外加营养物对干旱区土壤硫交换通量的影响

应用静态箱式采样法,利用热解析仪与气相色谱联用的方法进行定量分析,研究不同营养添加物对干旱区水稻田土壤挥发性有机硫化物(VOSCs)地-气交换通量的影响。结果显示:在稻田土壤中施入不同的营养添加物后,除硫酸钠外,其余添加物质均可以促进VOSCs的释放;作为有机硫源,甲硫氨酸和半胱氨酸的添加明显地提高了土壤VOSCs的释放通量,表明含硫氨基酸是VOSCs的有效前体,淹水稻田土中的微生物通过分解作用释放VOSCs,释放的气体除了有大量的COS(羰基硫)和CS_2(二硫化碳)外,还有少量的DMS(二甲基硫)、CH_3SH(甲硫醇)以及DMDS(二甲基二硫);作为氮、硫源,硝酸铵和硫酸铵均可促进VOSCs的释放,但硫酸铵的作用时间相对较长,这主要归因于氮源和硫源的共同作用;碳源也能少量地促进VOSCs的释放。另外,培养条件(如温度等)对VOSCs的地-气交换通量也有一定的影响。     

质地对土壤物理性质的影响及调节研究

以耕地棕壤为试验材料,采用室内培养的方法研究了外源砂不同添加量对土壤物理性质的影响,并进一步研究了添加有机质对不同含砂量土壤物理性质的调节作用。结果表明:与对照(含砂量31.51%)比,随土壤含砂量的增加,容重增加了2%~15%,持水量降低了1%~11%。在不同含砂量的条件下,添加有机质的土壤容重比对照降低10%左右,土壤含砂量在30%~70%时,添加有机质处理能明显提高土壤的持水能力,当含砂量超过70%时,添加有机质处理对土壤持水能力影响不大,随有机质添加量增加土壤氧化还原电位下降。     

微水溶性胶结包膜肥料氮素释放速率与预测

应用恒温培养试验研究了适用于半干旱气候条件下的微水溶性胶结包膜肥料在不同土壤含水量条件下的氮素释放速率,并基于一级化学反应、采用田间试验数据构建了氮素释放预测方程。结果显示:微水溶性胶结包膜肥料氮素累积释放量与土壤含水量呈一定的正相关关系,在75 d左右的时候,在22%土壤含水量下其氮素释放达到了85%~90%,14%土壤含水量下达到了60%~82%,6%土壤含水量下达到了35%~42%。同时,田间试验结果也说明了微水溶性胶结包膜肥料氮素瞬时释放速率受降雨及土壤含水量的影响显著;在降雨后或土壤含水量高的情况下,微水溶性胶结包膜肥料的释放速率加快。在此基础上,通过最小二乘法求参等方式构建了以土壤含水量为主要因子的微水溶性胶结包膜肥料氮素释放预测方程,预测值与实测值拟合程度较好,决定系数达到了0.976。     

活性炭对农田土壤孔隙结构的影响

分析了农田土壤中施用不同用量活性炭(活性炭用量分别占土壤质量的0、0.1%、0.3%、0.6%、0.9%和1.2%)对土壤总孔隙的影响,及其随着时间(0、30、60 d和90 d)的变化;利用DE双指数模型计算了土壤毛管度和非毛管孔隙度,定量评价了活性炭对土壤不同大小等级孔隙状况的影响。结果表明:活性炭对土壤的毛管孔隙影响不大,主要增加了土壤的非毛管孔隙,培养90 d时,相比对照处理,活性炭处理(从低到高)的土壤非毛管孔隙度分别增加5.8%、2.5%、8.7%、9.1%和14.7%;活性炭处理减小了土壤容重,增大了土壤总孔隙度,培养90 d时,活性炭处理(从低到高)的总孔隙度比对照处理分别增加1.9%、1.8%、2.3%、2.7%和4.3%;活性炭处理显著减小了土壤毛管孔隙孔径(P0.05),而显著增大了土壤非毛管孔隙孔径(P0.05)。活性炭对土壤孔隙的影响随着时间的延长越来越明显,这可能主要与活性炭自身特性和添加活性炭所引起的有机质和微生物变化有关。     

