氮肥高效施用在低碳农业中的关键作用

低碳农业是我国集约化农业发展的必然趋势。深入理解氮肥高效施用是实现低碳农业的关键,可以更加明确如何集成优化农业管理措施增加产量、减少农田生态系统碳排放、提高土壤固碳效应,综合实现固碳、减排、增产的低碳农业发展目标。本文概述了低碳农业评价指标的三个阶段性研究特点,从田间温室气体排放的综合温室效应拓展为涵盖固碳效应的净温室效应,再拓展为涵盖生命周期评价碳排放的综合净温室效应以及兼顾作物产量的温室气体强度。提出了如何利用当季作物试验来估算农田生态系统净碳收支、结合生命周期评价当季作物综合净温室效应和单位产品温室气体强度的方法。按照现阶段低碳农业的评价指标,以我国稻–麦轮作生态系统集约化生产的低碳农业模式为案例,解析氮肥施用在低碳农业各组成包括作物产量、固碳效应、CH₄和N₂O排放、农业措施碳排放中的重要作用,明确氮肥高效施用在农田生态系统综合净温室效应和温室气体强度中的关键作用,从而实现低碳农业可持续发展。     

有机农业发展的低碳机理分析

温室气体排放引起的全球气候变暖是人类关注的环境热点问题之一。本文从农业生态系统影响全球变暖的主要温室气体(CO₂、N₂O 和CH₄)的产生和排放出发, 探讨有机农业在生产减排和土壤固碳方面的机理。研究发现相对于常规农作而言, 有机农业在减排和固碳方面具有很大优势和潜力; 然而, 从长期来看, 通过土壤固碳减少大气温室气体的排放不是无限制的, 到一定程度后会达到一个平衡。因此, 更多的有效固碳途径和管理措施有待于进一步研究。同时, 从低碳理念出发, 强调中国加强有机农业环境效益研究的必要性。     

我国发展低碳农业的政策、法规和技术体系分析

针对我国保障粮食安全和应对全球变化的双重目标,分析了我国发展低碳农业存在的主要问题,并提出了发展对策。建议基于生态农业、循环农业和生态高值农业的原则,从政策、法规和技术3个方面促进我国低碳农业的发展。发展对策主要包括:贯彻中央一号文件,制定完善的政策法律法规体系及财政补贴;立足各地农情,大力发展区域低碳农业适应性体系;推广低成本低碳农业适应性技术,发展农村低碳农业合作组织;优化低碳农业发展外部环境,提高公众低碳农业认知意识。     

低碳视角下农业创新策略研究

农业既是温室气体排放源,也是温室气体的吸收汇,随着气候变化对全球环境和生态系统的影响日益加深,发展低碳农业以保证农业的可持续发展显得尤为必要;作为农业大国,树立可持续发展的理念,促进农业的生态化、有机化、绿色化,     

双碳目标下黑龙江省低碳农业发展探究

农业不仅是温室气体的重要来源,而且是一个巨大的碳汇系统,对实现双碳目标意义重大。黑龙江省作为我国粮食安全的”压舱石“,发展低碳农业对着力推动全省乃至全国经济社会发展具有重要意义。但黑龙江省在发展低碳农业过程中一直存在着农业技术水平低、绿色金融政策支持不到位、宣传普及不到位等问题。为推动黑龙江省低碳农业发展,在综合分析历年黑龙江省农业碳排放总量及碳排放强度变化趋势的基础上,提出加强低碳农业技术创新发展、加大农业金融支持力度、加强低碳农业理念培训和宣传等建议。     

低碳农业与可持续发展之我见

低碳农业是在农业生产、经营中排放最少的温室气体,同时获得最大社会效益的农业发展模式,有利于实现农业持续协调全面发展。本文阐述了发展低碳农业的必要性与可能性,提出发展低碳农业的基本途径。     

低碳技术在农作物秸秆利用中的应用

为了应对全球气候变化,各国均以减少二氧化碳排放为目标,积极发展低碳技术。中国作为农业大国,秸秆资源丰富且农作物秸秆开发利用技术已经得到一定的发展,秸秆综合利用可避免因秸秆露天焚烧造成的环境问题,有利于农田生态系统的稳定,有利于节能减排、防治污染、保护环境,促进循环经济发展与社会主义新农村建设。本文从农作物秸秆利用技术的3个主要方面入手,分析低碳技术在其中的应用,同时大力倡导开发农作物秸秆利用技术,减少温室气体排放,实现农业可持续发展。     

