This research has been partially funded by a grant (Beca de Investigaci&#242;n Ambiental) from the Servicio de Medio Ambiente de la Diputaci&#242;n Provincial de Toledo (gran number 133/10) and the research project PEII-2014-025-P of the Junta de Comunidades de Castilla-La Mancha.

1.收集，干燥，过筛试验样品<ol><li>收集在该领域的土壤样品（用铲子或镘）并将其存储在一个聚乙烯袋中。 注:样品的体积取决于土壤的类型而变化:在100至1000 g的细土（粘土和淤泥）通常是足够的，但在沙质土壤和那些含有砾石和卵石，可能需要大量的，由几到几千克。 </li><li>通过在实验室四分法降低采样，如果这是过于冗长（如果有必要使用的土壤分离器）。 </li><li>放置在托盘上的样品，并在不超过60℃的温度下干燥的土壤中。 注意:两个烘干和风干都是有效的。即使在干燥步骤可以在非常细的土壤被忽略，如果它们包含在测试（含水量高于塑性极限而不实际是粘性的）合适的天然水分。 </li><li>通过研钵手动分解土壤。小心不要折断沙粒，所以最好是用橡皮覆盖杵。 </li><li>通过0.40毫米（或0.425毫米）筛子通过样品。只保留下0.40毫米或0.425毫米馏分（删除由筛上的土壤分数）。 </li></ol> 2.准备两个湿土球<ol><li>用洗涤瓶以约20-40克土壤的添加上一个非吸收性平滑玻璃板蒸馏水，直到获得均匀的土壤 - 水混合物用金属铲揉。 </li><li>形状用手土球从土壤 - 水混合物，该混合物是厘米，直径约3和5之间（最好是穿乳胶手套）。 </li><li>重复步骤2.1和2.2相同的土壤样品，获得不同含水量的另一球。 <ol><li>土壤添加更多或更少的水在步骤2.1得到这个含水量不同，或者只是在步骤2.2比这一步表明形成较大的土球（例如直径6-7厘米的），取一个部分OF该并用手轻轻擦干，或加水至该得到不同含水量的土球。 注:关于步骤2.1至2.3，在粘性土壤（主要是粘质土），加入适量水应该提供一个土壤可以不拘一格手被卷一致性。这是在讨论进一步阐述。 </li></ol></li><li>裹保鲜膜每个土球，并把它们密封的袋子里封闭式的条件下24小时。 </li></ol> 3.进行弯曲试验<ol><li>称重空容器，重量记录到至少为0.01克精度。 </li><li>回火期间后，取土壤球之一，并用手压平的吸收性平滑玻璃板（使用乳胶手套以防止水分损失），直至厚度超过3mm略高。在这一点上，完成与螺纹成形机（ 图2A，B，C）的平坦化，以获得一个厚度正好3毫米。 注意:螺纹成形机被设计成这样一种方式，有哪些形状土壤螺纹和玻璃板（ 图2A）之间的部分恰好3mm的空间。 </li></ol><img alt="图2" src="/files/ftp_upload/54118/54118fig2.jpg" /> 图2.图纸和螺纹成型机和钢推杆毫米尺寸 （A）侧视图，（B）俯视图，（C）螺纹成型机的底视图。 （D）前视图和钢推杆（E）俯视图。这个数字已经从莫雷诺- Maroto 与阿隆索Azcárate25修改。 <a href="https://www.jove.com/files/ftp_upload/54118/54118fig2large.jpg" target="_blank">请点击此处查看本图的放大版本。</a> <ol start="3"><li>切变平土体的锯齿状边缘用抹刀（切口一定要挺直）。 </li><li>切割用刮铲土条是在至少52毫米长和大约3×3毫米的正方形截面。 </li><li>形状直径正好3毫米，长52毫米圆柱形土壤线程。 <ol><li>卷圆与螺纹成型机的3×3毫米a土壤条:用手移动螺纹成型机相继向前和向后直到其土壤线程的最初方形截面变圆的确切时刻，所以现在它必须为3mm直径。 <ol><li>如果初始土壤条是很难用螺纹成型机（ 例如，在低粘性土壤，甚至在接近PL含水量塑料土壤）推出，一开始，圆方形截面的手很小心（使用手套） 。只是后，如在步骤3.5.1描述直到获得直径土壤螺纹的准确3毫米滚动与螺纹成形机的土壤线程。 </li><li>放置土壤螺纹和螺纹摩尔的前侧明镜并拢。使用线程成型机作为模板的宽度和切断的土壤螺纹用金属铲的尖端，以获得的长度恰好52毫米土壤圆柱体。 注意: 如图2 B，C的螺纹成形机测量52毫米宽。 </li></ol></li></ol></li><li>弯曲土壤线程，直到裂解（ 图3）的点。 <ol><li>打开螺纹成型机倒挂，以至于现在它是由它的圆柱形件和设备后部的支持。把圆筒形件的螺纹成形机的在与3毫米直径×52毫米长的土壤螺纹的中央部分接触。 </li><li>放置钢推杆（ 图2D，E），与土壤螺纹（ 图3A）的中心的接触，使土壤螺纹位于（这些工作移动支点）和的圆柱形部分在两个钢推动器之间螺纹成型机（这可以作为一个固定的支点）。 </li><li>为大致圆形路径小心移动从中心到土壤螺纹（ 图3B）的尖端的钢推动器。重复这个动作，直到开裂（ 图3C）的点;在这一点上，停止弯曲。 <ol><li>如果裂纹出现了土壤线（ 图3D）， 即接近螺纹秘诀之一的中央第三，保持周围的其他尖端弯曲，直到另一个出现裂缝（ 图3D，E）。通过这种方式，沿着土壤线程获得的两个裂纹。 </li></ol></li><li>右后，取出螺纹成形机和测量线的尖端（D）之间的距离用卡尺并将它记录到0.1mm的精确度。