西安南郊夏秋季不同土壤碳排放量的变化研究

根据NaOH溶液吸收CO2原理,对西安南郊不同土层CO2释放量进行了观测,探讨了土壤CO2释放量的变化规律及其影响因素。资料表明,关中地区夏秋季土壤(厚土层)CO2释放量变化规律,与气温变化规律负相关,CO2释放量存在一定的"滞后性",一般滞后4~6h;而薄土层土壤CO2释放量变化规律,与气温变化规律正相关,CO2释放量不存在"滞后性",且释放量明显小于厚土层;深层土壤释放量波动小,且释放量小与厚土层;土壤CO2释放量的变化与温度和天气密切相关,温度高、天气晴朗时释放量大,反之则小;厚土层CO2释放量白昼小于夜间,白天约占1/3,夜间约占2/3;薄土层CO2释放量白昼大于夜间,白天约占2/3,夜间约占1/3。土层CO2观测揭示了CO2释放量与释放规律与土层厚度、深度有关。     

不同盐渍化土壤N2O排放对生物炭添加和土壤水分的响应

为探讨不同盐渍化程度土壤N₂O排放对生物炭添加和土壤水分的响应,开展为期30 d的室内培养试验,设置5个土壤盐渍化水平(S0、S1、S2、S3、S4:盐分添加量分别为土壤质量的0%、0.25%、0.5%、0.75%、1%)、2个生物炭添加方式(B0:不添加;B1:添加量为土壤质量的5%)和2个水分条件(W0:60%田间持水量;W1:100%田间持水量)。结果表明：土壤盐分对N₂O累积排放量具有显著影响,盐分含量越高则降幅越大,与S0处理相比,S1、S2、S3、S4处理N₂O累积排放量分别降低43.9%、66.5%、91.9%、93.2%。土壤水分对N₂O累积排放量具有极显著影响,水分含量越高则累积排放量越大,与W0处理相比,W1条件下各盐分处理N₂O累积排放量分别增加3.0%、84.8%、187.4%、729.4%、306.7%。生物炭添加对N₂O累积排放量存在一定影响,与B0处理相比,低水含量下,B1处理累积排放量增幅为3.4%～20.6%,高水含量增幅...     

不同改良材料对灌漠土微生物量磷及生物有效性的影响

通过培养和盆栽试验，向灌漠土土壤中加入等量磷和不同添加比例的硫磺S（0.05%、0.15%、0.45%）、生物菌肥B（0.25%、0.50%、1.00%）、有机肥OM（0.50%、1.00%、2.00%）和小麦秸秆WS（1.00%、2.00%、4.00%），研究不同改良材料配施磷肥土壤微生物量磷的变化特征，及其与Olsen P、小麦吸磷量之间的关系。结果表明，添加不同改良材料处理的土壤微生物量磷含量均显著高于对照（不添加改良材料），且随着添加比例的增大而增加。在第16天时，各处理土壤微生物量磷含量达到最大值，OM₂2.00、B₂1.00、WS₂4.00和S₂0.45处理分别较对照显著增加了34.66%、34.52%、28.19%和23.89%；经过30 d的培养，硫磺、生物菌肥、有机肥和小麦秸秆处理的土壤微生物量磷含量较对照分别增加了19.51%、43.08%、47.92%和41.68%。在一定范围内（Olsen P约90 mg·kg^-1），土壤微生物量磷随土壤Olsen P提高而增加。在培养的第16天和第30天时，小麦植株吸磷量也与土壤微生物量磷存在极显著的相关关系。总体看来，有机肥或生物菌肥配合磷肥施用于灌漠土能促进土壤微生物量磷的增加，提高磷的生物有效性，对于灌漠土磷素高效利用具有重要意义。     