发展低碳农业面临的挑战及应对思路

1 低碳农业的提出 自18世纪工业革命以来人类＂高碳＂活动产生大量CO2、CH4、N2O等温室气体,导致全球气候变暖,气温、大气环流异常,自然灾害频繁发生,人类生存环境遭受严重威胁.面对全球气候变暖的严峻挑战,发展以低能耗、低污染、低排放为基础的低碳经济已成为全球共识和必然趋势.低碳经济实质是节约能源、高效利用能源、循环利用能源、开发使用清洁能源.＂低碳＂在社会生产中、在科学研究中、在工作学习中、在日常生活中都能广泛践行,作为与自然环境关系最为紧密的农业,更是发展低碳经济的重要领域.     

从健康、低碳角度看农业畜牧业的发展

从我国地大物博、人口众多、人均占有资源少的基本国情入手,阐述可持续发展必须合理使用资源的问题。具体分析了农业畜牧业发展在自然资源消耗、温室气体排放及肉类产品对人体健康效应方面所起的作用,提出理智合理消费畜牧产品、减少肉类消费、放缓农业畜牧业发展脚步将对人类个体健康、自然资源节约、减少环境污染以及温室气体减排均有不可估量的益处。从理论研究、政策制定、生产者及消费者共同关注,到媒体及社会教育多方面参与,为实现可持续发展共同努力。     

农业减排温室气体的技术描述

大气中温气体含量的不断增加是影响今后气候变化的重要因素,如何减少温室气体的排放是当今世界各国十分关注的问题,本文根据当前我国农业生产及农村经济状况,研究了农业减排温室气体各种可能途径,并初步分析了各种途径的减排潜力及存在的问题,为我国政府及有关部门应因气候变化的决策工作提供依据。     

Which are the most favourable conditions for reducing soil CO2 emissions with no-tillage? Results from a meta-analysis

No-tillage practices have a recognised beneficial impact on soil and water conservation while reducing erosion processes and enhancing soil organic matter content. However,scientists continue to debate the effectiveness of no-tillage in reducing soil carbon dioxide (CO 2 ) emissions from farming. Following the same line of inquiry pursued by the authors who reviewed the impact of conservative practices on direct CO 2 emissions,we applied meta-analytic and machine learning techniques to unravel the effect of no-tillage under contrasting pedo-environmental conditions and agricultural management. We analysed fifty-six experimental studies investigating direct soil CO 2 emissions from no-tillage and conventional tillage practices (102 paired observations),considering pedological (soil texture,soil organic carbon content),environmental (climate type),and management (crop rotation,experiment duration) factors. We estimated the effect of different practices on the daily amount of soil CO 2 emissions,and the impact of tillage in the period immediately following the event. The main insights of this study are: (i) the conditions leading to the highest reduction of CO 2 emissions due to no-tillage were long-term experiments (standardised mean difference β ˆ = 0.64) conducted in arid environments ( β ˆ = 0.76) and clay soils ( β ˆ = 0.81),with low organic carbon content ( β ˆ = 0.79) where crop rotations ( β ˆ = 0.65) were performed; (ii) the same conditions were associated with the lowest absolute CO 2 emissions,irrespective of soil management; (iii) the highest contribution to the variability of absolute soil CO 2 emissions was associated with soil texture (mean decrease in accuracy of Random Forest models,MDA = 4.57),rotation (MDA = 3.07),experiment duration (MDA = 2.93) and soil organic carbon content (MDA = 2.24),rather than to tillage practices; (iv) soil CO 2 emissions almost doubled in the first day after a tillage event,consistently across studies (p = 0.001). This meta-analysis offers quantitative figures on the impact of tillage practices on soil CO 2 emissions and releases data for informing policies aimed at promoting climate change mitigation.View The PDF     

