1.0 objective

A good understanding of soil and also its characteristics is one of the most essential of the plenty of factors which should be taken into consideration for successful freshwater fish culture. The objective of this hand-operated is to provide the an easy knowledge of the soil the is essential for the building of ponds, a water supply, canals, reservoirs, barrages, little dams, and for the reliable management that fish ponds.

To carry out this, you will certainly learn:

just how to investigate your very own soil by conducting her own an easy tests; Why part tests require an abilities and devices too devoted for you, and also should therefore be carry out by a soil laboratory; how to know the technical language of soil scientists and also civil designers so the you can manipulate soil analyses and also soil laboratories.

1.1 What is soil?

soil is a complex mixture of living organisms, organic matter, minerals, water and also air. Take it a grasp of soil and look in ~ it closely. You have the right to see that it is a mixture of plenty of different kinds of little particles.

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Soil is made up of: Organic corpuscle of decayed plant and animal materials which come from living plant and animal bodies; Mineral corpuscle such as sand, clay, stones or gravel which were when parts of larger rocks.

Depending on your texture, structure and consistency, assorted kinds of soil hold much more or less water and also air. Girlfriend will study the make-up of soil in an ext detail in section 1.6.

1.2 Why is it crucial to investigate your soil?

Soil is your straightforward material

If you are going to make a success the freshwater fish-farming, girlfriend must recognize your floor well. The bottom of her pond is soil. Once you destruction your pond, friend will use the floor you take out to build your dikes. If you are going to build a reservoir to store water, girlfriend will build a dam utilizing soil. Friend will have to dig ditches or canals in the soil for a water supply to your ponds.



How fine does her soil host water?

the is vital to know how well her soil holds water. This is referred to as soil permeability. Soil which is permeable does not host water. Soil which is impermeable hold water. Before you construct a fish-pond, you will need to test her soil to see if the permeability is suitable for structure a pond. If the loss of water with seepage is as well great, you might need to seal the bottom of your pond, you might need to seal the dikes, or you may uncover that you shed too much water from your supply canals.

Remember ...

once you are building a pond, good soil ensures strong and impermeable dikes so that the water stays in the ponds. Wet and also swampy grounds room usually great for pond construction;
prevent building-sites for ponds with holes or cracks, anthills or rock outcroppings or through the root of large bushes or trees. Here, water losses might be excessive and it can be an overwhelming to seal the pond bottom properly;
If you plan to build a tiny reservoir, select a great site because that the dam with suitable soil located nearby for that is construction.

How to command a soil inspection

Before you start to develop a pond, you need to do a soil inspection to watch if the site is satisfactory because that pond building. You will learn just how to carry out this in chapter 2, Planning and also making a floor survey.

1.3 The origin and also evolution of soil

What is the origin of soil and how do various rocks develop?

All soils loss into two key categories: the mineral soils and the necessary soils.

Mineral soils come from parent rock referred to as parent material. They develop over time as the parent material is broken down by various physical, chemical and also biological processes due to climate, drainage, leaching, erosion, vegetation, life organisms and human activity. This is referred to as weathering. For example, high soil temperatures breakdown rocks into smaller fragments, owing to heating and cooling. The parent product is gradually lessened to particles, larger areas come in contact with water, and also the chemistry composition the the minerals existing changes. Soluble chemicals space washed down, or leached, to deeper components of the soil while much less soluble products are left in the upper components of the soil. Additional weathering takes location and, in time, mineral soils develop to their actual state.
Peat soils room a common kind of organic soil. They form on poorly drained areas such as river valleys and lake shores i m sorry are frequently under water and where decomposition of vegetal organic matter is very slow, or even stops. The class of necessary matter, being developed by the vegetation, then start to heap layer by class on top of the mineral soil and also can be number of metres thick. Peat soils, made up of around 80 percent partially decomposed essential matter, have really high water content and permeability.

There room two species of mineral soils

Some mineral soils develop from a parent material which is damaged down on location into little particles v weathering. These are called residual soils.

Other mineral soils construct from tiny particles comes from mineral soils developed in an additional location, transported for part distance, and also deposited. This are dubbed sedimentary soils.

Soils emerged from a regional parent material: residual soils

Residual soils are usually uncovered in the hills and extend under to the foothills along the edge of valleys. They space rarely discovered in large level areas but room usually uncovered in locations ranging from gently sloping to rather steep. Solid absent or partly decomposed absent material listed below the subsoil suggests that residual floor was developed here.

Soils developed from a transported parent material: sedimentary soils

The floor particles consisting of sedimentary soils may have been transported by wind or by water. If the particles have been transported through wind, the soil creates from a loess, which is typically the best farming topsoil puffy from other areas. The is common in rolling or hilly topography. Loess is often quite fertile and contains a same amount of organic matter to an excellent depths; If the particles have actually been transported by water, the soil develops from an alluvium and the resulting sedimentary floor is one alluvial soil. Soil might be transported by relocating water such as rain, a flow or a tidal area. Precipitate may happen in was standing water such together a lake, swamp or sea. The water may be fresh or saline (inland, seaside or delta estuary). The deliver may have actually taken place a lengthy time ago, or it might still be taking place today.
Old alluvium has remained in place long sufficient to present distinct layers led to by soil formation processes. The is usually located high above present flood levels. The topography is likely to be level or tenderness sloping.