土壤高锰对空心莲子草生长与草甘膦耐性的影响

研究了空心莲子草Alternanthera philoxeroides在土壤中含高浓度锰(简称高锰)胁迫下的生长特性及对草甘膦的耐性。空心莲子草在锰添加量为8～128 mg/kg的土壤中培养20 d后,分枝数比对照(4.43个/株)增加了22.57％～48.31%, 主茎长度比对照(23.85 cm)增长了16.60％～19.87%,地下根茎数比对照(1.54个/株)增加29.87％～47.40%,全株干重比对照(0.23 g)增加22.45%～27.00%;植株叶面积在锰添加量为32～128 mg/kg范围内也显著高于对照(增加10.53%～11.10%)。用草甘膦(有效成分按草甘膦酸计) 68、102和136 g/hm2分别进行茎叶处理后21 d,锰添加量为128 mg/kg的处理,鲜重抑制率分别比不添加锰处理组下降27.39％、24.57％和30.06％。结果表明,土壤高锰条件下空心莲子草的生长和繁殖能力增强,这可能是土壤酸化背景下空心莲子草蔓延加剧的重要原因。土壤高锰条件下生长的空心莲子草对草甘膦的耐性显著增强,使得该杂草的防控形势更为严峻。     

棉隆熏蒸联合生物炭和沸石对土壤微生态及土传病原菌的影响

采用室内培养法研究棉隆熏蒸后添加常用剂量的生物炭和沸石对土壤微生态和土传病原菌的影响。结果表明：与对照相比,各处理土壤硝态氮的含量均显著增加。与仅棉隆熏蒸相比,熏蒸后添加沸石处理土壤硝态氮含量显著增加6.29%～11.74%。棉隆熏蒸后添加生物炭处理在培养期结束时土壤有效磷、速效钾、有机质含量以及电导率显著增加,土壤酸碱度降低,效果优于添加沸石处理。此外,与对照相比,棉隆熏蒸后添加生物炭还可提高土壤过氧化氢酶(5.68%～14.51%)和蔗糖酶(3.71%～12.08%)的活性。棉隆熏蒸后添加沸石的处理其土壤酶活性在培养期结束时和对照、仅棉隆熏蒸处理间无显著差异。对土壤微生物的分析结果表明,与仅棉隆熏蒸相比,棉隆熏蒸后添加生物炭和沸石处理其细菌数量显著增加3.49%～33.95%,真菌数量呈现先降低后增加的趋势。对病原菌数据分析表明,棉隆熏蒸后添加生物炭和沸石均可提高对镰刀菌和疫霉的防治效果,但沸石防治效果更好、更持久,培养期结束时对镰刀菌和疫霉的抑制率高达89.29%和72.58%。我们的研究结果表明棉隆熏蒸土壤后添加生物炭和沸石可提高土壤养分,改善土壤微生态环境,同时加强对病原菌的...     

绿洲干旱区土壤COS和CS_2交换通量影响因素的研究

文中通过静态箱采样,利用Turbo Matrix 100型热解析仪与气相色谱联用法,分析了环境因子,如水分、温度、光照和玉米秸秆添加等对绿洲干旱区土壤羰基硫(COS)和二硫化碳(CS_2)交换通量的影响。结果表明:干旱土壤COS和CS_2的平均通量分别为1.17、3.28pmol·m~(-2)·s~(-1),淹水土壤COS和CS_2的平均通量分别为-11.11、-3.41pmol·m~(-2)·s~(-1),干旱土壤作为COS和CS_2的源,淹水土壤则为其汇,且淹水土壤交换强度高于干旱土壤。与淹水土壤相比,玉米秸秆的添加使得COS和CS_2的交换强度分别提高了34.2%和149.27%。同时测得COS具有明显的日变化规律,干旱土壤总交换量基本平衡,表现为微弱的释放,淹水土壤总体表现为较强的吸收。CS_2则表现不明显。水分和温度虽然与交换通量之间没有显著相关性,但对交换方向和强度有重要影响。对以上过程的讨论提示我们非生物产生和消耗过程存在的可能性。     

Sulfur assimilation in plants and weed control: Potential targets for novel herbicides and action sites of certain safeners

