Growing fruit trees on the slopes of rolling hills in South China was causing serious environmental problems because of heavy application of chemical fertilizers and soil erosion. Suitable sources of fertilizers and p...Growing fruit trees on the slopes of rolling hills in South China was causing serious environmental problems because of heavy application of chemical fertilizers and soil erosion. Suitable sources of fertilizers and proper rates of applications were of key importance to both crop yields and environmental protection. In this article, the impact of four fertilizers, i.e., inorganic compound fertilizer, organic compound fertilizer, pig manure compost, and peanut cake （peanut oil pressing residue）, on chestnut （Castanea mollissima Blume） growth on a slope in South China, and on the total N and total P concentrations in runoff waters have been investigated during two years of study, with an orthogonal experimental design. Results show that the organic compound fertilizer and peanut cake promote the heights of young chestnut trees compared to the control. In addition, peanut cake increases single-fruit weights and organic compound fertilizer raises single-seed weights. All the fertilizers increased the concentrations of total N and total P in runoff waters, except for organic compound fertilizer, in the first year experiment. The observed mean concentrations of total N varied from 1.6 mg/L to 3.2 mg/L and P from 0.12 mg/L to 0.22 mg/L, which were increased with the amount of fertilizer applications, with no pattern of direct proportion. On the basis of these experiment results, organic compound fertilizer at 2 kg/tree and peanut cake at 1 kg/tree are recommended to maximize chestnut growth and minimize water pollution.展开更多
In this study, phosphorus(P) sorption of thirteen light-weight aggregates(LWAs) from USA was compared during batch equilibrium experiments in order to identify those materials which had the highest P sorption capacity...In this study, phosphorus(P) sorption of thirteen light-weight aggregates(LWAs) from USA was compared during batch equilibrium experiments in order to identify those materials which had the highest P sorption capacity for further study. Seven different levels of sorption activity were observed, which were broadly grouped into three categories—high performing, middle performing, and low performing aggregates. Chemical analysis of Ca, Al, Fe, and Mg was used to describe the differences between LWAs. There was a significant correlation between cation(especially Al, Ca, Fe, and Mg) content and P sorbed. Langmuir isotherms were used to describe P sorption maximum and binding affinity for four of the top five performing LWAs, Universal, Stalite "D", Stalite "Mix", and TXI.The fifth aggregate, Lehigh, exhibited more complex sorption, and was better described by the Freundlich isotherm. Universal had a mean P sorption at the highest concentration of 824 mg kg-1, well above its calculated sorption maximum(702 mg kg-1), and also had the highest binding affinity(1.1 L mg-1). This experiment suggests that the top performing LWA(Universal) may perform poorly in column and field studies due to observed precipitates, which could degrade constructed wetland performance. Other LWAs may exhibit superior field performance due to their high calculated sorption maxima. In general, these results highlight the importance of batch experiments as a first step in identifying materials suitable for column and field experiments.展开更多
Leaf N and P stoichiometry in terrestrial ecosystems has been widely investigated in recent years owing to the importance of these elements in improving the predicted vegetation responses to global changes.The vertica...Leaf N and P stoichiometry in terrestrial ecosystems has been widely investigated in recent years owing to the importance of these elements in improving the predicted vegetation responses to global changes.The vertical distribution of leaf N and P stoichiometry has attracted increasing attention because of the dramatic changes in environmental factors at regional scales.However,the characteristics of leaf N and P stoichiometry in the southeast Qinghai–Tibet plateau(SET)are not clear,although this area is sensitive to global change.Here,we analyzed the leaf N and P concentrations in dominant plant species on natural altitudinal gradients on the Duoxiongla(DXL),Sejila(SJL),Mila(ML),and Gangbala(GBL)mountains across the SET all the way to central Tibet.Our results showed that the leaf N concentrations were comparable among the regions,whereas the leaf P concentrations dramatically decreased from SET to central Tibet(CT).The leaf N concentrations were 23.6,21.3,20.8,and 22.4 g kg^(-1),and the leaf P concentrations were 2.40,2.49,1.94,and 1.59 g kg^(-1) on the SJL,DXL,ML and GBL mountains,respectively.The leaf N/P ratios on the DXL,SJL,ML,and GBL mountains were 8.81,10.3,11.2,and 14.2,respectively.Considering the increasing trend of the leaf N/P ratio from southeast Qinghai–Tibet plateau to central Tibet,N limitation might widely exist in well vegetated ecosystems in the Qinghai–Tibet plateau.展开更多
