Utilizing Landsat TM Imagery to Map Greenhouses in Qingzhou, Shandong Province, China

To build a rapid and accurate method for greenhouse vegetable landinformation extraction using an index model derived from TM digital data of Qingzhou City, ShandongProvince, based on a systematic analysis of the spectral characteristics of different land use typesin the study area, a subset of the image was first made to eliminate the mountainous region notassociated with vegetable distribution, and then water body pixels were masked. With this the V_Iindex model for greenhouse vegetable land extraction was developed. The index model indicatedgreenhouse vegetable land for Qingzhou in April 2002 was concentrated in the southeast and aroundrural residential areas. Field data used for an accuracy evaluation showed that greenhouse hectaresdetermined with remote sensing were 95.9% accurate, and accuracy for the spatial distribution ofgreenhouse vegetable land cross checked with a random sample was 96.3%. Therefore, this approachprovided an effective method for greenhouse vegetable land information extraction and has potentialsignificance for management of greenhouse vegetable production in the study area, as well as NorthChina.

Research Advances of Effects of Land Use Pattern on Greenhouse Gas Fluxes in Grassland Ecosystem

The grassland is the largest terrestrial ecosystem in China,and greenhouse gas fluxes such as CO2,CH4 and N2O play an important role in the global climate change. The differences in grazing,cultivation and management measures will affect greenhouse gas emissions in grassland ecosystem. Studies suggest that reclamation will lead to increased CO2 fluxes,and fertilization will lead to increased N2 O fluxes; no grazing in summer can reduce greenhouse gas emissions,but impacts of grazing and management measures on greenhouse gas fluxes have not yet reached the same conclusion. The different results may be related to local natural conditions,management measures and research methods. Future research should be focused on unity and standardization in these areas,making the results scientific and comparable,and finally providing the basis for emission reduction of greenhouse gases in grassland ecosystem.

Water, land, and energy use efficiencies and financial evaluation of air conditioner cooled greenhouses based on field experiments

High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled(EV-cooled)greenhouse in winter and summer seasons.Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University,Oman,with dimensions of 6.0 m long and 3.0 m wide.The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes(LED)lights were used as a source of light,while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source.Three cultivars of high-value lettuce were grown for experimentation.To evaluate the technical efficiency of greenhouse performance,we conducted measures on land use efficiency(LUE),water use efficiency(WUE),gross water use efficiency(GWUE)and energy use efficiency(EUE).Financial analysis was conducted to compare the profitability of both greenhouses.The results showed that the LUE in winter were 10.10 and 14.50 kg/m^(2) for the AC-and EV-cooled greenhouses,respectively.However,the values reduced near to 6.80 kg/m^(2) in both greenhouses in summer.The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8%in winter and 26.8%in summer.The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water;it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%.The EUE in the EV-cooled greenhouse was higher in both seasons.Financial analysis showed that in winter,gross return,net return and benefit-to-cost ratio were better in the EVcooled greenhouse,while in summer,those were higher in the AC-cooled greenhouse.The values of internal rate of return in the AC-and EV-cooled greenhouses were 63.4%and 129.3%,respectively.In both greenhouses,lettuce investment was highly sensitive to changes in price,yield and energy cost.The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter.Finally,more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.

Dual-Roof Solar Greenhouse—A Novel Design for Improving the Heat Preserving Capacity in Northern China

Dual-roof solar greenhouse, a new style of solar greenhouse, was designed in this study intending to reduce heat loss in cold time and improve land use efficiency in Beijing, the Capital city of China. Designing and applying the dual-roof greenhouse in metropolitan area had dual effects of saving energy and enhancing land use efficiency. According to the monitoring study and analysis conducted in winter of 2012, the averaged night temperature of south room was about 12.1°C in December, which was satisfying for growing average leaf vegetables. Total energy saved by dual-roof in whole winter was quantified as 1.1 × 107 MJ&#46yr-1 (winter), potentially about 37.4 t coal was saved in Beijing area during whole winter-growing period. Considering the application of north room, the land use efficiency was improved by 62.5% in dual-roof solar greenhouse.

