its effects on nutrient recovery characteristics and associated microbial abundance are still poorly understood.In this study,an investigation was conducted to determine C,N,and P recovery patterns and microbial communities in abandoned REE mining tailings with different abandoned durations of 1.5(1.5-Y),7(7-Y),10(10-Y),and 14(14-Y)years and at an unmined site(the control group)in Jiangxi Province,China.Longitudinal tailing delamination at each site was investigated in 0–15(layer 1)and 15–30(layer 2)cm tailing layers.During the abandoned duration of REE tailings,C and P in layer 1 continued to recover from 1.62 to 8.51 g kg^(-1) and from 0.71 to 1.94 g kg^(-1),respectively;N losses of 0.60 and 0.22 g kg^(-1) occurred at the 1.5-Y and 10-Y sites,while N in layer 1 slightly increased at the 14-Y site.Mesorhizobium,Methylosinus,Bradyrhizobium,Pseudomonas,and Azospirillum were dominant bacteria at the 14-Y site and in the control.The relative abundances of N-fixing bacteria Mesorhizobium(32.94%),Sinorhizobium(0.24%),Frankia(0.71%),and Burkholderia(2.38%)at the 14-Y site were 1.33–3.97 times those in the control(24.19%,0.18%,0.32%and 0.60%,respectively),which was helpful for tailing N recovery.At the 14-Y site,Tylospora(50.24%),Luellia(11.02%),Tomentella(6.94%),and Chaetomium(4.34%)were the dominant fungal genera,while Tylospora(56.93%),Suillus(11.45%),and Penicillium(6.78%)predominated in the control.The relative abundance of the P-dissolving fungus Aspergillus at the 14-Y site(0.42%)was 4.2 times that in the control(0.1%),which may lead to the improved tailing P solubility.At the 14-Y site,woody plants such as Pinus massoniana and native pioneering herbs and ferns such as Dicranopteris dichotoma and Nephrolepis auriculata probably invaded from adjacent areas.This study unraveled the natural restoration of plant and microbial communities along with soil nutrient changes in abandoned REE tailings,thus providing a novel insight into ecological recovery and restoration after mining.展开更多
Aspalathus linearis is a commercially important plant species endemic to the Cape Floristic Region of South Africa and is used to produce a herbal tea known as rooibos tea.Symbiotic interactions between A.linearis and...Aspalathus linearis is a commercially important plant species endemic to the Cape Floristic Region of South Africa and is used to produce a herbal tea known as rooibos tea.Symbiotic interactions between A.linearis and soil bacteria play an important role in the survival of Aspalathus plants in the highly nutrient-poor,acidic fynbos soil.The aim of this study was to characterize and compare rhizosphere and bulk soil bacterial communities associated with natural and commercially grown A.linearis,as well as the effect of seasonal changes on these communities.Bacterial communities were characterized using high throughput amplicon sequencing,and their correlations with soil chemical properties were investigated.The N-fixing bacterial community was characterized using terminal restriction fragment length polymorphism and real time quantitative polymerase chain reaction.Actinobacteria,Proteobacteria,and Acidobacteria were the most dominant bacterial phyla detected in this study.Highly similar bacterial communities were associated with natural and commercially grown plants.Significant differences in the bacterial community were observed between rhizosphere and bulk soils collected in the dry season,while no significant differences were detected in the wet season.This study provides insights into bacterial community structure and potential factors shaping bacterial community structure with commercially important A.linearis.展开更多
Leaves of multipurpose tree species （those providing more than one function or product of human use） can serve as sources of fer- tilizer for nutrient supply, especially nitrogen （N）. In this study chopped leaves ...Leaves of multipurpose tree species （those providing more than one function or product of human use） can serve as sources of fer- tilizer for nutrient supply, especially nitrogen （N）. In this study chopped leaves of tropical tree species （5 N-fixing species, 5 non-N-fixing species and combinations of 5 N-fixing with a non-N-fixing species） were in- corporated in soil to evaluate its effects on wheat biological productivity （including grain yield, GyIELD） under dryland conditions. High quality leaves of N-fixing tree species （e.g. Dalbergia sissoo, Cassia fistula and Prosopis cineraria） had lower carbon/nitrogen （C/N）, lignin/nitrogen （L^o/N）, polyphenol/nitrogen （PPt/N） and lignin＋polyphenol /nitrogen （L~＋PpL/N） ratios than low quality leaves of non-N-fixing species. Com- bination treatments had intermediate values of different parameters, Application of high quality leaves caused greater increases in wheat productivity and yield than other species.展开更多
With the aim to apply the beneficial microorganisms to peanut （groundnut （Arachis hypogaea）） growing in sandy soil of Binhdinh province in Vietnam, the paper was conducted to study the isolation, selection of N-fi...With the aim to apply the beneficial microorganisms to peanut （groundnut （Arachis hypogaea）） growing in sandy soil of Binhdinh province in Vietnam, the paper was conducted to study the isolation, selection of N-fixing, phosphate, potassium solubilizing and slime producing microorganism from sandy soil and peanut root samples, and evaluate the capability of selected isolates to adapt to the sandy soil condition. The isolation and selection of beneficial microbes were based on the biological activity of isolates, which was determined by acetylene reduction assay and nodulation on the peanut for Rhizobium spp., by testing the capability to solubilize Ca3（PO4）2 or fenspat in the growth medium for phosphate, potassium solubilizing