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- Abstract：The purpose of this study was to determine the effect of no-till and residue retention on carbon sequestration and yield in Chinese farmland. Based on 1 162 pairs of data from published literatures from 1995 to 2019, this study comprehensively analyzed the farmland ecology and production effect of no-till and residue retention. The results showed that: At the national scale(excluding Hong Kong and Macao Special Administrative Regions and Taiwan Province), considering the effect of tillage, 75. 00% of no-till experiments showed an increase in carbon sequestration rate, and 42. 70% showed an increase in yield; Considering the influence of straw, 88. 23% of residue retention experiments showed an increase in carbon sequestration rate and 79. 80% showed an increase in yield. Under the situation that no-till and residue retention were fully promoted, the carbon sequestration potential of no-till and residue retention could be increased up to 2. 22×1010 and 7. 00×1010 kg/year and with increases of 63. 90% and 7. 00%. The no-till and residue retention would increase the national grain output to 6. 09×108 and 6. 39×108 t, with increases of -1. 16% and 3. 72%. Regression analysis showed that the effects of no-till on crop yield and organic carbon were significantly correlated with the average temperature and clay content. The effects of residue retention on crop yield were very significantly correlated with experimental years, correlated with pH, and significantly correlated with clay content and pH. In general, compared with conventional tillage, the no-till and residue retention could significantly improve the carbon sequestration capacity of soil, but there were regional differences. Compared with conventional tillage, the no-till and residue retention increases the carbon sequestration rate in Region Ⅰ, Region Ⅱ and Region Ⅳ. In the future, the interaction effects between no-tillage and residue retention should be further explored to improve farmland ecology and increase crop yield.Keywords：no-till;residue retention;farmland;carbon sequestration;yield6|13|14<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore the physiological characteristics of the resistance to Tetranychus cinnabarinus, two cassava varieties ‘Xinxuan 048' and ‘GR4' were used as materials in this experiment. According to the observation on damaged to different cassavas, then evaluated its resistance, and determine the contents of soluble sugar, free proline, soluble protein, chlorophyll and tannin in leaves to analyze the relationship between cassava varieties with damage degree of T. cinnabarinus in the period of T. cinnabarinus hazards. The result showed that ‘Xinxuan 048' was resistant and ‘GR4' was susceptible to T. cinnabarinus with significant difference in disease index. Respectively, the ‘Xinxuan 048' had higher tannin and chlorophyll contents, but lower soluble sugar, soluble protein and free proline in leaves than those in ‘GR4'. There was significant negative correlation between chlorophyll and tannin contents and mite damage index, while there was significant positive correlation between free proline, soluble protein and soluble sugar and mite damage index. The cassava′s resistance to T. cinnabarinus was closely related to tannin and chlorophyll contents, soluble sugar, soluble protein and free proline in leaves, which could be used as main evaluation indicators for the resistance of cassava T. cinnabarinus.Keywords：cassava;Tetranychus cinnabarinus;resistance;inclusions;tannin;soluble sugar1|8|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to study the current situation of policy making and implementation of management of livestock and poultry manure in China, and put forward suggestions on the development of animal husbandry and the treatment and utilization of animal manure, the number of related literatures on animal manure in China published from 1980 to 2018 were summarized. The documents on livestock and poultry excrement management policies, plans and standards issued by the state government departments from 2000 to 2018(27), as well as the relevant regulations and standards issued by the provincial and municipal governments(78)were analyzed. The results showed that: The number of papers on livestock and poultry excrement in China(excluding Hong Kong and Macao Special Administrative Regions and Taiwan Province)was summarized from 1980 to 1997, and it was found that there was a slow upward trend, with the annual number of papers ranging from 1 to 23 per year. However, the number of papers published from 1998 to 2017 increased from 28 to 688 per year, which showed that the attention of livestock and poultry manure resources, utilization and pollution increased sharply during this period. The results of policy analysis showed that there were many problems in the management of livestock and poultry excrement policy, such as imperfect laws and regulations, inadequate supervision, lack of effective incentive mechanism, unreasonable regional planning, low cost of utilization and low level of livestock