[Objective] The aim was to overview the emission of greenhouse gases in farmland. [Method] Based on domestic and foreign references, production mechanism, discharging characters and major influential factors of CO2, C...[Objective] The aim was to overview the emission of greenhouse gases in farmland. [Method] Based on domestic and foreign references, production mechanism, discharging characters and major influential factors of CO2, CH4 and N2O in soils of farmland were overviewed. [Result] Production and discharge of CO2, CH. and N2O played an important role in circulation of carbon and nitrogen in terrestrial ecosystem and constituted a key method for carbon and nitrogen output. It is significant to conduct research on reduction of greenhouse gas and increase of absorption. [Conclusion] The research is beneficial for exploration on discharge rule and influential factors of greenhouse gases, providing theoretical references for reduction of greenhouse gases and study on climate change.展开更多
A pot experiment with a sandy loam soil and spring wheat as test crop was conducted to compare the N2O emission from soil system with plant cut off and from soil-plant system with plant kept. The results showed that a...A pot experiment with a sandy loam soil and spring wheat as test crop was conducted to compare the N2O emission from soil system with plant cut off and from soil-plant system with plant kept. The results showed that after urea fertilizer applied, the N2O emission from soil and soil-wheat system decreased exponentially with time, and its total amount was 0.34%~0.63% and 0.33%~0.58% of applied urea-N respectively, no significant difference being found between these two systems. The N2O emission had a very significant negative relationship (P = 0.01) with the biomass of wheat plant. A combined application of urease inhibitor hydroquinone and nitrification inhibitor dicyandiamide could reduce the N2O emission by 50%~83% and 46%~74%, respectivelyl from soil and soil-wheat system. The N2O was mainly produced and emitted from soil, and the soil biochemical regulation, i.e., applying related inhibitors into soil could effectively diminish the urea derived N2O emission.展开更多
Rural off-farm employment,rapid loss of agricultural land,and advanced technology popularization had led agricultural production in Chinese typical rural areas come at a critical transformation and upgrade stage.Based...Rural off-farm employment,rapid loss of agricultural land,and advanced technology popularization had led agricultural production in Chinese typical rural areas come at a critical transformation and upgrade stage.Based on sample survey data gathered from 401 households in Yucheng City,Shandong Province,this paper focuses on the characteristics and mechanism of agricultural transformation in typical rural areas of the eastern China.It was found that 74.3% of households surveyed kept at least one member engaging in off-farm employment,and 57.1% looked forward to expanding the operational scale of arable land,while just 13.7% had actually transferred their agricultural land.Since growing off-farm employment does not result in the collapse of traditional subsistence agriculture,therefore,agricultural production in Yucheng City is at an incomplete transformation phase from traditional small-holder farming to modern scale economy.It is caused by both macro environments and family characteristics,while urban-rural dual structure,imperfect rural development policy and agricultural technology popularization make peasant economy strengthen upon maintenance,and small-holder farming becomes peasant's natural response owing to pluriactivity,local off-farm employment,reverse elimination,etc.In order to achieve smooth agricultural transformation of typical rural areas in the eastern China,it needs to promote professional differentiation among peasants,under clear policies adopted by central government.Providing comprehensive services for agricultural production and improving production skills and knowledge of farmers who are still living in the countryside will effectively stimulate the process of agricultural transformation.展开更多
Both the labor shortage that began in 2000 and the wave of migrant workers returning to the countryside in 2009 sparked intense debates among scholars about whether China had reached the Lewis turning point. Based on ...Both the labor shortage that began in 2000 and the wave of migrant workers returning to the countryside in 2009 sparked intense debates among scholars about whether China had reached the Lewis turning point. Based on agricultural economics and the dual-sector model the author conducted an empirical analysis and arrived at the followingfive conclusions. First, the dual economy is structured differently among agricultural industrial sectors and regions. Second, surplus labor still exists in the backyard stockbreeding sector (hogs, beef cattle, sheep, and dairy cattle), implying that it has still not passed the first turning point. Third, the sector of production of staple food grains and minor cereals has passed the shortage point, but is still far from the commercialization point. Fourth, cash crop production has passed out of the subsistence sector into the capitalist sector. Fifth, regional differences are stark. the majority of China's eastern region is either approaching or has surpassed the commercialization point, whereas the central and western regions have not.展开更多
Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a s...Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a summer maize field using the dataset obtained in the North China Plain with eddy covariance technique. The performances of the LS-SVMs were compared to the corresponding models obtained with radial basis function (RBF) neural networks. The results indicated the trained LS-SVMs with a radial basis function kernel had satisfactory performance in modelling surface fluxes; its excellent approximation and generalization property shed new light on the study on complex processes in ecosystem.展开更多
The diamondback moth, Plutella xylostella L., has developed resistance to most insecticides used for its management. Suggested alternatives to forestall this process include biorational insecticides in mixtures with l...The diamondback moth, Plutella xylostella L., has developed resistance to most insecticides used for its management. Suggested alternatives to forestall this process include biorational insecticides in mixtures with low-risk insecticides. The aim of this study was to select an insecticide or insecticide mixture that could be adopted by small-scale growers for diamondback moth management. The effectiveness of four insecticide mixtures, i.e., Agroneem Plus (neem-derived), Spinosad (microbial origin), thiamethoxam (neonicotinoid) and a homemade methanol Jalapefio pepper extract, in laboratory bioassays was evaluated. Binary mixtures were tested against single products at manufacturer's label rates. These were applied to collard greens using the leaf dip method and fed to the newly molted 2nd or 3rd instar larvae. Mixtures were evaluated for efficacy based on larval mortality and consumption of leaf discs. The results showed interactions between Jalapefio pepper extract and Spinosad and between the neem-derived Agroneem Plus and thiamethoxam at some of the tested concentrations. Mixtures with at any amount of Spinosad killed all larvae. The neem-based product gave inconsistent results in some treatments; in some case, increased leaf damage did not result in commensurate larval mortalities. The reported resistance of diamondback moth larvae to Spinosad was not observed during this study, neither with Spinosad alone nor in mixtures.展开更多
Northeast China is an important agricultural region in China. The NortheastPlain is the largest plain in the country and one of the three famous black soil zones in the world.Despite of fertility of the soil, however,...Northeast China is an important agricultural region in China. The NortheastPlain is the largest plain in the country and one of the three famous black soil zones in the world.Despite of fertility of the soil, however, large-scale agricultural development mainly took placesince 1900. The land exploitation and utilization has been fast and intensive in this region sincethen and change in the land-cover process has been remarkable. Both national and internationalresearchers on land use and land cover are paying more attention to these processes in this regionand their implication for local ecological environment. This article discusses the land reclamationprocesses and their main driving forces in Northeast China since 1900. According to the research,the 20th century was the most important period for land reclamation in Northeast China. In theseyears the rate, intensity and quantity of land reclamation have been staggering, and more than 100000km^2 of land was converted into farmland. This magnitude of land reclamation inland is unique inthe world. Research on the land reclamation of Northeast China can provide some data on the effectof human activity on environment. As in many other places in the world, the primary driving force ofreclamation in Northeast China was the increasing pressure of population. In the 20th century thepopulation increased from 10 x 10~6 to 110 x 10~6 in Northeast China and from 400 x 10~6 to 1. 3 x10^9 in China. Population pressure is thus the most important driving force for land reclamation.展开更多
Forty-five rhizofungal isolates were isolated, identified and characterized from 11 herbicides polluted-soil. Among the isolates, 10 fungal species proved to be the most potent and promising ones in herbicides toleran...Forty-five rhizofungal isolates were isolated, identified and characterized from 11 herbicides polluted-soil. Among the isolates, 10 fungal species proved to be the most potent and promising ones in herbicides tolerance. The herbicides exhibited severe and dramatic effect and modulation on fungal DNA and protein represented in DNA and protein profile. Severely loss in the total soluble cell ions (SCI) and total cell protein percentage (TCPC) concentrations were observed. The loss of SCI by glyphosate, Aspergillus flavus (86,30%) was the most affected one, followed by Penicillium spiculisporus (76,30%), Penicilliurn verruculosum (64.40%) and Alternaria tenuissima (64%), respectively. For pendimethalin, Alternaria tenuissima (54.01%) was the most affected fungi. For diclofop-methyl, Penicillium spiculisporus (74.20%) was the most affected fungi. The loss of TCPC by glyphosate, Alternaria tenuissima (64.71%) was the most effected fungi, followed by Penicillium spiculisporus (57.14%), respectively. For pendimethalin, A. terreus (54.29%) w, as the most affected fungi. For diclofop-methyl, Penicillium spiculisporus (60%) was the most affected fungi, fbllowed by Alternaria tenuissima (58.82%), Aspergillus tamarii (55.56%), respectively. The results proved severe reductions and alteration in protein, SCI, TCPC and DNA in fungal strains exposed to these herbicides which might reflex a degree of tolerance occurred during the assimilation of those toxic compounds from the pesticides polluted-soil.展开更多