出自发梢（ 图3C中的E）的中央部采取这种测量。 <ol><li>把土线程进入它的重量是以前记录（步骤3.1）的容器盖，以防止水分流失。 </li><li>如果高清弯曲ormations是如此之大，甚至在线程前端抵接， 即，D = 0毫米（ 图3F），除去按压件和螺纹成形机和弯曲用手土壤线程，直到裂纹如在图3G示意性示出的点。测量螺纹尖端之间的距离， 如图3H和带负号记录下来。最后，重复步骤3.6.4.1。 </li></ol></li></ol></li></ol><img alt="图3" src="/files/ftp_upload/54118/54118fig3.jpg" /> 图3示意图，其中弯曲和提示距离测量技术是详细。（A）中的钢推动器的初始位置，土壤螺纹和在玻璃板上的螺纹成形机的筒状的部分。 （B）由从中心向其中进行非常carefu尖端的大致圆形路径的装置一般弯曲技术LLY（见箭头路径）。在其中央部分破获一个线程（C）通常的顶端距离测量技术。已经破解其中央第三及弯曲技术（D）的土壤螺纹应遵循周围的其他尖端（即由箭头指示）。 （E）已经破解了它的中央第三的线程的常见顶端距离测量技术。 （F）土壤螺纹，其中提示接触，并且可以形成一个封闭的环。当土壤线程能够弯曲超出一个封闭环和（H）前端的距离测量技术为最后这种情况下要进行（G）的弯曲的技术。这个数字已经从莫雷诺- Maroto 与阿隆索Azcárate25修改。 <a href="https://www.jove.com/files/ftp_upload/54118/54118fig3large.jpg" target="_blank">请点击此处查看本图的放大版本。</a> <ol start="7"><li>形状等土壤THRE从相同的广告按步骤3.4，3.5.1，3.5.1.1扁平土体。不要削减他们的提示。最后，把它们放入容器和覆盖它（步3.6.4.1）。 注意:这些线程的作用是简单地以获得足够的材料来正确地确定水分含量。如果接触表面（玻璃板和螺纹成型机）为塑造一个线程后变脏，请他们用湿布和一张纸迅速干燥。 </li><li>至少在土线程重复步骤3.4至3.6.4.2。形状这些线程具有一定交替相对于在步骤3.7获得的那些。如果顶端距离（D）的第二测量是相同或非常相似，在第一土壤线程获得，不弯多个线程。如果不是，形状和弯曲的至少一个另外的土壤线程。 注意:术语"某交替"指的是，建议弯曲线程不形一前一后， 也就是说，它们应不能从扁平土体的相同区域，以获得整个土体的代表性的测量作出。因此，一些人土线程未剪切和弯曲（步骤3.7）应该弯曲的人之间形成的。如果有一个在展平土体的不均匀湿气分布（这是不可能的），将它纠正这种方式。 </li><li>权衡与土壤线程容器至少为0.01克精度。形状和根据步骤3.4，3.5.1，3.5.1.1添加更多的线程，如果土壤线程的重量小于5克，直到超过该重（5之间的重量和7 g是合适的）。 </li><li>重复步骤3.1至3.9的其它土球（球形，在步骤2.3）。 <ol><li>在非常低的可塑性的土壤的情况下，省略步骤3.10如果土壤的可塑性太低而不能正确进行的测试为两个球具有不同的水含量（使得仅土球将被测试）。 </li></ol></li></ol><ol><li>放置两个容器（对应于测试的两种土壤球）与它们各自的土壤线程在烘箱中在105±5℃下至少18小时（如果施加步骤3.10.1，存在与土壤只有一个容器变干）。在此之后，留下干燥的土壤容器在干燥器中，当他们冷静，它们的权重记录到至少为0.01 g的精度。 </li><li>再次放置容器与干土成在105±5℃的烘箱中至少6小时的。然后让它们先冷却并如在步骤4.1指示再次记录其重量。如果重量是恒定的， 即，如果此重量在本质上是一样的在步骤4.1获得，所述土壤是完全干燥，因此使用该数据来计算在步骤5.2中的水分含量（W）。 <ol><li>如果重量是不同的，重复步骤4.2根据需要多次，直到重量与干土容器是恒定的。 </li></ol></li></ol> 5.计算弯曲处开裂（B）和水分（W）的<ol><li>计算弯曲在如下开裂（B）以mm: B = 52.0-D 其中，52.0是指长度在土壤螺纹毫米，D是在毫米裂化时的末端之间测得的平均距离: D =（D 1 + D 2 ... + D N）/ N 其中，n为至少2（参见步骤3.8） </li><li>以百分比计算出水分含量（W）如下: W =（M1-M2）/（M2-M3）×100 哪里: M1为与湿土壤的容器的重量（参见步骤3.9） M2是与干土容器的重量（参见步骤4.2） M3是容器的重量（参见步骤3.1） </li></ol> 6.计算塑限（PL） <ol><li>计算第一个土球的限塑令，如下所示: PL 1= W×（B / 2.135）-0.108 其中，2.135是指在PL在24土壤按原弯曲试验中得到的弯曲曲线上的平均B，而-0.108指平均弯曲斜率（m），这些24土壤（弯曲曲线表1和图4）。 </li><li>重复步骤6.1的第二个土球，并取得2 PL。 </li><li>计算PL作为平均PL 1和PL 2的 PL =（PL 1 + PL 2）/ 2 注意:如果已经获得两个以上的实验点，对PL也是PL结果的平均值， 即，PL =（PL 1 + PL 2 ... + PL n）的 / N。 </li><li>省略步骤6.2和6.3，如果已获得唯一一个实验点（见步骤3.10.1），因此在这种情况下: PL PL = 1 注:突出，在本研究中的PL通过步骤6计算具有蜂是很重要Ñ ​​名为PL nb的以从与原始的弯曲试验和标准滚丝试验，已分别命名为PL 的ob和PL ST取得的PL结果区分开。 </li></ol>

