IV. COUNTRY REPORTS

1. Afghanistan
2. Algeria
3. Bahrain
4. Arab Republic of Egypt
5. Iran
6. Iraq
7. Jordan
8. Lebanon
9. Arab Republic of Libya
10. Morocco
11. Pakistan
12. Sudan
13. Syrian Arab Republic
14. Tunisia
15. People's Democratic Republic of Yemen

1. Afghanistan

by
Dost M. Noori
Ministry of Agriculture and Irrigation
Kabul, Afghanistan

1.1 INTRODUCTION

Most of the soils under arid and semi-arid climatic conditions in Afghanistan are significantly characterized as zonal soils. These are grouped in the Great Soil groups such as desert soils, grey desert soils, red desert soils, sierozem, reddish brown soils and brown soils. Some other Great Soil groups under the orders of Azonal and Interazonal are comprised of regosols, lithosols, alluvials, solonchak, and solonetz soils.

Mainly these desert soils are unstable regarding structure stability and more porous than alluvial soils. Water holding capacity is low, permeability and infiltration rate are high due to coarse texture, and limited content of organic matter.

Where calcification and gypsification are the main chemical processes, the predominant cation is calcium which has given a calcareous characteristic to the soils in most cases.

Due to the limited amount of precipitation, especially on the alluvial deposits in arid regions of Afghanistan, these soils owe their distinctive character to the fact that they contain excessive amounts of either soluble salts or exchangeable sodium or both. For agricultural purposes such soils are regarded as problem soils which require special management practices.

1.2 PHYSICAL AND CHEMICAL PROPERTIES

1.2.1 Physical Properties of the Soil

Among the most important physical characteristics of these soils under arid and semi-arid regions are: structure, soil-water, temperature, aeration, infiltration rate, permeability, density and pore-size distribution. There is a wide range of variation regarding physical properties of these soils in the country. For example, alluvial soils, sierozems and brownsoils are more productive and have more moderate physical properties than desert soils, regosols and lithosols. We can conclude that most of the soils in arid and semi-arid regions are unstable in structure, low in organic matter and high in apparent density.

In general, organic matter content even in the alluvial deposits is not higher than 2.5 percent, while the organic content in sandy soils is less than 0.2 percent.

1.2.2 Chemical Properties of the Soil

Soil reaction is one of the most important factors which affects the uptake of plant nutrients in a large extent. The pH of the soils, except in forest areas is generally higher than 7. Soil reaction is dependent upon the composition of exchangeable cations, the nature of the cation exchange materials, and the composition and concentration of soluble salts in the soils.

Soils having pH greater than 8.5 indicate an exchangeable sodium percentage of 25 or more. Soils having pH value lower than 7.5 contain almost no alkaline earth carbonates.

In our case, due to the arid and semi-arid climatic conditions, pH is generally greater than 7, because of the high amount of alkaline earth carbonates and high exchangeable sodium percentage.

On the basis of the above-mentioned data salt affected soils in this region are classified as follows:

	EC x 103	ESP	pH
1. Normal soil	<4	<15	<8.5
2. Saline soil	> 4	<15	<8.5
3. Sodic soil	<4	>15	>8.5
4. Saline sodic soil	>4	>15	>8.5

Soil reaction combined with other factors such as cation exchange capacity which consists for the most part of various clay minerals, soluble salts, and organic matter are the most important factors considering chemical properties of the soils.

In Afghanistan due to the high pH of the soil and the high amount of alkaline earth carbonates and low organic matter content, fixation of phosphorus makes it less available to plants.

1.3 ORGANIC MATTER CONTENT AND MICROBIAL ACTIVITY

1.3.1 Organic Matter Status in the Soils

In the arid and semi-arid regions where precipitation is a limiting factor, lack of vegetative cover and the decomposition of organic matter is an effective problem in these regions.

It has been recognized that organic matter and clay fractions are both responsible for the major portion of soil aggregation. Organic matter has also an effective influence on the release of macro nutrients which makes them more available to the plant use.

In Afghanistan where annual precipitation is limited, organic matter content is very rare in the desert soils, lithosols and regosols, but in the sierozems, brown and alluvial soils, the organic matter content is present up to 2.5 percent.

All these beneficial effects on soil aggregation stability, formation of the clay particles and release of micro-elements are originated from the integrated activity of soil micro-organisms, decomposition of organic matter and other related factors.

1.3.2 Microbial Activities in the Soil

The decomposition of organic matter is very important for the stability of soil structure. Organic matter without mological transformation by fungi actinomycetes, bacteria and yeasts has little, if any effect, on soil aggregation. Organic matter itself is a source of energy for soil micro-organisms without organic matter, organisms are ineffective in producing soil aggregation.

These micro-organisms under suitable conditions produce a large number of mycelia, therefore, these mycelia under metabolic processes synthesize more complex organic molecules.

Polysaccharides, organic acids humus, aminoacids, lignin and other more complicated organic compounds are the results of micro-organism activities after the decomposition of organic matter under a specific condition in the soils.

In the arid regions precipitation and vegetative cover are not enough to increase the population and kinds of micro-organisms as well as their activity. These problems are added to the others.

1.4 CONCLUSION

i. In arid and semi-arid regions most of the Great Soil Groups are desert soils, brown and sierozems. Some other soils such as lithosols, regosols, alluvials, solonchak and solonetz are associated under the orders of Azonals and Interazonal soils.

ii. Physical and chemical properties are affected by the climatic factors. Structure and texture are not satisfactorily developed. These soils are more susceptible to water and wind erosion with their low water-holding capacity.

iii. Chemically, these soils have low cation exchange capacity. High pH is due to the high amount of alkaline earth carbonates and high content of sodium ions. Accumulation of soluble salts needs special management practices.

iv. Because of the limited precipitation and insufficient vegetative cover, the content of organic matter and soil micro-organism activities are low.

v. Considering all the above-mentioned limitations, these soils need special agronomical practices. The addition of organic and mineral fertilizers is important from the standpoint of fertility status. Crop rotations combined with good irrigation practices and water management should be used.

2. Algeria

by
S. Boutebila
(Ingenieur agronome)
Ministry of Agriculture and Agrarian Reform
Algiers

Algeria has more than 2 000 000 km² fifths of the total land area. in the arid zone which is about four-fifths of the total land area.

The following are the characteristics of this zone:

Relief: is very variable: there are as well as vast stretches cut by wadis, ranges of mountains (volcanic origin) in Hoggar and Tassili, and also dunes.