microbes, and by measurement of the viscosity of Hansen medium for slime producing microorganism. All isolates were evaluated for the effectiveness on the nutrition uptake and growth of peanut by carrying out at the greenhouse and field experiments. To evaluate the adaptation of selected isolates to the sandy soil condition, the experiments were carried out in the laboratory to determine the microbial density in suitable medium, containing different NaCI concentrations or with different pH or at different temperatures. The results showed that rhizobial strain RA18 had an N-fixing activity value of 3,458 ＋ 10.95 nmol C2H2/plant and can supply 30% of N required for peanut. The bacterial strain P 1107 is able to solubilize phosphate and can increase phosphorus uptake by 30% in peanut. Further, inoculation of peanut with the bacterial strain S3.1 can save 30% required mineral potassium, and the Lipomyces strain PT5.1 can produce the slime, which can provide the sandy soil to keep moisture for 15 d longer than the control without the inoculation. All selected isolates are able to grow at temperatures from 20 ℃ to 35 ℃, pH from 4.5 to 6.0 and the salinity of 0.2%o-0.6%o NaCI, and can well adapt to the sandy soil conditions.展开更多
Water erosion process induces differences to the nitrogen(N)functional microbial community structure,which is the driving force to key N processes at soil-water interface.However,how the soil N trans-formations associ...Water erosion process induces differences to the nitrogen(N)functional microbial community structure,which is the driving force to key N processes at soil-water interface.However,how the soil N trans-formations associated with water erosion is affected by microorganisms,and how the microbial respond,are still unclear.The objective of this study is to investigate the changes of microbial diversity and community structure of the N-cycle function microorganisms as affected by water erosion under application of organic manure and straw cover.On the basis of iso-nitrogen substitution,four treatments were set up:1)only chemical fertilizer with N 150 kg ha^(-1),P2O560 kg ha^(-1) and K2O 90 kg ha^(-1)(CK);the N was substituted 20%by 2)organic manure(OM);3)straw(SW);and 4)organic manure+straw(1:1)(OMSW).The results showed that applying organic manure and straw to sloping farmland can increase soil N contents,but reduce runoff depth,Kw,sediment yield and N loss,especially in the OMSW.Straw cover and straw+organic manure increased the diversity(Chao1)of nitrifier(AOB),and both diversity and uniformity(Shannon)of denitrifier(nirK/S)were increased in the OMSW.All erosion control mea-sures reduced N-fixing bacteria diversity and increased their uniformity,and the combined application of organic manure and straw cover was a better erosion control measure than the single application of them.Improved soil chemistry and erodibility were the main drives for the changes of N-functional microbial community structure and the appearance of dominant bacteria with different organic materials.展开更多
Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism,respiration and photosynthesis and its supply at low levels can affect legume nodulation,N2 fixation,and C assimilation.A twoyea...Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism,respiration and photosynthesis and its supply at low levels can affect legume nodulation,N2 fixation,and C assimilation.A twoyear field study was conducted in Ethiopia in 2012 and 2013 to evaluate the effects of P supply on growth,symbiotic N2 nutrition,grain yield and water-use efficiency of three groundnut genotypes.Supplying P to the genotypes significantly increased their shoot biomass,symbiotic performance,grain yield,and C accumulation.There was,however,no effect on shootδ13C values in either year.Compared to the zero-P control,supplying 40 kg$ha–1 P markedly increased shoot biomass by 77%and 66%in 2012 and 2013,respectively.In both years,groundnut grain yields were much higher at 20 and 30 kg$ha–1 P.Phosphorus supply markedly reduced shootδ15N values and increased the%Ndfa and amount of Nfixed,indicating the direct involvement of P in promoting N2 fixation in nodulated groundnut.The three genotypes differed significantly inδ15N,%Ndfa,N-fixed,grain yield,C concentration,andδ13C.The phosphorusgenotype interaction was also significant for shoot DM,N content,N-fixed and soil N uptake.展开更多
文摘Plant biofertilization involves introducing compounds containing living mi-croorganisms into the coating medium to sustainably enhance plant production and soil health. This is a complex process that undergoes multiple stages of development before yielding a final product. The final biofertilizer is used by legumes-protein-rich crops in symbiosis with rhizobia to enable biological nitrogen fixation increasing natural soil fertility. This study aims to determine the optimal formulation of a rhizobial biofertilizer to improve the performance of soybean (Glycine max L. cv. Docko). To this end, soybean seeds obtained from IRAD were coated with different formulations derived from locally sourced materials. Palm kernel oil was used as an adhesive in one group, while corn powder served as an adhesive in another. The coated seeds were then sown in the field. The results indicate that the combination of pigeon pea powder + sugarcane molasses, with palm kernel oil as an adhesive, produced the best nodulation (nitrogen fixation). This formulation also led to significant improvements in growth (+350%) and total nitrogen content (+1100%) compared to the bacterial broth inoculum control (B0) (P ≤ 0.01). These findings represent a significant advancement in improving nitrogen-fixing bacterial inoculants and enhancing soil fertility for the sustainable cultivation of soybeans in this tropical soil.
