This paper summarizes crop straw utilization policies at abroad from the aspects of investment support policies,tax revenue and unsecured loan policies,and reviewed China s crop straw utilization policies from the asp...This paper summarizes crop straw utilization policies at abroad from the aspects of investment support policies,tax revenue and unsecured loan policies,and reviewed China s crop straw utilization policies from the aspects of technical training,project subsidies,straw collection,storage and transportation system construction and socialized service system construction.Combined with the actual situation of Xinjiang,this paper puts forward policy formulation suggestions on crop straw comprehensive utilization.展开更多
This paper introduces in detail the current situation of crop straw resources and comprehensive utilization in Liaoning Province and the basic situation of enterprises using crop straw to produce organic fertilizers.I...This paper introduces in detail the current situation of crop straw resources and comprehensive utilization in Liaoning Province and the basic situation of enterprises using crop straw to produce organic fertilizers.In addition,it analyzes in detail the problems existing in the production of organic fertilizers in Liaoning Province,and finally comes up with some recommendations for using crop straw to produce organic fertilizers.展开更多
Utilizing straw as feed and applying cattle and sheep manure fertilizer to the field plays an important role in solving the shortage of feed raw material resources,alleviating the conflict between human beings and liv...Utilizing straw as feed and applying cattle and sheep manure fertilizer to the field plays an important role in solving the shortage of feed raw material resources,alleviating the conflict between human beings and livestock,and realizing the full utilization of straw as a resource and green and low-carbon circular development.We carried out an investigation on the feed utilization of crop straw in Sichuan Province,comprehensively grasped the crop straw resources and its utilization as feed in this province,deeply analyzed the existing problems,and put forward countermeasures and suggestions according to the actual situation in Sichuan,which plays an important role in accelerating the process of straw feed utilization,promoting green development,implementing the rural revitalization strategy,and building a beautiful Sichuan.展开更多
A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter(OM) during composting of sewage sludge. The four crop straws included rape straw, wheat str...A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter(OM) during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances(HS), fulvic-like acids(FA) and humic-like acids(HA) were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. T he maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg^(–1), respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.展开更多
Five crop straws (wheat, rice, maize, oil-rape, and cotton) were first steam-exploded for 2 min at 210℃, 2.5 MPa and then pyrolyzed at 500℃ for 2 h. Steam explosion (SE) induced 47–95% and 5–16% reduction of hemic...Five crop straws (wheat, rice, maize, oil-rape, and cotton) were first steam-exploded for 2 min at 210℃, 2.5 MPa and then pyrolyzed at 500℃ for 2 h. Steam explosion (SE) induced 47–95% and 5–16% reduction of hemicellulose and cellulose, respectively, in the crop straws. The biochars derived from SE-treated feedstocks had a lower specific surface area (SSA) and pore volume, compared to those from pristine feedstocks, with one exception that SE enhanced SSA of oil-rape straw biochar by approximately 16 times. After SE, biochars had significant higher anion exchange capacity (AEC) (6.88–11.44 cmol kg–1) and point of zero net charges (PZNC) (pH 3.61–5.32) values. It can thus be speculated that these biochars may have higher potential for anions adsorption. In addition, oil-rape straw might be suitable to SE pretreatment for preparing biochar as a soil amendment and sorbent as well. Further work is required for testing its application in soil.展开更多
Spring maize is one of the most popular crops planted in northeastern China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high ...Spring maize is one of the most popular crops planted in northeastern China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high rates of nitrogen(N) fertilizers application could have introduced a great amount of nitrous oxide(N2O) into the atmosphere. It is crucial for sustaining the maize production systems to reduce N2O emissions meanwhile maintaining the optimum yields by adopting alternative farming management practices. The goal of this study was to evaluate effects of alternative fertilization and crop residue management practices on N2O emission as well as crop yield for a typical maize field in northeastern China. Field experiments were conducted during the 2010-2011 maize growing seasons(from early May to late September) in Liaoning Province, northeastern China. N2O fluxes were measured at the field plots with six different treatments including no N fertilizer use(CK), farmers' conventional N fertilizer application rate(FP), reduced N fertilizer rate(OPT), reduced N fertilizer rate combined with crop straw amendment(OPTS), slow-release N fertilizer(CRF), and reduced N fertilizer rate combined with nitrification inhibitor(OPT+DCD). The static chamber method combined with gas chromatography technique was employed to conduct the measurements of N2O fluxes. The field data showed that N2O emissions varied across the treatments. During the maize growing season in 2010, the total N2O emissions under the treatments of CK, FP, OPT, OPTS, and CRF were 0.63, 1.11, 1.03, 1.26, and 0.98 kg N ha-1, respectively. The seasonal cumulative N2O emissions were 0.54, 1.07, 0.96, 1.12, and 0.84 kg N ha-1, respectively, under CK, FP, OPT, OPTS, and OPT+DCD in 2011. In comparison with FP, CRF or OPT+DCD reduced the N2O emissions by 12 or 21%, respectively, while the crop yields remained unchanged. The results indicate that the reduction of N-fertilizer application rate in combination with the slow-release fertilizer type or nitrification inhibitor could effectively mitigate N2O emissions from the tested field. The incorporation of crop residue didn't show positive effect on mitigating N2O emissions from the tested cropping system. The field study can provide useful information for the on-going debate on alternative N fertilization strategies and crop straw management in China. However, further studies would be needed to explore the long-term impacts of the alternative management practices on a wide range of environmental services.展开更多
