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1.
转变耕作方式对长期旋免耕农田土壤有机碳库的影响 总被引：3，自引：6，他引：3
土壤深松是解决长期旋免耕农田耕层浅薄化、亚表层（>15～30 cm）容重增加等问题的有效方法之一,而将长期旋免耕农田进行深松必然导致农业生态系统中土壤有机碳（soil organic carbon,SOC）及碳固定速率的变化。因此,为对比将长期旋免耕转变为深松前后农田土壤有机碳库变化,该研究利用连续12a 的旋耕和免耕长期定位试验以及在此基础上连续6 a旋耕-深松和免耕-深松定位试验,对比了转变耕作方式对农田土壤0～30 cm有机碳含量、周年累积速率及其固碳量的影响。研究结果表明,经过连续12 a的旋耕和免耕处理（2002－2014）,2014年免耕处理土壤0～30 cm有机碳储量比试验初期（2002年）提高38%,旋耕处理降低了30%,而对照常规处理无显著差异。免耕处理土壤0～30 cm有机碳储量比旋耕处理高约2.6倍（2014年）。长期免耕显著提高了土壤0～30 cm的有机碳含量,2002~2014年其土壤0～30 cm固碳量为16.69 t/hm2,但长期旋耕导致土壤0～30 cm SOC含量显著降低,表现为土壤有机碳的净损耗,年损耗速率为?0.75 t/hm2。而长期旋耕后进行深松（旋耕-深松处理）6年其土壤0～30 cm的有机碳含量较原旋耕处理提高32%～67%,且显著提高了土壤固碳量及周年累积速率;免耕-深松土壤0～30 cm的有机碳周年累积速率较免耕处理下降了42%。长期旋耕造成有机碳水平下降的条件下,将旋耕处理转变为深松处理在短期内更有利于促进土壤有机碳的积累,而将长期免耕处理转变为深松措施,降低了土壤有机碳的累积速率和固碳量。 相似文献
2.
基于热脉冲技术的能量平衡方法是一种原位实时监测土壤蒸发速率技术。热脉冲方法的准确性受地表气象条件、土壤类型等因素影响,目前该技术多应用于质地较砂北方旱地土壤。为进一步验证热脉冲方法在质地较黏的南方红壤上监测蒸发速率的适用性,该研究利用热脉冲传感器与微型蒸渗仪开展了为期30 d的监测试验,对比了热脉冲能量平衡方法与微型蒸渗仪测得日蒸发速率以及累积蒸发量,并通过监测土壤含水率变化和气象因子,评价了红壤区土壤蒸发的主要影响因素。结果表明,热脉冲方法测得的日蒸发速率与微型蒸渗仪监测值变化趋势相同,试验期间两种方法测得日蒸发速率最大相差0.80 mm/d,最小相差0.02 mm/d,决定系数R2=0.52。两种方法测得的累积蒸发量随时间变化值之间具有更强的相关性（R2=0.99）,30 d内微型蒸渗仪监测的总累积蒸发量为19.3 mm,热脉冲方法监测的累积蒸发量为24.4 mm。由于降水影响,微型蒸渗仪漏测了7 d的蒸发速率,剔除该7 d数据后,二者仅相差4.6%。相比于传统的微型蒸渗仪法,热脉冲方法具有自动化的优点,且能够实时监测剖面微尺度（mm尺度）上蒸发动态。研究区红壤的日蒸发速率与各因子的相关程度由大小为土壤含水率、净辐射、风速、气温。研究结果表明热脉冲能量平衡方法能够准确地监测南方红壤区土壤蒸发动态,研究可为红壤区水热循环研究提供技术和理论支撑。 相似文献
3.
长期施肥条件下黑土有机碳和氮的动态变化 总被引：9，自引：2，他引：7
以黑土地区海伦农田生态系统国家野外科学观测研究站的农田长期(1990～2004年)肥料定位试验土壤为试验材料,对不同施肥处理有机碳和氮进行了系统分析。结果表明,长期不施化肥(CK),土壤中有机碳、全氮、碱解氮及C/N呈现下降趋势;长期施用氮肥,土壤有机碳亏损速率较大,但土壤氮素变化较小,C/N保持相对稳定;长期施用磷肥,土壤有机碳含量下降速率较小,但全氮含量下降速率较大,因而C/N保持上升趋势;长期施用钾肥,土壤有机碳、氮及C/N变化趋势相同,但土壤有机碳含量下降速率较小,C/N增加较快。因此,通过调控化肥可以维持土壤的有机碳、全氮及碱解氮含量,保持土壤的持续生产力及提高作物产量。 相似文献
4.