Climate: with rare exceptions, is very hot in summer (48°C in the shade), cold in winter (-5°C) with great fluctuations in temperature between day and night. Rain is extremely rare.

Soil: the sandy soils have different natures:

- Soils in wadis are the richest and this enables the growing without difficulty of a large range of market garden, fodder and fruit crops.

- Soils with a high clay content are rare and form an exception.

- Sandy soils are found with a gypsiferous crust between 20 and 100 cm deep and they are very difficult to work because regular breaking of the crust is necessary.

- Sandy soils of variable texture exist and cover most of the area requiring appropriate improvements.

Water: is of various origins:

- Rain: very rare over the whole zone, it forms the main water contribution for certain regions which often suffer great difficulties in dry years. This is the case at present in the extreme south which generally receives the tail of the monsoon and is now in the same situation as the adjacent countries (Niger, Mali, etc). Some oases use "foggaras".

- Groundwater: it is from this source that 95% ^of area is irrigated. It collects at a depth varying from 100 to 1 800 m, sometimes flowing, sometimes not. Thus for groundwater collected at shallow depth there is no particular difficulty; the groundwater at 1 800 m is very hot (60°C), rich in carbonate and sulphate salts; this causes inconveniences, particularly in the choice of equipment.

The cultivation of date palms is now the principal source of wealth because, in the very difficult Sahara conditions, it is the only perennial plant which can resist the harshness of the climate.

Recently, great efforts for intensification have been made and we can foresee the future from another angle. In effect, the growing of market garden and fodder crops has allowed economic aspects to be introduced into agriculture, which confirms our hypothesis. For example, the export of early tomatoes, from 15 January, to the high consumption markets (Paris, Brussels, Frankfurt). Efforts to cultivate melons in "fertile pots" has given conclusive results and has made production in open fields possible in this country. The technique consists of raising the plants in "fertile pots" under a plastic tunnel. The soil is covered with black plastic sheets or gravel in order not to break the roots at transplantation. The leaf mould is well spread out and disinfected beforehand. Farmers are given plants which have had the first pinching out of shoots. The time for transplanting must be carefully chosen because it has been found that when soils are saline, it is preferable to transplant before the roots have passed through the pots in order not to lose the benefit of the operation by stopping temporarily the growth of roots.

In our country activities are also carried out to revive old palm groves as well as new irrigated areas. The old palm groves are characterized by deficient drainage because they are very often located in low places and lack organic manure. The new areas to which great attention has been paid, very often suffer from a lack of organic manure, sandy winds and hot water. To overcome these, different methods have been used:

i. Organic manure: introduction of stock farming and of alfalfa in an appropriate crop rotation; utilization of sediment obtained from purification plants for residual water.

ii. Wind breaks: the following materials are used:

- live hedges: canes, eucalyptus, casuarina, acacia cyanophyla, date palms, tamarix articulata.

- dry hedges: dry palm fronds

- "tabias": these are embankments raised around the oases with wind circulation corridors which form an exit for the sand dunes which are a hindrance.

During the first year of development work it is very often found that the deposits of sand originate from the irrigated area itself, therefore alfalfa is grown for three reasons:

- soil stabilization,
- enrichment of the soil,
- fodder production.

iii. Hot water: it is 50 to 55°C at exit from the bore hole and about 35°C at the time of its use. Its carbonate and sulphurous nature have necessitated the use of semi circular channels (seguias). The lack of technical knowledge of farmers and the distance added to the previous points, demonstrates the complexity of the situation. General systematic formulae do not exist; each oasis has its own peculiarities.

3. Bahrain

IRRIGATION AND SOILS

by
Ghaffar Habib

1. INTRODUCTION

The total agricultural area in Bahrain is estimated, to be 15 000 ac, in other words, about 10% of the total area which amounts to 622 km². Two-thirds of this agricultural area is planted with date palms and this is considered the main crop. The rest includes vegetable crops, berseem, some orchards and some flowers. The total agricultural area at present has been reduced to 4 000 ac due to irrigation and drainage problems and soil deterioration.

The climate is characterized by high temperatures and humidity in the summer; the average annual temperature is 27°C and rainfall is 72 mm. The maximum diurnal humidity reaches 85% and the minimum 48%. Wind is mostly north-western.

2. MOST IMPORTANT CHARACTERISTICS OF THE SOILS AND IRRIGATION WATER

Concerning the soil, it is mostly sand, poor in organic matter and with impervious layers at depths between 75 and 300 cm in various regions of the country. For this reason there are large areas of agricultural land submerged with water or where the water table is very close to the surface at depths varying between 37 and 300 cm. With the presence of factors leading to salinization, such as the excessive use of irrigation water, absence of good drainage systems and sea-water intrusion, all these factors have to be considered when land is improved for better agricultural production or else the case will be worse.

The sand percentage in most of the soils is more than 90% as can be seen in Table 1 which shows the different physical characteristics of the soil. The technique used in the country is to add sand over soil to decrease the effect of salinity and to provide a salt free zone for the growth and development of roots, but this is an uneconomic practice due to costs.

As to the water, the main source is groundwater which extends from the northern coast of the Kingdom of Saudi Arabia where the water is found in three aquifers in which the salinity is respectively 2 000, 3 200 and 8 000 ppm. The total water consumption is estimated at about 165 million m2, 80% of which is used in agriculture and the balance for domestic and industrial use. For irrigation purposes 6 m is used per year which is rather a large volume. The monthly distribution of this quantity for vegetable production is given in Table 2.

Table 1 PHYSICAL CHARACTERISTICS OF THE SOIL

Hole No.	Depth cm	Particles Size			Text	Moisture		%	Hydraulic Conductivity mm/h
		Sand	Silt	Clay		Saturation	F. Capacity	W. Point	Initial	24 hrs
2	0-35	94	1	5	S	28	11.8	6.4	>125	>125
	35-45	93	4	3	S				>7125	>125
	45-115	93	4	3	S				>125	>125
	45-140	96	3	1	S				>7125	>125
4	0-50	90	6	4	S	36	9.2	5.0	115	108
	50-90	64	21	15	SL				98	90
	110-130	82	13	5	LS				7125	>125
	130-160	81	14	5	LS				68	63
7	0-20	96	2	2	S	21	10.0	5.4	>125	>125
	20-60	98	1	1	S				>125	>125
10	0-35	93	4	3	S	24	13.4	7.3	>125	>125
	35-95	96	3	1	S				>125	>125
	95-135	83	12	5	LS				106	83
13	0-50	69	16	15	SL	36	18.8	10.2	>125	>125
	50-90	73-	15	12	SL				>125	>125
	90-130	91	5	4	S				77	73
18	0-40	73	17	10	SL	40	19.2	10.4	56	51
	40-80	59	19	22	ScL				57	31

Table 2 MONTHLY DISTRIBUTION OF WATER FOR VEGETABLE PRODUCTION

January	0.294 meters
February	0.350 meters
March	0.437 meters
April	0.375 meters
May	0.442 meters
June	0.313 meters
July	0.618 meters
August	0.827 meters
September	0.592 meters
October	0.571 meters
November	0.528 meters
December	0.560 meters
Total:	6.071 meters

3. METHODS USED TO CHECK SOILS AND WATER PROBLEMS

The main procedures to check these problems were experimented in Badie Experimental Station hoping that they would be applicable on a wider scale.