Returning crop straw to the field not only improves the nitrogen(N) supplying capacity and N retention of soil but also decreases the amount of rural organic waste and prevents air pollution. Therefore, understanding ...Returning crop straw to the field not only improves the nitrogen(N) supplying capacity and N retention of soil but also decreases the amount of rural organic waste and prevents air pollution. Therefore, understanding the mechanisms of the N release and re-adsorption dynamics on crop straw residue during straw decomposition in agricultural soil is important, and this understanding can help us strengthen N fertilizer management during the crop growth period. An on-farm incubation experiment was conducted in the Jianghan Plain in Central China under flooded conditions using the nylon mesh bag method. Results showed that the decomposition rate of crop straw was much faster at the beginning of the incubation stage, whereas it was steady during the later stage with no observed differences among the three types of crop straw. After 120 d of incubation, the cumulative decomposition proportion of rice straw, wheat straw and rape straw was 72.9, 56.2, and 66.9%, respectively. The proportion of N that released from the three crop straws was 52.0, 54.4 and 54.9%, respectively. The zeta potentials and Brunauer, Emmett and Teller(BET) surface area of the rice, wheat and rape straw residues increased gradually as the decomposition period progressed. The water adsorption capacity of the rice straw was significantly affected during the decomposition period. The saturated water adsorption capacity of rice straw was the highest at 30 d of decomposition(4.17 g g^–1) and then decreased slightly. The saturated water adsorption of wheat and rape straws reached the lowest value at 30 d and then gradually increased and became stable. All the results demonstrated that crop straw and straw residue can re-adsorb NH4^+ ions from the surrounding solution. The re-adsorption was affected by the decomposition period and concentration of exogenous NH4^+ and was independent of the crop species via the combined efforts of physical and chemical adsorption, ion exchange and water retention on residue surfaces. Future studies will focus on straw returning and N fertilizer application at different levels of moisture content of the soil reduce potential negative effects such as water-logging and excess N caused by the straw substrate.展开更多
Crop residue is a major source of soil organic matter;therefore,application of crop straw to soil contributes to the sustainable development of organic agriculture.To better understand the transformation of crop straw...Crop residue is a major source of soil organic matter;therefore,application of crop straw to soil contributes to the sustainable development of organic agriculture.To better understand the transformation of crop straw in orchard soils,we investigated the relationship between the characteristics of straw decomposition and functional diversity of associated microbial communities in a long-term peach orchard,China.Mesh bags,each containing 30 g of corn or bean straw,were buried at a soil depth of 20 cm in a 12-year-old peach orchard for 360 d(October 2011–October 2012).Three treatments were applied,i.e.,fresh corn straw,fresh corn straw with nitrogen fertilizer(urea,10.34 g/kg),and fresh bean straw.Changes in straw residual rate,straw water content and soil conditions were monitored after treatment.The functional diversity of straw-associated microbial communities was analyzed by the Biolog-Eco microplate assay.During the decomposition process,straw residual rates did not vary considerably from 10 d(30.4%–45.4%)to 360 d(19.0%–30.3%).Irrespective of nitrogen addition,corn straw decomposed faster than bean straw.Corn straw with nitrogen fertilizer yielded the highest average well color development(AWCD)values(1.11–1.67),followed by corn straw(1.14–1.68)and bean straw(1.18–1.62).Although the AWCD values did not differ significantly among the three treatments,substantial differences occurred across various time periods of the decomposition process(P<0.01).In terms of carbon source utilization,the dominant microbial groups fed mainly on saccharides.Hard-to-decompose substances gradually accumulated in the middle and late stages of straw decomposition.Of the six categories of carbon sources tested,the utilization rate of aromatics was the lowest with corn straw,whereas that of polymers was the lowest with bean straw.Among different treatments,straw residual rate was negatively correlated to soil available phosphorous,soil available potassium and soil temperature(P<0.05),but not to soil water content.In some cases(corn straw with or without nitrogen fertilizer),straw residual rate was negatively correlated to straw water content,amino acid utilization and carboxylic acid utilization,and positively correlated with microbial species richness and evenness(P<0.05).Microbial community associated with corn and bean straw decomposition in soil was respectively dominated by aromatic-and polymer-metabolizing groups during the middle and late stages of this process,which could reduce the stability of microbial community structure and decrease the rate of straw decomposition in the fruit tree orchard.展开更多
To realize the straw biomass industrialized development,it should speed up building crop straw resource recycle logistics network, increasing straw recycle efficiency,and reducing straw utilization cost. On the basis ...To realize the straw biomass industrialized development,it should speed up building crop straw resource recycle logistics network, increasing straw recycle efficiency,and reducing straw utilization cost. On the basis of studying straw recycle process,this paper presents innovative concept and property of straw recycle logistics network,analyses design thinking of straw recycle logistics network,and works out straw recycle logistics mode and network topological structure. Finally,it comes up with construction and operation strategies of the straw logistics network from infrastructure,organization network,and information platform.展开更多
Straw return is a promising strategy for managing soil organic carbon(SOC)and improving yield stability.However,the optimal straw return strategy for sustainable crop production in the wheat(Triticum aestivum L.)-cott...Straw return is a promising strategy for managing soil organic carbon(SOC)and improving yield stability.However,the optimal straw return strategy for sustainable crop production in the wheat(Triticum aestivum L.)-cotton(Gossypium hirsutum L.)cropping system remains uncertain.The objective of this study was to quantify the long-term(10 years)impact of carbon(C)input on SOC sequestration,soil aggregation and crop yields in a wheat-cotton cropping system in the Yangtze River Valley,China.Five treatments were arranged with a single-factor randomized design as follows:no straw return(Control),return of wheat straw only(Wt),return of cotton straw only(Ct),return of 50%wheat and 50%cotton straw(Wh-Ch)and return of 100%wheat and 100%cotton straw(Wt-Ct).In comparison to the Control,the SOC content increased by 8.4 to 20.2%under straw return.A significant linear positive correlation between SOC sequestration and C input(1.42-7.19 Mg ha^(−1)yr^(−1))(P<0.05)was detected.The percentages of aggregates of sizes>2 and 1-2 mm at the 0-20 cm soil depth were also significantly elevated under straw return,with the greatest increase of the aggregate stability in the Wt-Ct treatment(28.1%).The average wheat yields increased by 12.4-36.0%and cotton yields increased by 29.4-73.7%,and significantly linear positive correlations were also detected between C input and the yields of wheat and cotton.The average sustainable yield index(SYI)reached a maximum value of 0.69 when the C input was 7.08 Mg ha^(−1)yr^(−1),which was close to the maximum value(SYI of 0.69,C input of 7.19 Mg ha^(−1)yr^(-1))in the Wt-Ct treatment.Overall,the return of both wheat and cotton straw was the best strategy for improving SOC sequestration,soil aggregation,yields and their sustainability in the wheat-cotton rotation system.展开更多
Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSP...Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.展开更多
In addition to their value as cereal grains, wheat (Triticum aestivum L.) and triticale (× Triticosecale Wittmack) are important cool-season annual forages and cover crops. Yearling steer (Bos taurus) performance...In addition to their value as cereal grains, wheat (Triticum aestivum L.) and triticale (× Triticosecale Wittmack) are important cool-season annual forages and cover crops. Yearling steer (Bos taurus) performance was compared in the spring following autumn establishment as for age cover crops after soybean [Glycine max (L.) Merr.] grain harvest. Replicated pastures (0.4 ha) were no-till seeded in three consecutive years into soybean stubble in autumn, fertilized, and grazed the following spring near Ithaca, NE, USA. Each pasture (n = 3) was continuously stocked in spring with four yearling steers (380 ± 38 kg) for 17, 32, and 28 d in 2005, 2006, and 2007, respectively. In 2005, average daily gain (ADG) for steers grazing triticale exceeded the ADG for wheat by 0.31 kghd<sup>-1</sup>d<sup>-1</sup>. In 2006, wheat ADG exceeded that for triticale by 0.12 kghd<sup>-1</sup>d<sup>-1</sup>. In 2007, steers grazing wheat lost weight, while steers grazing triticale gained 0.20 kghd<sup>-1</sup>d<sup>-1</sup>. Based on the 3-year average animal gains valued at $1.32 kg<sup>-1</sup>, mean net return ($ ha<sup>-1</sup> yr<sup>-1</sup>) was $62.15 for triticale and $22.55 for wheat. Since these grazed cover crops provide ecosystem services in addition to forage, grazing could be viewed as a mechanism for recovering costs and adds additional value to the system. Based on this 3-year grazing trial, triticale was superior to wheat and likely will provide the most stable beef yearling performance across years with variable weather for the western Cornbelt USA.展开更多
Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far o...Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far only a few studies have assessed the performance of GGCMs in China, and these studies mainly focused on the average and interannual variability of national and regional yields. Here, a systematic national-and provincial-scale evaluation of the simulations by13 GGCMs [12 from the GGCM Intercomparison(GGCMI) project, phase 1, and CLM5-crop] of the yields of four crops(wheat, maize, rice, and soybean) in China during 1980–2009 was carried out through comparison with crop yield statistics collected from the National Bureau of Statistics of China. Results showed that GGCMI models generally underestimate the national yield of rice but overestimate it for the other three crops, while CLM5-crop can reproduce the national yields of wheat, maize, and rice well. Most GGCMs struggle to simulate the spatial patterns of crop yields. In terms of temporal variability, GGCMI models generally fail to capture the observed significant increases, but some can skillfully simulate the interannual variability. Conversely, CLM5-crop can represent the increases in wheat, maize, and rice, but works less well in simulating the interannual variability. At least one model can skillfully reproduce the temporal variability of yields in the top-10 producing provinces in China, albeit with a few exceptions. This study, for the first time, provides a complete picture of GGCM performance in China, which is important for GGCM development and understanding the reliability and uncertainty of national-and provincial-scale crop yield prediction in China.展开更多
Biogasification of coal is important for clean utilization of coal. Experiments on the fermentation of single lignite, single straw and their mixture were performed to explore the variation characteristics of gas prod...Biogasification of coal is important for clean utilization of coal. Experiments on the fermentation of single lignite, single straw and their mixture were performed to explore the variation characteristics of gas production potential, microbial community and methanogenic metabolic pathways of mixture. Research has shown that mixed fermentation of lignite and straw significantly promoted biomethane production. The abundance of hydrolytic acidifying functional bacteria genera (Sphaerochaeta, Lentimicrobium) in mixed fermentation was higher than that in the fermentation of single lignite and single straw. The abundance of some key CAZy metabolic enzyme gene sequences in mixed fermentation group was increased, which was favorable to improve methane production. Aceticlastic methanogenesis was the most critical methanogenic pathway and acetic acid pathway was more competitive in methanogenic mode during peak fermentation. Macrogenomics provided theoretical support for the claim that mixed fermentation of coal and straw promoted biomethane metabolism, which was potentially valuable in expanding methanogenesis from mixed fermentation of lignite with different biomasses.展开更多
Birds are a huge hazard to agriculture all around the world,causing harm to profitable field crops.Growers use a variety of techniques to keep them away,including visual,auditory,tactile,and olfactory deterrents. This...Birds are a huge hazard to agriculture all around the world,causing harm to profitable field crops.Growers use a variety of techniques to keep them away,including visual,auditory,tactile,and olfactory deterrents. This study presents a comprehensive overview of current bird repellant approaches used in agricultural contexts,as well as potential new ways. The bird repellent techniques include Internet of Things technology,Deep Learning,Convolutional Neural Network,Unmanned Aerial Vehicles,Wireless Sensor Networks and Laser biotechnology. This study’s goal is to find and review about previous approach towards repellent of birds in the crop fields using various technologies.展开更多