and poultry excrement treatment technology and so on. According to the actual situation of production and management of livestock and poultry manure at present, some suggestions were put forward, such as improving laws and regulations and standard system, building market trading mechanism and strengthening technical industry support and so on.Keywords：organic waste;resource utilization;environmental pollution;financial subsidies;planning;policy recommendations1|8|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To evaluate the effects of manure application rates and different cultivation histories on soil fungi communities in apple orchards, and provide valuable reference for playing the biological potential of fungi, soil samples collected from apple orchards of different tree ages and manure application rates in Beijing were taken as study material. High-throughput sequencing technologies were employed to analyze soil microbial properties. The relationships of soil fungal community with soil physic-chemical properties and fruit qualities were analyzed using the redundancy analysis(RDA). The results showed that: 1)In Beijing apple orchard, long-term manure application increased the soil organic matter and available nutrient(especially alkali-hydrolyzable N). 2)Under same manure application rate, the apple orchard soil fungal richness increased with the age of trees, the application rate of manure affected the soil fungal richness in young apple orchards and affected the diversity of soil fungi community in mature orchards. 3)The apple orchard soil fungal community was composed of seven types of phyla, and the dominant fungi at the phylum level were affiliated to Ascomycota and Basidiomycota. The proportion of these dominant fungi varied with the manure application rates, along with the increase of manure application, the relative abundance of Ascomycota increased, but the relative abundance of Basidiomycetes decreased. 4)RDA analysis showed that the relative abundance of Pseudallescheria, Chaetomium and Fusarium were significantly positively correlated with soil organic matter and available nutrition, and positively correlated with titratable acid and soluble sugar. In conclusion, the cultivation and manure application rate are the predominant factors which change the soil properties and also affected the soil fungi community structure.Keywords：apple orchard;cultivation history;manure application rates;soil fungi communities;soil property;fruit qualities4|13|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to realize the synchronous soil-covering function of orchard straw mulching(OSM)machine and solve the fire hazard in orchard and straw pileup due to wind or rain, a double-direction soil throwing-covering scheme was proposed. A novel structure of the throwing wheel was designed and its key parameters, the diameter, blade number and rotation speed, were determined. EDEM simulation software was used to analyze the influence law of trenching depth, speed and throwing angle of the throwing wheel on soil cover effect. Field soil covering tests were carried out with a single soil throwing wheel on a self-developed test bench. The results showed that the soil covering width within 152. 3-251. 3 cm, the thickness within 10. 4-18. 3 mm, the standard deviation within 1. 4-4. 1 mm, and the miss rate of 0 could meet the requirements of soil covering of orchard straw mulch layer. The coefficients of determination of the thickness and width models of the soil cover established with throwing angle, trenching depth and rotating speed, were higher than 0. 943 6 and 0. 932 2, respectively, indicating that the thickness and width models were well fitted.Keywords：orchard straw mulching;soil throwing wheel;soil covering;thickness;width;EDEM simulation1|8|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To investigate the relationship between cell wall components, enzyme activity and decay rate during sweetpotato storage roots storage. The storage roots of ‘Sushu 8', ‘Nanshu 88' and ‘Zheshu 13' were used as materials and stored in a fresh-keeping storehouse at 12 ℃ and a 85% humidity for 102 days. The cell wall components and enzyme activity were measured with samples taken at 0, 7, 15, 30, 45, 60, 81 and 102 d, respectively. The results showed that the soluble pectin content increased and the propectin content decreased during the storage period in the three varieties of sweetpotato storage roots. The content of cellulose(66. 53 mg/g)and lignin(26. 8 mg/g)of ‘Sushu 8' with good storage resistance were higher on the storage day, and the lignin content fluctuated little during the storage period. When the ‘Nanshu 88' of poor storage resistance began to rot, the activity of cellulase and hemicellulase reached peak values, which were respectively 5 209. 02 and 18 486. 91 μg/(g·h). Furthermore, when ‘Nanshu 88' was stored for 102 days, the activity of β-galactosidase was 2. 