Based on urban-rural contrast coefficient,this article designs the agriculture relative development index(ARDI) as indicators measuring the intensity of urban-rural dual structure which is comparable among the countri...Based on urban-rural contrast coefficient,this article designs the agriculture relative development index(ARDI) as indicators measuring the intensity of urban-rural dual structure which is comparable among the countries of the world.This article calculates ARDI of 40 countries from 1980 to 2004.The result shows that ARDI in the developed countries and most of the middle-income countries are rising and yet there are declines in most of the low-income countries.The result also showed that most countries' ARDI will see a decline at the earlier stage of industrialization,so their dual economic structure will also aggravate and urban-rural gap will widen.With the economic development,the tendency will change and ARDI presents a U-shape change overall.The turning point is when a country becomes a middle-income one.展开更多
Intensity of tillage practices can enhance organic matter decomposition, increasing CO2 emissions from soil to the atmosphere. Conservation tillage (CT) has been proposed as a means of counteracting potential damage...Intensity of tillage practices can enhance organic matter decomposition, increasing CO2 emissions from soil to the atmosphere. Conservation tillage (CT) has been proposed as a means of counteracting potential damages to the environment. In this study the effects of two CT systems, reduced tillage in a long-term experiment (RTL) and no-tillage in a short-term experiment (NTs), were compared to traditional tillage (TT) in the long (TTL) and short-term experiments (TTs). CO2 fluxes, total soil organic carbon (SOC) and dehydrogenase activity (DHA) were evaluated at 0-5, 5-10 and 10-15 cm depths throughout the three years studied (Oct. 2006 Jul. 2009). Traditional tillage increased C02 emissions compared to CT. The CT treatments (RTL and NTs) accumulated more SOC in the surface layer (0 5 cm) than the TT treatments (TTL and TTs). SOC accumulation was moderate but DHA consistently increased in CT in the surface soil, especially with a legume crop included in the crop rotation. Values of stratification ratio of all parameters studied were higher in the CT treatments (RTL and NTs). The agricultural and environmental benefits derived from CT make this system recommendable for semi-arid Mediterranean rain-fed agriculture.展开更多
Lunar titanium characterization is an important goal of the China Lunar Exploration Program. We suggest a method to determine the lunar titanium abundance using Chang'E-1 IIM (Interference Imaging Spectrometer) im...Lunar titanium characterization is an important goal of the China Lunar Exploration Program. We suggest a method to determine the lunar titanium abundance using Chang'E-1 IIM (Interference Imaging Spectrometer) imagery. Using samples from Apollo and Luna landing sites, the method firstly establishes the spectral parameters that possess good non-linear correlations with lunar titanium abundance. Secondly, the method estimates lunar titanium abundance using a DT-SVM (Decision Tree Method C5.0-Support Vector Machine) method. Namely, according to the established spectral parameters, it uses the C5.0 algorithm to classify the titanium abundance into the 4 classes of very low, low, intermediate and high. Then, in terms of the spectral parameters and the corresponding classes, it employs the SVM to estimate the titanium abundance. The method makes good use of hyperspectral information, analyzes the nonlinear correlations between spectral characteristics of lunar soils and the composition parameter, and well determines the titanium abundance. Validated by the Apollo and Luna station samples, the RMSE (root mean square error) is 0.72wt% TiO2 and the correlation coefficient of the measured and predicted values is 97.29%. So, the method proposed in this paper has a good predictive capability for TiO2 abundance on the lunar surface. The maps of TiO2 content in the partial region of Sinus Iridium, the Apollo 17 landing site and the Apollo 16 landing site are constructed by our method. This paper demonstrates the potential of IIM data for the investigation of lunar surface chemistry and mineralogy.展开更多
基金Supported by the Special R&D Fund for Public Welfare IndustryApplication of Remote Sensing Technology in Agrometeorological Forecast(GYHY201106027)~~
文摘[Objective] The aim was to overview the emission of greenhouse gases in farmland. [Method] Based on domestic and foreign references, production mechanism, discharging characters and major influential factors of CO2, CH4 and N2O in soils of farmland were overviewed. [Result] Production and discharge of CO2, CH. and N2O played an important role in circulation of carbon and nitrogen in terrestrial ecosystem and constituted a key method for carbon and nitrogen output. It is significant to conduct research on reduction of greenhouse gas and increase of absorption. [Conclusion] The research is beneficial for exploration on discharge rule and influential factors of greenhouse gases, providing theoretical references for reduction of greenhouse gases and study on climate change.