Annual forage legumes are important components of livestock production systems in East Texas and the southeastern US. Forage legumes contribute nitrogen (N) to cropping systems through biological N fixation, and their...Annual forage legumes are important components of livestock production systems in East Texas and the southeastern US. Forage legumes contribute nitrogen (N) to cropping systems through biological N fixation, and their seasonal biomass production can be managed to complement forage grasses. Our research objectives were to evaluate both warm- and cool-season annual forage legumes as green manure for biomass, N content, ability to enhance soil organic carbon (SOC) and soil N, and impact on post season forage grass crops. Nine warm-season forage legumes (WSL) were spring planted and incorporated as green manure in the fall. Forage rye (Secale cereale L.) was planted following the incorporation of WSL treatments. Eight cool-season forage legumes (CSL) were fall planted in previously fallow plots and incorporated as green manure in late spring. Sorghum-sudangrass (Sorghum bicolor x Sorghum bicolor var. sudanense) was planted over all treatments in early summer after forage rye harvest and incorporation of CSL treatments. Sorghum-sudangrass was harvested in June, August and September, and treatments were evaluated for dry matter and N concentration. Soil cores were taken from each plot, split into depths of 0 to 15, 15 to 30 and 30 to 60 cm, and soil C and N were measured using combustion analysis. Nylon mesh bags containing plant samples were buried at 15 cm and used to evaluate decomposition rate of above ground legume biomass, including change in C and N concentrations. Mungbean (Vigna radiata L. [Wilczek]) had the highest shoot biomass yield (6.24 t DM ha<sup>-1</sup>) and contributed the most total N (167 kg∙ha<sup>-1</sup>) and total C (3043 kg∙ha<sup>-1</sup>) of the WSL tested. Decomposition rate of WSL biomass was rapid in the first 10 weeks and very slow afterward. Winter pea (Pisum sativum L. spp. sativum), arrow leaf clover (Trifolium vesiculosum Savi.), and crimson clover (Trifolium incarnatum L.) were the most productive CSL in this trial. Austrian winter pea produced 8.41 t DM ha<sup>-1</sup> with a total N yield of 319 kg N ha<sup>-1</sup> and total C production of 3835 kg C ha<sup>-1</sup>. The WSL treatments had only small effects on rye forage yield and N concentration, possibly due to mineralization of N from a large SOC pool already in place. The CSL treatments also had only minimal effects on sorghum-sudangrass forage production. Winter pea, arrow leaf and crimson clover were productive cool season legumes and could be useful as green manure crops. Mungbean and cowpea (Vigna unguiculata [L.] Walp.) were highly productive warm season legumes but may include more production risk in green manure systems due to soil moisture competition.展开更多
An in vitro study was conducted to investigate the impacts of microplastics on enzyme activities and soil bacteria. The study included four different treatments of microplastics including a control. Different levels o...An in vitro study was conducted to investigate the impacts of microplastics on enzyme activities and soil bacteria. The study included four different treatments of microplastics including a control. Different levels of microplastics were applied to the soil ranging from 0% to 5%, to assess the impacts of microplastics on soil enzymes and subsequent soil bacteria. After 30 days of incubation, the soil samples were collected and growth parameters of bacteria were assessed. Activities of β-glucosidase, urease and dehydrogenase enzymes were also determined. Our results showed that the presence of microplastics in the soil significantly reduced bacterial population together with bacterial strains. The activities of β-glucosidase, urease and dehydrogenase enzymes were reduced significantly to approximately 32%, 40% and 50% in microplastics treated soils respectively. Concentration of microplastic has a role to play towards this direction;the higher the concentration of microplastic the greater is the impact on enzymes and soil bacteria. The present study on the microbial soil health vis-à-vis microplastic application indicates that the material can have negative effect on the soil bacterial population of and thus ultimately may jeopardize soil health and crop production.展开更多
This study evaluated eight different types of heat supply modes based on crop residues utilization in the rural area of Northern China,including straw densified solid fuel combustion,pyrolysis char combustion,biogas c...This study evaluated eight different types of heat supply modes based on crop residues utilization in the rural area of Northern China,including straw densified solid fuel combustion,pyrolysis char combustion,biogas combustion,and pyrolysis gas combustion for single household heating;straw densified solid fuel combustion,baling straw combustion,biogas combustion,and pyrolysis gas combustion for centralized heating;centralized gas supply and centralized pyrolysis gas supply modes.Comprehensively evaluation was the cost of these different eight heat supply modes.The results showed that the cost of straw densified solid fuel combustion,pyrolysis char combustion for single household heating were 2346 RMB/household and 2390 RMB/household.With the heating scale of 200-500 households,the pipe network distance was 8 m/household,and the total annual heating cost was predicted at 2201-2992 RMB/household.Among them,the cost of straw baling combustion for centralized heating was the lowest,the cost of densified solid fuel,biogas,and pyrolysis for centralized heating was the second,and the cost of biogas and pyrolysis gas for centralized gas supply was the highest.For the increase in every 1 m of the pipeline distance,the investment cost will increase by about 645 RMB for each household.This study provides a basis for the implementation of clean heat supply technologies in less-developed areas and guidance of village heat-supply subsidy policies.展开更多
Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000― 2003 from the...Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000― 2003 from the government statistics, taking into account the ratio of residue and grain, the total amount of crop straw production is estimated to be about 600 Tg per year, 76% of which are rice, wheat and corn straw. With reference to the data of living standards, the percentage of crop straw burnt in fields for counties are obtained and consequently the total amount of burnt straws is approximately 140 Tg/year. With the emission factors from literature and experiments, appropriate emission factors have been obtained. The total amounts of PM, SO_2, NO_x, NH_3, CH_4, BC, OC, VOC, CO, CO_2 emissions from field burning of crop straw in China are estimated. All emissions are presented at county level. Some pollutants, such as BC, VOC, OC, CO and CO_2, are contributing a major portion to the total emissions of China. This paper uses a map with resolution of 0.2°×0.2° to present the PM emissions distribution from crop straw burnt in 2003. The results show a significant regional unevenness of emissions, with larger amounts of pollutions coming from the provinces in eastern and northeast China. The regions with higher emissions per unit area are located as a belt stretching from northeast China to eastern China.展开更多
基金Supported by Natural Science Foundation of Xinjiang Autonomous Region(2021D01F06).
