WATER REPELLENCY OF SIEVE FRACTIONS FROM SANDY SOILS AND RELATIONSHIPS WITH ORGANIC MATERIAL AND SOIL STRUCTURE
WATER REPELLENCY OF SIEVE FRACTIONS FROM SANDY SOILS AND RELATIONSHIPS WITH ORGANIC MATERIAL AND SOIL STRUCTURE
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DOI：
10.1016/0016-7061(93)90103-r
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发表时间：
1993-03-15
期刊：
影响因子：
6.1
通讯作者：
SCHOUTE, JFT
中科院分区：
文献类型：
--
作者：
BISDOM, EBA;DEKKER, LW;SCHOUTE, JFT
在土壤微观形貌方面，大多数研究是用光学和电子显微镜对选定样品的薄片进行的。获取土壤成分和特征的性质、分布、大小、形态、数量等信息。用筛分法可以提供不易从薄片中获得的重要数据。在这些数据中有特定的土壤结构（圆形的大团聚体、微团聚体和被包裹的植物碎片），它们可能部分或全部由土壤生物群形成。在研究荷兰西南部农业和未开垦的沙质土壤的防水性时，每个样本都经过筛选、洗涤和过氧化氢处理。通过测量土壤样品及其筛分的水滴渗透时间（WDPT），并通过显微镜检查土壤成分和特征，可以指出哪些土壤成分对疏水性的建立是重要的。拒水的外观和程度与有机物（植物碎片、根系等）密切相关。这种有机质可以构成土壤结构的一部分（如微观和宏观团聚体）或本身就是主要成分。由微团聚体引起的疏水性（WDPT bbb50 s）已经可以在可湿性土壤中发生，在10个筛分中最细的（< 53 μ m）中。最细筛分的拒水性不影响整个样品的润湿性，因为其他9个筛分（53 ~ 2000）是可湿性的。随着疏水性的增加，从轻度疏水性到极疏水性的土壤，更多的筛分被含有疏水性有机残留物的土壤结构和成分所占据，如大团聚体、植物碎片和沙粒上的涂层。这些结构和微聚集体大部分可能部分或全部是由土壤生物群形成的。反之，有机质的分解和植物碎片的非疏水土壤材料的覆盖可以降低土壤的疏水程度；土壤生物群也活跃的过程。
In soil micromorphology most studies are done with light and electron microscopes on thin sections from selected samples. Information is obtained on nature, distribution, size, form, quantity, etc. of soil constituents and features. Significant data, not readily obtainable from thin sections, can be supplied by using sieve fractions. Amongst such data are specific soil structures (rounded macro-aggregates, micro-aggregates and coated plant fragments) which may, partly or wholly, have been made by soil biota.During the study of water repellency of agricultural and uncultivated sandy soils in the southwestern Netherlands, each sample was sieved, washed and treated with hydrogen peroxide. By measuring the water drop penetration time (WDPT) of a soil sample and of its sieve fractions, and by microscopic examination of soil components and features in each of these, one can indicate which soil constituents are important to the building up of water repellency.The appearance and degree of water repellency are closely related with organic matter (plant fragments, roots, etc.). This organic matter can form a part of soil structures (e.g. micro- and macroaggregates) or be the principal component itself. Water repellency (WDPT > 5 s), caused by microaggregates, can already occur in wettable soils, in the finest ( < 53 mum) out of ten sieve fractions. Water repellency of the finest sieve fraction did not affect the wettability of the whole sample because the other nine sieve fractions (53 mum to > 2000 mum) were wettable.With increasing water repellency, from slightly to extremely water-repellent soils, more sieve fractions are occupied by soil structures and components that contain water-repellent organic remains, e.g. macro-aggregates, plant fragments and coatings on sand grains. Most of these structures and microaggregates have presumably, partly or wholly, been made by soil biota. Conversely, the degree of water repellency of soils can be reduced by decomposition of organic matter and by coating of plant fragments with fine non-water-repellent soil materials; processes in which soil biota are also active.