共查询到19条相似文献,搜索用时 171 毫秒
1.
为揭示黑土单向冻融过程对不同土层有机碳矿化的影响,该研究以东北典型季节性冻融黑土为研究对象,通过添加13C标记葡萄糖(初始添加浓度为200μg/g)模拟春季解冻期土壤最常见有机碳组分,采用室内由外而内的单向冻融(-10~10℃)模拟田间自上而下单向冻融过程,对比分析渐次解冻剥离的外、中、内3个土层在恒温培养15 d过程中的CO2释放速率变化规律,以及激发效应差异。结果表明:1)单向冻融后,各土柱外层土壤水分均显著增高(为初始含水率的1.20~1.27倍),而内层则明显失水(仅为初始含水率的78.4%~84.5%),且未添加葡萄糖处理的内外层水分差异比添加葡萄糖处理的更加显著;2)未添加葡萄糖土柱单向冻融后,内层累积CO2释放量均值为138.8μg/g,显著高于外层(95.1μg/g);而添加葡萄糖土柱单向冻融后,内层CO2释放速率表现出明显的时间变异性,前期峰值突出(第4天),可达外层和中层峰值的1.7和2.0倍,但后期快速衰退,最终累积CO2释放速率为外层和中层的1.2和1.3倍;3)添加葡萄糖土... 相似文献
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东北黑土区土壤侵蚀研究进展与展望 总被引:1,自引:0,他引:1
东北黑土区是我国重要的商品粮生产基地,强烈水土流失导致的黑土厚度下降及土壤质量退化,直接威胁国家粮食安全。系统分析黑土区土壤侵蚀研究成果,对阻控黑土退化、维持土地生产力、保障国家粮食安全具有重要意义,论述了黑土区土壤侵蚀环境与侵蚀环境效应、土壤侵蚀过程与机理、土壤侵蚀时空变化和未来研究展望。多营力复合、缓坡长坡是黑土区独特的侵蚀环境,黑土厚度下降与坡耕地土壤质量退化是该区最典型的侵蚀环境效应。细沟间、细沟、浅沟、切沟及冻融侵蚀发育的动力机制与主控因素差异明显,输沙耗能驱动的泥沙输移对土壤分离的反馈效应是侵蚀强度沿坡长呈强弱交替的根本原因,浅沟和切沟主要发育在坡耕地,侵蚀强度受耕作方式等人类活动的显著影响。冻融侵蚀强度显著小于水力侵蚀,但可通过降低土壤抗蚀性能和促进坡面径流及壤中流发育影响水力侵蚀。土壤侵蚀类型与强度在小流域尺度上沿坡面呈明显的垂直分带特征,在区域尺度上呈南北与东西递变的纬度和经度地带性。全球气候变化可能导致黑土区水力侵蚀加强、冻融侵蚀减弱。未来亟需加强黑土厚度及土地生产力对侵蚀响应机理、复合侵蚀动力过程与耦合机制、典型侵蚀类型时空变化与主控因素等方面的研究。 相似文献
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[目的]研究侵蚀作用对黑土区坡耕地侵蚀沟表层土壤的影响,为该区土壤资源合理运用和区域水土流失治理工作提供理论支持。[方法]以黑龙江省哈尔滨市延寿县不同发育程度侵蚀沟为研究对象,对切沟沟头的沟坡和沟底土壤的粒径分布及蓄水性进行定量描述。[结果](1)不同深度处土壤容重、最大吸持贮水量、最大滞留水量、总库容、死库容、最大有效库容差异显著(p<0.05)。随土层加深,土壤容重增大,贮水量、持水性、有效水分下降。各层最大吸持贮水量占饱和贮水量均约90%,有效水分利用率分别为44.79%和41.87%,侵蚀沟发育对土壤有效水分影响明显。(2)入渗特征总体表现为:初始入渗速率>30 min入渗速率>稳定入渗速率,3者在不同编号沟道的A2—A4间随土层的加深,入渗性能下降。在20—40 cm层A1—A4的入渗特征均表现为:CK(对照)>A1>A4>A2>A3,呈先下降后上升趋势。随着侵... 相似文献
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横、顺坡垄作对黑土坡面侵蚀-沉积周期规律的影响 总被引:3,自引:0,他引:3