基金supported by the National Natural Science Foundation of China(31930078,32301559)the Ministry of Science and Technology of China(2021YFD2200405,2021YFD2200402)+1 种基金Fundamental Research Funds of CAF(CAFYBB2021ZW001)the program for scientific research start-up funds of Guangdong Ocean University。
文摘Biodiversity experiments have shown that soil organic carbon(SOC)is not only a function of plant diversity,but is also closely related to the nitrogen(N)-fixing plants.However,the effect of N-fixing trees on SOC chemical stability is still little known,especially with the compounding effects of tree species diversity.An experimental field manipulation was established in subtropical plantations of southern China to explore the impacts of tree species richness(i.e.,one,two,four and six tree species)and with/without N-fixing trees on SOC chemical stability,as indicated by the ratio of easily oxidized organic carbon to SOC(EOC/SOC).Plant-derived C components in terms of hydrolysable plant lipids and lignin phenols were isolated from soils for evaluating their relative contributions to SOC chemical stability.The results showed that N-fixing tree species rather than tree species richness had a significant effect on EOC/SOC.Hydrolysable plant lipids and lignin phenols were negatively correlated with EOC/SOC,while hydrolysable plant lipids contributed more to EOC/SOC than lignin phenols,especially in the occurrence of N-fixing trees.The presence of N-fixing tree species led to an increase in soil N availability and a decrease in fungal abundance,promoting the selective retention of certain key components of hydrolysable plant lipids,thus enhancing SOC chemical stability.These findings underpin the crucial role of N-fixing trees in shaping SOC chemical stability,and therefore,preferential selection of N-fixing tree species in mixed plantations is an appropriate silvicultural strategy to improve SOC chemical stability in subtropical plantations.
基金supported by the National Natural Science Foundation of China (No. 30630015,30771704)
文摘We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation（ACp）,10-species-mixed plantation（Tp）,and 30-species-mixed plantation（THp） using the static chamber method in southern China.Four forest management treatments,including（1） understory removal（UR）;（2） C.alata addition（CA）;（3） understory removal and replacement with C.alata（UR＋CA）;and（4） control without any disturbances（CK）,were applied in the above four forest plantations with three replications for each treatment.The results showed that soil CO2 fluxes rates remained at a high level during the rainy season（from April to September）,followed by a rapid decrease after October reaching a minimum in February.Soil CO2 fluxes were significantly higher（P 〈 0.01） in EUp（132.6 mg/（m2.hr）） and ACp（139.8 mg/（m2.hr）） than in Tp（94.0 mg/（m2.hr）） and THp（102.9 mg/（m2.hr））.Soil CO2 fluxes in UR and CA were significantly higher（P 〈 0.01） among the four treatments,with values of 105.7,120.4,133.6 and 112.2 mg/（m2.hr） for UR＋CA,UR,CA and CK,respectively.Soil CO2 fluxes were positively correlated with soil temperature（P 〈 0.01）,soil moisture（P 〈 0.01）,NO3？-N（P 〈 0.05）,and litterfall（P 〈 0.01）,indicating that all these factors might be important controlling variables for soil CO2 fluxes.This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.
基金supported by the National Natural Science Foundation of China(Nos.42293350,42293354,42293355,and 21707177).