Effect on greenhouse gas balance of converting rice paddies to vegetable production

Rice paddies are increasingly being converted to vegetable production due to economic benefits related,in part,to changes in demand during recent decades.Here,we implemented a parallel field experiment to simultaneously measure annual emissions of CH_4and N_2O,and soil organic carbon(SOC)stock changes,in rice paddies(RP),rice paddy–converted conventional vegetable fields(CV),and rice paddy–converted greenhouse vegetable fields(GV).Changing from rice to vegetable production reduced CH_4emissions by nearly 100%,and also triggered substantial N_2O emissions.Furthermore,annual N_2O emissions from GV significantly exceeded those from CV due to lower soil p H and higher soil temperature.Marginal SOC losses occurred after one year of cultivation of RP,CV,and GV,contributing an important share(3.4%,32.2%,and 10.3%,respectively)of the overall global warming potential(GWP)balance.The decline in CH_4emissions outweighed the increased N_2O emissions and SOC losses in CV and GV,leading to a 13%–30%reduction in annual GWP as compared to RP.These results suggest that large-scale expansion of vegetable production at the expense of rice paddies is beneficial for mitigating climate change in terms of the overall GWP.

Evaluation of Parametric Limitations in Simulating Greenhouse Gas Fluxes from Irish Arable Soils Using Three Process-Based Models

Globally a large number of process-based models have been assessed for quantification of agricultural greenhouse gas (GHG) emissions. Modelling approaches minimize the presence of spatial variability of biogeochemical processes, leading to improved estimates of GHGs as well as identifying mitigation and policy options. The comparative performance of the three dynamic models (e.g., DNDC v9.4, DailyDayCent and ECOSSE v5+) with minimum numbers of common input parameters was evaluated against measured variables. Simulations were performed on conventionally-tilled spring barley crops receiving N fertilizer at 135 - 159 kg·N·ha-1·yr-1 and crop residues at 3 t·ha-1·yr-1. For surface soil nitrate (0 - 10 cm), the ECOSSE and DNDC simulated values showed significant correlations with measured values (R2 = 0.31 - 0.55, p 0.05). Only the ECOSSE-simulated N2O fluxes showed a significant relationship (R2 = 0.33, p 0.05) with values measured from fertilized fields, but not with unfertilized ones. The DNDC and DailyDayCent models significantly underestimated seasonal/annual N2O fluxes compared to ECOSSE, with emission factors (EFs), based on an 8-year average, were 0.09%, 0.31% and 0.52%, respectively. Predictions of ecosystem respiration by both DailyDayCent and DNDC showed reasonable agreement with Eddy Covariance data (R2 = 0.34 - 0.41, p 0.05). Compared to the measured value (3624 kg·C·ha-1·yr-1), the ECOSSE underestimated annual heterotrophic respiration by 7% but this was smaller than the DNDC (50%) and DailyDayCent (24%) estimates. All models simulated CH4 uptake we

Improving Municipal Solid Waste Land Filling Disposal Process: Experiments with a Laboratory Scale Rotary Kiln

Developing countries often face the challenge of managing continuously growing quantity of municipal waste. Waste is often disposed of by stockpiling and land filling because these have been found the cheapest waste disposal methods in the world. Unfortunately, these waste disposal methods are often source of visual pollution, water contamination and greenhouse effect gas emissions. Waste disposal by incineration has been found effective and now is one of the mostly used waste disposal method in several developed countries. Nevertheless, setting up appropriate waste incinerator requires a good of the combustion process. Unfortunately, direct studies on industrial facilities are not easily feasible because of technical issues and financial limitations. Studies and throughout testing frequently need to be carried out at laboratory scale. Work herein reported first overviewed operation conditions of the landfill facility in the town of Ouagadougou. In the second time for incineration simulation, batch experiments are carried out with a rotary kiln furnace to study the effects of the residence time on emissions of NO, NO2, CO, CO2 and SO2 in the atmosphere. For each rotation speed, emissions of NO, NO2, CO, CO2 and SO2 from the incineration of a household combustible fraction model waste consisting of wood (53%), cardboard (25%) and plastics (22%) have been recorded. The lifespan of the land filling facility with incineration has been estimated. Our work show that it may be improved up to roughly three times that of simple land filling. Visual pollution maybe drastically reduced and atmospheric pollution reduced.