3.1 Canal Lining

It has been found that more than 30% of the flowing water is lost from unlined canals due to the high permeability of the sandy soils. The most effective method used for canal lining is polythene and cement. There is no doubt that apart from saving water losses, canal lining also reduces the conditions leading to salinization.

3.2 Use of Modern Irrigation Methods

The traditional method of basin irrigation increases the problems of irrigation and soils and since there is a pressing need to adopt other methods, drip irrigation has been introduced and has proved successful, having the advantages of water control, regulation of irrigation frequencies and intervals and saving on labour.

3.3 Windbreaks

Windbreaks were established to reduce erosion which caused the loss of the fertile surface layer.

3.4 Water conservation

Studies were carried out on the possibility of collecting and conserving water resources, especially from the natural springs which have been affected by decreasing water level and increasing salinity due to sea-water intrusion. The coordination and cooperation between Bahrain and the Kingdom of Saudi Arabia is enough to overcome these problems.

FAO in cooperation with the Agriculture Department in Bahrain and within the frame of the FAO/UNDP Project BAH/71/501 has carried out a soil and water survey and consequently it was possible to evaluate the location and extent of the agricultural areas in the north and western parts of the country with the objective of defining suitable drainage and land reclamation measures. The execution of this project will certainly lead to increasing the available agricultural land which amounts to 15 000 ac.

REFERENCES

ITALCONSULT. 1971 Water and Agricultural Studies in Bahrain. FAO Rome

FAO Conference. 1969 Report of Bahrain to the 15th Session of the FAO General Conference. FAO Rome.

Ayub Mohammed. 1970 Irrigation with polythene. Government of Bahrain, Department of Agriculture.

4. Arab Republic of Egypt

Special consideration has been given to studies and research on the utilization of sandy soils since large areas of the potentially irrigable lands belong to this category. The total area reclaimed of these soils is 300 000 ac, of which 50 000 ac in Upper Egypt and 250 000 ac in the Delta. With the exception of small scattered areas in the Delta and Nile Valley most of the sandy soils are in the desert which makes up more than 95% of the total area of Egypt.

The sandy soils vary in their properties according to their origin and formation. Those soils dominant in the western desert are made up of quartz formed from weathering of the standstone after exposure of this area to tectonic movements that resulted in the formation of the large depression in the western desert - the Qattara Depression.

The northern coast of this desert region is an exception because the sandy soils are of marine origin made of oolitic limestone with the calcium carbonate content up to 98%. The sandy soils predominant in the eastern desert and the north of Sinai are composed of quartz developed from sediments carried by Nile water over the ages; this has been confirmed by the similarity of the heavy mineral composition to that of Nile mud, the delta and the valley soils. On the contrary, sandy soils in the other parts of Sinai originated from geologic formation found in the El Tin plateau.

Although sandy soils differ in their origin, formation and properties, yet they can be considered as one group having common problems. Due to the differences previously mentioned, the studies in Egypt to solve the problems of sandy soils deal with inter-related factors and conditions which govern the possibilities of attaining the best economic utilization of these lands. Such studies include water relations, use of low quality water, physical, chemical and biological properties of these soils and their different environmental and agricultural systems beside the geologic and hydrogeologic studies.

The research planned to find solutions for sandy soil problems with the objective of increasing their economic utilization, includes studies of means to raise their water holding capacity and fertility, to improve structure by application of physical and chemical amendments and fertilizers.

With the aim of providing for macro and micro nutrient requirements surveys are carried out to find the limit of nutrients in different areas and furthermore, the fertilization techniques most suitable to each soil at appropriate times according to crop and agricultural practices.

It is worth mentioning that the reclamation of sandy soils in Egypt was dependent upon the annual addition of Nile mud besides that which was added from clearing irrigation canals and drains as well as the organic material. But the reduction in quantities of clay and silt after the construction of the High Aswan Dam has led research to be directed toward application of different methods such as asphalt emulsions, chemical amendments, whether by direct mixing or in barriers.

Regarding the management of these soils, consideration has been given to practical applications that limit the probable occurrence of rising water table, spread of salinity and erosion effects. In spite of this reclamation of sandy soils, Egypt is still faced with many problems that await correct solution. It seems that the attention paid to these soils does not agree with 'the normal economic measures used for evaluating other agricultural systems but due to the increasing rate of growth of population and the pressure on horizontal expansion of land resources, the utilization of these soils is a "must". It is our hope that through study and research timely solutions can be provided, for the problems of sandy soils.

5. Iran

SANDY SOILS: DISTRIBUTION, RESEARCH AND DEVELOPMENT

by
M. H. Banai and A. Kowsar

5.1 DISTRIBUTION

Iranian territory covers an area of some 1 650 000 km² and extends between latitude 25° and 40° N., and longitude 44° and 63° E.

Iran is covered to a large extent by the mountains (over 50% of the total land surface is highly broken in topography) which surround the saline, sandy or rocky deserts of the central plateau, thus making the plateau a closed basin. There are four main physiographic systems in Iran, these are:

i. The great Zagros and Alborz mountain ranges, which together form a great V shape;

ii. The area within the V, which begins as a high plateau with its own secondary ranges, and gradually levels towards the interior deserts;

iii. The low lying plain of Khuzestan, which is a continuation of the Mesopotamian plain; and

iv. The Caspian coast, which lies below the sea level and forms a separate climatic zone.

The sandy soils described in this context are soils in which the percentage of particles between 2-0.05 mm exceeds 60% of the total constitution. Thus these soils cover the loamy sand and sands. This is a grouping of soil units geographically associated in the landscape and selected in order to correspond to broad climatic and physiographic units, Map 1.