Sulfur is an indispensable element for plants. It is found in sulfur-containing amino acids, cysteine and methionine, and in various other important biochemical components and processes. Inhibitors of sulfur assimilation, or cysteine and methionine synthesis, could be potential herbicides. In the present paper, the sulfur assimilation pathway in plants is described, followed by the introduction of several compounds (inhibitors and safeners) acting on this pathway. Uptake of inorganic sulfate through the roots is the first step of sulfur assimilation in plants. Sulfate is reduced mainly in chloroplasts to sulfide by a multistep process, and sulfide is then incorporated into cysteine. Cysteine is converted to cystathionine, homocysteine and methionine. Cysteine is incorporated into glutathione (GSH) by γ-glutamylcysteine synthetase and GSH synthetase. Three enzymes involved in cysteine and methionine biosynthesis, cysteine synthase, cystathionine γ-synthase and cystathionine β-lyase, have been investigated as target sites for herbicides. Several inhibitors of these enzymes (e.g. rhizobitoxine and propargylglycine) were also phytotoxic, suggesting that the synthetic pathway of sulfur-containing amino acids could be a new target site for herbicides. Some safeners for herbicides were found to act on the sulfur assimilation pathway and on GSH synthesis to increase GSH, which can be involved in herbicide metabolism and detoxification. Several safeners elevate GSH levels by increasing the activities of enzymes involved in sulfur assimilation and GSH synthesis. Further studies on plant sulfur metabolism may lead to the discovery of new herbicides and to the comprehensive understanding of the mode of action of safeners.     

硫磺改良盐渍土效果初探

采用田间试验方法,探索了以硫磺为改土材料对渭南盐渍土的初步改良效果。结果表明,硫磺的施用对于土壤及作物(棉花)的养分状况表现出一定的改善作用;并且降低了土壤pH值,相对于施用石膏的处理,硫磺在降低土壤pH上有更明显的作用;另外,虽然硫磺的施用增加了土壤中各离子的含量及EC值,但随着硫磺用量的逐渐增加,土壤中各离子含量及EC值呈现出降低的趋势。因此,硫磺的施用对于该地土壤具有一定的改良作用。但是,虽然结果显示硫磺在该地土壤的改良中起到了一定的作用,但总体效果有限,其主要原因可能是硫磺施用量太低(试验中最高用量为225 kg/hm2),因此,在本试验基础上如果进一步加大硫磺用量将可能会对该地盐碱化土壤具有更为明显的改良作用,但最佳施用量还需要进一步研究。     

Artificial root exudates and soil organic carbon mineralization in a degraded sandy grassland in northern China

Plant root exudates contain various organic and inorganic components that include glucose, citric and oxalic acid. These components affect rhizosphere microbial and microfaunal activities, but the mechanisms are not fully known. Studies concerned from degraded grassland ecosystems with low soil carbon（C） contents are rare, in spite of the global distribution of grasslands in need of restoration. All these have a high potential for carbon sequestration, with a reduced carbon content due to overutilization. An exudate component that rapidly decomposes will increase soil respiration and CO2 emission, while a component that reduces decomposition of native soil carbon can reduce CO2 emission and actually help sequestering carbon in soil. Therefore, to investigate root exudate effects on rhizosphere activity, citric acid, glucose and oxalic acid（0.6 g C/kg dry soil） were added to soils from three biotopes（grassland, fixed dune and mobile dune） located in Naiman, Horqin Sandy Land, Inner Mongolia, China） and subjected to a 24-day incubation experiment together with a control. The soils were also analyzed for general soil properties. The results show that total respiration without exudate addition was highest in grassland soil, intermediate in fixed dune and lowest in mobile dune soil. However, the proportion of native soil carbon mineralized was highest in mobile dune soil, reflecting the low C/N ratio found there. The exudate effects on CO2-C emissions and other variables differed somewhat between biotopes, but total respiration（including that from the added substrates） was significantly increased in all combinations compared with the control, except for oxalic acid addition to mobile dune soil, which reduced CO2-C emissions from native soil carbon. A small but statistically significant increase in pH by the exudate additions in grassland and fixed dune soil was observed, but there was a major decrease from acid additions to mobile dune soil. In contrast, electrical conductivity decreased in grassland     