水氮互作对稻田温室气体排放的影响

水肥管理对农田土壤肥力质量和环境质量有重要影响。依托安徽科技学院长期定位试验小区,通过设置两种灌溉模式（控制灌溉C1和常规灌溉C2）以及三个施氮水平(低氮N1、中氮N2和高氮N3),研究水氮互作对稻田温室气体CH4、N2O和CO2排放及土壤理化性质的影响。结果表明,与常规灌溉相比,控制灌溉可显著降低稻田中的CH4和N2O的累计排放量,降幅分别为43.12%和23.53%;常规灌溉条件下,低、中、高施氮处理的土壤铵态氮含量分别为35.26、38.90和35.20 mg?kg-1,而控制灌溉分别为33.08、34.30和42.40 mg?kg-1;控制灌溉条件下,CO2排放量高于常规灌溉,且随施氮水平的提高而增加。根据总体温室效应分析,控制灌溉下稻田的全球增温潜势（global warming potential,GWP）为0.55 t?hm-2（以CO2当量计）,远低于常规灌溉下稻田0.82 t?hm-2,且中氮处理下稻田的GWP远低于低氮和高氮处理。水氮耦合是稻田N2O排放的主要影响因素,且在中、高氮施肥条件下,稻田N2O排放对于温室效应的贡献大于CH4。因此,采用控制灌溉结合氮肥减量施用,可有效减少农田温室气体CH4和N2O的排放,维持较高的土壤铵态氮水平,这对提高土壤肥力质量和发展可持续农业具有重要意义。     

施肥与大气环境质量——论施肥对环境的影响(1)

无机肥和有机肥都是人类可持续发展不可或缺的资源,只要科学使用不会对环境和生态造成负面影响。不良施肥对大气环境的威胁主要来自有机肥,过量使用有机肥可促进土壤中CO2和CH4的排放;有机肥和畜禽粪肥堆放场地有大量氨气污染,有机物的焚烧可直接向大气排放大量的CO2、CH4及固体微粒,使城乡空气严重污染。有机肥和无机N肥的过量使用,都会导致土壤N素积累。土壤中N素的反硝化作用产生N2O, NOx 的排放。避免有机肥和N肥过量,禁止焚烧有机物,覆盖有机肥和畜禽粪肥堆放场,控制反硝化作用,以减少负面效应,保护大气环境质量。     

水分类型对土壤排放的温室气体组成和综合温室效应的影响

实验室研究表明,土壤排放出的温室气体（ＣＯ２、ＣＨ４和Ｎ２Ｏ）组成及总理显著地受土壤水分类型和施用秸秆的影响。连续淹水条件下,土壤仅排放微理的Ｎ２Ｏ,但排放出大量的Ｃ睡Ｃ敢条件下,土壤不排放Ｃ上键合的但排放出大量的Ｎ２Ｏ;虽然淹水的土壤排水促进Ｎ２Ｏ排放,但显著抑制ＣＨ４的排放,淹水好气交替处理的土壤其排放的ＣＯ２、ＣＨ４和Ｎ２Ｏ均在好气和连续淹水之间。根据各种温室产生温室效应的相对潜力,计算土壤     

Nitrous oxide and methane emissions from long-term tillage under a continuous corn cropping system in Ohio

Nitrous oxide (N₂O) and methane (CH₄) emitted by anthropogenic activities have been linked to the observed and predicted climate change. Conservation tillage practices such as no-tillage (NT) have potential to increase C sequestration in agricultural soils but patterns of N₂O and CH₄ emissions associated with NT practices are variable. Thus, the objective of this study was to evaluate the effects of tillage practices on N₂O and CH₄ emissions in long-term continuous corn (Zea mays) plots. The study was conducted on continuous corn experimental plots established in 1962 on a Crosby silt loam (fine, mixed, mesic Aeric Ochraqualf) in Ohio. The experimental design consisted of NT, chisel till (CT) and moldboard plow till (MT) treatments arranged in a randomized block design with four replications. The N₂O and CH₄ fluxes were measured for 1-year at 2-week intervals during growing season and at 4-week intervals during the off season. Long-term NT practice significantly decreased soil bulk density (ρ_b) and increased total N concentration of the 0–15 cm layer compared to MT and CT. Generally, NT treatment contained higher soil moisture contents and lower soil temperatures in the surface soil than CT and MT during summer, spring and autumn. Average daily fluxes and annual N₂O emissions were more in MT (0.67 mg m⁻² d⁻¹ and 1.82 kg N ha⁻¹ year⁻¹) and CT (0.74 mg m⁻² d⁻¹ and 1.96 kg N ha⁻¹ year⁻¹) than NT (0.29 mg m⁻² d⁻¹ and 0.94 kg N ha⁻¹ year⁻¹). On average, NT was a sink for CH₄, oxidizing 0.32 kg CH₄-C ha⁻¹ year⁻¹, while MT and CT were sources of CH₄ emitting 2.76 and 2.27 kg CH₄-C ha⁻¹ year⁻¹, respectively. Lower N₂O emission and increased CH₄ oxidation in the NT practice are attributed to decrease in surface ρ_b, suggesting increased gaseous exchange. The N₂O flux was strongly correlated with precipitation, air and soil temperatures, but not with gravimetric moisture content. Data from this study suggested that adoption of long-term NT under continuous corn cropping system in the U.S. Corn Belt region may reduce GWP associated with N₂O and CH₄ emissions by approximately 50% compared to MT and CT management.     