The areas of each of the soil associations mapped is given below:

5.2 DESCRIPTION OF MAPPING UNITS

5.2.1 Soils of the plains and valleys

Soils of the plains and valleys are formed by soil material which is not residual but is brought by the usual agencies of water and wind.

i. Coarse textured alluvial and colluvial soils and regosols including sand dunes

These are colluvial soils and soils of coalescing alluvial fans which have been and in most cases are still being built up by material carried by flood waters from the mountains to relatively narrow valleys. They are usually developed on coarse to medium textured material with inclusion of finer textured soils in places (Regosols). Because of much gravel, low water holding capacity and infertility, they are not of great use for agricultural development. The distribution of these soils are in foothill areas throughout the arid and semi-arid parts of the country.

ii. Sand dunes (including coastal sands)

Sand dunes are common in most of the arid and semi-arid regions if Iran. They consist of loose sand, occurring within or near the margins of deserts and coasts, and are composed largely of quartz or fragments of many different minerals. Sand dunes may be mobile or fixed. Unstabilized mobile sand dunes may migrate over the land, destroying crops, agricultural areas, villages, etc. Mobile sand dunes are normally devoid of any vegetation. Stable or fixed dunes usually have short growth of grass or scattered shrubs in arid and semi-arid regions. In coastal sands in the humid and sub-humid areas, some shrubs and low lying tree species are also found to occur. In this case a slight profile development may occur. In some cases where sand dunes are fixed or stabilized they may be used for pastures although their carrying capacity is low. Sand dunes cover a large area in the central, southern and south eastern parts of Iran.

The last mapping units are desert soils and sierozem soils in association with sand dunes and regosols in arid regions.

To summarize, most of the sandy soils in Iran occur as sand dunes which are not being cultivated due to limitations on physico-chemical properties such as low water holding capacity and nutrient deficiencies, etc. Though at present these soils are not so important for crop production point of view, since the mobility of these sands is threatening farms, urban areas, industrial centres and communications, the stabilization of these dunes is of very great importance to the country.

5.3 RESEARCH AND DEVELOPMENT

Considering the vastness of the area covered with active and potentially hazardous sand dunes, 182 900 km² in all, the immensity of the responsibility for carrying on the research and development activities becomes obvious.

Sand dune stabilization activities are relatively young in Iran; it was only around 1959 that two small areas, one of 2 ha and another of 3 ha were selected on active sand dunes 30 km north of Ahvaz. Palisades made of stalks of the grass Imperata cylindrica. one meter high were erected in rectangles of 10 x 7 m. Seedlings, seeds and cuttings of different plant species and slips of grasses were planted in these rectangles.

It was in 1965 that a more active interest was taken in the moving sand problem. Under the authorization of the Forest Act a hazardous area of 2 000 km² was declared restricted in the Khorasan Province. No grazing or other means of destroying the vegetative cover was allowed in the area. Windbreaks made of the stems of Ferula galvanifera (a biennial umbellifera) and Aristida pennata (a perennial tall grass) were erected and seedlings of Haloxylon persicum were planted in these windbreaks. Seeds of Haloxylon were first imported from the U.S.S.R., but later they were collected locally. Sowing seeds both by hand and by plane were tried and the former was successful in years of normal precipitation.

In 1966 two 10 ha experimental areas were selected and palisaded in two locations near Ahvaz. The successful species of previous trials, namely: Tamarix pallisii, Calatropis procera, Calligonum polygonoides and grasses like Panicum antidotale, Pennisetum dichotatum were planted in these areas with irrigation. It is estimated that the cost of palisading alone was about 19 000 Rials per ha. The results of these treatments were encouraging and very good covers of vegetation were obtained in both places.

The spraying of petroleum mulch for sand dune stabilization was started on a trial basis in one of the pilot areas 75 km south of Qazvin in 1968. The stabilized area was then planted with suitable species. The remaining area (about 5 km²) was sprayed with the mulch in 1969.

Since the start of the developmental activities the achievements have bean excellent and there has been near-perfect stabilization of large areas of moving sand dunes by the following actions:

i. Protection of the hazardous areas in	24 177.5 km2
ii. Erection of mechanical windbreaks for	14 744 km
iii. Repair of broken windbreaks for	68.5 km
iv. Planting of 94 million seedlings
v. Sowing seeds in	2 203 km2
vi. Collection of 1673 metric tons of seeds of trees, shrubs and grasses used in the planting process.

The proposed work load for the current year should cover 402 km of planting and 793 km² of seeding.

In conjunction with the above named activities over 73 km² of sand dunes near towns, railroad tracks and airports have been sprayed with petroleum mulch and planted with suitable species.

The Research Institute of Forests and Rangelands which was established in 1968 took a very active interest in sand dune fixation and with the help of an FAO expert started doing research in the related areas (Map 2). The main objectives of 28 trials (some terminated) have been:

a. Finding the most effective and the most economic means of stabilizing moving sand dunes.
b. Utilizing the stabilized areas according to their potentials.
c. Conducting basic studies concerning the nature and the extent of the problem.

Studies are conducted by these stations or substations in the nearby areas. Movement of sand dunes, soil moisture conservation, different heights, patterns and the materials used in erecting windbreaks, effect of media on establishment of seedlings, different planting and sowing periods, size of cuttings, spacing, pretreatment of seeds with pesticides, cultural practices, effect of chemical mulches on sand dune fixation, heritability of the resistance to fungal attack of Haloxylon persicum species trial, and ecological studies are some of the subjects on which research is being carried out.

A paper reporting the results of studies on mechanical windbreaks, their effectiveness and cost is in press. About a 50% reduction in cost compared with the old method, has been achieved by a new design. Another report covering the Tamarix plantation and its economic values is being prepared for print. A basic study on the dynamics of moving sand dunes in the Qazvin area is also ready.

REFERENCES

Bhimaya, C. P. 1971 Sand Dune Stabilization. Report to the Government of Iran. TA 2954 FAO Rome. 32 p.

Dewan, M. L. and J. Famouri. 1964 The Soils of Iran. FAO, Rome. 319 p.

IRAN - SAND DUNE FIXATION CENTRES

6. Iraq

by
Khalil Mosluh
State Organization of Soil and Land Reclamation
Abu Ghraib

This report will not deal with morphology and classification of sandy soils since these have already been mentioned in the paper on Classification and Distribution of Sandy Soils in the Near East Region prepared by Dr. Kadry for this Seminar. It will deal with the following points.

1. Types of sandy soils.
2. Their problems and effect on agricultural development in Iraq.
3. Facilities available in Iraq for the development of these soils.