5 times higher than that of ‘Sushu 8'. Correlation analysis results showed that the decay rate was significantly positively correlated with β-galactosidase and weight loss rate, negatively correlated with lignin and positively correlated with cellulase. In conclusion, ‘Sushu 8' with good storage resistance has high lignin content, low hemicellulase and cellulase activity, and low and stable β-galactosidase activity in the middle and later stage of storage.Keywords：sweetpotato;storage;cell wall enzyme;lignin;decay rate1|8|6<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore the effect of nitrogen on the morphological traits of Chrysanthemum vestitum, and provide references for the improvement of chrysanthemum ornamental traits, a mixed petal type of C. vestitum was used as a test material to analyze the differences of various morphological traits of C. vestitum under nitrogen levels of 15, 30, 60 and 90 mg/L. The results showed that the plant height and leaf number of C. vestitum increased with the increase of nitrogen level at 96 d and the number of leaves eventually increased slowly until they stopped. The leaf length, leaf width and leaf length-to-width ratio showed a regular changing trend and the degree of cracking of the leaves edge increased as the nitrogen level increase. The flowering time was the earliest at the nitrogen level of 90 mg/Land the flowering time was the latest at the level of 15 mg/L, they were 22 days in between. The difference in the diameter of the inflorescence and the number of head flowers per plant was significant, and the number of head flowers was up to 29. 40 for 90 mg/L, and was the least for 15 mg/L, only 3. 50. The total number of lingual flowers and diameter of the flower of flat petals, petals, tube and single inflorescence of the lingual flower were not significantly different under different nitrogen levels, and the total number of lingual flowers were between 13 and 14. The S value distribution of the tongue flower was the most in the range of S∈(0. 00, 0. 25】 and S∈(0. 25, 0. 50】, followed by S∈(0. 50, 0. 75】, S=1. 00, S∈(0. 75, 1. 00), S=0. 00 was none. The results above indicated that the bud flower of the mixed petal type of C. vestitum had more or less cracking, and there were no complete closure. In summary, the overall growth status and rate of C. vestitum increased with the increase of nitrogen level in the vegetative growth stage. The reproductive indicators also showed differences especially in the flowering time and the number of flower head under different nitrogen levels, indicating nitrogen played an important role in the development of C. vestitum.Keywords：nitrogen level;Chrysanthemum vestitum;morphological traits;differences0|9|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to explore the appropriate protein level of milk replacer for yak calves, three milk replacers of different protein levels were used in this study to investigate their effects on the body weight and serum parameters of mountain yak calves during lactation period. Forty newborn male yaks in Dangxiong County were selected and randomly divided into four treatment groups(n=10). The calves in the control group were fed naturally by their mothers, and the calves in the test groups were fed with three yak milk replacers with protein content of 21. 95%(LP), 24. 28%(MP)and 26. 11%(HP), respectively. From age of 30 to 90 d, the body weight of yak calves was measured and their serum samples were collected at 30, 60 and 90 d of age. The results showed that the body weight of yak calves in the experimental groups were significantly higher than in the control group(P<0. 001). At 120 d of age, the body weight of yak in MP group was the highest, and there was a significant difference between the control group and HP group(P<0. 05). The GSH-Px activity in HP group was significantly higher than that of LP group. The contents of MDA and TNF-a in HP group were relatively low. And the IgG, IgM, ALT and AST levels were relatively high. In conclusion, the growth performance and serum index of yak were the best in the HP group with protein level of milk replacer 26%.Keywords：yak calves;milk replacer;serum;body weight0|8|6<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to investigate the pathogeny of Hu sheep in a farm of Sichuan Province, one affected Hu sheep was taken as the study case and its clinical symptoms and anatomical changes of diseased sheep were observed. The pathological changes of the parenchymal organs were analyzed by H. E. staining. Strain Z-1 was isolated from diseased sheep and identified by physiological and biochemical methods and 16S rDNA gene sequencing. The strain Z-1 was analyzed by animal feedback experiment and drug sensitivity test. The results showed that the sick sheep had high fever, severe cough and panting. Yellow thick secretions were observed around its mouth and nose. The anatomical changes displayed the tumefaction and congestion of multiple parenchymal organs including congestion of the lungs, dark red color, and bloody foamy fluid flowing out of the incision. The pathological tissue sections showed swelling, congestion, and bleeding of tissue cells such as lung, liver, and spleen; There were a large number of pink cellulose exudates and inflammatory cells in the alveolar