文摘Rare earth element(REE)mining has wrought severe ecosystem destruction,particularly in the loss of carbon(C),nitrogen(N),and phosphorus(P).Furthermore,its effects on nutrient recovery characteristics and associated microbial abundance are still poorly understood.In this study,an investigation was conducted to determine C,N,and P recovery patterns and microbial communities in abandoned REE mining tailings with different abandoned durations of 1.5(1.5-Y),7(7-Y),10(10-Y),and 14(14-Y)years and at an unmined site(the control group)in Jiangxi Province,China.Longitudinal tailing delamination at each site was investigated in 0–15(layer 1)and 15–30(layer 2)cm tailing layers.During the abandoned duration of REE tailings,C and P in layer 1 continued to recover from 1.62 to 8.51 g kg^(-1) and from 0.71 to 1.94 g kg^(-1),respectively;N losses of 0.60 and 0.22 g kg^(-1) occurred at the 1.5-Y and 10-Y sites,while N in layer 1 slightly increased at the 14-Y site.Mesorhizobium,Methylosinus,Bradyrhizobium,Pseudomonas,and Azospirillum were dominant bacteria at the 14-Y site and in the control.The relative abundances of N-fixing bacteria Mesorhizobium(32.94%),Sinorhizobium(0.24%),Frankia(0.71%),and Burkholderia(2.38%)at the 14-Y site were 1.33–3.97 times those in the control(24.19%,0.18%,0.32%and 0.60%,respectively),which was helpful for tailing N recovery.At the 14-Y site,Tylospora(50.24%),Luellia(11.02%),Tomentella(6.94%),and Chaetomium(4.34%)were the dominant fungal genera,while Tylospora(56.93%),Suillus(11.45%),and Penicillium(6.78%)predominated in the control.The relative abundance of the P-dissolving fungus Aspergillus at the 14-Y site(0.42%)was 4.2 times that in the control(0.1%),which may lead to the improved tailing P solubility.At the 14-Y site,woody plants such as Pinus massoniana and native pioneering herbs and ferns such as Dicranopteris dichotoma and Nephrolepis auriculata probably invaded from adjacent areas.This study unraveled the natural restoration of plant and microbial communities along with soil nutrient changes in abandoned REE tailings,thus providing a novel insight into ecological recovery and restoration after mining.
基金supported by the National Research Foundation Biodiversity Information Program:Biodiversity Surveys in Priority Inland Areas(FBIP)(South Africa)(No.87602)the National Research Foundation for funding the equipment based at the Central Analytical Facilities of Stellenbosch University,South Africa(No.74452)
文摘Aspalathus linearis is a commercially important plant species endemic to the Cape Floristic Region of South Africa and is used to produce a herbal tea known as rooibos tea.Symbiotic interactions between A.linearis and soil bacteria play an important role in the survival of Aspalathus plants in the highly nutrient-poor,acidic fynbos soil.The aim of this study was to characterize and compare rhizosphere and bulk soil bacterial communities associated with natural and commercially grown A.linearis,as well as the effect of seasonal changes on these communities.Bacterial communities were characterized using high throughput amplicon sequencing,and their correlations with soil chemical properties were investigated.The N-fixing bacterial community was characterized using terminal restriction fragment length polymorphism and real time quantitative polymerase chain reaction.Actinobacteria,Proteobacteria,and Acidobacteria were the most dominant bacterial phyla detected in this study.Highly similar bacterial communities were associated with natural and commercially grown plants.Significant differences in the bacterial community were observed between rhizosphere and bulk soils collected in the dry season,while no significant differences were detected in the wet season.This study provides insights into bacterial community structure and potential factors shaping bacterial community structure with commercially important A.linearis.
基金supported by Ministry of Environment and Forests,New Delhi,India
文摘Leaves of multipurpose tree species （those providing more than one function or product of human use） can serve as sources of fer- tilizer for nutrient supply, especially nitrogen （N）. In this study chopped leaves of tropical tree species （5 N-fixing species, 5 non-N-fixing species and combinations of 5 N-fixing with a non-N-fixing species） were in- corporated in soil to evaluate its effects on wheat biological productivity （including grain yield, GyIELD） under dryland conditions. High quality leaves of N-fixing tree species （e.g. Dalbergia sissoo, Cassia fistula and Prosopis cineraria） had lower carbon/nitrogen （C/N）, lignin/nitrogen （L^o/N）, polyphenol/nitrogen （PPt/N） and lignin＋polyphenol /nitrogen （L~＋PpL/N） ratios than low quality leaves of non-N-fixing species. Com- bination treatments had intermediate values of different parameters, Application of high quality leaves caused greater increases in wheat productivity and yield than other species.