文摘This paper summarizes crop straw utilization policies at abroad from the aspects of investment support policies,tax revenue and unsecured loan policies,and reviewed China s crop straw utilization policies from the aspects of technical training,project subsidies,straw collection,storage and transportation system construction and socialized service system construction.Combined with the actual situation of Xinjiang,this paper puts forward policy formulation suggestions on crop straw comprehensive utilization.
文摘This paper introduces in detail the current situation of crop straw resources and comprehensive utilization in Liaoning Province and the basic situation of enterprises using crop straw to produce organic fertilizers.In addition,it analyzes in detail the problems existing in the production of organic fertilizers in Liaoning Province,and finally comes up with some recommendations for using crop straw to produce organic fertilizers.
基金Mutton Sheep High-Quality and High-Yield Forage Variety Selection and Production Application Post of Sichuan Mutton Sheep Innovation Team(sccxtd-2020-14).
文摘Utilizing straw as feed and applying cattle and sheep manure fertilizer to the field plays an important role in solving the shortage of feed raw material resources,alleviating the conflict between human beings and livestock,and realizing the full utilization of straw as a resource and green and low-carbon circular development.We carried out an investigation on the feed utilization of crop straw in Sichuan Province,comprehensively grasped the crop straw resources and its utilization as feed in this province,deeply analyzed the existing problems,and put forward countermeasures and suggestions according to the actual situation in Sichuan,which plays an important role in accelerating the process of straw feed utilization,promoting green development,implementing the rural revitalization strategy,and building a beautiful Sichuan.
基金funded by the the Key Technologied R&D Program of China during the 12th Five-Year Plan period (2013BAJ11B03)the Science & Technology Commission of Chongqing, China (CSTC, 2008AC7013)
文摘A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter(OM) during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances(HS), fulvic-like acids(FA) and humic-like acids(HA) were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. T he maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg^(–1), respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.
基金funded by the National Key Technology R&D Program of China(2015BAD05B03)
文摘Five crop straws (wheat, rice, maize, oil-rape, and cotton) were first steam-exploded for 2 min at 210℃, 2.5 MPa and then pyrolyzed at 500℃ for 2 h. Steam explosion (SE) induced 47–95% and 5–16% reduction of hemicellulose and cellulose, respectively, in the crop straws. The biochars derived from SE-treated feedstocks had a lower specific surface area (SSA) and pore volume, compared to those from pristine feedstocks, with one exception that SE enhanced SSA of oil-rape straw biochar by approximately 16 times. After SE, biochars had significant higher anion exchange capacity (AEC) (6.88–11.44 cmol kg–1) and point of zero net charges (PZNC) (pH 3.61–5.32) values. It can thus be speculated that these biochars may have higher potential for anions adsorption. In addition, oil-rape straw might be suitable to SE pretreatment for preparing biochar as a soil amendment and sorbent as well. Further work is required for testing its application in soil.
基金the National Natural Science Foundation of China(31270486)the Special Fund for Agriculture Scientific Non-Profit Research of China(201103039)+1 种基金the National Basic Research Program of China(2012CB417104)the National Nonprofit Institute Research Grant of Chinese Academy of Agricultural Sciences(IARRP-2014-402-15)
文摘Spring maize is one of the most popular crops planted in northeastern China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high rates of nitrogen(N) fertilizers application could have introduced a great amount of nitrous oxide(N2O) into the atmosphere. It is crucial for sustaining the maize production systems to reduce N2O emissions meanwhile maintaining the optimum yields by adopting alternative farming management practices. The goal of this study was to evaluate effects of alternative fertilization and crop residue management practices on N2O emission as well as crop yield for a typical maize field in northeastern China. Field experiments were conducted during the 2010-2011 maize growing seasons(from early May to late September) in Liaoning Province, northeastern China. N2O fluxes were measured at the field plots with six different treatments including no N fertilizer use(CK), farmers' conventional N fertilizer application rate(FP), reduced N fertilizer rate(OPT), reduced N fertilizer rate combined with crop straw amendment(OPTS), slow-release N fertilizer(CRF), and reduced N fertilizer rate combined with nitrification inhibitor(OPT+DCD). The static chamber method combined with gas chromatography technique was employed to conduct the measurements of N2O fluxes. The field data showed that N2O emissions varied across the treatments. During the maize growing season in 2010, the total N2O emissions under the treatments of CK, FP, OPT, OPTS, and CRF were 0.63, 1.11, 1.03, 1.26, and 0.98 kg N ha-1, respectively. The seasonal cumulative N2O emissions were 0.54, 1.07, 0.96, 1.12, and 0.84 kg N ha-1, respectively, under CK, FP, OPT, OPTS, and OPT+DCD in 2011. In comparison with FP, CRF or OPT+DCD reduced the N2O emissions by 12 or 21%, respectively, while the crop yields remained unchanged. The results indicate that the reduction of N-fertilizer application rate in combination with the slow-release fertilizer type or nitrification inhibitor could effectively mitigate N2O emissions from the tested field. The incorporation of crop residue didn't show positive effect on mitigating N2O emissions from the tested cropping system. The field study can provide useful information for the on-going debate on alternative N fertilization strategies and crop straw management in China. However, further studies would be needed to explore the long-term impacts of the alternative management practices on a wide range of environmental services.
基金This work was supported by the National Major Science and Technology Program for Water Pollution Control and Treatment[grant number 2017ZX07101001]the National Natural Science Foundation of China[grant numbers 41573079 and 41675144]the Chinese Academy of Sciences Pioneer Hundred Talents Program.