我国东北黑土区的水土流失和土地退化正严重制约着东北地区农业经济发展,威胁国家粮食生产安全。掌握不同垄作方向耕作措施下的东北黑土区土壤侵蚀规律,对合理布设水保措施、控制水土流失等具有重要意义。采用137Cs示踪技术并结合小波分析方法,对不同垄作方向坡耕地土壤侵蚀-沉积速率的空间变化规律开展研究。结果表明:(1)横、顺坡垄作坡面137Cs平均浓度分别为1 802 Bq·m-2和1 770 Bq·m-2,均小于当地背景值2 417 Bq·m-2,说明在两种垄作方向下均发生了不同程度的土壤侵蚀。(2)横坡垄作的坡面平均侵蚀速率(1 341 t·km-2·a-1)小于顺坡垄作(1 477 t·km-2·a-1),表明在长期平均条件下前者的水土保持作用优于后者。尽管研究区土壤侵蚀属于轻度侵蚀,但其侵蚀速率远大于黑土区的土壤容许流失量(200 t·km-2·a-1 相似文献
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为了研究干旱河谷区坡耕地农作物种植对耕作侵蚀的影响,在不同作物类型坡耕地(玉米地和荞麦地)上进行耕作试验,通过磁性示踪法测量坡耕地顺坡耕作的耕作位移距离,分析了不同作物类型下的耕作侵蚀速率特征。结果表明:(1)试验地类的耕作位移距离表现为玉米地<荞麦地<裸地(对照地)的变化趋势,荞麦地和玉米地的耕作位移距离均显著低于裸地(p<0.05),表明坡耕地种植玉米和荞麦可以显著减小坡耕地土壤耕作位移距离;(2)3种地类的耕作位移距离与坡度均呈显著正相关关系,玉米地和荞麦地的耕作位移距离系数k2值和传输系数k4值明显小于裸地,说明作物因素减小了耕作位移距离随坡度的增加幅度;(3)裸地的耕作侵蚀速率显著高于玉米地和荞麦地(p<0.01),分别是玉米地和荞麦地的1.99倍和1.88倍,说明坡地种植农作物可明显减小坡面耕作侵蚀。综上,种植农作物可有效减少坡耕地耕作侵蚀,研究成果丰富了对坡耕地作物根系防蚀特性的认识,也为完善耕作侵蚀模型奠定重要基础。 相似文献
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在全球气候变暖背景下,愈加广泛和频繁的冻融现象将会对土壤碳的生物地球化学循环过程产生深远的影响,因此归纳总结冻融作用对土壤二氧化碳(CO2)排放的影响,可为科学揭示冻融作用对土壤CO2排放的影响机理提供理论支撑。在总结相关文献的基础上,系统地分析了冻融格局(冻融温度、循环次数及持续时间等)对土壤CO2排放量的影响,并从土壤理化性质、土壤微生物等方面归纳总结土壤CO2排放对冻融作用的响应机制。冻融作用能降低土壤团聚体稳定性,促进溶解性有机碳的释放,并能够使微生物的数量降低,细胞破裂,释放碳氮营养物质以供存活的微生物利用,从而促进土壤CO2排放的增加,且与冻结温度和冻融循环次数密切相关。但由于生态系统类型、土壤理化性质、冻结温度等的差异,冻融作用也可能会促进土壤团聚体稳定性增加,抑制活性碳的释放和微生物的活性,减少土壤CO2的排放。虽然目前已有研究能够对冻融作用对土壤CO2排放的影响及其驱动机制作出初步解释,但由于存在实验参数缺乏原位性、对土壤微生物的研究不够深入和数据难以量化等不足,致使研究结果存在较大的差异和不确定性,因此还需进一步深入研究。 相似文献
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典型黑土直型坡耕地土壤侵蚀强度的小波分析 总被引:3,自引:0,他引:3
土壤侵蚀导致东北黑土坡耕地土地质量严重退化,研究东北黑土区典型坡耕地的土壤侵蚀规律,对控制坡耕地的水土流失以及深化土壤侵蚀规律的认识具有重要的意义。本研究通过采集开垦近100年的黑土直型坡耕地的土壤样品,利用137Cs示踪技术,结合小波分析方法,研究了长坡长直型坡耕地50多年来土壤侵蚀强度的空间变化规律,结果显示4个断面顺坡方向上的坡面侵蚀强度均存在着坡长为142m的强弱交替变化的波动周期,这反映了长坡长直型坡土壤在长期的降雨侵蚀过程中,泥沙沿坡面输移的强弱交替变化。通过对4个断面的侵蚀速率的数学拟合发现,用正弦函数的和拟合的结果最好,R2均在0.96以上,进一步说明了直型坡面侵蚀随坡长变化的波动性规律。所研究的断面控制面积内平均侵蚀速率为3054 t.km-2.a-1。 相似文献
8.