土壤风化速率研究及其应用 总被引：4，自引：1，他引：3
土壤矿物风化是土壤、也是整个生态系统中无机矿质养分的最重要来源,不仅为植物长期提供养分和保持土壤的化学平衡稳定性,并缓冲土壤和地表水的酸化,还影响全球气候变化。风化速率在全球碳循环、酸临界负荷和土壤侵蚀等研究中都是非常重要的参数。土壤化学风化是一个不断进行的自然释放过程,气候是最主要的驱动力,而矿物本身的稳定性也影响了风化速率的快慢。由于人为影响下的大气酸沉降和农业活动已经非常普遍,目前的土壤风化速率也因此而改变。本文从风化速率的研究方法、风化速率的影响因素以及风化速率在全球变化中的应用3个方面介绍了近年来在风化速率方面的研究进展,并探讨了相关研究未来的发展趋势。 相似文献
5.
透气隔水埋体对土壤水分入渗与溶质运移的影响 总被引：2，自引：0，他引：2
为分析透气隔水(弱透水)埋体促进水分入渗与溶质运移功效,开展了不同容重(1.40,1.45,1.50,1.60 g/cm~3)透气隔水(弱透水)埋体的一维垂直土柱入渗试验,分析了不同容重的透气隔水(弱透水)埋体对土壤水分入渗与溶质分布的影响。结果表明,透气隔水(弱透水)埋体能够增加土壤累积入渗量,推动湿润锋运移,在一定范围内,随着透气隔水(弱透水)埋体容重增加,湿润锋推进速度与土壤入渗率均增加。600 min时,土壤累积入渗量相对增加7.42%～29.17%,湿润锋深度达到27 cm,入渗时间相对减少26.97%～64.27%。相比于对照组,不同容重的透气隔水(弱透水)埋体均能降低溶质向深层土壤迁移数量。Philip模型和代数模型均能描述透气隔水(弱透水)埋体土壤水分入渗过程,且Philip模型中吸渗率S和代数模型中综合形状系数α均与透气隔水(弱透水)埋体内外容重比呈正相关关系。研究结果表明透气隔水(弱透水)埋体能够通过改变上层土壤吸力分布提高水分入渗能力与溶质传输效率,实现对城市雨水径流调控和净化。 相似文献
6.
间歇入渗对土壤溶质淋洗效率的影响 总被引：1，自引：1，他引：0
针对间歇入渗条件下土壤溶质运动规律研究的不足,采用室内土柱试验的方法,研究了相同灌水总量、不同灌水频次条件下的水分和溶质运动规律。试验结果表明:在无蒸发的条件下,间歇入渗会显著提高入渗和排水的速率,但不会影响到排水总量;在一定灌水频次范围内,间歇入渗会在不影响溶质淋洗效率的条件下提高溶质淋出的速率,但过多的灌水频次会导致土壤中水分运动速率过快,不能有效地携溶质向下层土壤迁移,导致溶质淋洗效率降低。该研究结果可为制定合理的间歇灌水制度提供一些依据和参考。 相似文献
7.
8.
泰乐菌素和土霉素在农业土壤中的消解和运移 总被引：3，自引：0，他引：3
长期施用禽畜排泄物可导致抗生素在土壤中的积累, 对环境产生不良影响.为了解进入农田后抗生素的去向及残留动态, 选择2个典型农业土壤, 利用田间小区试验, 研究了田间实际状况下泰乐菌素和土霉素2种抗生素在土壤中的消解与运移行为.研究表明, 抗生素在土壤中的消解和运移与抗生素种类和土壤性质有关.抗生素在砂质土壤(清水砂)中的下移明显高于粘壤土(泥质田), 泰乐菌素在土壤中的垂直迁移强于土霉素.表层土壤中抗生素因降解和下移随时间逐渐下降, 消解速率在试验初期大于后期, 并且土霉素消解速率大于泰乐菌素.砂质土壤中抗生素的消解速率在试验初期明显高于粘壤土, 但至试验后期, 二者渐趋相似.田间条件下测得的抗生素消解速率明显低于实验室条件下, 这可能与抗生素进入田间深层土壤后稳定性增加有关.农田施用抗生素初期产生的径流中含较高浓度的抗生素, 但随时间(10 d之内)很快下降至检测下限以下; 试验初期径流中抗生素浓度为泰乐菌素大于土霉素, 砂质土高于粘壤土. 相似文献
9.