基金supported by the National Key Research & Development Program of China (2018YFD0200900)the Young and Middle-Aged Talents Project of Hubei Provincial Department of Education, China (Q20181303)the Open Fund of Key Laboratory of Fertilizer Utilization, Ministry of Agriculture and Rural Affairs, China (KLFAW201901)。
文摘Returning crop straw to the field not only improves the nitrogen(N) supplying capacity and N retention of soil but also decreases the amount of rural organic waste and prevents air pollution. Therefore, understanding the mechanisms of the N release and re-adsorption dynamics on crop straw residue during straw decomposition in agricultural soil is important, and this understanding can help us strengthen N fertilizer management during the crop growth period. An on-farm incubation experiment was conducted in the Jianghan Plain in Central China under flooded conditions using the nylon mesh bag method. Results showed that the decomposition rate of crop straw was much faster at the beginning of the incubation stage, whereas it was steady during the later stage with no observed differences among the three types of crop straw. After 120 d of incubation, the cumulative decomposition proportion of rice straw, wheat straw and rape straw was 72.9, 56.2, and 66.9%, respectively. The proportion of N that released from the three crop straws was 52.0, 54.4 and 54.9%, respectively. The zeta potentials and Brunauer, Emmett and Teller(BET) surface area of the rice, wheat and rape straw residues increased gradually as the decomposition period progressed. The water adsorption capacity of the rice straw was significantly affected during the decomposition period. The saturated water adsorption capacity of rice straw was the highest at 30 d of decomposition(4.17 g g^–1) and then decreased slightly. The saturated water adsorption of wheat and rape straws reached the lowest value at 30 d and then gradually increased and became stable. All the results demonstrated that crop straw and straw residue can re-adsorb NH4^+ ions from the surrounding solution. The re-adsorption was affected by the decomposition period and concentration of exogenous NH4^+ and was independent of the crop species via the combined efforts of physical and chemical adsorption, ion exchange and water retention on residue surfaces. Future studies will focus on straw returning and N fertilizer application at different levels of moisture content of the soil reduce potential negative effects such as water-logging and excess N caused by the straw substrate.
基金the Project of State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau,Chinese Academy of Sciences(A314021402-1916)the Key Project of the Ministry of Science and Technology of China(2017YFD0200200)the Innovative Engineering Project of Shaanxi Province,China(2016slkj-15)。
文摘Crop residue is a major source of soil organic matter;therefore,application of crop straw to soil contributes to the sustainable development of organic agriculture.To better understand the transformation of crop straw in orchard soils,we investigated the relationship between the characteristics of straw decomposition and functional diversity of associated microbial communities in a long-term peach orchard,China.Mesh bags,each containing 30 g of corn or bean straw,were buried at a soil depth of 20 cm in a 12-year-old peach orchard for 360 d(October 2011–October 2012).Three treatments were applied,i.e.,fresh corn straw,fresh corn straw with nitrogen fertilizer(urea,10.34 g/kg),and fresh bean straw.Changes in straw residual rate,straw water content and soil conditions were monitored after treatment.The functional diversity of straw-associated microbial communities was analyzed by the Biolog-Eco microplate assay.During the decomposition process,straw residual rates did not vary considerably from 10 d(30.4%–45.4%)to 360 d(19.0%–30.3%).Irrespective of nitrogen addition,corn straw decomposed faster than bean straw.Corn straw with nitrogen fertilizer yielded the highest average well color development(AWCD)values(1.11–1.67),followed by corn straw(1.14–1.68)and bean straw(1.18–1.62).Although the AWCD values did not differ significantly among the three treatments,substantial differences occurred across various time periods of the decomposition process(P<0.01).In terms of carbon source utilization,the dominant microbial groups fed mainly on saccharides.Hard-to-decompose substances gradually accumulated in the middle and late stages of straw decomposition.Of the six categories of carbon sources tested,the utilization rate of aromatics was the lowest with corn straw,whereas that of polymers was the lowest with bean straw.Among different treatments,straw residual rate was negatively correlated to soil available phosphorous,soil available potassium and soil temperature(P<0.05),but not to soil water content.In some cases(corn straw with or without nitrogen fertilizer),straw residual rate was negatively correlated to straw water content,amino acid utilization and carboxylic acid utilization,and positively correlated with microbial species richness and evenness(P<0.05).Microbial community associated with corn and bean straw decomposition in soil was respectively dominated by aromatic-and polymer-metabolizing groups during the middle and late stages of this process,which could reduce the stability of microbial community structure and decrease the rate of straw decomposition in the fruit tree orchard.
基金Supported by Qinglan Project of Jiangsu Colleges and Universities and General Program of Huaiyin Institute of Technology Scientific Research Foundation (No.:HGB0905)
文摘To realize the straw biomass industrialized development,it should speed up building crop straw resource recycle logistics network, increasing straw recycle efficiency,and reducing straw utilization cost. On the basis of studying straw recycle process,this paper presents innovative concept and property of straw recycle logistics network,analyses design thinking of straw recycle logistics network,and works out straw recycle logistics mode and network topological structure. Finally,it comes up with construction and operation strategies of the straw logistics network from infrastructure,organization network,and information platform.
基金supported by the National Natural Science Foundation of China(32071968)the Jiangsu Agricultural Science and Technology Innovation Fund,China(CX(22)2015))the Jiangsu Collaborative Innovation Center for Modern Crop Production,China。
文摘Straw return is a promising strategy for managing soil organic carbon(SOC)and improving yield stability.However,the optimal straw return strategy for sustainable crop production in the wheat(Triticum aestivum L.)-cotton(Gossypium hirsutum L.)cropping system remains uncertain.The objective of this study was to quantify the long-term(10 years)impact of carbon(C)input on SOC sequestration,soil aggregation and crop yields in a wheat-cotton cropping system in the Yangtze River Valley,China.Five treatments were arranged with a single-factor randomized design as follows:no straw return(Control),return of wheat straw only(Wt),return of cotton straw only(Ct),return of 50%wheat and 50%cotton straw(Wh-Ch)and return of 100%wheat and 100%cotton straw(Wt-Ct).In comparison to the Control,the SOC content increased by 8.4 to 20.2%under straw return.A significant linear positive correlation between SOC sequestration and C input(1.42-7.19 Mg ha^(−1)yr^(−1))(P<0.05)was detected.The percentages of aggregates of sizes>2 and 1-2 mm at the 0-20 cm soil depth were also significantly elevated under straw return,with the greatest increase of the aggregate stability in the Wt-Ct treatment(28.1%).The average wheat yields increased by 12.4-36.0%and cotton yields increased by 29.4-73.7%,and significantly linear positive correlations were also detected between C input and the yields of wheat and cotton.The average sustainable yield index(SYI)reached a maximum value of 0.69 when the C input was 7.08 Mg ha^(−1)yr^(−1),which was close to the maximum value(SYI of 0.69,C input of 7.19 Mg ha^(−1)yr^(-1))in the Wt-Ct treatment.Overall,the return of both wheat and cotton straw was the best strategy for improving SOC sequestration,soil aggregation,yields and their sustainability in the wheat-cotton rotation system.