The sandy soils of Iraq can be grouped into four categories according to texture, composition, presence on surface or subsurface and their physical and chemical characteristics; also method of utilization.

i. Sandy soils on river banks and water courses

In this type of sandy soil the percentage of fine fraction such as silt is dominant. The soils are frequently inundated either by floods from the river or high water table levels. Such soils are utilized for vegetable crops, legumes and rice production. Inorganic fertilizers are used to improve their productivity. In most cases these soils are not irrigated since they obtain their water requirements through capillary rise.

ii. Levee soils

These are of widespread occurrence in the alluvial plain in central and southern Iraq. Usually these soils are of light texture or contain a sandy layer which differs in thickness and depth. Some problems have appeared when executing land reclamation projects in this type of soil, especially in the construction of irrigation schemes and tile and open drains. There is a need for a comprehensive study of the effect of these layers on the basic principles of irrigation and drainage design up to the farm level.

iii. Sandy soils in the plains of central and southern Iraq

The area has a width of 5 to 25 km and extends from north-west to southeast, starting from Mussayeb project down to Zubair. In these areas the soils are characterized by an additional problem which is salinity and high water table level.

iv. Sandy soils in the northern and southern deserts of the Ghezira

Here the soils are characterized by the high gypsum content.

The most direct and indirect problems of sandy soils in agricultural development in Iraq could be summarized as follows:

i. Management and development of sandy soils either in the fields of irrigation fertilization or erosion control. This is particularly necessary close to highly populated rural areas, since this type of soil could be the only source for agricultural land.

ii. Difficulties facing the construction of irrigation and drainage systems due to the presence of sandy layers which require special studies for design execution and management of the systems.

iii. The effect on agricultural and grazing lands of sandy dunes and their movement due to wind erosion.

iv. The dual problem of salinization and poor management of sandy soils which has resulted in shifting agriculture as is the case in Zubair region where poor quality groundwater was used for vegetable crops.

v. The difficulties of sandy gypsiferous soils and rainfed lands in the northern and southern deserts where a land settlement project for Bedouins is being carried out and small scale dams are being constructed for irrigation and drinking water.

i. The Institute of Natural Resources which belongs to the Organization of Scientific Research is carrying out some studies on the characteristics of these soils in addition to ecological studies and groundwater quality in these sandy areas.

ii. Recently the State Organization for Soils and Land Reclamation was established with a special Division for studying the problems of desert and rainfed lands. An experimental station has been established to carry out studies on the management of these soils. It is hoped that the Organization will expand its efforts in this field, especially after the support given by the higher authorities of the country.

iii. The General Department of Forestry which carries out studies on sand dune fixation in relation to wind and water erosion.

We would suggest the setting up of a special committee of those specialized in soil science, irrigation and management of sandy soils to look into the major problems of these soils, to set up guidelines and procedures for reclaiming and utilizing them, making use of existing studies and experts at the national and world level.

7. Jordan

Coarse-textured soils have only recently begun to attract attention in Jordan. The geological stratigraphy has been such that coarse-textured soils are of limited extent in the central plateau area where the traditional agriculture is based on either rainfall or irrigation from perennial springs.

In the desert southern and north-eastern parts of Jordan, agriculture has recently become possible due to national efforts to tap he available groundwater or peak spring flows. Recent studies have shown good supplies of water, but many of them are in the vicinity of coarse-textured, alluvial and colluvial soils, as in Wadi Rum, Wadi Araba and Azraq basin.

In Wadi Rum, the ongoing pilot studies indicate the feasibility of agriculture but the suitable soils are extremely limited in extent. Here the landscape is characterized by mud-flats with no visible surface drainage and is surrounded by an undulating area dominated by shifting sand dunes and towering sandstone hills. The intervening area is transitional in texture but is frequently very stratified; though sandy textures appear to dominate the surface layers, sandy layers are also encountered between the clayey layers. Only a small proportion of the area located in the transitional zone has a medium texture and can be used with the conventional technology. The mud-flats are highly saline and alkaline, having a very low permeability, and have no feasible drainage outlet due to unfavourable topography. Only the fringes surrounding the mud-flats appear to be usable and this too requires the addition of 10 to 15 cm of sand and deep ripping to improve water penetration. The outlying sandy soils which are of considerable extent have a great potential if techniques for stabilizing the shifting dunes, and for irrigating and managing sandy soils can be developed.

The Azraq basin in the north-eastern desert also has extensive areas of sandy soils, and here too good quality groundwater that can be used for agriculture is known to be available.

In Wadi Araba, which extends from the Dead Sea southwards to the Gulf of Aqaba, coarse-texture soils are widespread on the undulating valley floor. Water for agriculture is available from the Wadi Mujib as well as from wells.

Up to the present, coarse-textured soils have been classified as non-arable as far as irrigated agriculture is concerned. They can have a great potential if the use of techniques for frequent applications of small amounts of irrigation water, the use of artificial or natural surface mulch to conserve moisture, and a choice of climatically adapted economic crops, which will also protect the soil and improve its structure and water-holding capacity, are found feasible.

It is hoped that the deliberations of this Seminar will provide guidelines for the economic utilization of the scarce, good quality, groundwater found in the vicinity of the coarse-textured soils.

8. Lebanon

RECLAMATION AND MANAGEMENT OF SANDY SOILS

by
Ahmed Osman
Agriculture Research Institute
Tel-Amara, Lebanon

8.1 INTRODUCTION

Sandy soils in Lebanon cover an area of about 70 000 ha of which 80% is sand. and 20% loamy sand and sandy loam. This area is about 1/5 of the total cultivated land. The sandy soils are not affected by salts compared to most of the Middle East. The 80% fall under sub-humid conditions and their origin is mostly sandstone, thus they are not calcareous; whilst the 20% originated from sand dunes and are calcareous.

8.2 ORIGIN AND DISTRIBUTION

Sandy soils in Lebanon are formed on Nubian sands of the lower Cretaceous and are found between sea level and about 1 000 m height in the direction of west-east. From the north they start after the basaltic flow in Akkar and extend up to Jezzin (Saida) in the South.

The sand dunes are found interruptedly along the coastal line and extend inward about 3 km in the Akkar region. They originated from the Miocene and Pleocene deposition.

8.3 MORPHOLOGY

In general the sandy soils are classified as entisols and xerorthents in the 7th Approximation and as Sols Mineraux Bruts in the French system with A-C horizons.

Between 800 and 1 000 they tend to develop to para podzolic under pine and natural vegetation with a thin organic layer (0) and albic horizon. The severe erosion prevents them forming true podzols. They are very steep from 20% to 60%. The pH is about 6.