北方土石山区土壤侵蚀对土壤质量的影响 总被引：7，自引：1，他引：6
沂蒙山区是我国北方典型的土石山区,当地土壤由片麻岩、砂岩发育而来,质地疏松易流失,目前缺乏对土壤侵蚀监测的长期观测数据。以山东省沂蒙山区某一小流域为研究对象,利用137Cs示踪技术与杨氏土壤侵蚀等模型,对该流域坡耕地与非耕地的土壤侵蚀速率进行了初步估算,坡耕地土壤侵蚀速率5 961.6 t/km2.a,坡地非耕地侵蚀速率2 530.5 t/km2.a,并探讨了土壤侵蚀对土壤质量的影响。研究结果表明:整个研究流域土壤侵蚀严重,土壤侵蚀量大的区域,土壤有机质、全氮等含量相对较低,而土壤全磷含量变化和缓,总体上土壤质量状况较差。该研究对我国北方土石山区土地资源的合理开发利用和生态环境保护具有积极的意义。 相似文献
10.
土壤中钾素在固液相间的转化速率及数量取决于K+与土壤固相表面的作用方式,并决定着K+进入土壤后的去向和土壤供钾能力。研究K+在土壤固液相间转化的动力学性质,对于了解阳离子型养分在土壤固相表面的作用机理及评价土壤保持、供应钾素能力有重要的理论与实践意义,国内外众多学者就此展开了深入研究[1-9]。施肥是影响K+在土壤固液相间转化动力学的重要因素,而长期定位施肥试验是持续研究土壤肥力动态变化的重要手段。国内已有学者研究了长期定位施肥紫色土、非石灰性潮土K+的吸附、解吸动力学性质,明确了长期不同施肥带来的土壤基本理化性质的变化是土壤K+的吸附、解吸动力学性质差异的根本原因,比较了长期不同施肥处理带来 相似文献
11.
A re-examination of closed flux chamber methods for the measurement of trace gas emissions from soils to the atmosphere 总被引：2，自引：0，他引：2
The most widely used method for measuring the emission of a trace gas such as N2O from soil to the atmosphere involves the accumulation of the gas under closed chambers followed by sampling and analysis (by gas chromatography or infrared methods). These chambers can affect the gas exchange, and so improved designs have been proposed. We have tested their performance. One design includes a vent tube to allow ambient pressure fluctuations to occur also inside the chamber. We tested it against a sealed version on two different grassland sites during N2O peak emissions in spring 1997. On a welldrained soil with a fairly large air permeability vented chambers yielded fluxes as much as five times those of sealed chambers, depending on wind speed. By contrast, on a heavier and wetter soil with smaller air permeability vented chambers averaged only 88% of the fluxes observed with sealed chambers. The effects of venting cannot be explained solely on the basis of mean pressure differences inside and outside the chamber. It seems more likely that wind blowing over the vent depressurizes the chamber (Venturi effect), resulting in significant gas flow from the more permeable soil into the interior of the chamber. The opposite trend for the less permeable soil suggests that diffusion losses through the vent tube are greater than the increase in concentration due to soil gas flow. Venting can create larger errors than the ones it is supposed to overcome. 相似文献
12.
利用改进的ZC-2015型渗气仪对不同类型的原状风干和重塑的马兰黄土进行渗气试验,分析土样体积、渗径、干密度、取样深度等对渗气率ka的影响,并利用扫描电镜(SEM)试验得到的孔隙结构参数解释黄土渗气特性。结果表明:渗气率ka不仅是气体渗透特性的衡量指标,也是描述非饱和马兰黄土孔隙和结构特征的重要参数。不同体积的土样由于尺寸效应,其渗气率随着土样体积的增大而增大。另外,渗气率随着渗径、干密度的增大而减小。对比3种不同类型黄土的透气性试验结果和电镜照片,并结合统计的孔隙结构参数,得出渗气率在区域和深度上有一定的规律,区域上黄土颗粒中黏粒含量增高,总孔隙和大孔隙面积减小,土体有效渗气孔隙减少,重塑黄土的渗气率随着取土深度的增加有微小的减小。 相似文献
13.
An apparatus was constructed to measure diffusivity of krypton-85 and gas permeability in an enclosed core of soil of field structure or in other porous material. Sample enclosure decreased water loss by evaporation, reduced mass flow caused by changes in ambient temperature and pressure during diffusion measurement, and allowed subsequent measurement of gas permeability without further sample disturbance. When a bundle of tubes was used as a test sample to calibrate the apparatus, the resistances to diffusion and viscous flow agreed approximately with those calculated from the tube size and number. Gas movement was measured in dry sieved soil and in undisturbed cores of silty loam soil to illustrate the practical value of the method. In the dry cores, diffusivity relative to free air (DA/Do) was greater in ploughed soil, 0.18, than in direct drilled soil, 0.14, nearly in proportion to the greater air porosity in the ploughed soil, but air permeability in ploughed soil was four times greater than in direct drilled soil and was about 1 000 times greater than in compacted sieved soil. 相似文献
14.