基金supported by the Scientific and Innovative Action Plan of Shanghai(21N31900800)Shanghai Rising-Star Program(23QB1403500)+4 种基金the Shanghai Sailing Program(20YF1443000)Shanghai Science and Technology Commission,the Belt and Road Project(20310750500)Talent Project of SAAS(2023-2025)Runup Plan of SAAS(ZP22211)the SAAS Program for Excellent Research Team(2022(B-16))。
文摘Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.
文摘In addition to their value as cereal grains, wheat (Triticum aestivum L.) and triticale (× Triticosecale Wittmack) are important cool-season annual forages and cover crops. Yearling steer (Bos taurus) performance was compared in the spring following autumn establishment as for age cover crops after soybean [Glycine max (L.) Merr.] grain harvest. Replicated pastures (0.4 ha) were no-till seeded in three consecutive years into soybean stubble in autumn, fertilized, and grazed the following spring near Ithaca, NE, USA. Each pasture (n = 3) was continuously stocked in spring with four yearling steers (380 ± 38 kg) for 17, 32, and 28 d in 2005, 2006, and 2007, respectively. In 2005, average daily gain (ADG) for steers grazing triticale exceeded the ADG for wheat by 0.31 kghd<sup>-1</sup>d<sup>-1</sup>. In 2006, wheat ADG exceeded that for triticale by 0.12 kghd<sup>-1</sup>d<sup>-1</sup>. In 2007, steers grazing wheat lost weight, while steers grazing triticale gained 0.20 kghd<sup>-1</sup>d<sup>-1</sup>. Based on the 3-year average animal gains valued at $1.32 kg<sup>-1</sup>, mean net return ($ ha<sup>-1</sup> yr<sup>-1</sup>) was $62.15 for triticale and $22.55 for wheat. Since these grazed cover crops provide ecosystem services in addition to forage, grazing could be viewed as a mechanism for recovering costs and adds additional value to the system. Based on this 3-year grazing trial, triticale was superior to wheat and likely will provide the most stable beef yearling performance across years with variable weather for the western Cornbelt USA.
基金co-supported by the Guangdong Major Project of Basic and Applied Basic Research (Grant No. 2021B0301030007)the National Key Research and Development Program of China (Grant Nos. 2017YFA0604302 and 2017YFA0604804)+1 种基金the National Natural Science Foundation of China (Grant No. 41875137)the National Key Scientific and Technological Infrastructure project “Earth System Science Numerical Simulator Facility” (Earth Lab)。
文摘Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far only a few studies have assessed the performance of GGCMs in China, and these studies mainly focused on the average and interannual variability of national and regional yields. Here, a systematic national-and provincial-scale evaluation of the simulations by13 GGCMs [12 from the GGCM Intercomparison(GGCMI) project, phase 1, and CLM5-crop] of the yields of four crops(wheat, maize, rice, and soybean) in China during 1980–2009 was carried out through comparison with crop yield statistics collected from the National Bureau of Statistics of China. Results showed that GGCMI models generally underestimate the national yield of rice but overestimate it for the other three crops, while CLM5-crop can reproduce the national yields of wheat, maize, and rice well. Most GGCMs struggle to simulate the spatial patterns of crop yields. In terms of temporal variability, GGCMI models generally fail to capture the observed significant increases, but some can skillfully simulate the interannual variability. Conversely, CLM5-crop can represent the increases in wheat, maize, and rice, but works less well in simulating the interannual variability. At least one model can skillfully reproduce the temporal variability of yields in the top-10 producing provinces in China, albeit with a few exceptions. This study, for the first time, provides a complete picture of GGCM performance in China, which is important for GGCM development and understanding the reliability and uncertainty of national-and provincial-scale crop yield prediction in China.
文摘Biogasification of coal is important for clean utilization of coal. Experiments on the fermentation of single lignite, single straw and their mixture were performed to explore the variation characteristics of gas production potential, microbial community and methanogenic metabolic pathways of mixture. Research has shown that mixed fermentation of lignite and straw significantly promoted biomethane production. The abundance of hydrolytic acidifying functional bacteria genera (Sphaerochaeta, Lentimicrobium) in mixed fermentation was higher than that in the fermentation of single lignite and single straw. The abundance of some key CAZy metabolic enzyme gene sequences in mixed fermentation group was increased, which was favorable to improve methane production. Aceticlastic methanogenesis was the most critical methanogenic pathway and acetic acid pathway was more competitive in methanogenic mode during peak fermentation. Macrogenomics provided theoretical support for the claim that mixed fermentation of coal and straw promoted biomethane metabolism, which was potentially valuable in expanding methanogenesis from mixed fermentation of lignite with different biomasses.
文摘Birds are a huge hazard to agriculture all around the world,causing harm to profitable field crops.Growers use a variety of techniques to keep them away,including visual,auditory,tactile,and olfactory deterrents. This study presents a comprehensive overview of current bird repellant approaches used in agricultural contexts,as well as potential new ways. The bird repellent techniques include Internet of Things technology,Deep Learning,Convolutional Neural Network,Unmanned Aerial Vehicles,Wireless Sensor Networks and Laser biotechnology. This study’s goal is to find and review about previous approach towards repellent of birds in the crop fields using various technologies.