Below 800 m the climatic conditions will not allow the para podzolic formation; they are classified as xerorthents. Most of the sandy soils in the coastal region are deep with A-C or A (B) C horizons and are classified as calcixerollic xerorthents or xerochrepts respectively, whilst the others are shallow, formed on consolidated sand dunes (Ramleh). The composition of the consolidated parent material is quartz, shale fragment, and other materials which are cemented by calcium carbonate. The organic matter content is low. The pH is about 7.5 to 8.0. The calcium carbonate content is about 10 to 20%.

8.4 LIMITING FACTORS

8.4.1 Erosion

The erosion in the mountainous region is caused, by the high rainfall, 800 to 1 200 mm, which comes with great intensity, whilst in the coastal region the erosion is due to wind.

The measures which are being taken to prevent erosion are to build terraces in the mountain region and to plant wind-break trees in the coastal region.

The sand dunes are being fixed by planting shrubs and pine trees.

8.4.2 Fertility

The fertility of these soils is poor, thus high rates of inorganic fertilizers, crop residues and manure are applied. In addition, some of the micronutrients are applied. The fertilizers are split into 4 to 6 applications during the growing season. These soils are being utilized for orchards and cash crops.

8.4.3 Water Consumption

Due to the low water holding capacity of these soils (6-10%) and to the high evapotranspiration, irrigation water is frequently applied.

There is an intrusion of sea-water into the coastal underground water due to its high intensity of use for irrigation. This low quality water is used safely on the sandy soils.

8.5 INVESTIGATIONS

Recently there have been investigations at some sub-stations to study the evolution of structure through the application of high rates of organic matter.

The Irrigation Department is studying water consumptive use. Concrete lysimeters, 10 by 10 meters, are being utilized in this study. The crop used is banana.

Research on soil conditioners will start this coming year in cooperation with the Soils and Irrigation Department of the American University of Beirut.

9. Arab Republic of Libya

RECLAMATION AND DEVELOPMENT OF SANDY SOILS IN AL GEFARA PLAIN

by
General Department of Forestry, Range Management and Natural Resources
Ministry of Agriculture and Agrarian Reform

1. INTRODUCTION

There is great concern for agricultural development and land reclamation in Libya at present with the objective of increasing agricultural production. There have been numerous studies in scattered areas of the country for soil and water resources, mainly based on soil survey and classification and water inventory for ground or surface water. On the basis of these studies several areas have been given priority for reclamation and development. The Gefara Plain is one of these selected areas.

2. LOCATION AND TOPOGRAPHY

The total area of the Gefara Plain is 17 000 km² starting from the Tunisian borders in the west and extending east to Al Khums, to the Mediterranean in the north and southward to Gebal Nafusah where the elevation reaches 400 to 700 m above sea level. The length from east to west is 170 km, the breadth in the north-south direction is about 100 to 110 km. It is divided into two areas: the first is known as the coastal strip, which runs parallel to the sea shore varying from 1 to 15 km wide. This strip is one of the most important agricultural areas at present as there are many forms of agricultural activity. The second or inner part is the plain which extends from the coastal strip to the southern mountains; within this plain there are valleys varying in elevation and width. Most of these wadis are found in the eastern and central part of the plain.

3. CLIMATE

The dominant climate is Mediterranean but to the south it is semi desert. The annual rainfall at Tripoli varies from 300 to 380 mm and decreases towards the south until it reaches 50 mm and where it could be rainless for several years. The average temperature on the coast is 19.5°C and increases to the south until it reaches on the average 30.5°G.

4. GEOLOGIC FORMATIONS

Geological and morphological studies of the Gefara Plain indicate that the land utilized at present or that is under reclamation and development developed from transported sands or material deposited in the middle and late Quaternary. In the sub layers of the soil profile there is an accumulation of lime in varying formations of old pedological origin.

5. DOMINANT SOILS IN AL GEFARA PLAIN

Weathering by wind, heat and water followed by chemical weathering are the dominant soil forming factors responsible for the formation of the soils in the Plain which are generally sandy and vary in texture from pure sand to loamy sand, dominant on the northern coastal strip. In the wadis soils are sandy clay.

Sand dunes in many areas form a belt extending along the coast where the sand grains vary from coarse to medium size and are rarely fine. The soil is often immature and the profile is very deep; pH of all the soils is greater than 7 and reaches 8,5 in some cases. The soil survey studies indicated that the dominant soils are:

i. Brown podzolic regosols

They are sandy, pervious, have a deep profile, are free of salts with no gravel or stones and the soil needs protection against erosion. These soils are found along the coastal strip and in some parts of the inner valley as is the case in Al Aziziyah. The following table gives an analysis representative of the profile of these soils.

Location: Sidi Al Misri
Profile: No. 34
Depth:	0-30 cm	30-80 cm
Mechanical analysis
Sand	88	82
Silt %	9.6	15.6
Clay %	2.4	2.4
Texture	Sand	Loamy sand
Chemical analysis
pH	7.9	8.1
EC mmhos/cm	.50	.81
CaCO3 %	2.1	1.0
OM	.32	.14
Carbon %	.18	.08
Total Nitrogen %	0.02	0.01
Soluble phosphorus ppm	55	24
HCO3 meq/l	1.1	2.4
Cl	2.0	3.1
SO4	2.0	2.7
Ca + Mg	3.2	5.6
Na	1.8	3.0
K	.6	.53

ii. Alluvial soils of the interior plain

These soils are formed by deposition of sediments carried by water from the northern mountains forming fans and then plains in the wadis. They are the most fertile and the profile is free from salts but is less pervious than the previous type. Silt is the dominant size fraction with a higher clay content relative to the previous type. The following is the analysis of a representative profile:

Location: Wadi Al Meganeen
Profile: No. 4
Depth:	0-25 cm	25-62 cm	100-130 cm
Mechanical analysis
Sand percentage	63.6	63.6	69.6
Silt %	34.2	32.2	25.2
Clay %	2.2	4.2	5.2
Texture	Sandy loam	Sandy loam	Sandy loam
Chemical analysis
pH	7.6	7.9	8.0
EC mmhos/cm	.71	.63	1.07
CaCO3 %	6.0	9.0	6.3
OM	.08	.02	.01
Carbon %	.45	.12	.06
Total Nitrogen %	.04	.01	.06
Soluble phosphorus ppm	114	134	195
HCO3 meq/l	3.8	3.2	2.0
Cl	2.8	2.5	6.4
SO4	3.8	3.2	2.0
Ca + Mg	3.3	3.8	4.2
Na	3.0	2.6	6.5
K	.1	0.0	0.0.

iii. Solonchak soils

This type of soil is found in certain areas along the coastal strip, closer to the sea shore, especially in the west near Zuwarah where there are large areas forming bare lagoons separated by sand dunes. These soils have not yet been thoroughly studied.