东北黑土坡耕地不同水力条件下坡长对土壤细沟侵蚀的影响 总被引:4,自引:2,他引:2
集中水流条件下细沟土壤侵蚀过程对研究细沟侵蚀机理与土壤侵蚀预报有着重要的意义,并且为土壤侵蚀模型其他重要参数比如剥蚀率、可蚀性参数提供基础数据。为了研究东北黑土坡耕地不同水动力条件下坡长对土壤细沟侵蚀的影响,该文采用室内模拟试验方法,测量含沙量随坡长的分布。试验设计包括4个坡度(5?、10?、15?、20?)与3个流量(1、2、4 L/min),在不同水力条件下,测量不同坡长(0.5、1、2、3、4、5、6、7、8m)含沙量。结果表明含沙量在各种水力条件下均随坡长增加,且其增加的速率随坡长减小。对坡长与含沙量系列数据用幂指数函数拟合,其决定系数R2在0.85到0.99之间。因此,黑土坡耕地细沟侵蚀产生的含沙量随坡长呈幂指数增加,且含沙量在一定坡长之后将达到最大值。随坡度和流量的增大,水流在更短的坡长上侵蚀并携带更大的最大含沙量。该文对进一步理解与研究细沟侵蚀过程有着重要的意义,且为深入研究细沟侵蚀提供了数据支撑,为土壤侵蚀模型剥蚀率、可蚀性参数等提供依据。 相似文献
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东北黑土区坡耕地水蚀与风蚀速率的定量区分 总被引:6,自引:0,他引:6
用137Cs含量测定和USLE水蚀预报模型,研究了东北黑土区2块坡耕地的水蚀与风蚀速率,结果表明:直型坡耕地和凸型坡耕地的年均侵蚀速率分别为3054和3548t.km2.a-1;由于坡向的不同,2块坡面的风蚀速率分别为631和1155t.km2.a-1,即研究区每年约有0.5~1.0mm的表层土壤被风吹蚀掉,风蚀分别占总侵蚀的20.7%和32.6%;而水蚀仍为研究区主要的侵蚀方式,2块坡面的水蚀速率分别占总侵蚀的79.3%和67.4%。因此,东北黑土区坡耕地水土流失的防治要充分考虑水和风的不同影响,综合治理。 相似文献
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暴雨条件下黄土高原长陡坡耕地细沟侵蚀特征 总被引:5,自引:3,他引:2
细沟侵蚀是黄土高原坡耕地侵蚀的重要形式,已有的坡耕地细沟研究成果主要集中于裸土细沟侵蚀特征及其发生机制的小区或水槽试验,极端暴雨条件下细沟侵蚀观测很少,对于田间细沟侵蚀的预报仍然缺少实用的方法。该研究旨在基于实地测量数据,分析极端暴雨条件下黄土高原长陡坡耕地细沟侵蚀特征。2017年无定河流域"7.26"暴雨后,在暴雨中心附近选择15个样地进行细沟侵蚀测量,结合Google影像和无人机航拍影像,调查分析不同类型坡耕地细沟侵蚀特征。研究结果表明:1)暴雨条件下坡耕地是坡面细沟侵蚀的主要地类。长陡坡裸露坡耕地侵蚀模数为22 478 t/km~2,坡长20 m时,约为种植作物的平作坡耕地的1.5倍,且坡长越长,差异越大。等高垄作能够有效减少细沟侵蚀。撂荒坡耕地细沟侵蚀模数仅为裸露坡耕地的12%,草地未发现细沟侵蚀。2)幂函数可以很好地拟合细沟侵蚀模数与坡长的关系,裸露坡耕地坡长指数为0.831。暴雨强度越大,坡长指数也越大。3)上坡来水在坡耕地上造成了严重的细沟侵蚀,与地块上承接的降水相比,上坡来水对细沟侵蚀的影响更大。坡面浅沟汇水明显减小细沟侵蚀强度,浅沟发育程度越高,细沟侵蚀强度就越小。该研究可为估算黄土高原丘陵区不同类型坡耕地的细沟侵蚀提供重要参考。 相似文献
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利用室内培养实验,分析燥红壤和砖红壤中分别施加N0(不添加氮素)、N1(氮添加量为100mg·kg−1)、N2(氮添加量为200mg·kg−1)和N3(氮添加量为300mg.kg−1)4个水平氮后对土壤性质及N2O、CO2排放的影响。结果表明:氮肥添加显著降低了土壤pH和有机碳含量。相较于N0,燥红壤N1、N2和N3处理pH和有机碳降幅分别为8%~18%和4%~12%,砖红壤降幅分别为5%~23%和3%~15%;添加氮肥后各处理土壤全氮含量显著增加,燥红壤和砖红壤分别增加15%~54%和13%~52%。氮施入增加了土壤NH4+−N和NO3−−N含量,各处理土壤铵态氮和硝态氮含量均表现为N3>N2>N1>N0。氮添加促进土壤N2O和CO2排放,相较于N0,燥红壤N2O和CO2累积排放量分别增加1176%~2425%和124%~281%,砖红壤分别增加1054%~1887%和138%~256%。施氮量和土壤类型是影响农田土壤N2O和CO2排放的重要因素。土壤N2O和CO2排放与施氮量呈线性显著相关,减少施肥是降低土壤N2O排放最直接和最有效的措施。与砖红壤相比,燥红壤N2O和CO2排放对氮素添加的响应更敏感。 相似文献
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Crop rotation and nitrogen fertilization effect on soil CO2 emissions in central Iowa 总被引:1,自引:0,他引:1
Depending upon how soil is managed, it can serve as a source or sink for atmospheric carbon dioxide (CO2). As the atmospheric CO2 concentration continues to increase, more attention is being focused on the soil as a possible sink for atmospheric CO2. This study was conducted to examine the short-term effects of crop rotation and N fertilization on soil CO2 emissions in Central Iowa. Soil CO2 emissions were measured during the growing seasons of 2003 and 2004 from plots fertilized with three N rates (0, 135, and 270 kg N ha−1) in continuous corn and a corn–soybean rotation in a split-plot design. Soil samples were collected in the spring of 2004 from the 0–15 cm soil