On-farm experiments were conducted in farmers' fields at 6 different sites in Western Usambara Mountains(WUM)in northern Tanzania during the 2000-2001 cropping season.The objectives were to study the effects of Tu...On-farm experiments were conducted in farmers' fields at 6 different sites in Western Usambara Mountains(WUM)in northern Tanzania during the 2000-2001 cropping season.The objectives were to study the effects of Tughutu(Vernonia subligera O.Hoffn)pruning in combination with Minjingu phosphate rock(MPR)or triple super phosphate(TSP)supply on the concentration of P in the tissues and seed yields of common bean,and to assess the economic returns of these different technologies to farmers.The experimental design was a randomized complete block with each of the 6 farmers' fields used as a replicate.The treatments included:control,MPR or TSP each at 26 kg P ha^(-1),Tughutu at 2.5 t ha^(-1), and Tughutu at 2.5 t ha^(-1)combined with MPR or TSP at 26 kg P ha^(-1). Addition of MPR or TSP alone significantly raised P concentration in bean shoots from 1.27 mg g^(-1)to 1.70 and 1.95 mg g^(-1)respectively.Combining MPR or TSP with Tughutu increased P concentration above the proposed deficiency level of 2 mg g^(-1).The relative agronomic effectiveness(RAE)of MPR ranged from 12.5% to 45.0%.Seed yields of common bean was markedly increased by 28%-104% from MPR or TSP supply alone,and 148%-219% from Tughutu application combined with 26 kg P ha^(-1)of MPR or TSP relative to the control.With Tughutu alone,seed yield increased by 53%. From economic analysis,the increase in seed yield with the supply of MPR or TSP combined with Tughutu translated into a significantly(P≤0.001)higher marginal rate of return and dollar profit for common bean farmers in WUM in northern Tanzania.It is concluded that Tughutu and its combined application with MPR or TSP is an appropriate integrated nutrient management strategy that may increase bean yields and dollar profit to the rural poor communities in Tanzania.展开更多
Two new freshwater atyid shrimps, Caridina angustipes sp nov.and C clavipes sp nov.from Hunan Province,China are described. C angustipes sp nov.is similar to C baojingensis Guo,He et Bai,1992,b...Two new freshwater atyid shrimps, Caridina angustipes sp nov.and C clavipes sp nov.from Hunan Province,China are described. C angustipes sp nov.is similar to C baojingensis Guo,He et Bai,1992,but with longer rostrum,15-27 dorsal teeth,3-6 ventral teeth,and straighter inner margin of endopods in male 1st pleopods. C clavipes sp nov.is similar to C angustipes ,but with narrower distal and fewer spines on inner margin of endopds in male 1st pleopods,and shorter and thinner appendix masculina in male 2nd pleopods with only 1 spine on inner lateral margin and 4 spines in apex.The holotypes are deposited in Shanghai Fisheries University.Some representative paratypes are deposited in Foshan Science and Technology College.展开更多
Due to long-term positive P-balances many surface soils in areas with high livestock density in Germany are over-supplied with available P, creating a potential for vertical P losses by leaching. In extensive studies ...Due to long-term positive P-balances many surface soils in areas with high livestock density in Germany are over-supplied with available P, creating a potential for vertical P losses by leaching. In extensive studies to characterize the endangering of ground water to P pollution by chemical soil parameters it is shown that the available P content and the P concentration of the soil solution in the deeper soil layers, as indicators of the P-leaching potential, cannot be satisfactorily predicted from the available P content of the topsoils. The P equilibrium concentration in the soil solution directly above ground water table or the pipe drainage system highly depends on the relative saturation of the P-sorption capacity in this layer. A saturation index of <20% normally corresponds with P equilibrium concentrations of <0.2 mg P/L. Phytoremediation may reduce the P leaching potential of P-enriched soils only over a very long period.展开更多
基金Project supported by the Science and Technology Department of Guang-dong Province (No: 2004B33301007)the Rockefeller Brothers Fund
