By using correlation analysis method,regression analysis method and time sequence method,we combine time and space,to establish grain yield spatio-temporal regression prediction model of Henan Province and all prefect...By using correlation analysis method,regression analysis method and time sequence method,we combine time and space,to establish grain yield spatio-temporal regression prediction model of Henan Province and all prefecture-level cities.At first,we use the grain yield in prefecture-level cities of Henan in the year 2000 and 2005,to establish regression model,and then taking the grain yield in one year as independent variable,we predict the grain yield in the fifth year afterwards.Taking the dependent variable value as independent variable again,we predict the grain yield at an interval of the same years,and based on this,predict year by year forward until the year we need.The research shows that the grain yield of Henan Province in the year 2015 and 2020 is 59.849 6 and 67.929 3 million t respectively,consistent with the research results of other scholars to some extent.展开更多
Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency(WUE) of maize for seed producti...Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency(WUE) of maize for seed production. Five planting densities of 6.75, 8.25, 9.75, 11.25 and 12.75 plants/m^2 were conducted in 2012, and a planting density of 14.25 plants/m^2 was added from 2013 to 2015. Through comparison with the Aqua Crop yield model, a modified model was developed to estimate the biomass accumulation and yield under different planting densities using adjustment coefficient for normalized biomass water productivity and harvest index. It was found that the modified yield model had a better performance and could generate results with higher determination coefficient and lower error. The results indicated that higher planting density increased the leaf area index and biomass accumulation, but decreased the biomass accumulation per plant. The total yield increased rapidly as planting density increased to 11.25 plants/m^2, but only a slight increase was observed when the density was greater than 11.25 plants/m^2. The WUE also reached the maximum when planting density was 11.25 plants/m^2, which was the recommended planting density of maize for seed production in Northwest China.展开更多
This study quantified the impacts of soil organic carbon (SOC) content on the grain yield of crops using a biogeochemical model (DNDC, denitrification-decomposition). Data on climate, soil properties, and farming ...This study quantified the impacts of soil organic carbon (SOC) content on the grain yield of crops using a biogeochemical model (DNDC, denitrification-decomposition). Data on climate, soil properties, and farming management regimes of cropping systems were collected from six typical agricultural zones (northeast, north, northwest, mid-south, east and southwest regions of China, respectively) and integrated into a GIS database to support the model runs. According to the model, if the initial SOC content in the cropland was increased by 1 g C kg^-1, the crop yield may be increased by 176 kg ha^-1 for maize in the northeast region, 454 kg ha^-1 for a maize-wheat rotation in the north region, 328 kg ha^-1 for maize in the northwest region, 185 kg ha^-1 for single-rice in the mid-south region, 266 kg ha^-1 for double-rice in east region, and 229 kg ha^-1 for rice and wheat rotation in southwest region. There is a great potential for enhancing the crop yield by improving the SOC content in each region of China.展开更多
Although the agriculture in Heilongjiang Province has develope poor historical basis and differences between rural and urban institutional fa d ct effectively in recent years, due to issues such as ors, the backward o...Although the agriculture in Heilongjiang Province has develope poor historical basis and differences between rural and urban institutional fa d ct effectively in recent years, due to issues such as ors, the backward of the agricultural fundamental infrastructure is always the major obstacle in rural economic development of Heilongjiang Province, which prevents the advantage of agricultural production from being fully developed, leading to the increase rate of the grain yield to grow slowly. The backward reflects in the following aspects, the serious aging of water facilities, insufficient agricultural machinery and equipment, low leve of rural roads, lacking of research equipment, shortage of ecological protection facilities, and so on. Based on the latcr data of Heilongjiang Province, this paper analyzed the connection between agricultural fundamental infrastructure and grain yield by using the gray connected model, differentiated primary rural fundamental infrastructure from the secondary one, and provided some suggestions to develop rural areas展开更多