<ol>
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Civil Eng. - Geotec. 162 (3), 175-185 (2009).</li><li>Barnes, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+apparatus+for+the+determination+of+the+workability+and+plastic+limit+of+clays.">An apparatus for the determination of the workability and plastic limit of clays.</a> Appl. Clay Sci. 80-81, 281-290 (2013).</li><li>Moreno-Maroto, J. M., Alonso-Azc&#225;rate, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+accurate,+quick+and+simple+method+to+determine+the+plastic+limit+and+consistency+changes+in+all+types+of+clay+and+soil:+The+thread+bending+test.">An accurate, quick and simple method to determine the plastic limit and consistency changes in all types of clay and soil: The thread bending test.</a> Appl. Clay Sci. 114, 497-508 (2015).</li><li>Bain, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+plasticity+chart+as+an+aid+to+the+identification+and+assessment+of+industrial+clays.">A plasticity chart as an aid to the identification and assessment of industrial clays.</a> Clay Miner. 9 (1), 1-17 (1971).</li></ol>

The authors have nothing to disclose.

阿太堡限塑令1在土壤中一个非常重要的参数，主要是因为它被广泛用于土工目的10,11,12。为PL测定标准滚丝测试已被广泛批评，因为它是高度依赖于谁是进行测试，因此新的方法来获得PL声称操作者的技能和判断6,7,9,13,15- 20，23-25。然而，简单性，低成本和标准的PL测试的快速性能给它优于提议迄今为止的不成功的替代品，尽管事实上，操作者的主观性在大多数的替代方法?...

