In recent years,due to the widespread application of flotation,a large number of plant remains related to the origin of rice agriculture have been found in the middle and lower reaches of the Yangtze River.Through the...In recent years,due to the widespread application of flotation,a large number of plant remains related to the origin of rice agriculture have been found in the middle and lower reaches of the Yangtze River.Through the study of these new findings,it has been discovered that the origin of rice agriculture was a long and gradual process lasting for thousands of years.This process can be divided into four stages:the stage of gestation took place around 10,000 years ago—human society was still in the hunting and gathering phase,but archaeological evidence of human-used or even cultivated Oryza plants from that time has been discovered;the early stage of transition took place around 9000–7000 years ago—archaeological evidence of rice farming from that time has been found,such as villages,domesticated rice,farming tools,etc.,but subsistence then was still mainly based on hunting and gathering,whereas rice farming and pig breeding,which fall into the agricultural production category,were only auxiliary production activities;the late stage of transition took place around 7000–5000 years ago,when the proportion of subsistence attained by hunting and gathering gradually declined while the proportion of rice farming increased day by day;and the stage of completion took place about 5000 years ago,when hunting and gathering was replaced by rice agriculture in the middle and lower reaches of the Yangtze River successively.展开更多
Large amount of pre-plant nitrogen （N） fertilizer results in low N use efficiency due to poor synchrony between soil N supply and maize N demand, especially during N sensitive growth stages. The objectives of the st...Large amount of pre-plant nitrogen （N） fertilizer results in low N use efficiency due to poor synchrony between soil N supply and maize N demand, especially during N sensitive growth stages. The objectives of the study were to compare growth and yield of maize （Zea rnays L.） under conventional and site-specific N management in a dryland farming system. The study, which was designed as randomized complete block design was conducted over three site-years under continuous maize cropping system in the semi-arid regions of the Limpopo Province in South Africa. Treatments of the study consisted of three N management strategies on a maize field planted to drought resistant SNK 2147 hybrid maize cultivar. Treatments were： （i） no N application （NO）, （ii） site-specific N at variable rates ranging between 18 kg N/ha and 33 kg N/ha based on soil analysis results （N l） and （iii） conventional and uniform N application broadcasted during planting at 58 kg N/ha （N2）. Sufficiency index as indication of N deficiency was determined using CCM-200 on maize leaves based on leaf numbers during maize vegetative growth stages V6, V10 and Vl4, and thereafter N was applied only when needed. The highest maize grain yield of 5.2 Mg/ha for N 1 was significantly higher （P 〈 0.05） than 3.2 Mg/ha and 4.0 Mg/ha of N0 and N2 in site-year I, respectively. Maize grain yield of 2.2 Mg/ha （Nl） at site-year ll was significantly higher （P _〈 0.05） than 1.7 Mg/ha of the NO. The maize growth and yield under N2 and N1 was compared, N1 required between 43% and 69% lesser N fertilizer as compared to N2 over site-years, and resulted in higher maize height, number of leaves per plant, leaf length, and leaf area than that of conventional N management strategy. Therefore, site-specific N management strategy sustains and improves growth and yield of maize using minimal N fertilizer as compared to conventional approach in low fertility soils of semi-arid regions in dryland farming systems. In examining the results of this study, there was a consistent benefit of site-specific N management strategy on improving growth and yield of maize while saving fertilizer use in small-scale dryland maize farming system.展开更多
In this paper,the authors have analyzed the relationship between energy intensity gap and GDP per worker gap of China's western and eastern provinces over the period 1997-2006.Using panel data model with lag adjus...In this paper,the authors have analyzed the relationship between energy intensity gap and GDP per worker gap of China's western and eastern provinces over the period 1997-2006.Using panel data model with lag adjustment,taking the above provinces and six industrial sectors (agriculture,forestry,animal husbandry,and fisheries,industry,construction industry,transport,storage and post & telecommunications,wholesale and retail trades & catering industry,and other sectors of tertiary industry.) as the investigated subjects,the authors have conducted empirical study on the convergence of GDP per worker gap and the convergence of energy intensity gap with respect to the variation of GDP per worker gap,and have concluded that:First,the GDP per worker gap of the six industrial sectors and provinces are convergent,and of this,the convergence rate of GDP per worker gap of Construction Industry is the fastest,while that of Industry is the slowest.Second,the overall energy intensity gap between eastern and western provinces is convergent,that is,with the narrowing of GDP per worker gap between eastern and western provinces,the energy intensity gap converges,but its convergence rate is slower than that of GDP per worker gap.Third,energy intensity gap between various industrial sectors of the east and the west is either convergent or divergent,and there are differences.The energy intensity gap of agriculture,forestry,animal husbandry,and fisheries,industry,and construction industry is convergent,while that of the other three industrial sectors is divergent.Fourth,the convergence of the overall energy intensity of the western provinces is not in conformity with the convergence of the various industrial sectors,and there are significant differences,indicating that the western provinces and autonomous regions should take measures to more effectively improve their overall energy utilization efficiency at the industrial sector level.展开更多
Mining industry is a substantial consumer of the energy indispensable to power mining and mineral processing equipment and processes. As more and more mine operations move to remote locations, the access to reliable, ...Mining industry is a substantial consumer of the energy indispensable to power mining and mineral processing equipment and processes. As more and more mine operations move to remote locations, the access to reliable, secure and environment friendly energy sources becomes a key concern. At present, a great majority of remote mines relies heavily on diesel fuel that has to be transported over long distances. In this context, some of the renewable energy sources such as wind power or solar energy seem to provide potentially interesting and viable alternatives. Mine operations, however, have a very particular character, much different from other industries and from other potential applications of renewable power sources. This paper presents operational conditions of some mining operations, particularly those in remote regions, in the context of their energy needs. The authors analyse current and future capacities to decrease a reliance of remote mines on conventional fuels and energy. The paper also analyses and discusses the conditions to be met by alternative energy sources so that they might become a viable alternative for remote mining operations.展开更多
文摘In recent years,due to the widespread application of flotation,a large number of plant remains related to the origin of rice agriculture have been found in the middle and lower reaches of the Yangtze River.Through the study of these new findings,it has been discovered that the origin of rice agriculture was a long and gradual process lasting for thousands of years.This process can be divided into four stages:the stage of gestation took place around 10,000 years ago—human society was still in the hunting and gathering phase,but archaeological evidence of human-used or even cultivated Oryza plants from that time has been discovered;the early stage of transition took place around 9000–7000 years ago—archaeological evidence of rice farming from that time has been found,such as villages,domesticated rice,farming tools,etc.,but subsistence then was still mainly based on hunting and gathering,whereas rice farming and pig breeding,which fall into the agricultural production category,were only auxiliary production activities;the late stage of transition took place around 7000–5000 years ago,when the proportion of subsistence attained by hunting and gathering gradually declined while the proportion of rice farming increased day by day;and the stage of completion took place about 5000 years ago,when hunting and gathering was replaced by rice agriculture in the middle and lower reaches of the Yangtze River successively.