基金the National Natural Science Foundation of China (No. 39730110) and the Ministryof Foreign Affairs, Belgium (ABOS) through "VL
文摘A pot experiment with a sandy loam soil and spring wheat as test crop was conducted to compare the N2O emission from soil system with plant cut off and from soil-plant system with plant kept. The results showed that after urea fertilizer applied, the N2O emission from soil and soil-wheat system decreased exponentially with time, and its total amount was 0.34%~0.63% and 0.33%~0.58% of applied urea-N respectively, no significant difference being found between these two systems. The N2O emission had a very significant negative relationship (P = 0.01) with the biomass of wheat plant. A combined application of urease inhibitor hydroquinone and nitrification inhibitor dicyandiamide could reduce the N2O emission by 50%~83% and 46%~74%, respectivelyl from soil and soil-wheat system. The N2O was mainly produced and emitted from soil, and the soil biochemical regulation, i.e., applying related inhibitors into soil could effectively diminish the urea derived N2O emission.
基金Under the auspices of National Natural Science Foundation of China (No 40635029, 40771014)National Key Technologies R&D Program of China (No 2006BAB15B05)
文摘Rural off-farm employment,rapid loss of agricultural land,and advanced technology popularization had led agricultural production in Chinese typical rural areas come at a critical transformation and upgrade stage.Based on sample survey data gathered from 401 households in Yucheng City,Shandong Province,this paper focuses on the characteristics and mechanism of agricultural transformation in typical rural areas of the eastern China.It was found that 74.3% of households surveyed kept at least one member engaging in off-farm employment,and 57.1% looked forward to expanding the operational scale of arable land,while just 13.7% had actually transferred their agricultural land.Since growing off-farm employment does not result in the collapse of traditional subsistence agriculture,therefore,agricultural production in Yucheng City is at an incomplete transformation phase from traditional small-holder farming to modern scale economy.It is caused by both macro environments and family characteristics,while urban-rural dual structure,imperfect rural development policy and agricultural technology popularization make peasant economy strengthen upon maintenance,and small-holder farming becomes peasant's natural response owing to pluriactivity,local off-farm employment,reverse elimination,etc.In order to achieve smooth agricultural transformation of typical rural areas in the eastern China,it needs to promote professional differentiation among peasants,under clear policies adopted by central government.Providing comprehensive services for agricultural production and improving production skills and knowledge of farmers who are still living in the countryside will effectively stimulate the process of agricultural transformation.
文摘Both the labor shortage that began in 2000 and the wave of migrant workers returning to the countryside in 2009 sparked intense debates among scholars about whether China had reached the Lewis turning point. Based on agricultural economics and the dual-sector model the author conducted an empirical analysis and arrived at the followingfive conclusions. First, the dual economy is structured differently among agricultural industrial sectors and regions. Second, surplus labor still exists in the backyard stockbreeding sector (hogs, beef cattle, sheep, and dairy cattle), implying that it has still not passed the first turning point. Third, the sector of production of staple food grains and minor cereals has passed the shortage point, but is still far from the commercialization point. Fourth, cash crop production has passed out of the subsistence sector into the capitalist sector. Fifth, regional differences are stark. the majority of China's eastern region is either approaching or has surpassed the commercialization point, whereas the central and western regions have not.