6. THE MOST IMPORTANT PROJECTS IN AL GEFARA PLAIN

The projects vary in location and objectives; some are dependent on ground-water resources, others on surface water flow from the wadis and others again depend on rainfall (rainfed agriculture). The most important of these projects are:

i. The Green Plateau Project

The total area of this project is 2 000 ha divided into small farms of 6 ha each. This project is located 5 km south of Tripoli and depends mainly on the use of sewage water after purification for irrigation by sprinkler. The project is to produce vegetables, fruits and certain field crops because of its proximity to markets and the possibility of food canning; there is also cattle breeding and bee keeping. It is under the supervision of the General Organization for Land Reform and Rehabilitation and the land has been distributed to farmers.

ii. Bir Al Ghanam

This project is divided into two parts:

a. Al Aziziyah-Al Amryah Project

The objective of the project is to reclaim and cultivate 1 100 ha to be divided into 100 farms, 75 of which have already been established. The project uses groundwater in the area.

b. Bir Terfas (South Az Zawiyah)

This project has just started and aims to establish 400 farms on an area of 6 000 ha as the first phase; work has started by digging wells in the area.

The first phase of the project is to reclaim 30 000 ha in the Al Heera-Al Deeka area south of Tripoli and will depend mainly on rainfall. Work is in progress on the establishment of 1 520 farms. A second part (Wadi Al Meganeen) depends on the water stored in the reservoir and is for 11 000 ha.

iv. Wadi Al Maiet and Al Athl Project

The objective of the project is to reclaim 25 000 ha in Wadi Al Maiet and 10 000 ha in Wadi Al Athl. It is also a rainfed project apart from the establishment of 625 farms for permanent irrigated agriculture which will depend on groundwater.

v. Al Karaboli Project

This is in the eastern part of the plain and consists of establishing 850 farms on an area of 20 000 ha. Some of the farms will be for rainfed agriculture and the others will be irrigated.

vi. Crop Development Project

This project is to improve the winter crops, mainly wheat and barley, on an area of 100 000 ha, including the wadis, over a period of 3 years which started in 1973. The project depends on rainfall.

vii. Forest Development and Rangeland Project

There is a project each for forestry and rangeland to utilize lands bordering the southern part of the plain in scattered areas of 5 000 ha each. The forestry project is to increase the vegetative covering where other traditional crops cannot grow and will therefore serve as an erosion control measure.

7. PROBLEMS OF LAND RECLAMATION IN AL GEFARA PLAIN

There are problems involved in land reclamation and development, especially in areas where soil is sandy, low in organic matter and nutrients and where water is scarce, of low quality and continuously degrading as is the case in Al Gefara Plain. The most important problems are:

i. Irrigation Water

The quantity and quality of irrigation water is the most critical factor for horizontal and vertical expansion. Rainfall is on the low side, besides being of seasonal distribution and evapotranspiration is very high. Also a great deal of the irrigation water is lost to the sea by run off and only the remainder can be utilized by the crop, with the continuous demand for this water, especially in summer, the level to groundwater has increased and the quality deteriorated. For water conservation measures dams have been built on the wadis to limit water loss to the sea and to recharge groundwater. Additional measures have been introduced to limit the growing of summer crops, e.g., groundnuts and others with a high water consumption during this season.

ii. Erosion Control

Large areas of the Al Gefara Plain suffer from erosion, especially by wind and sand dune encroachment on the agricultural land where southern winds in spring and summer cause much damage to agriculture. Efforts have been made to stop sand dune encroachment from south to north and of these measures the following have been used:

a. wind breaks and afforestation;
b. use of certain plants as surface cover;
c. use of dried plant material as sand dune stabilizers; and
d. recently, petrochemicals have been used as stabilizers followed by afforestation.

Up to the present it has been possible to control sand dune encroachment on large areas where forests have been developed.

iii. Soil Fertility

This is one of the serious problems since the sandy soils are low in nutrients as well as organic matter. Measures are being taken to use nitrogenous and phosphate fertilizers and, in some cases, potash, but until now micronutrients have not been used.

10. Morocco

10.1 GEOGRAPHIC AND CLIMATIC CHARACTERISTICS

10.1.1 Relief

Morocco covers 450 000 km² between the latitudes 27° and 36°N. It is traversed by two mountainous formations which give it very diverse geographic and climatic characteristics.

In the north the chain of the Riff borders the Mediterranean from east to west. In the centre crossing the whole country from south-west to northeast the Anti Atlas, the Middle Atlas and the High Atlas form a strong barrier against the Saharan influences. The High Atlas rise to a height of more than 4 000 m. Morocco consists of several plains crossed by rivers; the main ones are:

- the plains of Gharb, Tadla, Haouz, Souss, Tafilalet, Ouarzazate, Moulouya, Loukkos, etc. They are the subject of big hydro-agricultural development schemes.

January is the coldest month of the year. The mean minimums are all lower than 10°C and go down to 0°C in the mountains. The maximums occur most often in July and occasionally in August. They are over 30°C except on the Atlantic coast.

Rainfall varies according to the region from 400 to 800 mm annually.

10.2 MAIM TYPES OF SOIL

The main types of soil are:

- isohumic, found in the Mediterranean region. These soils are characteristic of the plains, foothills and plateaux of Atlantic Morocco (with the exception of the coastal strip).

- red and brown Mediterranean soils (mountainous zones).

- vertisols called "tirs" cover vast areas in Atlantic Morocco, mainly Gharb, Chaouia and Loukkos.

- hydromorphic soils in the periphery of the Gharb and the central plateau.

- halomorphic soils found in the arid and Saharan regions.

The deficiency of water inherent because of the long dry season, the irregular rainfall in the humid zone and the size of the arid and semi-arid zones with an almost permanent lack has led Morocco to search for means to improve and intensify agricultural production by using the maximum water resources possible.

The numerous areas with small or middle size water works represents on the national scale an important potential (40%) but their size and dispersion do not allow development of an industrial character.

Anxious to create as soon as possible a highly productive sector, Morocco has decided on large scale hydraulic works.

Since 1960, a huge effort has been made in the construction of dams and the equipment of large areas for irrigation for an integrated development. The potential national total available is estimated at 7.5 thousand million m³ which ought to permit irrigation of a million hectares. This perspective forms the principal objective of Moroccan agricultural policy.