space and bronchiole. The strain Z-1 was confirmed to be gram-positive bacteria. Its biochemical reactions to lactose, aescoside and sorbitol were positive, while reactions to newtol, mannose and melibiose were negative. The length of the target fragment of 16S rDNA gene was 1 428 bp, and its similarity with NR_026471 reached 98%. Therefore, it was comprehensively identified as Streptococcus. The animal feedback experiment displayed that the strain had strong pathogenicity to mice. The drug sensitivity tests showed that the bacterium was sensitive to ofloxacin, norfloxacin, ciprofloxacin and gentamicin, and resistant to ampicillin, penicillin and moxalactam. In summary, the diseased Hu sheep was suffered from Streptococcus infection of fibrinous pneumonia.Keywords：Hu sheep;fibrinous pneumonia;Streptococcus;histological observation;drug sensitive test0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to achieve rapid and nondestructive detection of lamb freshness, the total volatile basic nitrogen(TVB-N)prediction model was established for lamb with different storage days by hyperspectral imaging technology. Hyperspectral images of lamb samples in the near infrared(935-2 539 nm)regions were acquired by the hyperspectral imaging system. Taking the square of 20×20 pixels in the top left, bottom left, top right, bottom right and middle of the sample as the region of interest, the average spectrum of the sample was extracted and calculated. The hyperspectral characteristic variables of lamb TVB-N content were extracted using the binary particle swarm optimization(BPSO)and correlation coefficient(CC)method. Combining partial least squares regression(PLSR)with random forest regression(RFR)modeling algorithm, BPSO-PLSR, BPSO-RFR, CC-PLSR and CC-RFR prediction models for TVB-N content of lamb were established, respectively. In order to obtain the optimal numbers of regression subtrees and splitting features, the main parameters of the model were traversed and optimized according to the convergence for root mean square error of out-of-bag estimation. Comparing the prediction effects of the 4 models, BPSO-RFR prediction model achieved the highest accuracy. The R2c and RMSEC were 0. 87 and 2. 99 for calibration set, respectively, and the R2p and the RMSEP were 0. 86 and 3. 36 for prediction set, respectively. In short, the study demonstrated that hyperspectral imaging technology in combination with machine learning algorithm could effectively detect lamb freshness rapidly and non-destructively, and provide theoretical basis for developing rapid and effective detection method.Keywords：hyperspectral imaging;freshness;random forest regression;total volatile base nitrogen(TVB-N)2|11|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：This study aims to improve the purity of total triterpenoids of mycelium and fruiting body from Inonotus hispidus. The effect of organic solvent, height-to-diameter ratio(height of silica gel∶diameter of silica gel), sample mass-to-silica gel mass, and eluent ratio on purity of total triterpenoids were studied. Then, it is compared with other purification methods. The structure of total triterpenoids was analyzed by infrared spectroscopy. The bile salt binding abilities of the crude extract and the purified material were determined by in vitro simulation. The results showed that the optimal parameters were height-to-diameter ratio of 55∶22, sample mass-to-silica gel mass of 4∶80, acetone and petroleum ether as elution system with ratio of 3∶1. Under this condition, the highest purity of total triterpenoids extracted with ethyl acetate from mycelium and fruiting body were 65. 35% and 42. 32%, which were 4. 26 and 4. 60 times of total triterpenoids from the crude extract, respectively. This method attained the highest purity comparing with other results purified using macroporous resin and silica gel. Infrared spectroscopy analysis showed that there were differences between total triterpenoids from mycelium and fruiting body in —CH2, —CH3, —S-O, and etc, but they both conformed to the characteristic structure of triterpenoids. The bile salt binding ability of total triterpenoids was improved significantly after purification. The binding ability of total triterpenoids from mycelium with sodium cholate, sodium glycocholate and sodium taurocholate were the strongest. The highest values were 1. 14, 1. 78 and 2. 06 μmol/100 mg, which were respectively 1. 56, 1. 73 and 1. 72 times of crude extract from mycelium.Keywords：Inonotus hispidus;triterpenoids;purification;extraction;bile salt3|7|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to achieve the purpose of market control when a high proportion of energy micro grid with certain regulation ability is incorporated into a large distribution network or rural power grid. In this study, the incentive method of new energy micro grid participating in peak load regulation auxiliary service based on spot real-time balance market is used to study the incentive effect of new energy micro grid participating in peak load regulation auxiliary service under the market mechanism environment of spot real-time balance. Through example verification, the real-time equilibrium market clearing results show that under the incentive scenario of new energy micro grid participating in peak regulation, both the unit assessment cost and the peak regulation compensation cost are reduced, and the peak regulation revenue is increased by 55. 