文摘Large amount of pre-plant nitrogen （N） fertilizer results in low N use efficiency due to poor synchrony between soil N supply and maize N demand, especially during N sensitive growth stages. The objectives of the study were to compare growth and yield of maize （Zea rnays L.） under conventional and site-specific N management in a dryland farming system. The study, which was designed as randomized complete block design was conducted over three site-years under continuous maize cropping system in the semi-arid regions of the Limpopo Province in South Africa. Treatments of the study consisted of three N management strategies on a maize field planted to drought resistant SNK 2147 hybrid maize cultivar. Treatments were： （i） no N application （NO）, （ii） site-specific N at variable rates ranging between 18 kg N/ha and 33 kg N/ha based on soil analysis results （N l） and （iii） conventional and uniform N application broadcasted during planting at 58 kg N/ha （N2）. Sufficiency index as indication of N deficiency was determined using CCM-200 on maize leaves based on leaf numbers during maize vegetative growth stages V6, V10 and Vl4, and thereafter N was applied only when needed. The highest maize grain yield of 5.2 Mg/ha for N 1 was significantly higher （P 〈 0.05） than 3.2 Mg/ha and 4.0 Mg/ha of N0 and N2 in site-year I, respectively. Maize grain yield of 2.2 Mg/ha （Nl） at site-year ll was significantly higher （P _〈 0.05） than 1.7 Mg/ha of the NO. The maize growth and yield under N2 and N1 was compared, N1 required between 43% and 69% lesser N fertilizer as compared to N2 over site-years, and resulted in higher maize height, number of leaves per plant, leaf length, and leaf area than that of conventional N management strategy. Therefore, site-specific N management strategy sustains and improves growth and yield of maize using minimal N fertilizer as compared to conventional approach in low fertility soils of semi-arid regions in dryland farming systems. In examining the results of this study, there was a consistent benefit of site-specific N management strategy on improving growth and yield of maize while saving fertilizer use in small-scale dryland maize farming system.
基金sponsored by"Project Fund of Humanities and Social Sciences of Ministry of Edu-cation"(Grant No.:09YJA790157)"Proprietary Research Project of Humanities and Social Sciences of Wuhan University"(Grant No.:09ZZKY032)
文摘In this paper,the authors have analyzed the relationship between energy intensity gap and GDP per worker gap of China's western and eastern provinces over the period 1997-2006.Using panel data model with lag adjustment,taking the above provinces and six industrial sectors (agriculture,forestry,animal husbandry,and fisheries,industry,construction industry,transport,storage and post & telecommunications,wholesale and retail trades & catering industry,and other sectors of tertiary industry.) as the investigated subjects,the authors have conducted empirical study on the convergence of GDP per worker gap and the convergence of energy intensity gap with respect to the variation of GDP per worker gap,and have concluded that:First,the GDP per worker gap of the six industrial sectors and provinces are convergent,and of this,the convergence rate of GDP per worker gap of Construction Industry is the fastest,while that of Industry is the slowest.Second,the overall energy intensity gap between eastern and western provinces is convergent,that is,with the narrowing of GDP per worker gap between eastern and western provinces,the energy intensity gap converges,but its convergence rate is slower than that of GDP per worker gap.Third,energy intensity gap between various industrial sectors of the east and the west is either convergent or divergent,and there are differences.The energy intensity gap of agriculture,forestry,animal husbandry,and fisheries,industry,and construction industry is convergent,while that of the other three industrial sectors is divergent.Fourth,the convergence of the overall energy intensity of the western provinces is not in conformity with the convergence of the various industrial sectors,and there are significant differences,indicating that the western provinces and autonomous regions should take measures to more effectively improve their overall energy utilization efficiency at the industrial sector level.
文摘Mining industry is a substantial consumer of the energy indispensable to power mining and mineral processing equipment and processes. As more and more mine operations move to remote locations, the access to reliable, secure and environment friendly energy sources becomes a key concern. At present, a great majority of remote mines relies heavily on diesel fuel that has to be transported over long distances. In this context, some of the renewable energy sources such as wind power or solar energy seem to provide potentially interesting and viable alternatives. Mine operations, however, have a very particular character, much different from other industries and from other potential applications of renewable power sources. This paper presents operational conditions of some mining operations, particularly those in remote regions, in the context of their energy needs. The authors analyse current and future capacities to decrease a reliance of remote mines on conventional fuels and energy. The paper also analyses and discusses the conditions to be met by alternative energy sources so that they might become a viable alternative for remote mining operations.