液限（LL）和塑限（PL）是那些由阿太堡于1911年定义的两个最重要的土壤一致性限制1。LL标志着液塑状态之间的边界，以及塑料和半固体状态之间PL。 LL是根据通过卡萨格兰方法2,3或渗透试验4几个标准在世界各地获得的。这两种方法都是通过机械装置进行;因此，最少的操作干扰参与。在PL的情况下，所谓的"搓丝测试"是决心2,5最流行 ​​的和标准化的方法。此测试是基于直到操作员认为该土壤被破碎手工压延土壤成3mm线程。出于这个原因，它已被广泛批评，因为操作者的技能和判断起到测试的结果的关键作用。标准滚动试验是重要的受多种不可控因素，如作为所施加的压力，该接触几何，摩擦，轧制速度，样品的大小和土壤6,7的类型。美国社会测试和材料协会（ASTM）制定的ASTM D 4318标准，它包括一个简单的装置，以便最小化操作员干涉2,8，但是根据测试比较手册轧制试验时显著差异已经报道了一些土壤通过ASTM D4318装置9进行。 PL是岩土工程的目的非常重要的参数，因为塑性指数（PI）是由它（PI = 11 - PL）获得; PI用于按照ASTM D 2487 10所示的塑性图的土壤，基础卡萨格兰德11,12研究的基础上进行分类。在PL错误影响负这种分类13，因为这个原因，需要用于PL测定一个新的测试。 普费弗科恩测试，锥penetrome之三，毛细管流变仪，转矩流变仪或者应力-应变测试的测量土壤可塑性14的替代方法的一些示例，但这些都不是足够获得的PL。用落锥试验的特殊情况下，大量的研究人员已经试图定义为使用不同的透度计的PL测定的新方法设计15-20，但没有达到任何真正的协议。此外，所有的它是基于这样的假设，在PL中的剪切强度是LL处21，这是不正确的22的100倍。 巴恩斯23,24开发了模拟土壤气缸的轧制条件，企图放下对PL确定一个明确的标准的装置。尽管如此，一些缺点识别用这种方法，如它的复杂性，试验时间和主要计算的PL 25的可疑的装置。标准碾压试验成功在于它的简单，快速的性能和成本较低，因此没有别的选择方法将能够替代它，除非它满足这三个要求和其他的，诸如高的精度和低的操作者的干扰。 在由作者先前的研究中，一个新的PL方法被提议25:原始线程弯曲试验（或简单弯曲试验）允许从在其被表示含水量和弯曲变形的关系的曲线图获得的PL。获得并绘制了几个试验点，每个土壤作者（协议遵循以获得这些点的相同，在本纸表示），以使点的相关性可以用两种方式来定义，而不以任何方式损害点路径的正确定义:作为一个抛物线，命名为弯曲曲线（ 图1A），并作为两条相交直线与不同坡度，命名为硬塑料线和软塑料线。刚性塑料线是最陡之一，和PL从它计算为对应于这与y轴（ 图1B）的分界点的含水率。在此截止点产生的弯曲是零，这是按照塑性极限的概念， 即 ，PL为在该土壤不能经受低于该阈值（半固体状态）变形的水分含量，但它确实熊他们上面（塑料状态）。虽然在最初的研究中，PL不能直接由弯曲曲线（这不相交y轴）中得到，这条线是非常有用的，因为考虑到弯曲曲线和交叉线遵循非常相似的路径，弯曲从实验数据获得的曲线方程来获得额外的点，首先，修正任何偏差，其次，进行只数点测试， 如图1B所示 。&lt;<html> / P&gt; <img alt="图1" src="/files/ftp_upload/54118/54118fig1.jpg" /> 图1.在由原始的弯曲测试一个测试土壤的BW点的图形表示。（A）中的点的相关性被表示为抛物线曲线，命名为弯曲曲线的方程被包括。 （B）中的点的相关性是由两条相交线和其他加分相加（它们从弯曲曲线公式计算出）限定。 B值都为B = 52.0-D（其中D是在毫米裂化时的末端之间测得的平均距离）获得，对PL被计算为对应于硬​​塑料线与截止点的水含量y轴。这个数字已经从莫雷诺- Maroto 与阿隆索Azcárate25修改。K"&gt;点击此处查看该图的放大版本。 所有结果与那些经验丰富的操作人员通过传统的螺纹轧制方法取得了优异的协议。但是，原来的弯曲试验仍比标准螺纹滚压测试慢。在试图进一步节省试验时间，单点版本被提出。它是基于在24试土壤中得到的平均弯曲斜率（m），这是0.108（m是当在双对数刻度表示的弯曲曲线的斜率，M出现在图1A中弯曲曲线方程） 。通过在那里被列入此因子的方程的装置，无论是硬塑料和软塑料线被以图形绘制，并因此对PL估计。这些结果也高度同时与多点弯曲试验的标准轧制测试相关。尽管这一个点versio的n是速度甚至比传统的测试中，PL的计算比较复杂，因为策划是必要的。出于这个原因，统计标准的基础上用于PL计算一个新的方程已经开发在这项研究中，所以不要求绘图和结果只能与一个点来实现的，而实验方案是相同的原始弯曲测试。这个新版本满足必要的要求，以取代过时的螺纹轧制方法。