土壤导气率是重要、易测量的土壤参数,其价值在于可以预测田间饱和导水率,反映土壤孔隙和土壤结构特征。国内外学者提出不同土壤导气率测算模型。本文通过对比瞬态法和稳态法两种土壤导气率测算模型,分析两模型在测量效率、经济性等方面优缺点,以及测量结果的相对误差变化幅度。瞬态法相对稳态法,无须测量通过土样的气体数量,测量时间短,且只需少量体积的气体通过土样,对土样结构破坏小;而稳态法测量技术较成熟,计算方便。室内对60组土样测算结果表明,瞬态法与稳态法测量结果之间具有极显著的相关性,可用线性函数关系式y=0.979 1 x表示;以稳态法为标准,两种方法测量结果相对误差变化幅度在0.5%~45%之间,80%以上测量结果相对误差变化幅度<15%,仅有少数变化幅度>20%;同时,试验结果也验证了稳态试验中气体传导速率Q与测量仪内封闭气体压强值△P存在显著的线性关系,及Kirkham提出的在瞬态模型中被测土样密封端压力动态变化与时间t之间存在线性关系。 相似文献
15.
《国际水土保持研究(英文)》2022,10(3):457-469
Soil structure plays an important role in edaphic conditions and the environment. In this study, we investigated the effects of organic amendment on soil structure and hydraulic properties. A corn field in a semiarid land was separately amended with sheep manure compost at five different rates (2, 4, 6, 8 and 10 t/ha) and corn stover (6 t/ha) in combination with two decomposing agents. The soil structure of different amended soils was analyzed from the aggregate and pore domain perspectives. The internal pore structure of the soil was visualized through X-ray computed tomography and quantified using a pore-network model. Soil aggregate-size distribution and stability, saturated hydraulic conductivity, and water-retention curves were measured by sampling or in situ. The gas permeability and diffusivity of different amended soils were simulated based on the extracted pore networks. The aggregate stability of the amended soils was improved compared with the control, that is, the mean weight diameter increased and the percentage of aggregate destruction decreased. The stability of soil aggregates varied non-monotonically with the application rate of compost and decreased after treatment with corn stover and decomposing agents. The pore-network parameters including air-filled porosity, pore radius, throat length, and coordinate number increased for the amended soils compared with the control. The mean pore size increased with increasing compost incorporation rate. The saturated hydraulic conductivity of the compost-amended soils was higher than that of the control but varied quadratically with the application rate. The saturated hydraulic conductivity of soil treated with corn stover and decomposing agents was clearly higher than that without the agent and the control. The greater gas diffusivity and air permeability indicate that soil aeration improved following the incorporation of organic amendments. The air permeability versus air-filled porosity relationship followed a power law, and the gas diffusivity versus air-filled porosity relationship was characterized by a generalized density-corrected model regardless of amendment. The findings of this study can help improve the understanding of soil structure and hydrological function to organic fertilizer incorporation and further monitor the quality of soil structure through the pore space perspective. 相似文献
16.
高聚物对土壤结构改良的研究 Ⅲ.聚丙烯酰胺对赤红壤的改良研究 总被引：32，自引：0，他引：32
研究了不同离子类型 (中性、阴离子和两性 )聚丙烯酰胺对赤红壤的改良作用。实验结果显示 ,聚丙烯酰胺能够提高赤红壤 >0 .2 5mm水稳性团粒结构数量 ,降低土壤容重 ,增大土壤的毛管持水量和渗透系数 ,提高土壤的含水量 ;在施用量为 0 .0 0 5 %— 0 .2 0 0 %的范围内 ,改良剂对赤红壤的改良效果随其施用量的增大而增强 ;聚丙烯酰胺的离子类型和分子量及其施用方式和添加剂对土壤的改良效果有显著影响 相似文献
17.
Despite the current global attention on biochar (BC) as a soil amendment, knowledge is limited on how BC impacts the physical properties of coarse-textured soils (sand > 95%), particularly in tropical regions. A two-season field-study was conducted to investigate the effect of rice straw BC (3% w/w) on water retention, gas transport and structure of a sand-textured tropical soil. We sampled 3 months and 15 months after BC application and measured wet- and dry-region soil water retention, air permeability and gas diffusivity at selected matric potentials. At all measured potentials and for both sampling times, soil water retention was significantly higher (20–150%) for the BC treatment due to increased fraction of smaller pores (< 30 µm) at the expense of macropores (< 100 µm). Although there was no consistent effect of BC on air-filled porosity, BC significantly reduced air permeability and gas diffusivity (~20%) at ?30 kPa matric potential. After 15-months, air permeability decreased by ~15% after BC amendment, but analyses of the pore structure revealed a more tortuous and complex soil structure. Thus, application of rice straw BC to similar coarse-textured soils will improve soil-water relations and over time provide better structure for agricultural purposes. 相似文献
18.