文摘Growing fruit trees on the slopes of rolling hills in South China was causing serious environmental problems because of heavy application of chemical fertilizers and soil erosion. Suitable sources of fertilizers and proper rates of applications were of key importance to both crop yields and environmental protection. In this article, the impact of four fertilizers, i.e., inorganic compound fertilizer, organic compound fertilizer, pig manure compost, and peanut cake （peanut oil pressing residue）, on chestnut （Castanea mollissima Blume） growth on a slope in South China, and on the total N and total P concentrations in runoff waters have been investigated during two years of study, with an orthogonal experimental design. Results show that the organic compound fertilizer and peanut cake promote the heights of young chestnut trees compared to the control. In addition, peanut cake increases single-fruit weights and organic compound fertilizer raises single-seed weights. All the fertilizers increased the concentrations of total N and total P in runoff waters, except for organic compound fertilizer, in the first year experiment. The observed mean concentrations of total N varied from 1.6 mg/L to 3.2 mg/L and P from 0.12 mg/L to 0.22 mg/L, which were increased with the amount of fertilizer applications, with no pattern of direct proportion. On the basis of these experiment results, organic compound fertilizer at 2 kg/tree and peanut cake at 1 kg/tree are recommended to maximize chestnut growth and minimize water pollution.
基金Supported by the Soil Characterization Laboratory,University of Masachusetts,Amherst,MA,USA
文摘In this study, phosphorus(P) sorption of thirteen light-weight aggregates(LWAs) from USA was compared during batch equilibrium experiments in order to identify those materials which had the highest P sorption capacity for further study. Seven different levels of sorption activity were observed, which were broadly grouped into three categories—high performing, middle performing, and low performing aggregates. Chemical analysis of Ca, Al, Fe, and Mg was used to describe the differences between LWAs. There was a significant correlation between cation(especially Al, Ca, Fe, and Mg) content and P sorbed. Langmuir isotherms were used to describe P sorption maximum and binding affinity for four of the top five performing LWAs, Universal, Stalite "D", Stalite "Mix", and TXI.The fifth aggregate, Lehigh, exhibited more complex sorption, and was better described by the Freundlich isotherm. Universal had a mean P sorption at the highest concentration of 824 mg kg-1, well above its calculated sorption maximum(702 mg kg-1), and also had the highest binding affinity(1.1 L mg-1). This experiment suggests that the top performing LWA(Universal) may perform poorly in column and field studies due to observed precipitates, which could degrade constructed wetland performance. Other LWAs may exhibit superior field performance due to their high calculated sorption maxima. In general, these results highlight the importance of batch experiments as a first step in identifying materials suitable for column and field experiments.
基金funded by the Natural Science Foundation of Tibet Autonomous Region Department and Agriculture and Animal Husbandry University(XZ202101ZR0023G)the National Natural Science Foundation of China(42067036)the Forestry Innovation Team Construction project of Xizang Agriculture and Animal Husbandry University(2020-001)。
文摘Leaf N and P stoichiometry in terrestrial ecosystems has been widely investigated in recent years owing to the importance of these elements in improving the predicted vegetation responses to global changes.The vertical distribution of leaf N and P stoichiometry has attracted increasing attention because of the dramatic changes in environmental factors at regional scales.However,the characteristics of leaf N and P stoichiometry in the southeast Qinghai–Tibet plateau(SET)are not clear,although this area is sensitive to global change.Here,we analyzed the leaf N and P concentrations in dominant plant species on natural altitudinal gradients on the Duoxiongla(DXL),Sejila(SJL),Mila(ML),and Gangbala(GBL)mountains across the SET all the way to central Tibet.Our results showed that the leaf N concentrations were comparable among the regions,whereas the leaf P concentrations dramatically decreased from SET to central Tibet(CT).The leaf N concentrations were 23.6,21.3,20.8,and 22.4 g kg^(-1),and the leaf P concentrations were 2.40,2.49,1.94,and 1.59 g kg^(-1) on the SJL,DXL,ML and GBL mountains,respectively.The leaf N/P ratios on the DXL,SJL,ML,and GBL mountains were 8.81,10.3,11.2,and 14.2,respectively.Considering the increasing trend of the leaf N/P ratio from southeast Qinghai–Tibet plateau to central Tibet,N limitation might widely exist in well vegetated ecosystems in the Qinghai–Tibet plateau.