基于LMDI模型的东北地区农业碳排放测度与分解

通过对东北三省的农业碳排放进行测度,并基于LMDI(对数平均迪氏分解)模型将其分解为碳排放强度、农业收入、就业结构与人口总量四种驱动效应。研究结果:(1)从东北地区的农业碳排放总量来看,1996—2013年间黑龙江、吉林和辽宁三省的农业碳排放呈现逐年上升的趋势,分别增加了0.72、0.63倍和0.52倍,年平均增长率分别为3.23%、2.92%和2.51%,黑龙江碳排放总量和增速最大;(2)从东北地区农业碳排放的内部结构来看,农用资本与农地利用带来的碳排放是东北地区的主要碳源,占比58.65%,其次是牲畜养殖碳排放,占比22.59%;(3)碳排放强度效应对农业碳排放的影响为负,且表现出黑龙江辽宁吉林的特征;1996—2013年间,农业收入效应推动黑龙江、吉林和辽宁的农业碳排放分别增加了1480.57、883.17万t和839.10万t;就业结构效应对黑龙江和辽宁的农业碳排放有正向影响,但对吉林则呈现显著的负向作用;人口总量效应对农业碳排放总量的影响均为正,驱动辽宁的农业碳排放增加了51.02万t。     

银北地区硫磺改良盐碱土初探

采用盆栽试验方法,以石膏为对照,探讨硫磺对宁夏平罗盐碱土的改良效果。结果表明:施用硫磺能有效降低土壤pH值,增大EC值;土壤中Ca2 、Mg2 和SO42-含量增加明显,交换性Na 有一定程度的降低;玉米生物量增加,其中低硫用量效果最为明显,增加了18.4%。     

Influences of drip and flood irrigation on soil carbon dioxide emission and soil carbon sequestration of maize cropland in the North China Plain

The need is pressing to investigate soil CO_2(carbon dioxide) emissions and soil organic carbon dynamics under water-saving irrigation practices in agricultural systems for exploring the potentials of soil carbon sequestration. A field experiment was conducted to compare the influences of drip irrigation(DI) and flood irrigation(FI) on soil organic carbon dynamics and the spatial and temporal variations in CO_2 emissions during the summer maize growing season in the North China Plain using the static closed chamber method. The mean CO_2 efflux over the growing season was larger under DI than that under FI. The cumulative CO_2 emissions at the field scale were 1959.10 and 1759.12 g/m~2 under DI and FI, respectively. The cumulative CO_2 emission on plant rows(OR) was larger than that between plant rows(BR) under FI, and the cumulative CO2 emission on the irrigation pipes(OP) was larger than that between irrigation pipes(BP) under DI. The cumulative CO_2 emissions of OP, BP and bare area(BA) under DI were larger than those of OR, BR and BA under FI, respectively. Additionally, DI promoted root respiration more effectively than FI did. The average proportion of root respiration contributing to the soil CO_2 emissions of OP under DI was larger than that of OR under FI. A general conclusion drawn from this study is that soil CO_2 emission was significantly influenced by the soil water content, soil temperature and air temperature under both DI and FI. Larger concentrations of dissolved organic carbon(DOC), microbial biomass carbon(MBC) and total organic carbon(TOC) were observed under FI than those under DI. The observed high concentrations(DOC, MBC, and TOC) under FI might be resulted from the irrigation-associated soil saturation that in turn inhibited microbial activity and lowered decomposition rate of soil organic matter. However, DI increased the soil organic matter quality(the ratio of MBC to TOC) at the depth of 10–20 cm compared with FI. Our results suggest that the transformation from conventional FI to integrated DI can increase the CO2 emissions and DI needs to be combined with other management practices to reduce the CO_2 emissions from summer maize fields in the North China Plain.     

Environmental behavior and analysis of agricultural sulfur

Sulfur has been widely used for centuries as a staple for pest and disease management in agriculture. Presently, it is the largest‐volume pesticide in use worldwide. This review describes the sources and recovery methods for sulfur, its allotropic forms and properties and its agricultural uses, including development and potential advantages of nanosulfur as a fungicide. Chemical and microbial reactivity, interactions in soil and water and analytical methods for determination in environmental samples and foodstuffs, including inexpensive analytical methods for sulfur residues in wine, beer and other food/beverage substrates, will be reviewed. The toxicology of sulfur towards humans and agriculturally important fungi is included, with some restrictions on use to promote safety. The review concludes with areas for which more research is warranted. © 2015 Society of Chemical Industry     