<table border="0" cellpadding="0" cellspacing="0" width="978">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Shovel</td>
			<td style="width:76px;">Any</td>
			<td style="width:117px;">NA</td>
			<td style="width:541px;">It is preferable a round point metal shovel so that it can penetrate easily in the soil.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trowel</td>
			<td>Any</td>
			<td>NA</td>
			<td>It should be easy to handle both in field and laboratory, so approximately 500 g of soil should be the maximum of soil that could pick up.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Polyethylene bags</td>
			<td>Any</td>
			<td>NA</td>
			<td>The size of the bags depends on the collected soil volume. If we were interested in preserving the natural moisture, use sealing tape to close the bag.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Soil splitter&#160;</td>
			<td>PROETISA</td>
			<td>S0012</td>
			<td>It is not mandatory, because the quartering can be performed with the shovel, but in case of using it: it must be big enough to split several kg of sample in the cases of soils with large amounts of gravel or pebbles.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Oven</td>
			<td>SELECTA</td>
			<td>2001254</td>
			<td>The oven must be able to maintain constant temperature and should have some sort of slot or outlet opening to facilitate the release of water vapor.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lab trays</td>
			<td>Any</td>
			<td>NA</td>
			<td>Metal trays are preferred over plastic because the first ones tolerate the oven temperatures better than the second ones.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mortar and pestle</td>
			<td>MECACISA</td>
			<td>V112-02</td>
			<td>A ceramic mortar is valid.&#160; It is recommended to use a rubber covered pestle because if the pestle was of other different materials (like metal or a ceramic), it could break the sand particles.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.40 mm sieve (or 0.425 mm sieve)</td>
			<td>FILTRA</td>
			<td>0,400 (or 0,425)</td>
			<td>Make sure that the sieve mesh is in perfect conditions of use (it should not be neither broken or worn).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Brush</td>
			<td>Any</td>
			<td>NA</td>
			<td>It is useful for passing the soil during the sieving.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Wash-bottle</td>
			<td>Any</td>
			<td>NA</td>
			<td>It should have an approximate capacity of one litre and it should be easy to control the amount of water that it releases.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Distilled water</td>
			<td>Any</td>
			<td>NA</td>
			<td>Distilled water can be purchased or obtained by filtering from tap water (in this last case, a filtering system is necessary).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nonabsorbent smooth glass plate&#160;</td>
			<td>Any</td>
			<td>NA</td>
			<td>The plate should have a minimum area of approximately 30 &#215; 30 cm.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Metal spatula</td>
			<td>Any</td>
			<td>NA</td>
			<td>The metal blade of the spatula must be flexible. Dry it with a paper after water-cleaning to prevent rusting.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Latex gloves</td>
			<td>Any</td>
			<td>NA</td>
			<td>Latex, vinyl, nitrile or other impermeable materials are valid. They should be thin enough to sense the soil with the hands.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cling film</td>
			<td>Any</td>
			<td>NA</td>
			<td>Normal cling film is valid.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Airtight bags</td>
			<td>Any</td>
			<td>NA</td>
			<td>Remove the air before closing them.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thread molder</td>
			<td>Any</td>
			<td>NA</td>
			<td>It is a tool designed in this experiment (drawings with dimmensions are included in this paper).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Steel pushers</td>
			<td>Any</td>
			<td>NA</td>
			<td>It is a tool designed in this experiment (drawings with dimmensions are included in this paper).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Damp cloth</td>
			<td>Any</td>
			<td>NA</td>
			<td>A normal damph cloth is valid.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Roll of paper</td>
			<td>Any</td>
			<td>NA</td>
			<td>Normall rolls of paper used to dry hands are valid.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Caliper</td>
			<td>Any</td>
			<td>NA</td>
			<td>It must have an accuracy of at least 0.1 mm.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Paper and pen</td>
			<td>Any</td>
			<td>NA</td>
			<td>Paper and pen are used to write the results.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Containers with covers</td>
			<td>Any</td>
			<td>NA</td>
			<td>Small cylindrical glass containers are valid. If they do not have covers, watch glasses can be used as covers. Covers are useful to avoid the loss of water during the test and also to prevent the dry soil absorbs moisture from the air after oven drying.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Precision or analytical balance</td>
			<td>BOECO</td>
			<td>BPS 52 PLUS</td>
			<td>It must have an accuracy of at least 0.01 g.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Protective gloves</td>
			<td>Any</td>
			<td>NA</td>
			<td>Protective gloves are used to catch the metal trays from the oven.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tongs</td>
			<td>Any</td>
			<td>NA</td>
			<td>Tongs are used to catch the hot containers from the oven.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Desiccator</td>
			<td>MECACISA</td>
			<td>A036-01</td>
			<td>A normal glass desiccator with silica gel is valid to prevent the dry soil absorbs moisture from the air after oven drying.</td>
		</tr>
	</tbody>
</table>

a bending test for determining the atterberg plastic limit in soils

螺纹轧制试验是最常用的方法，以确定土壤中的塑性极限（PL）。它已被广泛批评，因为从执行的测试其性能时所涉及的运营商，这可能显著影响最终结果相当的主观判断。不同的替代方法已经提出，但他们不能在速度，简单性和成本的标准碾压试验竞争。 在由作者先前的研究，提出了一个简单的装置，以确定PL一个简单的方法（"线弯曲试验"或简称为"弯曲试验"）;以最小的操作者的干扰来获得允许对PL此方法。在本文件的原始弯曲试验的一个版本被示出。实验依据相同的原始弯曲试验:土壤线程它们是3毫米直径和52毫米长的弯曲，直到他们开始产生裂纹，所以，无论是bendiNG生产及其相关的水分含量被确定。但是，这种新的版本使PL的从方程式的计算，所以，没有必要来绘制任何曲线或直线，以获得该参数，并且在事实上，PL只能与一个试验点（但是两个试验点来实现推荐使用）。 这个新的版本获得的PL结果非常相似，由经验丰富的操作者通过原始的弯曲试验和标准轧制试验获得的那些。仅在高塑性粘性土的特定情况下，有在结果较大的差异。尽管如此，弯曲试验非常适用于所有类型的土壤，无论是凝聚力和非常低的可塑性的土壤，后者是最难通过的标准螺纹轧制方法测试。

在该协议的步骤6.1中所示的PL方程是通过在作者25（ 表1）的先前研究中测试的24个土壤的统计研究实现。其目的是要知道的最可能的弯曲斜率（弯曲曲线方程中的术语米 ，这显示在图1A）和B中的哪PL被按照原始的弯曲测试中得到的弯曲曲线上的平均值（原试验使用3个以上的实验点进行，并需要有图表来获得的PL， 如图1）。</st...