基金Project supported by the National Science Fund for OutstandingYouth Overseas (No. 40328001) and the Key Research Plan of theKnowledge Innovation Project of the Institute of Geographic Sciencesand Natural Resources, Chinese Academy of Sciences (No.KZCXI-SW-01)
文摘Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a summer maize field using the dataset obtained in the North China Plain with eddy covariance technique. The performances of the LS-SVMs were compared to the corresponding models obtained with radial basis function (RBF) neural networks. The results indicated the trained LS-SVMs with a radial basis function kernel had satisfactory performance in modelling surface fluxes; its excellent approximation and generalization property shed new light on the study on complex processes in ecosystem.
文摘The diamondback moth, Plutella xylostella L., has developed resistance to most insecticides used for its management. Suggested alternatives to forestall this process include biorational insecticides in mixtures with low-risk insecticides. The aim of this study was to select an insecticide or insecticide mixture that could be adopted by small-scale growers for diamondback moth management. The effectiveness of four insecticide mixtures, i.e., Agroneem Plus (neem-derived), Spinosad (microbial origin), thiamethoxam (neonicotinoid) and a homemade methanol Jalapefio pepper extract, in laboratory bioassays was evaluated. Binary mixtures were tested against single products at manufacturer's label rates. These were applied to collard greens using the leaf dip method and fed to the newly molted 2nd or 3rd instar larvae. Mixtures were evaluated for efficacy based on larval mortality and consumption of leaf discs. The results showed interactions between Jalapefio pepper extract and Spinosad and between the neem-derived Agroneem Plus and thiamethoxam at some of the tested concentrations. Mixtures with at any amount of Spinosad killed all larvae. The neem-based product gave inconsistent results in some treatments; in some case, increased leaf damage did not result in commensurate larval mortalities. The reported resistance of diamondback moth larvae to Spinosad was not observed during this study, neither with Spinosad alone nor in mixtures.
文摘Northeast China is an important agricultural region in China. The NortheastPlain is the largest plain in the country and one of the three famous black soil zones in the world.Despite of fertility of the soil, however, large-scale agricultural development mainly took placesince 1900. The land exploitation and utilization has been fast and intensive in this region sincethen and change in the land-cover process has been remarkable. Both national and internationalresearchers on land use and land cover are paying more attention to these processes in this regionand their implication for local ecological environment. This article discusses the land reclamationprocesses and their main driving forces in Northeast China since 1900. According to the research,the 20th century was the most important period for land reclamation in Northeast China. In theseyears the rate, intensity and quantity of land reclamation have been staggering, and more than 100000km^2 of land was converted into farmland. This magnitude of land reclamation inland is unique inthe world. Research on the land reclamation of Northeast China can provide some data on the effectof human activity on environment. As in many other places in the world, the primary driving force ofreclamation in Northeast China was the increasing pressure of population. In the 20th century thepopulation increased from 10 x 10~6 to 110 x 10~6 in Northeast China and from 400 x 10~6 to 1. 3 x10^9 in China. Population pressure is thus the most important driving force for land reclamation.
文摘Forty-five rhizofungal isolates were isolated, identified and characterized from 11 herbicides polluted-soil. Among the isolates, 10 fungal species proved to be the most potent and promising ones in herbicides tolerance. The herbicides exhibited severe and dramatic effect and modulation on fungal DNA and protein represented in DNA and protein profile. Severely loss in the total soluble cell ions (SCI) and total cell protein percentage (TCPC) concentrations were observed. The loss of SCI by glyphosate, Aspergillus flavus (86,30%) was the most affected one, followed by Penicillium spiculisporus (76,30%), Penicilliurn verruculosum (64.40%) and Alternaria tenuissima (64%), respectively. For pendimethalin, Alternaria tenuissima (54.01%) was the most affected fungi. For diclofop-methyl, Penicillium spiculisporus (74.20%) was the most affected fungi. The loss of TCPC by glyphosate, Alternaria tenuissima (64.71%) was the most effected fungi, followed by Penicillium spiculisporus (57.14%), respectively. For pendimethalin, A. terreus (54.29%) w, as the most affected fungi. For diclofop-methyl, Penicillium spiculisporus (60%) was the most affected fungi, fbllowed by Alternaria tenuissima (58.82%), Aspergillus tamarii (55.56%), respectively. The results proved severe reductions and alteration in protein, SCI, TCPC and DNA in fungal strains exposed to these herbicides which might reflex a degree of tolerance occurred during the assimilation of those toxic compounds from the pesticides polluted-soil.