中国设施种植土壤可持续利用的难点与应对策略

中国设施种植大多采用中低端装备土壤栽培模式,具有高投入、高产出和高强度利用的特点。截至2021年,设施播种面积在267万hm2左右,占全球设施总面积80%以上。但长期设施种植导致土壤质量下降,诱发面源污染加剧、温室气体排放增加、农产品产量和质量下降等诸多问题。本文聚焦设施种植土壤,总结分析了中国设施土壤可持续利用的难点,主要表现为:土壤养分失衡、环境质量下降、农产品产量和质量降低、设施农用地管理制度不健全等。设施种植可持续利用难题主要归因于:装备水平落后导致设施微环境和土壤养分供应调控不精准、施肥不合理和作物种类单一诱发土壤连作障碍、设施农用地管理制度革新动力不足导致土壤管理技术集成创新缓慢等。本文围绕设施土壤可持续利用提出了7项应对策略:建设期耕作层构建、休闲期土壤改良、设施微环境调控、投入品管控、轮作模式构建、作物抗逆调控以及设施农用地管理制度优化,旨在为小农中低端装备条件下设施土壤可持续利用提供研究思路和科学依据。

Field scale measurement of greenhouse gas emissions from land applied swine manure

Greenhouse gas emissions （GHGs） from swine production systems are relatively well researched with the exception of emissions from land application of manure. GttGs inventories are needed for process- based modeling and science-based regulations. Thus, the objective of this observational study was to measure GHG fluxes from land application of swine manure on a typical corn field. Assessment of GHG emissions from deep injected land-applied swine manure, Phil and reapplication in the spring, on a typical US Midwestern corn-on-corn farm was completed. Static chambers were used Ibr flux measurement along with gas analysis on a GC-FID-ECD＋ Measured gas concentrations were used to estimate GHGs flux using four different models： linear regression, nonlinear regression, first order linear regression and the revised Hutchinson and Mosier （HMR） model, respectively for comparisons.Cumulative flux esmnates after manure apphcatmn of 5.85×10 g·ha^-1（1 ha = 0.01 km） of CO2 6.60×10^1g·ha^-1 of CH4 and3.48 ×10^3g·ha^-1 N2O for the fall trial and 3.11×10^6g·ha^-1 of CO2,2.95×10^3g·ha^-1 of OH4, and 1.47×10^4g·ha^-1 N2O after the spnng reapphcation trial were observed. The N2O net cumulative flux represents 0.595% of nitrogen applied in swine manure for the fall trial.

Comparative analysis of greenhouse gas emission inventory for Pakistan: Part Ⅱ agriculture, forestry and other land use and waste

Understanding Pakistan's greenhouse gas(GHG)emission status is critical for identifying the national targets for GHG mitigation with respect to the nationally determined contributions(NDCs).This study focuses on the development of Pakistan's GHG(C0_(2),CH_(4),and N20)inventories for agriculture,forestry and other land use(AFOLU)and waste sectors using 2006 IPCC Guidelines.This study should be seen as a direct continuation of the preceding one(Part I[Available online at:https://doi.Org/10.1016/j.accre.2020.05.002])which discusses energy and industrial processes and product use in compliance with the 2006 and 1996 IPCC Guidelines.It also provides sector-specific comparative time series(1994-2017)analysis of GHG inventories,identification of key categories,and national GHG emissions trend for Pakistan.The results indicate an average relative difference(on average for time series 1994-2017)of 19%and 6%in total GHG emissions(C0_(2)-eq)from AFOLU and waste sector respectively between 2006 and 1996 IPCC Guidelines.The absolute difference over the entire time series for AFOLU and waste sector was in the range of 3-67 Mt C0_(2)-eq and 1-7 Mt CQ2-eq respectively.Findings further reveal that the quantity of national GHG emissions by 2006 IPCC Guidelines is 10%lower on average for complete time series compared to 1996 IPCC Guidelines.The average relative difference for total national emissions of C0_(2),CH_(4) and N20 is-1%,9%,and 48%respectively.Key category analysis based on 2006 IPCC Guidelines estimates identified three categories,each contributing>10%to the level assessment in the latest year 2017 and accounting for approximately half of the national GHG emissions.In order to further improve the reliability of GHG inventories,Pakistan needs to move from 1996 to 2006 IPCC Guidelines under a higher Tier approach particularly for identified key categories.

