Pasture has the potential to provide
1. The horses nutrition
2. A Safe exercise area
Potentials rarely achieved, often neglected

All information given here is believed to be correct but the author cannot be responsible for any consequences of it's use.

Pasture Management
for
Horses

by Denis Lindsell
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Soils




 


 

What is soil?

Soil can be thought of as having four constituents:
Minerals
Organic Matter
Water
Air








Minerals

These are the hard particles that usually make up most of the volume and have various chemical constituents which may provide plant nutrients. These mineral particles will have originated from various types of rock as follows:

Igneous (volcanic rock).

Sedemintary ( particles that have perhaps been deposited in a river bed which has become a hard rock due to the effect of pressure over a period of time).

Metamorphic (either of the above two that has been subject to extreme heat and/or pressure over a period of time causing changes to occur).

These rocks will have suffered the effects of weathering.
As a result the rock will be in relatively small particles and minerals may have become more soluble and subject to leaching. Another factor that may be involved here is that of transportation, possibly by the same wind or water that was involved in the weathering, causing the end results to be deposited away from the parent material and possibly being mixed with minerals from various sources.

The end result is that the soils we come across can be extremely varied in mineral content.

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Organic Matter

Organic material is any material that is derived from dead plants or animals. This occurs naturally in the soil.

Some of the grass in your paddock will be dying and this dead material will over a period of time be broken down by the action of bacteria and carried down into the soil by earthworms. These bacteria and earthworms will themselves die and add to the organic material in the soil.

It has been suggested that at any one time, a paddock may have a greater total weight of animal life under the soil than it has on top grazing.

Organic matter will be broken down in the soil if conditions are suitable, to form humus, a black or brown jelly like substance which is a valuable soil constituent. Humus effectively has a very small particle size and carries a negative electrical charge, which will help to hold positively charge nutrients in the soil. These nutrients will include calcium, magnesium, potassium, and sodium. (Note that clay particles also show similar colloidal properties).


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Water

Water will exist in the gaps between the solid particles and can be divided into four types according to the forces holding the water there..

Gravitational Water, the water that will freely drain away.



The condition illustrated is named Saturation - all spaces are full of water. The water in the larger spaces will freely drain away (as long as drainage is not impeded) as any capillary attraction forces present are not strong enough to overcome the forces of gravity.
Capillary Water, the water that is still held in the soil by cappillary attraction and is available to plants.



The condition illustrated is named Field Capacity - here all the gravitational water has drained out of the soil resulting in air being present in the larger spaces.
Hygroscopic Water, the water held by cappillary forces too strong to be available to plants.



The condition illustrated is named Wilting Point - in this situation, plants have removed all the water they can and are beginning to wilt due to lack of water. Any water that remains in the soil is held in very small spaces where the capillary forces are too strong for plants to compete.

The fourth type of water is Chemically Bound Water. This water, as the name implies is part of the chemical structure of the mineral molecules. This water is unavailable to plants and needn't concern us here.

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Air

Air and water are often grouped together for the simple reason that between them they occupy the spaces between the solid particles. Each are very necessary for the growth of plants and other life forms in the soil. The two are also related as an increase in water content, due to poor drainage, will result in a reduced air content of a soil.

If the soil only has small spaces between the particles, the movement of air between the atmosphere and the soil will be slow, causing carbon dioxide levels to be higher than normal and oxygen to be lower than normal. This will have a detrimental effect on plants and soil life.

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