文摘With the aim to apply the beneficial microorganisms to peanut （groundnut （Arachis hypogaea）） growing in sandy soil of Binhdinh province in Vietnam, the paper was conducted to study the isolation, selection of N-fixing, phosphate, potassium solubilizing and slime producing microorganism from sandy soil and peanut root samples, and evaluate the capability of selected isolates to adapt to the sandy soil condition. The isolation and selection of beneficial microbes were based on the biological activity of isolates, which was determined by acetylene reduction assay and nodulation on the peanut for Rhizobium spp., by testing the capability to solubilize Ca3（PO4）2 or fenspat in the growth medium for phosphate, potassium solubilizing microbes, and by measurement of the viscosity of Hansen medium for slime producing microorganism. All isolates were evaluated for the effectiveness on the nutrition uptake and growth of peanut by carrying out at the greenhouse and field experiments. To evaluate the adaptation of selected isolates to the sandy soil condition, the experiments were carried out in the laboratory to determine the microbial density in suitable medium, containing different NaCI concentrations or with different pH or at different temperatures. The results showed that rhizobial strain RA18 had an N-fixing activity value of 3,458 ＋ 10.95 nmol C2H2/plant and can supply 30% of N required for peanut. The bacterial strain P 1107 is able to solubilize phosphate and can increase phosphorus uptake by 30% in peanut. Further, inoculation of peanut with the bacterial strain S3.1 can save 30% required mineral potassium, and the Lipomyces strain PT5.1 can produce the slime, which can provide the sandy soil to keep moisture for 15 d longer than the control without the inoculation. All selected isolates are able to grow at temperatures from 20 ℃ to 35 ℃, pH from 4.5 to 6.0 and the salinity of 0.2%o-0.6%o NaCI, and can well adapt to the sandy soil conditions.
基金Financial support for this study was provided by the National Nature Science Foundation of China(No.41977072)the Special Fund for Agro-scientific Research in the Public Interest(201503119)the Agricultural Science and Technology Innovation Program(ASTIP).
文摘Water erosion process induces differences to the nitrogen(N)functional microbial community structure,which is the driving force to key N processes at soil-water interface.However,how the soil N trans-formations associated with water erosion is affected by microorganisms,and how the microbial respond,are still unclear.The objective of this study is to investigate the changes of microbial diversity and community structure of the N-cycle function microorganisms as affected by water erosion under application of organic manure and straw cover.On the basis of iso-nitrogen substitution,four treatments were set up:1)only chemical fertilizer with N 150 kg ha^(-1),P2O560 kg ha^(-1) and K2O 90 kg ha^(-1)(CK);the N was substituted 20%by 2)organic manure(OM);3)straw(SW);and 4)organic manure+straw(1:1)(OMSW).The results showed that applying organic manure and straw to sloping farmland can increase soil N contents,but reduce runoff depth,Kw,sediment yield and N loss,especially in the OMSW.Straw cover and straw+organic manure increased the diversity(Chao1)of nitrifier(AOB),and both diversity and uniformity(Shannon)of denitrifier(nirK/S)were increased in the OMSW.All erosion control mea-sures reduced N-fixing bacteria diversity and increased their uniformity,and the combined application of organic manure and straw cover was a better erosion control measure than the single application of them.Improved soil chemistry and erodibility were the main drives for the changes of N-functional microbial community structure and the appearance of dominant bacteria with different organic materials.
基金the Bill and Melinda Gates Foundationthe NRF+1 种基金the South African Research Chair in Agrochemurgy and Plant SymbiosesTshwane University of Technology for financial support to FDD’s research and bursary to SKM。
文摘Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism,respiration and photosynthesis and its supply at low levels can affect legume nodulation,N2 fixation,and C assimilation.A twoyear field study was conducted in Ethiopia in 2012 and 2013 to evaluate the effects of P supply on growth,symbiotic N2 nutrition,grain yield and water-use efficiency of three groundnut genotypes.Supplying P to the genotypes significantly increased their shoot biomass,symbiotic performance,grain yield,and C accumulation.There was,however,no effect on shootδ13C values in either year.Compared to the zero-P control,supplying 40 kg$ha–1 P markedly increased shoot biomass by 77%and 66%in 2012 and 2013,respectively.In both years,groundnut grain yields were much higher at 20 and 30 kg$ha–1 P.Phosphorus supply markedly reduced shootδ15N values and increased the%Ndfa and amount of Nfixed,indicating the direct involvement of P in promoting N2 fixation in nodulated groundnut.The three genotypes differed significantly inδ15N,%Ndfa,N-fixed,grain yield,C concentration,andδ13C.The phosphorusgenotype interaction was also significant for shoot DM,N content,N-fixed and soil N uptake.