不同施肥量对设施菜地N_2O排放通量的影响

为明确北京地区设施菜地的N2O排放特征,寻求既能减少N2O排放又使蔬菜增产或保持原有产量的切实有效措施,该研究采用静态箱/气相色谱法对北京地区设施菜地的黄瓜进行了全生长季N2O排放通量的观测,并分析了不同施肥量对N2O排放量、蔬菜产量和经济效益的影响。结果如下:土壤N2O排放通量的季节变化有明显的时间变异性,试验初期受基肥的影响,N2O排放量较大,随着时间的推移,土壤N2O排放量有所减少并保持稳定;试验后期由于追肥,出现一次排放高峰,且持续时间较长。各处理土壤N2O排放总量的次序是:T4(常规施肥量+鸡粪)>T3(3/4常规施肥量+鸡粪)>T1(1/4常规施肥量+鸡粪)>T2(1/2常规施肥量+鸡粪)>Tn(鸡粪)>T0(无肥处理),各处理之间N2O排放量差异达到极显著水平。综合考虑施肥量、N2O排放量和黄瓜产量,研究认为T3(3/4常规施肥量+鸡粪)的施肥量比较合理,可以为合理施肥、降低农民生产成本以及估算中国农田温室气体排放量和编制温室气体排放清单提供依据。

大跨度主动蓄能型温室温湿环境监测及节能保温性能评价

针对日光温室土地利用率低,单体小不能进行立体栽培果树种植,不利于机械化操作等问题。该文提出一种大跨度主动蓄能型温室,该温室南北走向,双屋面拱形钢骨架结构,并采用主动蓄放热系统进行能量的蓄积与释放。该试验以传统砖墙日光温室作为对照,对大跨度主动蓄能型温室室内外温湿度以及主动蓄放热系统的能量收支进行分析,并对比2种温室的建造成本,综合分析了试验温室保温节能效果及经济效益。结果表明：大跨度主动蓄能型温室土地利用率高达87.4%。温室夜间平均气温高于10℃,无极端低温,晴天夜间平均气温比对照温室高1.5～3.1℃,比室外高13.9～19.3℃;阴天夜间平均气温比对照温室高1.2～2.8℃,比室外高12.5～18.9℃。夜间室内相对湿度平均比对照温室低7%～10%。主动蓄放热系统性能系数COP（coefficient of performance）为3.4～4.2,平均每天能耗0.013 k Wh/m2,与传统燃煤锅炉加温系统相比,平均节能率为47%。大跨度主动蓄能型温室建造成本每平米307.2元,比传统砖墙日光温室低144.5元。大跨度主动蓄能型温室是一种土地利用率高,单体大,保温性能良好,能进行冬季果菜生产的新型温室类型,且投入少,综合其经济环境效益,值得推广应用。

农垦对温带草地生态系统CO_2、CH_4、N_2O通量的影响

2001年6～9月,利用静态暗箱法对内蒙古锡林河流域草甸草原及其开垦后的农田(春小麦)和休耕地的CO2、CH4和N2O的通量进行了野外实地观测。结果显示,草甸草原开垦为耕地对温带草地生态系统CO2、CH4和N2O源汇状况影响显著。从CO2排放量的平均值来看, 农田(545.8 mg穖-2穐-1)>草甸(301.9 mg穖-2穐-1)>休耕地(74.4 mg穖-2穐-1),其中草甸开垦为农田使CO2的排放增加了81%;在春小麦的生长期内,麦田的CO2排放量是草甸草原的2倍多,小麦死亡和收割后CO2排放锐减,可见农垦明显促进了CO2的排放。另外干旱使得草甸草原、农田和休耕地的CO2排放量表现出减少趋势。草甸开垦为农田后CH4吸收特征表现明显,但干旱减弱了其吸收趋势。就N2O而言,草地开垦后春小麦的种植总体上并未增加N2O的排放,只是改变了其排放特征;除小麦苗期外,N2O的排放都高于草甸草原;极端干旱还导致土壤对大气N2O的吸收。另外,农田的CH4吸收与N2O排放之间还存在此消彼长的关系。