文摘Annual forage legumes are important components of livestock production systems in East Texas and the southeastern US. Forage legumes contribute nitrogen (N) to cropping systems through biological N fixation, and their seasonal biomass production can be managed to complement forage grasses. Our research objectives were to evaluate both warm- and cool-season annual forage legumes as green manure for biomass, N content, ability to enhance soil organic carbon (SOC) and soil N, and impact on post season forage grass crops. Nine warm-season forage legumes (WSL) were spring planted and incorporated as green manure in the fall. Forage rye (Secale cereale L.) was planted following the incorporation of WSL treatments. Eight cool-season forage legumes (CSL) were fall planted in previously fallow plots and incorporated as green manure in late spring. Sorghum-sudangrass (Sorghum bicolor x Sorghum bicolor var. sudanense) was planted over all treatments in early summer after forage rye harvest and incorporation of CSL treatments. Sorghum-sudangrass was harvested in June, August and September, and treatments were evaluated for dry matter and N concentration. Soil cores were taken from each plot, split into depths of 0 to 15, 15 to 30 and 30 to 60 cm, and soil C and N were measured using combustion analysis. Nylon mesh bags containing plant samples were buried at 15 cm and used to evaluate decomposition rate of above ground legume biomass, including change in C and N concentrations. Mungbean (Vigna radiata L. [Wilczek]) had the highest shoot biomass yield (6.24 t DM ha<sup>-1</sup>) and contributed the most total N (167 kg∙ha<sup>-1</sup>) and total C (3043 kg∙ha<sup>-1</sup>) of the WSL tested. Decomposition rate of WSL biomass was rapid in the first 10 weeks and very slow afterward. Winter pea (Pisum sativum L. spp. sativum), arrow leaf clover (Trifolium vesiculosum Savi.), and crimson clover (Trifolium incarnatum L.) were the most productive CSL in this trial. Austrian winter pea produced 8.41 t DM ha<sup>-1</sup> with a total N yield of 319 kg N ha<sup>-1</sup> and total C production of 3835 kg C ha<sup>-1</sup>. The WSL treatments had only small effects on rye forage yield and N concentration, possibly due to mineralization of N from a large SOC pool already in place. The CSL treatments also had only minimal effects on sorghum-sudangrass forage production. Winter pea, arrow leaf and crimson clover were productive cool season legumes and could be useful as green manure crops. Mungbean and cowpea (Vigna unguiculata [L.] Walp.) were highly productive warm season legumes but may include more production risk in green manure systems due to soil moisture competition.
文摘An in vitro study was conducted to investigate the impacts of microplastics on enzyme activities and soil bacteria. The study included four different treatments of microplastics including a control. Different levels of microplastics were applied to the soil ranging from 0% to 5%, to assess the impacts of microplastics on soil enzymes and subsequent soil bacteria. After 30 days of incubation, the soil samples were collected and growth parameters of bacteria were assessed. Activities of β-glucosidase, urease and dehydrogenase enzymes were also determined. Our results showed that the presence of microplastics in the soil significantly reduced bacterial population together with bacterial strains. The activities of β-glucosidase, urease and dehydrogenase enzymes were reduced significantly to approximately 32%, 40% and 50% in microplastics treated soils respectively. Concentration of microplastic has a role to play towards this direction;the higher the concentration of microplastic the greater is the impact on enzymes and soil bacteria. The present study on the microbial soil health vis-à-vis microplastic application indicates that the material can have negative effect on the soil bacterial population of and thus ultimately may jeopardize soil health and crop production.
基金The authors acknowledge that this work was financially supported by the Agricultural Science and Technology Innovation Program(CAAS-ASTIP),China Agriculture Research System(CARS-02),which enables us to complete field surveys and data analysis.
文摘This study evaluated eight different types of heat supply modes based on crop residues utilization in the rural area of Northern China,including straw densified solid fuel combustion,pyrolysis char combustion,biogas combustion,and pyrolysis gas combustion for single household heating;straw densified solid fuel combustion,baling straw combustion,biogas combustion,and pyrolysis gas combustion for centralized heating;centralized gas supply and centralized pyrolysis gas supply modes.Comprehensively evaluation was the cost of these different eight heat supply modes.The results showed that the cost of straw densified solid fuel combustion,pyrolysis char combustion for single household heating were 2346 RMB/household and 2390 RMB/household.With the heating scale of 200-500 households,the pipe network distance was 8 m/household,and the total annual heating cost was predicted at 2201-2992 RMB/household.Among them,the cost of straw baling combustion for centralized heating was the lowest,the cost of densified solid fuel,biogas,and pyrolysis for centralized heating was the second,and the cost of biogas and pyrolysis gas for centralized gas supply was the highest.For the increase in every 1 m of the pipeline distance,the investment cost will increase by about 645 RMB for each household.This study provides a basis for the implementation of clean heat supply technologies in less-developed areas and guidance of village heat-supply subsidy policies.
基金Supported by the National Key Basic Research Project of China (Grant No. 2006CB403700)
文摘Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000― 2003 from the government statistics, taking into account the ratio of residue and grain, the total amount of crop straw production is estimated to be about 600 Tg per year, 76% of which are rice, wheat and corn straw. With reference to the data of living standards, the percentage of crop straw burnt in fields for counties are obtained and consequently the total amount of burnt straws is approximately 140 Tg/year. With the emission factors from literature and experiments, appropriate emission factors have been obtained. The total amounts of PM, SO_2, NO_x, NH_3, CH_4, BC, OC, VOC, CO, CO_2 emissions from field burning of crop straw in China are estimated. All emissions are presented at county level. Some pollutants, such as BC, VOC, OC, CO and CO_2, are contributing a major portion to the total emissions of China. This paper uses a map with resolution of 0.2°×0.2° to present the PM emissions distribution from crop straw burnt in 2003. The results show a significant regional unevenness of emissions, with larger amounts of pollutions coming from the provinces in eastern and northeast China. The regions with higher emissions per unit area are located as a belt stretching from northeast China to eastern China.