基金Project supported by the Directorate of Research and Development in the Ministry of Agriculture and Food Security of Tanzania,through Tanzania Agricultural Research Project No.Ⅱ World Bank project.
文摘On-farm experiments were conducted in farmers' fields at 6 different sites in Western Usambara Mountains(WUM)in northern Tanzania during the 2000-2001 cropping season.The objectives were to study the effects of Tughutu(Vernonia subligera O.Hoffn)pruning in combination with Minjingu phosphate rock(MPR)or triple super phosphate(TSP)supply on the concentration of P in the tissues and seed yields of common bean,and to assess the economic returns of these different technologies to farmers.The experimental design was a randomized complete block with each of the 6 farmers' fields used as a replicate.The treatments included:control,MPR or TSP each at 26 kg P ha^(-1),Tughutu at 2.5 t ha^(-1), and Tughutu at 2.5 t ha^(-1)combined with MPR or TSP at 26 kg P ha^(-1). Addition of MPR or TSP alone significantly raised P concentration in bean shoots from 1.27 mg g^(-1)to 1.70 and 1.95 mg g^(-1)respectively.Combining MPR or TSP with Tughutu increased P concentration above the proposed deficiency level of 2 mg g^(-1).The relative agronomic effectiveness(RAE)of MPR ranged from 12.5% to 45.0%.Seed yields of common bean was markedly increased by 28%-104% from MPR or TSP supply alone,and 148%-219% from Tughutu application combined with 26 kg P ha^(-1)of MPR or TSP relative to the control.With Tughutu alone,seed yield increased by 53%. From economic analysis,the increase in seed yield with the supply of MPR or TSP combined with Tughutu translated into a significantly(P≤0.001)higher marginal rate of return and dollar profit for common bean farmers in WUM in northern Tanzania.It is concluded that Tughutu and its combined application with MPR or TSP is an appropriate integrated nutrient management strategy that may increase bean yields and dollar profit to the rural poor communities in Tanzania.
文摘Two new freshwater atyid shrimps, Caridina angustipes sp nov.and C clavipes sp nov.from Hunan Province,China are described. C angustipes sp nov.is similar to C baojingensis Guo,He et Bai,1992,but with longer rostrum,15-27 dorsal teeth,3-6 ventral teeth,and straighter inner margin of endopods in male 1st pleopods. C clavipes sp nov.is similar to C angustipes ,but with narrower distal and fewer spines on inner margin of endopds in male 1st pleopods,and shorter and thinner appendix masculina in male 2nd pleopods with only 1 spine on inner lateral margin and 4 spines in apex.The holotypes are deposited in Shanghai Fisheries University.Some representative paratypes are deposited in Foshan Science and Technology College.
文摘Due to long-term positive P-balances many surface soils in areas with high livestock density in Germany are over-supplied with available P, creating a potential for vertical P losses by leaching. In extensive studies to characterize the endangering of ground water to P pollution by chemical soil parameters it is shown that the available P content and the P concentration of the soil solution in the deeper soil layers, as indicators of the P-leaching potential, cannot be satisfactorily predicted from the available P content of the topsoils. The P equilibrium concentration in the soil solution directly above ground water table or the pipe drainage system highly depends on the relative saturation of the P-sorption capacity in this layer. A saturation index of <20% normally corresponds with P equilibrium concentrations of <0.2 mg P/L. Phytoremediation may reduce the P leaching potential of P-enriched soils only over a very long period.