Watch this Scientific Journal Video about A Bending Test for Determining the Atterberg Plastic Limit in Soils at JoVE.com

A Bending Test for Determining the Atterberg Plastic Limit in Soils

用于确定土壤中塑性极限传统标准化测试是由手工进行，其结果取决于操作人员。基于弯曲测量的另一种方法，提出了这项研究。这使得具有明确和客观的标准得到了限塑令。

弯曲试验在土壤确定阿太堡限塑

The thread rolling test is the most commonly used method to determine the plastic limit (PL) in soils. It has been widely criticized, because a ...

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Bending

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20.3K 次观看.  University of Castilla-La Mancha. 用于确定土壤中塑性极限传统标准化测试是由手工进行，其结果取决于操作人员。基于弯曲测量的另一种方法，提出了这项研究。这使得具有明确和客观的标准得到了限塑令。 

视频: A Bending Test for Determining the Atterberg Plastic Limit in Soils

Determination of Microbial Extracellular Enzyme Activity in Waters, Soils, and Sediments using High Throughput Microplate Assays

Much of the nutrient cycling and carbon processing in natural environments occurs through the activity of extracellular enzymes released by microorganisms. Thus, measurement of the activity of these extracellular enzymes can give insights into the rates of ecosystem level processes, such as organic matter decomposition or nitrogen and phosphorus mineralization. Assays of extracellular enzyme activity in environmental samples typically involve exposing the samples to artificial colorimetric or fluorometric substrates and tracking the rate of substrate hydrolysis. Here we describe microplate based methods for these procedures that allow the analysis of large numbers of samples within a short time frame. Samples are allowed to react with artificial substrates within 96-well microplates or deep well microplate blocks, and enzyme activity is subsequently determined by absorption or fluorescence of the resulting end product using a typical microplate reader or fluorometer. Such high throughput procedures not only facilitate comparisons between spatially separate sites or ecosystems, but also substantially reduce the cost of such assays by reducing overall reagent volumes needed per sample.

Microplate based procedures are described for the colorimetric or fluorometric analysis of extracellular enzyme activity. These procedures allow for the rapid assay of such activity in large numbers of environmental samples within a manageable time frame.

在使用高通量微孔板测定水，土壤，沉积物和微生物测定胞外酶活性的

Much of the nutrient cycling and carbon  processing in natural environments occurs through the activity of extracellular  enzymes released by ...

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环境科学

Integrated Field Lysimetry and Porewater Sampling for Evaluation of Chemical Mobility in Soils and Established Vegetation

Potentially toxic chemicals are routinely applied to land to meet growing demands on waste management and food production, but the fate of these chemicals is often not well understood. Here we demonstrate an integrated field lysimetry and porewater sampling method for evaluating the mobility of chemicals applied to soils and established vegetation. Lysimeters, open columns made of metal or plastic, are driven into bareground or vegetated soils. Porewater samplers, which are commercially available and use vacuum to collect percolating soil water, are installed at predetermined depths within the lysimeters. At prearranged times following chemical application to experimental plots, porewater is collected, and lysimeters, containing soil and vegetation, are exhumed. By analyzing chemical concentrations in the lysimeter soil, vegetation, and porewater, downward leaching rates, soil retention capacities, and plant uptake for the chemical of interest may be quantified. Because field lysimetry and porewater sampling are conducted under natural environmental conditions and with minimal soil disturbance, derived results project real-case scenarios and provide valuable information for chemical management. As chemicals are increasingly applied to land worldwide, the described techniques may be utilized to determine whether applied chemicals pose adverse effects to human health or the environment.

Field lysimetry and porewater sampling allow researchers to evaluate the fate of chemicals applied to soils and established vegetation. The goal of this protocol is to demonstrate how to install required instrumentation and collect samples for chemical analysis during integrated field lysimetry and porewater sampling experiments.

综合外地Lysimetry和孔隙水采样的化学活动性土壤的评价和植被成立

Potentially toxic chemicals are routinely applied to land to meet growing demands on waste management and food production, but the fate of these chemicals ...

Measurement of Greenhouse Gas Flux from Agricultural Soils Using Static Chambers

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the biogeochemical drivers of climate change and to the development and evaluation of GHG mitigation strategies based on modulation of landscape management practices. The static chamber-based method described here is based on trapping gases emitted from the soil surface within a chamber and collecting samples from the chamber headspace at regular intervals for analysis by gas chromatography. Change in gas concentration over time is used to calculate flux. This method can be utilized to measure landscape-based flux of carbon dioxide, nitrous oxide, and methane, and to estimate differences between treatments or explore system dynamics over seasons or years. Infrastructure requirements are modest, but a comprehensive experimental design is essential. This method is easily deployed in the field, conforms to established guidelines, and produces data suitable to large-scale GHG emissions studies.

This article showcases the static chamber-based method for measurement of greenhouse gas flux from soil systems. With relatively modest infrastructure investments, measurements may be obtained from multiple treatments/locations and over timeframes ranging from hours to years.