基金Under the auspices of the Key Project of National Natural Science Foundation of China (Grant no. 40635029)
文摘Based on urban-rural contrast coefficient,this article designs the agriculture relative development index(ARDI) as indicators measuring the intensity of urban-rural dual structure which is comparable among the countries of the world.This article calculates ARDI of 40 countries from 1980 to 2004.The result shows that ARDI in the developed countries and most of the middle-income countries are rising and yet there are declines in most of the low-income countries.The result also showed that most countries' ARDI will see a decline at the earlier stage of industrialization,so their dual economic structure will also aggravate and urban-rural gap will widen.With the economic development,the tendency will change and ARDI presents a U-shape change overall.The turning point is when a country becomes a middle-income one.
基金Supported by the Interministerial Commission for Science and Technology(CICYT)of Spain(No.AGL2010-22050-C03-03)
文摘Intensity of tillage practices can enhance organic matter decomposition, increasing CO2 emissions from soil to the atmosphere. Conservation tillage (CT) has been proposed as a means of counteracting potential damages to the environment. In this study the effects of two CT systems, reduced tillage in a long-term experiment (RTL) and no-tillage in a short-term experiment (NTs), were compared to traditional tillage (TT) in the long (TTL) and short-term experiments (TTs). CO2 fluxes, total soil organic carbon (SOC) and dehydrogenase activity (DHA) were evaluated at 0-5, 5-10 and 10-15 cm depths throughout the three years studied (Oct. 2006 Jul. 2009). Traditional tillage increased C02 emissions compared to CT. The CT treatments (RTL and NTs) accumulated more SOC in the surface layer (0 5 cm) than the TT treatments (TTL and TTs). SOC accumulation was moderate but DHA consistently increased in CT in the surface soil, especially with a legume crop included in the crop rotation. Values of stratification ratio of all parameters studied were higher in the CT treatments (RTL and NTs). The agricultural and environmental benefits derived from CT make this system recommendable for semi-arid Mediterranean rain-fed agriculture.
基金supported by the National Natural Science Foundation of China (Grant No. 40902099)the Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan) (Grant No. CUG100702)
文摘Lunar titanium characterization is an important goal of the China Lunar Exploration Program. We suggest a method to determine the lunar titanium abundance using Chang'E-1 IIM (Interference Imaging Spectrometer) imagery. Using samples from Apollo and Luna landing sites, the method firstly establishes the spectral parameters that possess good non-linear correlations with lunar titanium abundance. Secondly, the method estimates lunar titanium abundance using a DT-SVM (Decision Tree Method C5.0-Support Vector Machine) method. Namely, according to the established spectral parameters, it uses the C5.0 algorithm to classify the titanium abundance into the 4 classes of very low, low, intermediate and high. Then, in terms of the spectral parameters and the corresponding classes, it employs the SVM to estimate the titanium abundance. The method makes good use of hyperspectral information, analyzes the nonlinear correlations between spectral characteristics of lunar soils and the composition parameter, and well determines the titanium abundance. Validated by the Apollo and Luna station samples, the RMSE (root mean square error) is 0.72wt% TiO2 and the correlation coefficient of the measured and predicted values is 97.29%. So, the method proposed in this paper has a good predictive capability for TiO2 abundance on the lunar surface. The maps of TiO2 content in the partial region of Sinus Iridium, the Apollo 17 landing site and the Apollo 16 landing site are constructed by our method. This paper demonstrates the potential of IIM data for the investigation of lunar surface chemistry and mineralogy.