土壤渗透性的区域变化规律及因子分析 总被引：1，自引：0，他引：1
通过应用数据挖掘和数据整合方法,以建立我国土壤渗透性数据库,并对影响土壤渗透性的各因子综合分析,揭示土壤渗透性的区域变化规律。结果表明:(1)土壤渗透性呈现明显的区域性变化,表现为西南地区<华北地区<东北地区。西南地区土壤渗透力最差,稳渗速率对数值为-0.5～-2.0;华北、东北地区整体数值均在0.5以上,土壤渗透力较强。(2)在影响土壤渗透力的各因子中,气候类型及林龄通过影响植被来间接改善土壤渗透力;植被能有效提升土壤渗透力,但不同植被类型间土壤渗透力并无显著差异;随土层深度的增加,土壤渗透力有所下降。土壤有机质、土壤容重及非毛管孔隙度对土壤渗透力的影响均存在一个阀值,其值分别为30%,1.0g/cm^3,30%。当各因子值超过此阀值,其对土壤渗透力的影响减弱。为更好地探究土壤类型对土壤渗透力的影响作用,在今后的研究中应加强对土壤结构、团聚体等数据的分析。(3)海拔、土层深度及土壤容重对土壤渗透力的影响主要通过影响土壤中非毛管孔隙数量来起作用的。非毛管孔隙度是影响土壤渗透力的主导因子,通径系数为0.34。 相似文献
19.
土石混合介质导气率变化特征试验 总被引：2，自引：1，他引：1
土壤中碎石的存在改变了土壤结构和孔隙分布,进而影响土壤通气性能。该文通过对碎石单粒径土石混合介质导气率变化特征研究,旨在探讨单粒径土石混合介质导气内在机理,为进一步研究复杂的野外土石混合介质的导气特性提供基础。为了研究土石混合介质中碎石对导气率的影响,该文通过试验研究,分析土壤颗粒小于2mm的样本(砂土、砂壤土、黏壤土)、碎石质量分数(10%、20%、30%、40%、50%)和碎石粒径(2～3、>3～5mm)对土石混合介质导气率的影响。结果表明:在土壤颗粒小于2mm的样本条件下,土壤导气率呈砂土>砂壤土>黏壤土;在相同碎石质量分数的土石混合介质中导气率呈砂壤土>砂土>黏壤土;碎石的存在改善黏壤土的导气性能,使黏壤土碎石混合介质的导气率大于黏壤土的导气率;降低了砂壤土和砂土的导气性能,且砂土的降低幅度远大于砂壤土;在砂壤土中碎石粒径2～3mm的导气率大于>3～5mm的导气率;在砂土中碎石质量分数30%之内,碎石粒径>3～5mm的导气率稍大于2～3mm的导气率,在40%则相反,但两种粒径下混合介质导气率差异不是很明显。 相似文献
20.
Gas diffusion, fluid flow and derived pore continuity indices in relation to vehicle traffic and tillage 总被引：2，自引：0，他引：2
Relative gas diffusivity, air permeability and hydraulic conductivity were measured in undisturbed soil cores from tillage and traffic experiments. Continuity indices were taken as the quotient of relative diffusivity and air-filled porosity, and of air permeability and air-filled porosity (and the square of air-filled porosity). These were applied to individual measurements or to treatment means. More general continuity indices were derived from the changes in flow or diffusion with porosity, where the variations in porosity were due to both field variability and applied changes of water potential. These indices were the exponent in the relationship between relative diffusivity and air-filled porosity and the slope of log–log plots of air permeability and air-filled porosity or hydraulic conductivity and degree of saturation. Some physical significance was attached to the exponents by comparison with models of soil porosity. Positive intercepts of the relative diffusivity or air permeability plots on the air-filled porosity axes were taken as porosities blocked to gas movement.
Continuity indices and flow measurements showed differences between tillage and traffic treatments which did not necessarily reflect differences in bulk density. Intrinsic permeability was better estimated from air permeability than from unsaturated hydraulic conductivity. 相似文献
Continuity indices and flow measurements showed differences between tillage and traffic treatments which did not necessarily reflect differences in bulk density. Intrinsic permeability was better estimated from air permeability than from unsaturated hydraulic conductivity. 相似文献