On the basis of empirical data concerning " four agricultural subsidies" in Chongqing City,we establish panel data model to analyze the general effect of " four agricultural subsidies" on grain yie...On the basis of empirical data concerning " four agricultural subsidies" in Chongqing City,we establish panel data model to analyze the general effect of " four agricultural subsidies" on grain yield,and the structural effect of " four agricultural subsidies" on grain yield. Based on the F-test and Hausman test,we estimate the model using GLS or FGLS method. The results show that " four agricultural subsidies" have significant positive effect on grain yield; the structural effect of " four agricultural subsidies" on grain yield is different (comprehensive subsidies for means of agricultural production has the strongest effect on grain yield,followed by subsidies for promotion of improved variety of seed; the effect of subsidies for purchase of agricultural machinery on grain yield is not significant) . Therefore,governments at all levels should continue to strengthen the support efforts in " four agricultural subsidies" ,and continually optimize the structure to increase grain yield.展开更多
An interdisciplinary investigation was conducted to assess the impact of climate change on grain yields using an economy-climate model (C-D-C). The model was formulated by incorporating climate factors into the clas...An interdisciplinary investigation was conducted to assess the impact of climate change on grain yields using an economy-climate model (C-D-C). The model was formulated by incorporating climate factors into the classic Cobb-Douglas (C-D) economic production function model. The economic meanings of the model output elasticities are described and elucidated. The C-D-C model was applied to the assessment of the impact of climate change on grain yields in China during the past 20 years, from 1983 through 2002. In the study, the land of China was divided into eight regions, and both the C-D-C and C-D models were applied to each individual region. The results suggest that the C-D-C model is superior to the classic C-D model, indicating the importance of climate factors. Prospective applications of the C-D-C model are discussed.展开更多
<span style="font-family:Verdana;">Modeling of irrigation methods </span><span style="font-family:Verdana;">is</span><span style="font-family:""><spa...<span style="font-family:Verdana;">Modeling of irrigation methods </span><span style="font-family:Verdana;">is</span><span style="font-family:""><span style="font-family:Verdana;"> one of the most important techniques that contribute to the future of modern agriculture. This will conserve water as water scarcity is a major threat for agriculture. In this study, AquaCrop model was used to model different irrigation methods of maize in field trails in Al-Yousifya, 15 km Southwest of Baghdad. Field experiments were conducted for two seasons during 2016 and 2017 using five irrigation methods including furrow, surface drip and subsurface drip with three patterns of emitter depth (10, 20 and 30 cm) irrigation. AquaCrop simulations of biomass, grain yield, harvest index and water productivity were validated using different statistical parameters under the natural conditions obtained in the study area. For 2016 and 2017 seasons, results of R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> were 0.98 and 0.99, 0.99 and 0.99, 0.99 and 0.97, and 0.8 and 0.73 for biomass, grain yield, harvest index and water productivity, respectively. The study has conducted that simulation using AquaCrop is considered very efficient tool for modeling of different irrigation applications</span><span style="font-family:Verdana;"> for maize production under the existing conditions</span><span style="font-family:Verdana;"> in the central region of Iraq.展开更多
The role-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly comp...The role-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline (NC) materials are treated as three-phase composites consisting of grain core phase, grain boundary (GB) phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.展开更多
北方地区是中国主要的玉米种植区,在中国玉米总产和播种面积中占有较大比例,同时也是中国易发生干旱的地区,北方地区干旱常态化严重制约着该地区玉米的稳定发展。该文基于北方地区14个省(市、自治区)217个气象台站1961-2010年的...北方地区是中国主要的玉米种植区,在中国玉米总产和播种面积中占有较大比例,同时也是中国易发生干旱的地区,北方地区干旱常态化严重制约着该地区玉米的稳定发展。该文基于北方地区14个省(市、自治区)217个气象台站1961-2010年的逐日气象数据以及作物、土壤和田间管理资料,依据春玉米生长季内降水量并以100 mm为间隔将全区划分为6个区域(Ⅰ~Ⅵ),选取作物水分亏缺指数为农业干旱指标,基于验证后的农业生产系统模型(agricultural production systems simulator,APSIM),明确了各生育阶段不同等级干旱对春玉米产量的影响。研究结果表明,北方地区干旱造成春玉米减产率在空间上呈由西向东下降趋势,降水的空间分布直接导致了灾损程度在各区的差异,其中西部灌溉绿洲农业区雨养种植春玉米干旱风险非常大,需大力发展节水灌溉,而东部雨养农业区自然降水已基本满足春玉米生长发育需要,干旱对春玉米产量影响较小,在模拟过程中很难准确的反映出旱级对产量造成的差异影响。春玉米在拔节—抽雄阶段发生干旱会对产量造成比较严重的影响,该阶段4个等级干旱造成春玉米减产率的四分位区间分别为特旱(20.1%~33.6%)、重旱(12.0%~20.3%)、中旱(6.3%~15.2%)、轻旱(4.7%~11.6%)。展开更多
基金Supported by Philosophical Social Sciences Research Project of Jiangsu Colleges(08SJD7900055)
文摘By using correlation analysis method,regression analysis method and time sequence method,we combine time and space,to establish grain yield spatio-temporal regression prediction model of Henan Province and all prefecture-level cities.At first,we use the grain yield in prefecture-level cities of Henan in the year 2000 and 2005,to establish regression model,and then taking the grain yield in one year as independent variable,we predict the grain yield in the fifth year afterwards.Taking the dependent variable value as independent variable again,we predict the grain yield at an interval of the same years,and based on this,predict year by year forward until the year we need.The research shows that the grain yield of Henan Province in the year 2015 and 2020 is 59.849 6 and 67.929 3 million t respectively,consistent with the research results of other scholars to some extent.
