Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization an...Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization and maintenance recommendations are based on the P concentrations measured by a common colorimetric molybdenum blue method although other P quantification methods have also been used for MMP measurements. In this study, we collected 120 surface soil samples of Caribou Sandy loam under potato cultivation or its rotation crops from Maine, USA, and 72 soil samples of Cecil sandy loam with cotton/corn crops under conventional tillage and no-till management with chemical and poultry litter fertilization in Georgia, USA. The MMP levels in all 192 dry samples were greater when they were measured by an inductively coupled plasma (ICP)-based method, compared to the corresponding data produced from colorimetry. Our results show the two sets of data were positively and significantly correlated (r = 0.93, P –1 with standard deviation of 12.9, compared to the average of colorimetric MMP level of 14.9 mg P kg–1 with standard deviation of 8.8. Based on the observations in this work, both colorimetric and ICP-based methods can be used for P fertilizer recommendation, but a conversion factor should be applied for ICP data as the current recommendation systems are based on colorimetric M&R data.展开更多
Phosphorus is an essential element in agricultural production and chemical industry. However, since the risk of casualties and economic loss by mining accidents, the application of clean and safe production in phospho...Phosphorus is an essential element in agricultural production and chemical industry. However, since the risk of casualties and economic loss by mining accidents, the application of clean and safe production in phosphorus mines encounters great challenges. For this purpose, a man-machine-environment system composed of evaluation indexes was established, and the grading standards of indexes were defined. Firstly, the measurements of 39 qualitative indexes were obtained through the survey data. According to the measured values of 31 quantitative indexes, the measurements of quantitative indexes were calculated by linear measurement function(LM) and other three functions. Then the singleindex measurement evaluation matrixes were established. Secondly, the entropy weight method was used to determine the weights of each index directly. The analytic hierarchy process(AHP) was also applied to calculate the weights of index and index factor hierarchies after the established hierarchical model. The weights of system hierarchies were given by the grid-based fuzzy Borda method(GFB). The comprehensive weights were determined by the combination method of AHP and GFB(CAG). Furthermore, the multi-index comprehensive measurement evaluation vectors were obtained.Thirdly, the vectors were evaluated by the credible degree recognition(CDR) and the maximum membership(TMM)criteria. Based on the above functions, methods, and criteria, 16 combination evaluation methods were recommended.Finally, the clean and safe production grade of Kaiyang phosphate mine in China was evaluated. The results show that the LM-CAG-CDR is the most reasonable method, which can not only determine the clean and safe production grade of phosphorus mines, but also improve the development level of clean and safe mining of phosphorus mines for guidance.In addition, some beneficial suggestions and measures were also proposed to advance the clean and safe production grade of Kaiyang phosphorus mine.展开更多
Nb_(2)P_(5) is a recently discovered Bardeen,Cooper,Schrieffer theory s-wave superconductor hosting nontrivial topological nodal-line structure,which could serve as an excellent platform for studying the interplay bet...Nb_(2)P_(5) is a recently discovered Bardeen,Cooper,Schrieffer theory s-wave superconductor hosting nontrivial topological nodal-line structure,which could serve as an excellent platform for studying the interplay between the superconductivity and nontrivial topological states.We report herein the superconducting and structural properties of Nb2P5studied by measuring the electrical resistivity and structure under high pressure up to ~28 GPa and performing first principles calculations.The superconducting transition temperature TCdecreases with applied pressure,and reaches a minimum of 1.9 K at ~20.0 GPa,followed by a continuous enhancement up to 50.0 GPa without saturation.Furthermore,at pressures above ~8.2 GPa,it is likely that a second superconducting transition appears and coexists with the initial one even up to~28 GPa.Theoretical calculations rule out the correlation between the second superconducting-like transition and structure.Moreover,the Nb2P5showed remarkable axial anisotropic compressibility,in which the b-axis is more compressible than the a-and c-axes.The variation of TCis discussed via considering the evolution of density of states around the Fermi level and the phonon spectrum.展开更多
[Objective] The aim was to find an efficient method to measure available nitrogen, phosphorus and potassium content in vegetable seedling substrate. [ Method] The suitable dosage of leaching agent, ratio of the substr...[Objective] The aim was to find an efficient method to measure available nitrogen, phosphorus and potassium content in vegetable seedling substrate. [ Method] The suitable dosage of leaching agent, ratio of the substrate to water and leaching time for the detection of nutrient contents in the substrate by a soil nutrient measuring instrument were discussed firstly, and then the results of nutrient contents measured by the soil nutrient measuring instrument were compared with that by conventional approaches. [ Result] In compadson with the conventional methods, the av- erage content of available nitrogen measured by the soil nutrient measuring instrument was slightly higher, while the average content of available phosphorus measured by the instrument was lower; the average content of available potassium measured by the instrument was close to that by the conventional method. [ Conclusion] This study could provide us a new method to detect available nitrogen, phosphorus and potassium content in seedling substrate efficiently.展开更多
文摘Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization and maintenance recommendations are based on the P concentrations measured by a common colorimetric molybdenum blue method although other P quantification methods have also been used for MMP measurements. In this study, we collected 120 surface soil samples of Caribou Sandy loam under potato cultivation or its rotation crops from Maine, USA, and 72 soil samples of Cecil sandy loam with cotton/corn crops under conventional tillage and no-till management with chemical and poultry litter fertilization in Georgia, USA. The MMP levels in all 192 dry samples were greater when they were measured by an inductively coupled plasma (ICP)-based method, compared to the corresponding data produced from colorimetry. Our results show the two sets of data were positively and significantly correlated (r = 0.93, P –1 with standard deviation of 12.9, compared to the average of colorimetric MMP level of 14.9 mg P kg–1 with standard deviation of 8.8. Based on the observations in this work, both colorimetric and ICP-based methods can be used for P fertilizer recommendation, but a conversion factor should be applied for ICP data as the current recommendation systems are based on colorimetric M&R data.
