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Most of the soil of UAE are silty sandy soil consisting of 85% sand, low in organic substance which range between 0.1m0.2% or very poor in major elements where nitrogen (N) range between 5-10 (ppm) part per million, phosphorous (p) range between 1-5 ppm, potassium (k)100-14 ppm while the minor elements are very low in concentration where the calcium carbonate ranges between 20-40%.

Irrigation water sources in UAE are only underground water where there around 30734 wells and salinity 200-5000 ppm used only for agricultural irrigation. When the United Arab Emirates was established in 1971, the state was divided into four agricultural areas.
Table No (1) shows distribution of those agricultural areas and objective of designation.

Division of Agricultural land

Gravel land

Gravel land are land consist of high percentage of gravel stones up to 35% of the soil. But the fine soil are sufficient for plant growing, such land can be divided to subgroups based on the following main characters.

• The quantity and depth of the gravels
• Character of the fine soil/ diameter less than 2 mm mixed gravels.
• The texture.
• The quantity of calcium carbonate.

Such soils are found in Al Battina valley between Oman mountains and Oman Gulf and Eastern side of the gravel plain. The quantity of gravels increases near Oman Mountains and Oman Gulf and Eastern side of the gravel plain. The quantity of gravels increases near Oman Mountains .

 Sandy land

Sandy land are deep and contains low gravels at adepth of more than 50 cin. These land are characterized by high quantities of calcium carbonate and found in some area of the gravel plain adjacent to the sandy desert.

Light texture land

These land are deep and low in gravels. The texture ranges between sandy loam and lamy sand. Depth of gravels is more than 50 cm. these lands are considered as most important areas in the gravel plain and covering big areas of the lime, Dhaid , Ghuraif and Al Maddam.

Medium texture land

These land are deep and contain high quantity of silt and clay. The texture is mostly sand clay and more than 60 cm thickness. These land are confined only west the gravel plain where the fine gravels precipitated in the valleys and not much mixed with desert soil.

Based on quantity of calcium carbonate in the soul, above divisions can be divided to the following subdivisions: -

• and of calcium carbonate content less than 25% and include most of the gravel land of Dhaid and Al Maddam plain.
• Land of calcium carbonate content ranges between 25-40% and include areas of light and medium texture south Al Daqdaqa area.
• Land of calcium carbonate content more than 40% which include the lime plain north of Al Daqdaqa area and increase when we go north or west.

Generally we can determine the main chemical character of the UAE soil having direct relation with the soil fertility as follows:

PH:

PH is negative concentration of hydrogen ions in the soil solution.UAE soil usually alkaline when PH is more than 7 ( ranges between 7.5-8.5).In such cases there will be problems in the absorption of feeding elements in the soil by plants particularly phosphorous and other elements live ferrous Zinc and manganese.

Percentage Of Calcium Carbonate

Percentage of calcium carbonate is very high in UAE and ranges between 25-40% and sometimes reaches 90% in Graft area. The increase of calcium carbonate in soil usually leads to many problems related to fertilization e.g. fixing of phosphorous and potassium elements in addition to minor elements in general e.g. ferrous. Deficiency of ferrous in the lime soil lead to phenomena known as yellowness. In such case ferrous available in soil but the plant cannot intake it. In addition to its effect on the soil natural character as making outer layer on the soil surface prohibiting aeration of roots and also cracks at the time the time drought causing death of the roots. Therefore it is very important to follow an efficient irrigation program and to avoid thirsty and long irrigation intervals. Presence of high quantity of calcium carbonate makes calcium dominate in exchange surface prohibiting the sodium from converting the soil to alkaline soil and makes it very difficult to grow plant.

The Percentage Of the Organic Substance

The percentage of organic substance in UAE soil is very low and mostly below 1% due to hot climate and quick decomposition of organic substance and also due to little addition of the same. It is well known that, the organic substances improve the soil physical characters in addition to its lack of nutritional elements, so it is very important to substitute that that by adding organic fertilizers in addition to minerals. Also to arrange for accurate and regular fertilization program and not to use much organic fertilizers.

Cation Exchange Capacity ( C.E.C):

Soil in UAE is very poor soil where C.E.C ranges between 6-12 mm / 11g of soil. This character varies with tyoe to the texture of the soil where it increases with increasing of clay percentage in the soil and depends on the type of dominating element.

Soil Texture:

Most soil in UAE are light textures since sand is more than silt and clay beside that no clay in some areas. There is course sand and big quantity of gravels in some areas resulting in quick leakage of nutritional elements by adding irrigation at short intervals instead of on time. Organic substances should added frequently to improve the soil capacity to maintain water.

Salinity

The salinity of irrigation water differ from one area to another e.g. it is normal at Dhaid Hatta while it is high in soil of the eastern region. Water salinity differs due to the variation in sources of he groundwater. Underground wells being the main source of the irrigation water, so we should be careful in selecting the location and the conduct necessary chemical analysis when operated for the first time and to undertake periodic analysis to make sure of non-increase of the salinity and to select the appropriate plant to lerating salinity.

Soil salinity varies with varies of areas and the salinity percentage. It increases near the sea and desert and decreases in far areas. Salinity problems start with the planting activities, frequent planting and use of high salinity water, in addition to the hot climate and of water drainage which leads to accumulation of lack salts in the soil. We have to avoid increase of soil salinity in order not to effect the plants, in case of high salinity levels in the soil,

we have to increase the irrigation water for leaking. Generally the salinity of the soil is very high in UAE and no doubt this will effect the intake of the nutritional elements necessary for growth and with more salinity the result is the plant life. Therefore we have to select the plants of different types suitable for growth under UAE conditions.