基金the research grants from the National Natural Science Foundation of China (51379208, 91425302, 51621061)the Government Public Research Funds for Projects of the Ministry of Agriculture (201503125)the Discipline Innovative Engineering Plan (111 Program, B14002)
文摘Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency(WUE) of maize for seed production. Five planting densities of 6.75, 8.25, 9.75, 11.25 and 12.75 plants/m^2 were conducted in 2012, and a planting density of 14.25 plants/m^2 was added from 2013 to 2015. Through comparison with the Aqua Crop yield model, a modified model was developed to estimate the biomass accumulation and yield under different planting densities using adjustment coefficient for normalized biomass water productivity and harvest index. It was found that the modified yield model had a better performance and could generate results with higher determination coefficient and lower error. The results indicated that higher planting density increased the leaf area index and biomass accumulation, but decreased the biomass accumulation per plant. The total yield increased rapidly as planting density increased to 11.25 plants/m^2, but only a slight increase was observed when the density was greater than 11.25 plants/m^2. The WUE also reached the maximum when planting density was 11.25 plants/m^2, which was the recommended planting density of maize for seed production in Northwest China.
基金supported by a bilateral scientific cooperation project financed by UGent-BOF,Belgium,and the Ministry of Science and Technology,China (20052)supported by the Non-profit Research Foundation for Agriculture of China (200803036)
文摘This study quantified the impacts of soil organic carbon (SOC) content on the grain yield of crops using a biogeochemical model (DNDC, denitrification-decomposition). Data on climate, soil properties, and farming management regimes of cropping systems were collected from six typical agricultural zones (northeast, north, northwest, mid-south, east and southwest regions of China, respectively) and integrated into a GIS database to support the model runs. According to the model, if the initial SOC content in the cropland was increased by 1 g C kg^-1, the crop yield may be increased by 176 kg ha^-1 for maize in the northeast region, 454 kg ha^-1 for a maize-wheat rotation in the north region, 328 kg ha^-1 for maize in the northwest region, 185 kg ha^-1 for single-rice in the mid-south region, 266 kg ha^-1 for double-rice in east region, and 229 kg ha^-1 for rice and wheat rotation in southwest region. There is a great potential for enhancing the crop yield by improving the SOC content in each region of China.
文摘Although the agriculture in Heilongjiang Province has develope poor historical basis and differences between rural and urban institutional fa d ct effectively in recent years, due to issues such as ors, the backward of the agricultural fundamental infrastructure is always the major obstacle in rural economic development of Heilongjiang Province, which prevents the advantage of agricultural production from being fully developed, leading to the increase rate of the grain yield to grow slowly. The backward reflects in the following aspects, the serious aging of water facilities, insufficient agricultural machinery and equipment, low leve of rural roads, lacking of research equipment, shortage of ecological protection facilities, and so on. Based on the latcr data of Heilongjiang Province, this paper analyzed the connection between agricultural fundamental infrastructure and grain yield by using the gray connected model, differentiated primary rural fundamental infrastructure from the secondary one, and provided some suggestions to develop rural areas
基金Supported by the Special Fund for General Project of Basic Scientific Research of Central Colleges (SWU1209457)
文摘On the basis of empirical data concerning " four agricultural subsidies" in Chongqing City,we establish panel data model to analyze the general effect of " four agricultural subsidies" on grain yield,and the structural effect of " four agricultural subsidies" on grain yield. Based on the F-test and Hausman test,we estimate the model using GLS or FGLS method. The results show that " four agricultural subsidies" have significant positive effect on grain yield; the structural effect of " four agricultural subsidies" on grain yield is different (comprehensive subsidies for means of agricultural production has the strongest effect on grain yield,followed by subsidies for promotion of improved variety of seed; the effect of subsidies for purchase of agricultural machinery on grain yield is not significant) . Therefore,governments at all levels should continue to strengthen the support efforts in " four agricultural subsidies" ,and continually optimize the structure to increase grain yield.