27%. In this study, by combining the assessment index of grid connected generating units to provide peak load regulation auxiliary services is proposed. The incentive method of new energy micro grid participating in peak load regulation auxiliary services in assessment and incentive link is added and it can effectively stimulate the potential and willingness of market peak load regulation subjects and ensure the safe and stable operation of the grid.Keywords：new energy microgrid;real-time balance;peak shaving;incentive mechanism0|8|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To investigate the effects of exogenous microorganisms on the fractions variation of heavy metals during composting, this study carried out a composting experiment in a self-made closed composting reactor. The inoculums of Trichoderma longibrachiatum(T1), Bacillus amylolyticus(T2)and Saccharomyces cerevisiae(T3)were used in the raw materials pig manure and corn straw with the initial C/N ratio of 25 and water content of 60%. The results showed that, inoculums shortened the time by 3, 3 and 1 days to reach 60 ℃, and prolonged the duration time of high temperature. T. longibrachiatum and B. amylolyticus shortened the maturity process by 14 days compared with the control. At the same time, the inoculums reduced the effectiveness of heavy metals Cu, Zn and Pb in compost products, among which B. amylolyticus had the best effectiveness on reduction of the availability of Cu, Zn and Pb, with the relative passivation rates 80. 96%, 5. 02% and 41. 00%, respectively. T. longibrachiatum reduced the effectiveness of Cu and Pb, with the relative passivation rates 67. 09% and 5. 01%, respectively. While S. cerevisiae had the relative passivation rates of 64. 46% and 11. 51% respectively. Therefore, suitable inoculants could improve the quality of compost and passivate the heavy metal availability simultaneously.Keywords：microorganisms;composting;heavy metals;morphological change;passivation3|15|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To understand the effects of different biochars on phosphate isotherm adsorption in soil, the biochars were prepared with peach wood, peanut hull and maize straw by slow pyrolysis at 300 and 500 ℃ respectively. The harvested biochars were then amended into red soil and alluvial soil at the rates of 0%, 0. 5%, 1%, 3% and 5%(M/M). Following four times of wetting and air-drying cycle, the isothermal adsorption characters for phosphate were determined by adding series of phosphate solution. The results showed that phosphate adsorption in all soil samples could be simulated by Langmuir equation. Adding activated carbon significantly reduced the isothermal adsorption parameters in both red and alluvial soils. However, biochar supplementation generally enhanced the maximum adsorption capacity(qm)of red soil by 11% on average, while decreased by 30% on average in alluvial soil. Furthermore, the values of KL and maximum buffer capacity(MBC)were respectively increased by 179% and 69% on average in the biochar-added alluvial soil. This study showed that the impacts of biochar amendment on isothermal adsorption of phosphate largely depended not only on soil, but also biochar and its addition rates. The relationships among qm, KL and MBC reflected such complexity. Further work is required to understand related mechanisms.Keywords：biochar;red soil;alluvial soil;phosphate;isothermal adsorption3|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To study future spatial scientific planning and reduce regional ecological risks, this study measures the level of spatial conflicts in Kunming based on ecological security and explores its influencing factors. Based on the spatial analysis method of ArcGIS, risk source-risk receptor-risk effect risk assessment model and geographic detector model, the changes in the intensity of land and space conflicts in Kunming from 1995 to 2015 were detected, and its dominant drivers and interactions were researched. The results showed that: 1)In general, the average spatial conflict intensity of Kunming City in 1995, 2005 and 2015 was characterized by low before and high after, which were respectively 0. 188, 0. 190 and 0. 