【目的】研究一次性施肥技术对黄淮海夏玉米产量、肥料利用效率和经济效益的影响,为黄淮海夏玉米区实现减肥增效、节本增收及轻简化生产技术的筛选提供理论依据。【方法】2015年和2016年在河北、河南、山东三省选择8个试验地点进行控释...【目的】研究一次性施肥技术对黄淮海夏玉米产量、肥料利用效率和经济效益的影响,为黄淮海夏玉米区实现减肥增效、节本增收及轻简化生产技术的筛选提供理论依据。【方法】2015年和2016年在河北、河南、山东三省选择8个试验地点进行控释氮肥随夏玉米播种一次性施用大田试验。与普通氮肥分次施用(习惯施肥(FP)和优化施肥(OPT))对比,通过设置控释氮肥等量投入(CRFA)、减量20%控释氮肥投入(CRFA80%N、CRFB80%N和CRFC80%N),研究一次性施肥技术对黄淮海夏玉米经济效益的影响,并验证一次性施肥技术的减量施氮可行性。【结果】(1)与农民习惯施肥(FP)相比,一次性施肥处理对黄淮海区夏玉米株高、穗部性状和两年的平均产量均无显著影响,氮肥农学效率和表观利用率虽有所提高,但未达显著性差异;但一次性减氮施肥处理较FP处理,氮肥偏生产力显著提高了33.85%以上(P<0.05)。此外,CRFA、CRFA80%N、CRFB80%N和CRFC80%N处理相比农民习惯施肥(FP),每季平均节氮量分别为8.15、50.65、50.65、50.65 kg N·hm^(-2),增加纯收入927.40元/hm^2以上。(2)除CRFA处理外,其余一次性施肥处理的硝态氮量均显著低于习惯施肥处理(FP);一次性减氮施肥处理(CRFA80%N、CRFB80%N、CRFC80%N)0—90 cm土层NO_3^--N含量显著低于优化施肥处理(OPT)(P<0.05)。【结论】一次性施肥技术实现了黄淮海夏玉米的轻简化施肥,提高了氮肥的利用效率,能够在保证稳产增产的前提下,实现氮肥的减量施用;推荐减少20%氮用量的CRFA施肥模式在黄淮海夏玉米生产上一次性施用。展开更多
During the last two decades,we have witnessed great progress in research on thermoelectrics.There are two primary focuses.One is the fundamental understanding of electrical and thermal transport,enabled by the interpl...During the last two decades,we have witnessed great progress in research on thermoelectrics.There are two primary focuses.One is the fundamental understanding of electrical and thermal transport,enabled by the interplay of theory and experiment;the other is the substantial enhancement of the performance of various thermoelectric materials,through synergistic optimisation of those intercorrelated transport parameters.Here we review some of the successful strategies for tuning electrical and thermal transport.For electrical transport,we start from the classical but still very active strategy of tuning band degeneracy(or band convergence),then discuss the engineering of carrier scattering,and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials.For thermal transport,we summarise the approaches for studying thermal transport based on phonon–phonon interactions valid for conventional solids,as well as some quantitative efforts for nanostructures.We also discuss the thermal transport in complex materials with chemical-bond hierarchy,in which a portion of the atoms(or subunits)are weakly bonded to the rest of the structure,leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures.In this review,we provide a summary of achievements made in recent studies of thermoelectric transport properties,and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment,and point out some challenges and possible directions.展开更多
文摘【目的】研究一次性施肥技术对黄淮海夏玉米产量、肥料利用效率和经济效益的影响,为黄淮海夏玉米区实现减肥增效、节本增收及轻简化生产技术的筛选提供理论依据。【方法】2015年和2016年在河北、河南、山东三省选择8个试验地点进行控释氮肥随夏玉米播种一次性施用大田试验。与普通氮肥分次施用(习惯施肥(FP)和优化施肥(OPT))对比,通过设置控释氮肥等量投入(CRFA)、减量20%控释氮肥投入(CRFA80%N、CRFB80%N和CRFC80%N),研究一次性施肥技术对黄淮海夏玉米经济效益的影响,并验证一次性施肥技术的减量施氮可行性。【结果】(1)与农民习惯施肥(FP)相比,一次性施肥处理对黄淮海区夏玉米株高、穗部性状和两年的平均产量均无显著影响,氮肥农学效率和表观利用率虽有所提高,但未达显著性差异;但一次性减氮施肥处理较FP处理,氮肥偏生产力显著提高了33.85%以上(P<0.05)。此外,CRFA、CRFA80%N、CRFB80%N和CRFC80%N处理相比农民习惯施肥(FP),每季平均节氮量分别为8.15、50.65、50.65、50.65 kg N·hm^(-2),增加纯收入927.40元/hm^2以上。(2)除CRFA处理外,其余一次性施肥处理的硝态氮量均显著低于习惯施肥处理(FP);一次性减氮施肥处理(CRFA80%N、CRFB80%N、CRFC80%N)0—90 cm土层NO_3^--N含量显著低于优化施肥处理(OPT)(P<0.05)。【结论】一次性施肥技术实现了黄淮海夏玉米的轻简化施肥,提高了氮肥的利用效率,能够在保证稳产增产的前提下,实现氮肥的减量施用;推荐减少20%氮用量的CRFA施肥模式在黄淮海夏玉米生产上一次性施用。
基金supported by National Basic Research Program of China(973-program)under project number 2013CB632501National Natural Science Foundation of China under contract number 11234012+7 种基金the Key Research Program of Chinese Academy of Sciences(Grant No.KGZD-EW-T06)research grants(14DZ2261200 and 15JC1400301)from Science and Technology Commission of Shanghai MunicipalityInternational S&T Cooperation Program of China(2015DFA51050)supported by the U.S.Department of Energy,Office of Basic Energy Sciences under award number DE-SC-0008574supported by the Department of Energy through the S3TEC Energy Frontier Research Center award#DE-SC0001299/DE-FG02–09ER46577supported by the U.S.Department of Energy under corporate agreement DE-FC26-04NT42278by GM,and by National Science Foundation under award number 1235535support from Shanghai Institute of Materials Genome.
文摘During the last two decades,we have witnessed great progress in research on thermoelectrics.There are two primary focuses.One is the fundamental understanding of electrical and thermal transport,enabled by the interplay of theory and experiment;the other is the substantial enhancement of the performance of various thermoelectric materials,through synergistic optimisation of those intercorrelated transport parameters.Here we review some of the successful strategies for tuning electrical and thermal transport.For electrical transport,we start from the classical but still very active strategy of tuning band degeneracy(or band convergence),then discuss the engineering of carrier scattering,and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials.For thermal transport,we summarise the approaches for studying thermal transport based on phonon–phonon interactions valid for conventional solids,as well as some quantitative efforts for nanostructures.We also discuss the thermal transport in complex materials with chemical-bond hierarchy,in which a portion of the atoms(or subunits)are weakly bonded to the rest of the structure,leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures.In this review,we provide a summary of achievements made in recent studies of thermoelectric transport properties,and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment,and point out some challenges and possible directions.