Spatial and temporal variability in CH4 and N2O fluxes from a Scottish ombrotrophic peatland: Implications for modelling and up-scaling

Peatlands typically exhibit significant spatial heterogeneity which can lead to large uncertainties when catchment scale greenhouse gas fluxes are extrapolated from chamber measurements (generally <1 m²). Here we examined the underlying environmental and vegetation characteristics which led to within-site variability in both CH₄ and N₂O emissions and the importance of such variability in up-scaling. We also consider within-site variation in the controls of temporal dynamics. Net annual emissions (and coefficients of variation) for CH₄ and N₂O were 1.06 kg ha⁻¹ y⁻¹ (300%) and 0.02 kg ha⁻¹ y⁻¹ (410%), respectively. The riparian zone was a significant CH₄ hotspot contributing ∼12% of the total catchment emissions whilst covering only ∼0.5% of the catchment area. In contrast to many other studies we found smaller CH₄ emissions and greater uptake in chambers containing either sedges or rushes. We also found clear differences in the drivers of temporal CH₄ dynamics across the site, e.g. water table was important only in chambers which did not contain aerenchymous plants. We suggest that depending on the heterogeneity of the site, flux models could be improved by incorporating a number of spatially distinct sub-models, rather than a single model parameterized using whole-catchment averages.     

褐藻类物质对土壤碳组分、酶活性和温室气体排放的影响

探究了海藻肥中的主要功能成分——褐藻类物质对土壤性质、碳组分、酶活性和温室气体排放的潜在影响。采用土壤室内培养的方法,设置空白对照（CK）、褐藻原粉处理（Sea）、黏度为66 mPa?s的海藻酸钠处理（Alg66）、黏度为360 mPa?s的海藻酸钠处理（Alg360）和岩藻多糖处理（Fuc）,共5个处理,在25 ℃下培养112 d,定期取样测定土壤理化性质、土壤碳组分、土壤酶活性和温室气体。结果发现,与CK相比,添加褐藻类物质均能提高土壤有机碳含量和全氮含量,Sea处理土壤有效磷和速效钾含量分别提高了19.83%和260.23%;褐藻提取多糖处理（Alg66、Alg360、Fuc）土壤有效磷含量分别降低了17.67%、2.74%和20.15%,土壤速效钾含量分别降低了11.41%、3.85%和6.36%。Fuc处理能显著提高活性碳组分含量,尤其是溶解性有机碳,在培养期结束时较其他处理差异显著,含量为CK的6.34倍。Fuc处理提高了土壤β-葡萄糖苷酶（BG）、纤维二糖水解酶（CBH）、β-木糖苷酶（BX）、β-N-乙酰氨基葡萄糖苷酶（NAG）的活性。与CK相比,添加褐藻类物质均提高了CO2排放量,Alg66、Alg360能够减少N2O排放,各处理对CH4排放的影响无明显差异。上述结果表明,褐藻类物质能够提高土壤碳氮养分。岩藻多糖显著提高土壤酶活性和活性碳组分含量,海藻酸钠能够降低N2O排放。由此可见,褐藻类物质具有一定的绿色增效潜力,其不同成分对土壤的作用效果各异,在新型肥料的生产与应用领域存在发展空间。     

施用秸秆和接种蚯蚓对土壤温室气体排放的影响

通过施用秸秆并接种蚯蚓于微系统实验研究发现,在 21 天的培养期内,蚯蚓活动显著增加土壤C02和N20的排放速率,与对照处理相比,单接种蚯蚓处理与单施加秸秆的处理导致CO2排放量分别增加了60%和1.35倍,相应的N2O .排放量增加了1.06倍和3.94倍.另一方面,与单施加秸秆的处理相比,接种蚯蚓配合施加秸秆的处理导致C02和N20排放分别增加了41%和45%.施用秸秆显著提高了土壤微生物生物量C含量,而单接种蚯蚓处理的土壤相比对照处理反而降低.接种蚯蚓显著提高了土壤N03--N和NH4 -N含量,秸秆处理土壤并不显著增加土壤中的NH4 -N含量.