206, and in a stable and controllable range. The level of conflict ecological security was high, but the spatial area of severely out of control areas kept increasing year by year, and the area of controllable areas was decreasing year by year; 2)Different spatial landscape types had large differences in the intensity of spatial conflicts. Among them, the spatial conflict intensity of forest land, grassland and cultivated land was low, while the spatial conflict intensity of water area, construction land and unused land was relatively high; 3)The results for geographical detection factor detector indicated that population and GDP were the main spatial conflicts in the study area. The interactive detector further explained the combinations of population and GDP, population and elevation, population and the distance from the road, which showed great synergy and regional spatial conflict.Keywords：Kunming City;spatial conflict;conflict intensity;ecological security;geographic detector1|8|11<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to formulate an optimal canal water distribution schedule which satisfies the actual conditions of canal system operation and soil moisture demand for crop growth, this study coupled the canal water distribution optimization model and soil moisture simulation model to build a two-level canal water distribution optimization model based on canal water transfer simulation and soil water balance simulation. Improved genetic algorithm was used to solve the Pareto optimal set, two-level canal in Xigan irrigation district in the middle reaches of Heihe River basin was taken as the research area. A total of 50 non-inferior optimal canal water distribution schemes were obtained. Three groups of representative schemes were selected on Pareto frontier for comparative analysis. The best scheme was then compared with actual irrigation scheme. The results showed that Pareto optimal set could reflect the tradeoff between the targets. When the weight deviated to the minimum target of water distribution, it affected the soil water content and other indicators, and the yield would decrease. When the weight deviated to the maximum yield target, it would cause the water waste. However, when the weight was in the middle level, both the yield and water distribution targets were well met, and compare with the actual irrigation scheme, the amount of water decrease by 1. 135 4 million m3 and the total yield increase by 660 t. The weight in the middle level achieved the effect of saving water and increasing yield. In this model, the tradeoff between the two targets was based on both canal system operating conditions and soil water content, and the results of Pareto optimal set could satisfy the different demands of decision makers for targets. This study provided theoretical basis and guidance for the decision making of various managers in irrigation district.Keywords：optimal canal water resource allocation;canal water transfer simulation;soil water balance;genetic algorithm;Pareto optimal set3|8|6<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To quantitatively study the resource-based city urbanization level and its contribution to the development of China urbanization, a total of 126 national resource-based prefecture-level cities(mainland China only)are taken as the research object. The basic situation of the resource-based city urbanization development since the reform and opening-up is analyzed and based on the results, the contribution of the urbanization development of resource-based cities to the urbanization development of China is investigated. The result shows that: 1)The urbanization levels of resource-based cities in four regions are unbalanced. The urbanization rate in northeast China keeps a leading level but has the lowest growth rate. The urbanization rate in eastern China is the fastest, but the average annual growth rate in all regions is in decline and the growth rate is slowing down. 2)The contribution of urbanization development of resource-based prefecture-level cities to China's urbanization development is between 0. 48 and 0. 90. Among them, 0. 79% of resource-based cities have medium contribution to China's urbanization, 40. 48% of resource-based cities have relatively high contribution to China's urbanization, and 58. 73% of resource-based cities have high contribution to China's urbanization. 3)In terms of resource types in resource-based city, the resource-based cities with metalloid, metal, coal and oil-gas which account for more than 50% of their respective total, show high contribution to China's urbanization. While the number of forest resource-based cities has a high contribution to China's urbanization, which is less than one third of the total. In terms of spatial distribution, the urbanization of resource-based cities in the east and central regions contributes more to China's urbanization development than that in the northeast and western regions. The development of China's urbanization has been promoted by the urbanization of resource-based cities, and different types and locations of resource-based cities have different contributions to China's urbanization.Keywords：resource-based city;urbanization;grey relational analysis;contribution1|6|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Threshold model and spatial durbin model were used in this study to explore the threshold effects and spatial spillovers of urbanization on chemical fertilizer non-point source pollution based on a panel data of 31 provinces from 2000-2016(the statistic data of Hongkong. Macao, Taiwan Region are not included, the same below. ). The results showed that the chemical fertilizer