我国东部样带土地利用方式对温室气体排放通量的影响

以中国东部南北样带为平台,以典型森林和草地生态系统为对象。

非耕地温室番茄微咸水灌溉试验研究

采用单因素随机区组试验，以微成水直接灌溉为对照，研究不同微成水利用方式对番茄生长发育、产量和品质、土壤理化性质等的影响。结果表明，与微成水直接灌溉相比，净水灌溉增产44．78％，0～20、20～40cm土层电导率分别降低67．21％、10．61％，果实中Vc、可溶性糖、可滴定酸、可溶性固形物差异均极显著，净水灌溉能够提高水分利用效率，但影响果实品质的提高；混灌模式增产26．56％，果实中营养物质量高于净水灌溉，但低于微咸水直接灌溉，根系分布密集层盐分累积不明显，生产成本降低50％。混灌模式为微成水淡化处理后最佳利用模式；高品质番茄生产以微成水直接灌溉为宜。

三江平原不同土地利用方式对区域气候的影响

以往土地利用变化对气候的影响多是从地表参数的改变角度去研究,而气候变化的一个重要方面是温室气体的增加。通过收集整理三江平原生长季(510月)不同土地利用类型的温室气体排放通量,根据温室气体的增热潜能,比较得出,在三江平原林地、小叶章、毛果、漂筏、稻田和大豆几种土地类型中,对区域气候影响的大小依次顺序为:大豆>小叶章>毛果>林地>稻田>漂筏。由此表明,三江平原稻田对于区域的气候的变化贡献比旱地小。在过去几十年中,由于土地利用变化而导致温室气体排放的总变暖潜力增加,为三江平原气候变暖提供了佐证。

内蒙古半干旱草原土壤植被大气相互作用(IMGRASS)综合研究

为深化对中纬半干旱草原气候生态相互作用过程、机制及其对全球变化的响应与贡献的认识 ,一项名为“内蒙古半干旱草原土壤植被大气相互作用 (IMGRASS)”的基金重大项目于 1997—2 0 0 1年在内蒙古锡林郭勒草原执行。IMGRASS计划在 1998年草原生长季节、在所选定的以典型草原为主 ,包括草甸草原、稀疏沙地草原等在内的中尺度试验区开展了多点、多要素的综合观测。观测内容包括土壤、植被、大气的相关要素和发生于地气界面的潜热、感热通量 ,还包括N2 O ,CH4 ,CO2 等微量气体交换量、辐射与降水分布。除 1998年中尺度观测试验外 ,在 1999— 2 0 0 1年在代表性地点进行了微量气体收支、遥感和沙尘天气相关的专项观测 ,结合草原站已进行的长期监测资料 ,分析气候生态长期相互作用 ,特别是人类活动干预的影响。在分析观测结果的基础上 ,对该地区的气候生态相互作用进行了数值模拟研究。文章作为介绍IMGRASS计划的第一部分 ,对该项研究计划作一全面简要介绍 ,包括科学目标、计划实施实验区背景、中尺度综合观测 ,并对实验所得大气边界层结构、辐射通量、沙地土壤水份状况、地表反射率谱与遥感测量等提供了个例分析 ,并简单介绍IMGRASS数据库。

不同水肥处理对设施菜地N_2O排放的影响

设施菜地是N2O排放的重要来源。本文通过田间试验对北京地区不同水肥处理的设施有机大白菜进行了全生长季N2O排放监测,以期为设施菜地N2O减排提供数据支撑。试验为灌溉和施氮量的双因素设计,分别为高灌溉量下的常规施氮(高氮HN1)、优化施氮(低氮HN2)和不施氮(HCK)以及低灌溉量下的常规施氮(LN1)、优化施氮(LN2)和不施氮(LCK)处理。结果显示,不同灌溉量对大白菜产量影响不显著,但常规施氮处理均显著高于优化和不施氮处理。试验初期,土壤N2O排放通量较高,随后逐渐降低;到第30 d,各施氮处理已累积释放了生育期N2O排放总量的80%以上;灌水对N2O排放的影响显著,试验期间灌溉三次后均出现排放高峰,且高灌溉量下各处理N2O的排放通量均高于低灌溉处理。常规施氮N2O排放通量高于优化施氮处理,并均显著高于不施氮处理。各施氮处理的N2O排放系数介于0.29%～0.39%之间。

淡水养殖系统温室气体CH4和N2O排放量研究进展

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