Good drainage starts with good soil structure, because well-structured soils contain enough pores—the gaps between soil particles—to allow air and water to flow freely. Ideally, the sand, silt, and clay particles are arranged so they occupy only half of the space, leaving the other half as pore space.While,Soil can drain poorly for several reasons, manmade or natural. Soils with a high proportion of clay contain smaller pore spaces that release water very slowly, so clay-heavy soils are often dense and wet. Water tends to collect and pool in soil that is in a low-lying spot, underlaid by rock or an impervious hardpan layer, or sits above a high water table.

Drainage problems: Drainage problem occur on lands, which we consider as an arid. The causes of drainage problems are as follows. This is also termed as causes of bad drainage or why soils become water logged or ill drained.

1. Excessive use of water: Water that is plentiful and cheap often is used in excess. The result is general water logged condition. Wild flooding continuous irrigation or excessively long irrigation turns to promote water logging.

2. Seepage of canals laterals or ditches: The seepage enters underground strata at elevations higher than those of irrigated lands enter and often becomes a direct source of water logging of low lying areas.

3. Internal stratification or irrigated soils: The internal natural drainage of soils is often poor. The slowly permeable soils, which when irrigation water is applied, impede the percolation of the excess water. The water cannot move down wards fast enough and accumulate on the surface forming a thin layer and obstruct aeration.

4. Low lying area: The area is low lying and excess rain cannot be carried away as a surface runoff rapidly into the drain causing water logged condition.

5. The water table may be high and the additional gravitational water just accumulates and checks the air spaces and saturates the surface and sub soil.

6. There may be a hard pan that affects seepage of water to lower strata.

7. There may be salts affecting water absorption by roots.

In addition to previous answer, I would add another causes, which might be important in temperate zones (Poland).

If we consider some soil developed from glacial till, with relatively uniform clay distribution with depth, and, for example, a texture of sandy loam or loam with moderate clay content (I think, sandy clay loams, some more clayey loams and othe soils rich in clay from their nature may be poorly drained due to their particle size distribution), I would point two additional causes of development of poor drainage:

a) clay illuviation, sometimes called "lessivage", although it's very time consuming process, in which some clay is being continously dispersed and transported downward with filtrating water, and then it coagulates and thus accumulates in subsoil and forms clay films, cutans and similar forms, sometimes filling the soil pores completely. Even without filling all pores, the subsoil with increased clay content, and poorer (from it's nature) in organic matter will have worse hydraulic conductivity than Ap horizon and this may or even must contribute to worse drainage and stagnic properties.  I attach interesting paper, which deals indirectly with this subject;

b) soil compaction due to tillage, sometimes referred as "plow pan", which is related to constant plowing to the same depth and without any subsoiling. Also the movement of heavy machinery, which causes soil compaction not only of plow layer (which is amended by plowing), but also deeper layers. In such case, the compacted subsoil , although with the same texture as plow layer, has smaller porosity, and, consequently, worse hydraulic conductivity....

Quality soil maps often include attributes for evaluating uses pertaining to drainage, flooding, hydric character, etc.  Areas that accumulate organics, would tend to hold more water.  Excessive compaction or rutting by heavy equipment or intense traffic by cattle also contribute to poor drainage under primarily wet soil conditions.  An old paper in SC USA piedmont documented that farming areas repeatedly and intense rains, released fine soil particles, filling macropore, reducing hydraulic conductivity.  

As stated, inherent soil properties are often responsible, clay layers, pans, etc.  In some conditions, the burial of organics or infusion of organics can develop into a restricted biolayer limiting drainage.  

Plants, especially deep rooting specis and trees, can do much to break up and maintain drainage.  But there are exceptions, such as the dense and deep network of roots in sedges and rushes do not drain wet meadows.  Roots cannot always penetrate restrictive layers.  

Soil scientists are often most knowledgeable about how to maintain or improve drainage if desired, such as no or low till planting, identifying and avoiding wetlands in development when possible to maintain important habitats and functions, idenifying species best adapted to sites, etc.  Certain equipment choices and timing of operations are sometimes ways to mitigate drainage effects.  We found a Brache scarifier with mounder that would mound a dollop of soil periodically for tree planting (loblolly, longlaf pine usually) was less impactive to hydrology than site bedding of soils in linear strips.  Increased attention to native species and site conditions and benefits leaves some sites best for bottomland hardwoods and wetlands, rather than drainage.  

But if the intent of drainage is decided, there are various tools such as ripping of soils deeply, developing a network of ditches or canals, installing drainage tiles, etc.  There are a variety of costs and benefits to weigh in these decisions, so consulting a soil scientist and other resource professionals can help to make informed decisions.  Occasionally there are soils that even with drainage and fertilization, productivity is not improved to justify treatment.

Dear All,

I'm very grateful for the answers provided. Very helpful useful in terms of improving my own understanding and better refining the question that I am posed above. Specifically, I am most interested in better understanding the natural pedogenic processes that may drive a transition in soil drainage class over geological time. 

I don't consider waterlogged soils with high hydraulic conductivity to be poorly drained, such as fibrous peat. Rather the water table is the key driver of water logging not the soil structure itself.  So, most interested in the drivers of the evolution of poor internal drainage. Specifically, what pedogenic pathways/processes favour the develop of poor internal drainage? Specifically, do people know of any studies that assess the relationship between landscape setting, pedogenic process or pathway that drives the development of poor internal drainage in soils? I'd like to develop an understanding of why soil drainage class varies across the landscape.  

So I'm very interested in more of your thoughts on the natural pedogenic controls over the development of poorly drained soils in response to weathering? Iron pans are also of interest as these clearly develop in response to soil weathering (including redox) processes and here in New Zealand are often important features governing soil hydrology

Thanks again.

Hi,  as explained by Michał Stępień , "lessivage" or clay illuviation is probably the main pedogenetic factor leading to decrease in drainage.

However, it really depends from the original texture of the geological parent material. Even young soil developped on clay stone will be from the beginning of their development poorly drained.

Structure and architecture of the soil and subsolum are very important, cracks density and orientation will change the condition of drainage to the subsolum.

Other very imporant factor is the bioturbation,especially earthworm burrow, so on a geological time scale du eto change in pluviometriy, temperature, etc,, soil fauna will also change and impact the bioturbation and consequently the drainage condition.

Look at the publication of South African colleagues from Free State University.

JJ

Article Using ancient and recent soil properties to design a concept...

Article Hydropedological Classification of South African Hillslopes

Article Towards more systematic perceptual model development: A case...

Hi Jerome,

Thank you for your great explanation and the papers. I found them very interesting.

Regards

Clint

Please see this article:

http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1955&context=extension_curall 

Regards. --- Hilmi

I agree with Jerome: an limiting horizon (a clayey B horizon) is decisive in the drainage. Another problem can be an stratum of compact calcium carbonate (caliche) which limits or delay the infiltration.