New alluvium is found in flood plains. It has actually been moved into place by recent floods and also is still subject to flooding. Soil layers are an overwhelming to see. The topography is normally level, but rolling low ridges and hollows are likewise found. These soils room usually highly fertile.

Note: a sea or lake may have actually been existing thousands that years back in a ar which now is covered with forest or savannah. This soil will certainly be one alluvial soil, also though water is no longer present.

flow flood-plains subjected to seasonal floods; river deltas where river deposits space found in addition to a long-term high water-table; flow estuaries wherein sedimentation is affected by tidal movements at the transition from fresh waters to marine waters; coastal plains where tides reason sea-water deposits.

1.4 The soil and also the subsoil the mineral soils

After soil has occurred for part time, you deserve to usually watch two significant horizontal great or strata which lie above the parent material. The surface stratum is the soil which is made up of the surface soil and also the floor proper. The bottom stratum is the subsoil.

The surface stratum: the soil

This is the class where most of the biological activity takes place, such as animal diggings, animal droppings, cultivation plant roots, decomposition of organic matter, and man"s agricultural activities. Circulation that air, water and chemicals is biggest here, and the soil is softer. As water washes down minerals and organic materials from the surface to the depth parts, one have the right to recognize in ~ this surface stratum 2 narrower layers i m sorry are:

The surface soil or the optimal layer which is normally shallow and also sometimes cultivated by man. The surface ar soil has organic material and also most of the feeder roots of the plants live top top it. That is darker in colour and, in certain cases, that may even be black. In ~ the bottom of this surface ar soil, friend may find a shallow class of gravel; The soil proper, the 2nd layer, which is lighter in colour and contains the roots of the bigger plants such as bushes and trees.

The bottom stratum: the subsoil

This is the deeper class where only the biggest tree roots will penetrate. Circulation of air, water, and chemicals is diminished here, and also the floor is hard. The general appearance that this subsoil will vary according to its origin:

If the is a, sedimentary soil (as shown here), the floor layers might be narrower. Each of lock may have actually its very own composition related to the means it was deposited. Usually, these soils are quite thick and the parent rock is then found several metres listed below the surface.

1.5 soil horizons in mineral soils

There are plenty of different type of soil

You have currently learned in section 1.3 the there are plenty of kinds that soil and also many sport of these type of soil. Soils might be shallow or really deep, they may be leached* or saline, they may be mature or immature. The attributes of soil vary according to:

regional conditions, such as topography, climate, vegetation and human activity;
Topography Sloping land has actually shallow soil; level land has actually deep soil.
Climate: Rainy locations have leached soil, water infiltration washing down soluble materials; dry areas have saline soil, water evaporation concentrating salts.
Vegetation: Soils covered with woodland vegetation have actually a high contents of necessary material; soils which have actually been much more exposed come the straight effects the high temperatures and also rainfall, such as savannah soils, have actually a lower content of necessary material.
Human activity: Forest clearing, land draining, irrigation and other agricultural activities will modify soils.
The nature of the product from i m sorry the soil has developed;


Residual soils differ from sedimentary soil; parent products as diverse as granite*, basalt*, gneiss* and micaschist* develop into different species of soils.

The size of time the soil has actually been developing.


Mature soils room those which room old and also well developed; immature soils room those i beg your pardon are new and not completely developed.

Soil horizons space layers which are characteristic that each sort of soil

As over there are countless kinds that soil and many sports of this soils, there are additionally variations that the horizontal layers typical to all soils. Floor layers tend to differ from place to place as to their number, individual thickness, colour, physical and chemical characteristics.

The major layers disputed in ar 1.4, The soil and the subsoil of mineral soils, room subdivided right into thinner layers dubbed master horizons. Each understand horizon may be more subdivided right into subhorizons.

How execute the soil horizons develop?

The physical properties of the soil stratum, indigenous the surface of the ground to a depth of about 1.5-2 metres or periodically deeper, are influenced by seasonal transforms of water content and also temperature and by various organic agents such as roots, worms, insects, and bacteria.

The upper component of the mineral soil, the A grasp horizon, is topic to the mechanical results of weathering and also to the lose of several of its constituents v leaching. In the lower part of the floor stratum, the B master horizon, few of the building material leached out from above are precipitation and built up .

Below the B grasp horizon, the character of the floor is determined by the type of parent-rock from which it to be formed, just how it was deposited and also by later on geological events.

How room these soil horizons labelled?

The labelling device used through soil researchers to designate soil horizons is complex. Here, the much more simplified system presented in Table ns designates understand horizons by the funding letters H, 0, A, E, B, C, and R.

Subhorizons will be designated by adding a number to the letter of the master horizon. This is done for each master horizon from top to bottom. Grasp horizon B, for example, deserve to be subdivided right into subhorizons B1, B2, B3 .
Organic horizon formed (or forming) from accumulation of organic product deposited ~ above the soil surface. It is composed of at least 20-30 percent necessary matter, the composition depending on the type of vegetation from which the organic material results. It can kind only in the lack of air, when soils are repeatedly waterlogged.