基金Project(51974362) supported by the National Natural Science Foundation of ChinaProject(2282020cxqd055) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2021-QYC-10050-25631) supported by the Department of Emergency Management of Hunan Province,China。
文摘Phosphorus is an essential element in agricultural production and chemical industry. However, since the risk of casualties and economic loss by mining accidents, the application of clean and safe production in phosphorus mines encounters great challenges. For this purpose, a man-machine-environment system composed of evaluation indexes was established, and the grading standards of indexes were defined. Firstly, the measurements of 39 qualitative indexes were obtained through the survey data. According to the measured values of 31 quantitative indexes, the measurements of quantitative indexes were calculated by linear measurement function(LM) and other three functions. Then the singleindex measurement evaluation matrixes were established. Secondly, the entropy weight method was used to determine the weights of each index directly. The analytic hierarchy process(AHP) was also applied to calculate the weights of index and index factor hierarchies after the established hierarchical model. The weights of system hierarchies were given by the grid-based fuzzy Borda method(GFB). The comprehensive weights were determined by the combination method of AHP and GFB(CAG). Furthermore, the multi-index comprehensive measurement evaluation vectors were obtained.Thirdly, the vectors were evaluated by the credible degree recognition(CDR) and the maximum membership(TMM)criteria. Based on the above functions, methods, and criteria, 16 combination evaluation methods were recommended.Finally, the clean and safe production grade of Kaiyang phosphate mine in China was evaluated. The results show that the LM-CAG-CDR is the most reasonable method, which can not only determine the clean and safe production grade of phosphorus mines, but also improve the development level of clean and safe mining of phosphorus mines for guidance.In addition, some beneficial suggestions and measures were also proposed to advance the clean and safe production grade of Kaiyang phosphorus mine.
基金support by the Postgraduate Education Reform and Quality Improvement Project of Henan Province (YJS2021AL098, YJS2021JD20, 2022YJSKC03)Key Scientific Research Projects of Henan Province (162102210238, 202102210216)Postgraduate Education Innovation Program of Zhengzhou University of Aeronautics (2020CX20, 2021YJSJGZX11, 2020YJSJD1)。
文摘Nb_(2)P_(5) is a recently discovered Bardeen,Cooper,Schrieffer theory s-wave superconductor hosting nontrivial topological nodal-line structure,which could serve as an excellent platform for studying the interplay between the superconductivity and nontrivial topological states.We report herein the superconducting and structural properties of Nb2P5studied by measuring the electrical resistivity and structure under high pressure up to ~28 GPa and performing first principles calculations.The superconducting transition temperature TCdecreases with applied pressure,and reaches a minimum of 1.9 K at ~20.0 GPa,followed by a continuous enhancement up to 50.0 GPa without saturation.Furthermore,at pressures above ~8.2 GPa,it is likely that a second superconducting transition appears and coexists with the initial one even up to~28 GPa.Theoretical calculations rule out the correlation between the second superconducting-like transition and structure.Moreover,the Nb2P5showed remarkable axial anisotropic compressibility,in which the b-axis is more compressible than the a-and c-axes.The variation of TCis discussed via considering the evolution of density of states around the Fermi level and the phonon spectrum.
基金Supported by the Scientific Research Project of Public Welfare Industry(Agriculture)(201303014-01)Science and Technology Innovation Team of Anhui Academy of Agricultural Sciences(14C0314)the Dean’s Youth Innovation Fund from Anhui Academy of Agricultural Sciences(15B0331)
文摘[Objective] The aim was to find an efficient method to measure available nitrogen, phosphorus and potassium content in vegetable seedling substrate. [ Method] The suitable dosage of leaching agent, ratio of the substrate to water and leaching time for the detection of nutrient contents in the substrate by a soil nutrient measuring instrument were discussed firstly, and then the results of nutrient contents measured by the soil nutrient measuring instrument were compared with that by conventional approaches. [ Result] In compadson with the conventional methods, the av- erage content of available nitrogen measured by the soil nutrient measuring instrument was slightly higher, while the average content of available phosphorus measured by the instrument was lower; the average content of available potassium measured by the instrument was close to that by the conventional method. [ Conclusion] This study could provide us a new method to detect available nitrogen, phosphorus and potassium content in seedling substrate efficiently.