non-point source pollution showed a dynamic evolution that was transferred from the east to the west. The impacts of urbanization on chemical fertilizer non-point source pollution displayed single threshold effect. When the income per capita was reaching threshold value, the impacts of urbanization on chemical fertilizer non-point source pollution changed from expansion effects to quality effects, namely, from promoting to restraining. The impacts of urbanization on chemical fertilizer non-point source pollution showed great spillover effects, which was larger than the direct effects caused by urbanization to the province itself. The rapid development of urbanization in one province might cause chemical fertilizer non-point source pollution to be passed on to its neighboring provinces.Keywords：urbanization;chemical fertilizer non-point source pollution;threshold effects;spatial spillovers5|8|6<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：By applying Stochastic Frontier gravity model, the potential efficiency of wool import trade between China and 15 major import countries is analyzed, and the social environmental factors that affect the inefficiency of China's wool import trade is deconstructed from five dimensions of social environment. The results show that: In general, China's wool import efficiency differs among different importing countries and has a certain loss of efficiency. The efficiencies of import trade from Australia and New Zealand is higher, which are 0. 72 and 0. 68, respectively. Most of other countries are below 0. 5. Social environmental factors strongly explain the reasons for the loss of wool import efficiency: Improvement of trade relations, increase of trade share of importing countries, enlargement of difference of recognition level and stability of political environment in partner countries have positively promoted the improvement of wool import trade efficiency in China. Finally, to improve the efficiency of wool import trade and optimize domestic wool production, corresponding policy suggestions on expanding wool import channels, promoting regional trade agreement negotiations and trade facilitation construction, and promoting domestic high-quality wool production are put forward.Keywords：trade;social environment;wool;random frontier;import efficiency1|9|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：By using emergy theory and economic analysis methods, the sustainability of ecological and economic of three kinds of production patterns of greenhouses vegetable in Beijing, including suburbs, farmers with conventional management(FC), enterprise with conventional management(EC)and enterprise with organic management(EO), were evaluated. The results showed as follows: 1)In terms of emergy evaluation, the annual total value of emergy input in EO pattern was 6. 81×1016 sej/hm2, which was lower than FC(1. 19×1017 sej/hm2)and EC(8. 53×1016 sej/hm2); The emergy investment ratio of EO pattern was 44. 20, which was 2. 41 times and 3. 81 times of FC and EC patterns; The environment load ratio of EO was 2. 14, which was lower than FC(3. 76)and EC(6. 29)patterns; The emergy sustainable index of EO was 0. 48, which was higher than 0. 28 for FC and 0. 19 for EC. 2)In terms of economic aspect, the unit profit of EO(1. 45×106 yuan/hm2)was much higher than FC(3. 34×105 yuan/hm2)and EC(negative profit). In conclusion, based on the comprehensive evaluation of ecologic and economic consequences, the EO is more sustainable among three production and operation patterns of greenhouse vegetables in Beijing suburbs.Keywords：emergy;cost-benefit analysis;greenhouse vegetable;organic agriculture;production and management patterns2|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to investigate the fertilizer's demand price elasticity in China's corn and cabbage production, the elasticity of substitution between fertilizer and labor, between fertilizer and machinery, translog cost function model and equations of shadow elasticity of substitution based on theoretical analysis were constructed by using the factor input and price data of corn and cabbage from 2004-2016. The results showed that: Various price variables such as fertilizer price, labor price and machinery price had significant effect on the amount of fertilizer input in corn production. Fertilizer price variable had significant effect on fertilizer input in cabbage production. The fertilizer's elasticity of demand of both corn and cabbage was in a low elasticity range, the fertilizer's elasticity of demand of cabbage was higher than that of corn. Currently, there were compensation relationship between fertilizer and labor input in China's corn production and an alternative relationship between fertilizer and labor input in cabbage production. There were strong alternative relationship between fertilizer and labor in corn production and compensation relationship between fertilizer and labor of cabbage.Keywords：agricultural production factors;fertilizer;demand price elasticity;elasticity of substitution;corn;cabbage0|8|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