Organic horizon as over except that it is no saturated v water for much more than a couple of days a year. It includes at the very least 35 percent necessary matter, consisting normally of partially decomposed essential material.

Mineral horizon created (or forming) in ~ the surface or adjacent to the surface. The either reflects an accumulation of humified organic matter (humus) intimately associated with mineral corpuscle or has a morphology obtained by floor formation. That is somewhat darker 보다 the basic B-horizon, the decomposed organic material being mixed with mineral product by biological activity.

Eluvial horizon, positioned beneath one H-, O- or A-horizon. It consists of less organic matter, mirrors an accumulation of unweatherable minerals, and is lighter in colour. The is formed by ns of iron, good clay, etc., which have actually been transported and accumulated in the basic B-horizon.

Mineral horizon the unconsolidated material from i beg your pardon the soil has developed. Bottom gravelly and also stony product which permits root development is likewise included here.

Layer of constant indurated rock sufficiently coherent when moist to make spade digging impracticable. This rock might contain cracks however these space too couple of and too small for far-reaching root development. In fact, this is not a genuine soil horizon.

Identification of floor horizons: the soil profile

The easiest way to identify and describe different soil horizons is come look in ~ a fresh soil profile. A soil profile is a vertical section made with the floor that shows the thickness and sequence of the separation, personal, instance horizons. To determine soil horizons, perform as follows:

Look in ~ the floor profile and also identify the grasp horizons; make a illustration of the floor profile mirroring the master horizons. Label each horizon as shown; examine each grasp horizon individually and, if they are present, determine the subhorizons. Brand the subhorizons by number is numbered them from the peak to the bottom that each master horizon, together shown; once you have actually finished the illustration of the floor profile, measure the depth the the top and bottom of every horizon and also write these depth on her drawing. Depths need to be measure in centimetres from the top of the soil (immediately below any kind of layer of pipeline or other non decomposed vegetation) to the top limit of each horizon and to its bottom limit.

Note: if friend see alters in the broad of the horizon in the profile, include a note offering the variety of this change. In the illustration, the top of the B2 subhorizon arrays from 51 to 62 centimetres and also the bottom native 90 to 94 centimetres. So, the B2 subhorizon broad varies indigenous 32 come 39 centimetres.

1.6 soil composition

You have already learned in section 1.1 that soil is a complicated mixture of living organisms, essential matter, minerals, water and air. In this section, friend will find out a little much more about several of these soil constituents.

Organic issue in soil

Some organic issue is big enough to see, together as little leaves, twigs, rotted pieces of wood and also worms. Various other organic issue is so tiny that girlfriend cannot see it. This is dubbed humus and also it is uncovered in the floor in the colloidal state.* Humus comes from dead plants and also animals i beg your pardon decompose in the soil. You cannot watch it as you can see minerals, but you recognize it is in the soil because of the colour. Humus renders the soil darker than usual, or also black. Humus particles have actually the residential or commercial property of strong attracting soil minerals come their surface through adsorption.*

Minerals in floor

Minerals are current as particles of various sizes. In some cases, these particles may sign up with together to kind clumps of bigger size. Mineral particles have various names follow to their size, such as boulder, stone, cobble, gravel, sand, silt or clay. Few of these particles may be easily seen, however some the the finer floor particles, such together silt and also clay, may be seen only with a microscope. The finest soil particles, called colloid clay *, are invisible. Colloid clay particles also have the building of strongly attracting floor minerals to their surface through adsorption.*

Mineral particles room classified on the communication of their size. Follow to the country and the purpose of the inspection (engineering, agriculture or floor conservation), various systems of category are used, although some initiatives have been made to standardize. Some various systems of category are displayed in Table 2.

Water in soil

In the soil, water might exist in 2 forms. This are cost-free water and also bound water. Cost-free water is uncovered in the floor pores,* and bound water is uncovered attached come the soil particles as a movie (cohesion*water) or that is adsorbed* in ~ the surface ar of the soil fragment (adhesion* water).

Soil permeability is the activity of cost-free water v the floor pores, cracks and holes. This will certainly be discussed further in thing 9. Bound water may be of an excellent importance, specifically when the soil particles are very fine, since of its direct influence on several of the design properties the a floor such as its shrink-swell potential (see ar 10.4). As soon as the soil particles are an extremely fine, such as with clay particles, water and chemicals may be very strongly adsorbed at their surface. Clay water content may hence vary greatly. Clay particles might adsorb approximately 600 percent of their dry weight which might correspond to a swelling* ten times their initial volume once dry.

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Air in floor

Soils likewise contain a proportion of wait in the complimentary pore spaces between soil particles and also clumps or aggregates. That is likewise found in the cracks and holes, resulting from the tasks of living organisms such as worms, termites, ants, rodents and plant roots.

The volume the the soil atmosphere is mostly determined by the physical nature the the soil, that is water content, that relative level of compaction*, and the importance and also nature of the tasks of life organisms present.