从农业土壤使用静态钱伯斯温室气体流量测量

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the ...

Extraction and Analysis of Microbial Phospholipid Fatty Acids in Soils

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about the overall structure of terrestrial microbial communities. PLFA profiling has been extensively used in a range of ecosystems as a biological index of overall soil quality, and as a quantitative indicator of soil response to land management and other environmental stressors.
The standard method presented here outlines four key steps: 1. lipid extraction from soil samples with a single-phase chloroform mixture, 2. fractionation using solid phase extraction columns to isolate phospholipids from other extracted lipids, 3. methanolysis of phospholipids to produce fatty acid methyl esters (FAMEs), and 4. FAME analysis by capillary gas chromatography using a flame ionization detector (GC-FID). Two standards are used, including 1,2-dinonadecanoyl-sn-glycero-3-phosphocholine (PC(19:0/19:0)) to assess the overall recovery of the extraction method, and methyl decanoate (MeC10:0) as an internal standard (ISTD) for the GC analysis.

Phospholipid fatty acids provide information about the structure of soil microbial communities. We present methods for extraction from soil samples with a single-phase chloroform mixture, fractionation of extracted lipids using solid phase extraction columns, and methanolysis to produce fatty acid methyl esters, which are analyzed by capillary gas chromatography.

提取及土壤微生物磷脂脂肪酸分析

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about ...

Methods of Soil Resampling to Monitor Changes in the Chemical Concentrations of Forest Soils

Recent soils research has shown that important chemical soil characteristics can change in less than a decade, often the result of broad environmental changes. Repeated sampling to monitor these changes in forest soils is a relatively new practice that is not well documented in the literature and has only recently been broadly embraced by the scientific community. The objective of this protocol is therefore to synthesize the latest information on methods of soil resampling in a format that can be used to design and implement a soil monitoring program. Successful monitoring of forest soils requires that a study unit be defined within an area of forested land that can be characterized with replicate sampling locations. A resampling interval of 5 years is recommended, but if monitoring is done to evaluate a specific environmental driver, the rate of change expected in that driver should be taken into consideration. Here, we show that the sampling of the profile can be done by horizon where boundaries can be clearly identified and horizons are sufficiently thick to remove soil without contamination from horizons above or below. Otherwise, sampling can be done by depth interval. Archiving of sample for future reanalysis is a key step in avoiding analytical bias and providing the opportunity for additional analyses as new questions arise.

Repeated soil sampling has recently been shown to be an effective way to monitor forest soil change over years and decades. To support its use, a protocol is presented that synthesizes the latest information on soil resampling methods to aid in the design and implementation of successful soil monitoring programs.

土壤重采样的方法监控森林土壤的化学浓度的变化

Recent soils research has shown that important chemical soil characteristics can change in less than a decade, often the result of broad environmental ...

Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.

Microplastics act as vector of potentially toxic organic contaminants with unpredictable effects. This protocol describes an alternative methodology for assessing the levels of organochlorine pesticides adsorbed on plastic pellets and identifying the polymer chemical structure. The focus is on pressurized fluid extraction and attenuated total reflectance Fourier transform infrared spectroscopy.

从塑料颗粒中提取有机氯农药和塑料类型分析

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment ...

Optimized Procedure for Determining the Adsorption of Phosphonates onto Granular Ferric Hydroxide using a Miniaturized Phosphorus Determination Method

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide (GFH), with little effort and high reliability. The phosphonate, e.g., nitrilotrimethylphosphonic acid (NTMP), is brought into contact with the GFH in a rotator in a solution buffered by an organic acid (e.g., acetic acid) or Good buffer (e.g., 2-(N-morpholino)ethanesulfonic acid) [MES] and N-cyclohexyl-2-hydroxyl-3-aminopropanesulfonic acid [CAPSO]) in a concentration of 10 mM for a specific time in 50 mL centrifuge tubes. Subsequently, after membrane filtration (0.45 &#181;m pore size), the total phosphorus (total P) concentration is measured using a specifically developed determination method (ISOmini). This method is a modification and simplification of the ISO 6878 method: a 4 mL sample is mixed with H2SO4 and K2S2O8 in a screw cap vial, heated to 148-150 &#176;C for 1 h and then mixed with NaOH, ascorbic acid and acidified molybdate with antimony(III) (final volume of 10 mL) to produce a blue complex. The color intensity, which is linearly proportional to the phosphorus concentration, is measured spectrophotometrically (880 nm). It is demonstrated that the buffer concentration used has no significant effect on the adsorption of phosphonate between pH 4 and 12. The buffers, therefore, do not compete with the phosphonate for adsorption sites. Furthermore, the relatively high concentration of the buffer requires a higher dosage concentration of oxidizing agent (K2S2O8) for digestion than that specified in ISO 6878, which, together with the NaOH dosage, is matched to each buffer. Despite the simplification, the ISOmini method does not lose any of its accuracy compared to the standardized method.

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide, with little effort and high reliability. In a buffered solution, the phosphonate is brought into contact with the adsorbent using a rotator and then analyzed via a miniaturized phosphorus determination method.