depth to determine soil organic C content. Crop residue input was estimated using a harvest index based on the measured crop yield. The results show that increasing N fertilization generally decreased soil CO2 emissions and the continuous corn cropping system had higher soil CO2 emissions than the corn–soybean rotation. Soil CO2 emission rate at the peak time during the growing season and cumulative CO2 under continuous corn increased by 24 and 18%, respectively compared to that from corn–soybean rotation. During this period, the soil fertilized with 270 kg N ha−1 emitted, on average, 23% less CO2 than the soil fertilized with the other two N rates. The greatest difference in CO2 emission rate was observed in 2004; where plots that received 0 N rate had 31% greater CO2 emission rate than plots fertilized with 270 kg N ha−1. The findings of this research indicate that changes in cropping systems can have immediate impact on both rate and cumulative soil CO2 emissions, where continuous corn caused greater soil CO2 emissions than corn soybean rotation. 相似文献
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J. lvaro-Fuentes C. Cantero-Martínez M.V. Lpez J.L. Arrúe 《Soil & Tillage Research》2007,96(1-2):331-341
In semiarid Mediterranean agroecosystems, low and erratic annual rainfall together with the widespread use of mouldboard ploughing (conventional tillage, CT), as the main traditional tillage practice, has led to a depletion of soil organic matter (SOM) and with increases in CO2 emissions from soil to the atmosphere. In this study, we evaluated the viability of conservation tillage: RT, reduced tillage (chisel and cultivator ploughing) and, especially, NT (no-tillage) to reduce short-term (from 0 to 48 h after a tillage operation) and mid-term (from 0 h to several days since tillage operation) tillage-induced CO2 emissions. The study was conducted in three long-term tillage experiments located at different sites of the Ebro river valley (NE Spain) across a precipitation gradient. Soils were classified as: Fluventic Xerocrept, Typic Xerofluvent and Xerollic Calciorthid. Soil temperature and water content were also measured in order to determine their influence on tillage-induced CO2 fluxes. The majority of the CO2 flux measured immediately after tillage ranged from 0.17 to 6 g CO2 m−2 h−1 and was from 3 to 15 times greater than the flux before tillage operations, except in NT where soil CO2 flux was low and steady during the whole study period. Mid-term CO2 emission showed a different trend depending on the time of the year in which tillage was implemented. Microclimatic soil conditions (soil temperature and water content) had little impact on soil CO2 emission following tillage. In the semiarid Mediterranean agroecosystems studied, NT had low short-term soil CO2 efflux compared with other soil tillage systems (e.g., conventional and reduced tillage) and therefore can be recommended to better manage C in soil. 相似文献