基金supported by the National Science and Technology Ministry (Nos. 2008BAK50B07 and 2007BAC29B05)the State Key Development Program for Basic Research of China (Grant No. 2006CB400503)
文摘An interdisciplinary investigation was conducted to assess the impact of climate change on grain yields using an economy-climate model (C-D-C). The model was formulated by incorporating climate factors into the classic Cobb-Douglas (C-D) economic production function model. The economic meanings of the model output elasticities are described and elucidated. The C-D-C model was applied to the assessment of the impact of climate change on grain yields in China during the past 20 years, from 1983 through 2002. In the study, the land of China was divided into eight regions, and both the C-D-C and C-D models were applied to each individual region. The results suggest that the C-D-C model is superior to the classic C-D model, indicating the importance of climate factors. Prospective applications of the C-D-C model are discussed.
文摘<span style="font-family:Verdana;">Modeling of irrigation methods </span><span style="font-family:Verdana;">is</span><span style="font-family:""><span style="font-family:Verdana;"> one of the most important techniques that contribute to the future of modern agriculture. This will conserve water as water scarcity is a major threat for agriculture. In this study, AquaCrop model was used to model different irrigation methods of maize in field trails in Al-Yousifya, 15 km Southwest of Baghdad. Field experiments were conducted for two seasons during 2016 and 2017 using five irrigation methods including furrow, surface drip and subsurface drip with three patterns of emitter depth (10, 20 and 30 cm) irrigation. AquaCrop simulations of biomass, grain yield, harvest index and water productivity were validated using different statistical parameters under the natural conditions obtained in the study area. For 2016 and 2017 seasons, results of R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> were 0.98 and 0.99, 0.99 and 0.99, 0.99 and 0.97, and 0.8 and 0.73 for biomass, grain yield, harvest index and water productivity, respectively. The study has conducted that simulation using AquaCrop is considered very efficient tool for modeling of different irrigation applications</span><span style="font-family:Verdana;"> for maize production under the existing conditions</span><span style="font-family:Verdana;"> in the central region of Iraq.
基金Project supported by the National Natural Science Foundation of China(No.10472061)Key Project of Shanghai Municipal Commission of Science and Technology(No.04JC14034)+1 种基金the Doctoral Foundation of Ministry of Education of China(No.20060280015)Shanghai Leading Academic Discipline Project(No.Y0103)
文摘The role-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline (NC) materials are treated as three-phase composites consisting of grain core phase, grain boundary (GB) phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.
文摘北方地区是中国主要的玉米种植区,在中国玉米总产和播种面积中占有较大比例,同时也是中国易发生干旱的地区,北方地区干旱常态化严重制约着该地区玉米的稳定发展。该文基于北方地区14个省(市、自治区)217个气象台站1961-2010年的逐日气象数据以及作物、土壤和田间管理资料,依据春玉米生长季内降水量并以100 mm为间隔将全区划分为6个区域(Ⅰ~Ⅵ),选取作物水分亏缺指数为农业干旱指标,基于验证后的农业生产系统模型(agricultural production systems simulator,APSIM),明确了各生育阶段不同等级干旱对春玉米产量的影响。研究结果表明,北方地区干旱造成春玉米减产率在空间上呈由西向东下降趋势,降水的空间分布直接导致了灾损程度在各区的差异,其中西部灌溉绿洲农业区雨养种植春玉米干旱风险非常大,需大力发展节水灌溉,而东部雨养农业区自然降水已基本满足春玉米生长发育需要,干旱对春玉米产量影响较小,在模拟过程中很难准确的反映出旱级对产量造成的差异影响。春玉米在拔节—抽雄阶段发生干旱会对产量造成比较严重的影响,该阶段4个等级干旱造成春玉米减产率的四分位区间分别为特旱(20.1%~33.6%)、重旱(12.0%~20.3%)、中旱(6.3%~15.2%)、轻旱(4.7%~11.6%)。