用小型化磷测定法测定膦酸在粒状氢氧化铁上吸附的优化方法

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric ...

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current measures to combat such pathogens have proved too conservative and, thus, not sufficiently effective, and they can potentially pose environmental risks. Therefore, it is extremely necessary to identify host-resistance factors to assist in controlling plant diseases naturally through the identification of resistant germplasm, the isolation and characterization of resistance genes, and the molecular breeding of resistant cultivars. In this regard, there is need to establish an accurate, rapid, and large-scale inoculation method to breed and develop plant resistance genes. The rice blast fungal pathogen Magnaporthe grisea causes severe disease symptoms and yield losses. Recently, M. grisea has emerged as a model organism for studying the mechanisms of plant-fungal pathogen interactions. Hence, we report the development of a plant virulence test method that is specific for M. grisea. This method provides for both spray inoculation with a conidial suspension and wounding inoculation with mycelium cubes or droplets of conidial suspension. The key step of the wounding inoculation method for detached rice leaves is to make wounds on plant leaves, which avoids any interference caused by host penetration resistance. This spray/wounding protocol contributes to the rapid, accurate, and large-scale screening of the pathotypes of M. grisea isolates. This integrated and systematic plant infection method will serve as an excellent starting point for gaining a broad perspective of issues in plant pathology.

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Here, we present a protocol to test plant virulence with the plant pathogen Magnaporthe grisea. This report will contribute to the large-scale screening of the pathotypes of fungi isolates and serve as an excellent starting point for understanding the resistant mechanisms of plants during molecular breeding.

植物感染试验: 以植物病原菌为载体的喷雾和伤口介导接种

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current ...

Sampling Soils in a Heterogeneous Research Plot

Soils are highly heterogeneous. In general, the number of soil samples required for soil research has always been determined arbitrarily and the associated accuracy is unknown. Here, we present a detailed protocol for efficient and clustered soil sampling in a research plot and, relying on a pilot sampling using this design, for demonstrating soil spatial heterogeneity and informing reasonable sample sizes and associated accuracy for future study. The protocol mainly comprises four steps: sampling design, field collection, soil analysis, and geostatistical analysis. The step-by-step procedure is modified according to former publications. Two examples will be presented to demonstrate contrasting spatial distributions of soil organic carbon (SOC) and soil microbial biomass carbon (MBC) under different management practices. In addition, we present a strategy to determine the sample size requirement (SSR) given a certain level of accuracy based on the plot-level coefficient of variation (CV). The field sampling protocol and the quantitative determination of the sample size will assist researchers in seeking feasible sampling strategies to meet research needs and resources' availability.

The traditional soil-sampling procedure determines the number of soil samples arbitrarily. Here, we provide a simple yet efficient clustered soil-sampling design to demonstrate soil spatial heterogeneity and quantitatively determine the number of soil samples required and the associated sampling accuracy.

在异构研究图中取样土壤

Soils are highly heterogeneous. In general, the number of soil samples required for soil research has always been determined arbitrarily and the ...

Combined Size and Density Fractionation of Soils for Investigations of Organo-Mineral Interactions

Combined size and density fractionation (CSDF) is a method used to physically separate soil into fractions differing in particle size and mineralogy. CSDF relies on sequential density separation and sedimentation steps to isolate (1) the free light fraction (uncomplexed organic matter), (2) the occluded light fraction (uncomplexed organic matter trapped in soil aggregates) and (3) a variable number of heavy fractions (soil minerals and their associated organic matter) differing in composition. Provided that the parameters of the CSDF (dispersion energy, density cut-offs, sedimentation time) are properly selected, the method yields heavy fractions of relatively homogeneous mineral composition. Each of these fractions is expected to have a different complexing ability towards organic matter, rendering this a useful method to isolate and study the nature of organo-mineral interactions. Combining density and particle size separation brings an improved resolution compared to simple size or density fractionation methods, allowing the separation of heavy components according to both mineralogy and size (related to surface area) criteria. As is the case for all physical fractionation methods, it may be considered as less disruptive or aggressive than chemically-based extraction methods. However, CSDF is a time-consuming method and furthermore, the quantity of material obtained in some fractions can be limiting for subsequent analysis. Following CSDF, the fractions may be analyzed for mineralogical composition, soil organic carbon concentration and organic matter chemistry. The method provides quantitative information about organic carbon distribution within a soil sample and brings light to the sorptive capacity of the different, naturally-occurring mineral phases, thus providing mechanistic information about the preferential nature of organo-mineral interactions in soils (i.e., which minerals, what type of organic matter).

Combined size and density fractionation (CSDF) is a method to physically separate soil into fractions differing in texture (particle size) and mineralogy (density). The purpose is to isolate fractions with different reactivities towards soil organic matter (SOM), in order to better understand organo-mineral interactions and SOM dynamics.

土壤联合粒径与密度的分离研究

Combined size and density fractionation (CSDF) is a method used to physically separate soil into fractions differing in particle size and mineralogy. CSDF ...