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不同施肥模式对设施土壤CO2排放特征及碳平衡的影响 总被引:1,自引:0,他引:1
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有机肥和秸秆炭分别替代部分尿素和秸秆降低黑土温室效应的效果 总被引:1,自引:1,他引:0
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【目的】菌渣被广泛认为是一种优良的植物生长基质和土壤改良剂,向土壤中施用菌渣可以提高土壤微生物活性与温室气体的排放,且土壤水分含量也可以调控菌渣对土壤酶活性与温室气体的排放。通过探究不同土壤湿度条件下平菇(Pleurotus ostreatus)菌渣对土壤酶活性的影响,以阐明不同土壤田间持水量下菌渣施用剂量-土壤温室气体排放-土壤酶活性之间的综合关系。【方法】本研究将平菇菌渣施入土壤并对土壤含水量进行调节,分析了在60%、75%、90%田间持水量条件下和菌渣添加量0.0%、2.5%、5.0%、10.0%时,菌渣添加量对土壤酶活性和温室气体排放的影响。【结果】脲酶、几丁质酶、β-葡糖苷酶与菌渣添加量呈正相关,在菌渣添加量为10.0%时活性最强,且在不同含水量下并无显著性差异。CO2排放量与菌渣添加量呈正相关,在菌渣添加量为10.0%时排放量最高,不同土壤含水量下并为CO2排放量其产生显著影响。N2O排放量在菌渣添加量2.5%和无菌渣添加时与含水量呈正相关,N2O排放量在菌渣添加量5.0%与10.0%时... 相似文献
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The impact of tillage systems on soil CO2 emission is a complex issue as different soil types are managed in various ways, from no-till to intensive land preparation. In southern Brazil, the adoption of a new management option has arisen most recently, with no-tillage as well as no burning of crops residues left on soil surface after harvesting, especially in sugar cane areas. Although such practice has helped to restore soil carbon, the tillage impact on soil carbon loss in such areas has not been widely investigated. This study evaluated the effect of moldboard plowing followed by offset disk harrow and chisel plowing on clay oxisol CO2 emission in a sugar cane field treated with no-tillage and high crop residues input in the last 6 years. Emissions after tillage were compared to undisturbed soil CO2 emissions during a 4-week period by using an LI-6400 system coupled to a portable soil chamber. Conventional tillage caused the highest emission during almost the whole period studied, except for the efflux immediately following tillage, when the reduced plot produced the highest peak. The lowest emissions were recorded 7 days after tillage, at the end of a dry period, when soil moisture reached its lowest rate. A linear regression between soil CO2 effluxes and soil moisture in the no-till and conventional plots corroborate the fact that moisture, and not soil temperature, was a controlling factor. Total soil CO2 loss was huge and indicates that the adoption of reduced tillage would considerably decrease soil carbon dioxide emission in our region, particularly during the summer season and when growers leave large amounts of crop residues on the soil surface. Although it is known that crop residues are important for restoring soil carbon, our result indicates that an amount equivalent to approximately 30% of annual crop carbon residues could be transferred to the atmosphere, in a period of 4 weeks only, when conventional tillage is applied on no-tilled soils. 相似文献