外源铅在土壤中的年际变化及对土壤有机碳矿化和速效养分的影响

以关中土为供试土样进行田间试验,向耕层土壤中添加不同浓度外源铅(Pb0:背景值,CK;Pb1:175 mg·kg~(-1)+背景值;Pb2:350 mg·kg~(-1)+背景值),进行小麦—玉米轮作试验。分别于2011—2013年小麦收获季采集耕层(0~20 cm)土壤,分析土壤中铅全量及有效态铅含量的年际变化,以及铅对小麦-玉米轮作模式下土壤有机碳(SOC)、溶解性有机碳(DOC)、微生物量碳(MBC)、碱解氮、速效磷、速效钾含量的影响。结果表明,三年中,施铅处理下土壤中铅全量及有效态铅含量分别下降13.22%和30.65%,总体呈现逐年下降趋势。与对照(CK)相比,Pb1、Pb2处理下SOC平均含量分别下降了16.30%和11.86%;DOC平均含量分别下降了4.05%和7.34%,与土壤铅含量呈现显著负相关关系;低浓度铅污染下土壤微生物商(q M)显著高于对照土壤,微生物量碳含量变化不显著。此外,土壤速效养分的分析显示,土壤碱解氮含量在外源铅加入初期下降明显,且在Pb1处理下碱解氮减少量最大;土壤速效磷含量随土壤铅含量增加而呈现下降趋势;土壤速效钾含量则随土壤铅含量的增加而增加。试验表明,外源铅的加入影响了土壤有机碳的稳定性,对土壤碳、氮循环产生了一定的影响;能够与土壤溶液中的磷酸根生成难溶性盐,与土壤胶体或土壤矿物晶格中的K+发生置换,加大土壤速效养分的流失风险。     

不同配料颗粒秸秆施用对土壤速效养分及小麦生长的影响

我国西北地区气温较低，秸秆直接还田腐解慢、养分循环慢、当季利用率低、影响作物出苗，导致秸秆还田率不高。针对以上问题，本研究以小麦秸秆为原料，以硫磺粉（养分活化剂）和麦秸生物炭（养分吸附剂）为外源添加材料，制成秸秆颗粒。硫磺粉的添加质量比为3%（WS3）、5%（WS5）、10%（WS10），生物质炭的添加质量比为5%（WC5）、10%（WC10）、15%（WC15），以秸秆颗粒（WK）、剪碎秸秆（W，W6）及无秸秆（CK）为对照，通过盆栽试验探究了秸秆颗粒对土壤速效养分及小麦生长的影响。结果表明：秸秆颗粒较剪碎秸秆处理相比，能显著提高土壤速效养分及小麦生物量和植株全量氮、磷、钾含量，添加硫磺或生物炭的秸秆颗粒提升效果更明显。各处理土壤硝态氮含量以WS3处理最高，较W处理提高14.44%；铵态氮含量以WC5处理最高，较W处理提高40.93%；速效磷含量以WS10处理最高，较W处理提高23.42%；速效钾含量以WC5处理最高，较W处理提高9.05%；差异均达显著水平（P<0.05）。小麦生物量以WS5处理最高，较WK处理提高29.61%；全氮含量以WS10最高，较WK处理提高11.44%；全磷含量以WS10处理最高，较WK处理提高21.82%；全钾含量以WC15最高，较WK处理提高12.53%；差异均达显著水平（P<0.05）。综上可知，秸秆颗粒在西北地区实现秸秆还田和养分循环，维持土壤肥力等方面具有很大应用前景。     

黑龙江省工业SO_2排放与经济发展关系演变及成因分析

经济与环境协调发展是建设资源节约型和环境友好型社会的核心内容。通过对1981-2006年黑龙江省工业SO2排放与经济发展之间动态关系的分析,结果表明:1981年以来黑龙江省工业SO2排放量经历了先减后升的过程,排放强度显著下降,主要来源于能源生产、造纸及纸制品、非金属矿物制品等制造业部门,资源型城市的排放量占全省工业SO2排放量的50%以上,而综合性工业城市则占到1/3左右。EKC模型对工业SO2排放与人均GDP之间关系的模拟结果表明,二者之间呈现较为典型的U型关系。分解分析结果显示,规模效应、清洁技术效应是影响工业SO2排放的重要因素,其中清洁技术效应对工业SO2减排目标的实现具有决定性控制作用。