In 1973, it was estimated that an area of 600 000 ha was irrigated every year, 400 000 ha permanently irrigated and 200 000 ha depending on contingencies.

In the 1973-77 Plan we expect to extend this area at the rate of 25 000 ha annually.

The equipment undertaken constitutes only an indispensable phase. But the real objective is the effective improvement of production and of the level of life of the farmers.

The scheme has been undertaken systematically in order to ensure an integrated management of the rural zones.

The areas which will be developed are:
- industrial crops (cotton, sugarbeet, sugarcane)	1/4
- fodder crops	1/4
- cereals	1/4
- tree crops	1/8
- market garden	1/8

In view of the shortage of water due to the aridity of the climate, the volume of water used annually is extremely high. The practice of gravity irrigation imposed by the land capability and local necessity does not allow, in spite of the efforts by the Moroccan experimental service, the limiting of losses by infiltration to a satisfactory level.

The rising of the watertable is therefore inevitable and requires effectual intervention as soon as the watertable effects the upper horizon's and inevitably causes their salinization.

Thus one must put in hand at the same time the equipment for hydro-agriculture and the drainage of these areas.

It should be noted that sprinkler irrigation has just been introduced recently over a large area (30 000 ha in the perimeter of Massa).

Drip irrigation is in the experimental stage and great hopes are being placed in this technique.

11. Pakistan

SANDY SOILS IN WEST PAKISTAN

by
M. Alim Mian
Soil Chemist
Soil Survey Project of Pakistan
Lahore

11.1 INTRODUCTION

West Pakistan has a total area of 312 000 mi² (about 800 000 km²) and supports a population of about 60 million. It lies between latitudes 23° and 37° north and longitudes 61° and 76° east. There are three broad physiographic divisions: (i) the mountainous area, (ii) the Indus plains and (iii) the Thar desert. The mountainous area covers more than two-thirds of the total area on the western side. The Indus plains occupy an area of about 80 000 mi² (205 000 km²), whereas the Thar deser covers about 25 000 mi² (64 000 km²).

11.2. CLIMATE

West Pakistan has an arid to semi-arid subtropical continental climate. According to the precipitation data, 67% of the area receives rainfall/snow below 10 inches (250 mm), 24% between 10 and 20 in (250 and 500 nun), 5.3% between 20 and 30 in (500 and 750 mm) and only 3.7% area gets rainfall above 30 in (750 mm). The highest precipitation occurs in the north-east and decreases rapidly in the south-west direction. The rainfall/snow is greatly variable in time as well as space. In the area east of the Indus above two-thirds of the annual rainfall is received during summer, mainly in July, August and September, the remaining one-third occurring during winter months. May and June are the hottest months when the maximum temperature may rise to 113°F (45°C.)In the area west of the Indus river about two-thirds of the precipitation occurs in winter and the remainder in summer. The hilly areas in the west and north have mild summers and severe winters.

11.3 SANDY REGIONS

There are three sandy regions in West Pakistan. The location of these regions is shown on the accompanying map. The potential, use and management problems of each region are described below.

11.3.1 Thal Sandy Area

The Thal is the most important sandy region in the country. It occupies an area of some 9 000 mi² (23 000 km²) between the Indus and Chenab rivers. It presents a complex pattern of alluvial deposition of sandy materials in Late Pleistocene, mainly by the Indus river and locally by the Chenab; progressively followed by wind resorting of the sediments into various forms of sand ridges; resorting and further deposition of sandy materials by water within spill channels passing through the sandy ridges; locally, modification of the sand ridges by river action; deposition of silty and clayey sediments by river spill channels; and present-day wind resorting of the sandy materials and locally, dune formation.

Most of the area is under longitudinal sand ridges; their size and orientation is variable depending upon wind regimes of the localities where they occur. The inter-ridge valleys have loamy soils under a semi-arid climate, but sandy loam soils in the arid area (classification: yermosols, FAO/Unesco; typic camborthids, USDA). The sand ridges are several feet higher than the valleys between them and have developed sandy soils. The subsoil is firm when dry and is slightly brighter than the surface soil or the sub-stratum. The proportion of fines in the sandy soils is higher under the semi-arid climate as compared to the ones under the arid condition, (classification: calcaric regosols, FAO/Unesco; ustipsamments and toripsamments in semi-arid and arid regions respectively, USDA).

The sandy soils of Thal are used at present for raising crops as well as for grazing. In the northern part of this region where annual rainfall is more than 10 in (250 to 300 mm), most of the area is sown to dry-farmed gram (Cicer arietinum) and mustard (Brassica juncea). The sandy soils in the arid part are exclusively used for grazing. In considerable areas over-grazing has transformed the surface of the sand ridges into shifting sands.

Around 1947, canal irrigation was introduced in the northern and western parts of this region. Subsequently, the irrigation was extended to areas further south. This development has affected the use and management of sandy soils in a number of ways.

i. In spite of the fact that the main canal was lined with bricks to check exclusive seepage losses, a rapid rise in watertable was noticed. This can be attributed to large-scale seepage losses from the unlined distributaries, water courses and also over-irrigation of highly permeable sandy soils having sandy substrata. There are some places where the sand ridges can be seen surrounded by marshes. In areas close to the main canals and where the sand ridges are not well marked, the sandy soils were subjected to high watertable and salinization.

ii. Irrigated valley bottoms were extended into the sandy ridges by disturbing the sandy soils and their sandy substrata, and then spreading the material on the loamy soils. In many places this caused deep burial of the productive soils with unproductive sand.

iii. The pressure of population has been responsible for bringing large areas of sandy soils under irrigation in this region. The flood irrigation has severely impoverished the soils of their nutrients by excessive teaching. Before irrigation the sandy soils were sown to gram which has a deep root system and builds up the nitrogen content of the soil. Cultivation of other crops under irrigation has incapacitated those soils from producing gram. This may also be due to the use of nitrogenous fertilizers only, causing acute deficiencies of phosphorous in the soil. Under these conditions the yields of other crops, especially wheat, sugarcane and guara (Cyamopsis psoralioides) are showing a steep decline and the plants indicate nutrient deficiency symptoms of all sorts. The irrigated sandy soils in Thal are going to pose a serious fertility problem in the coming years.

iv. The uncultivated sandy soils had a fair cover of vegetation under natural conditions and were used for grazing. In areas where valley soils are irrigated, the natural vegetation is rarely found in an undisturbed state, much of the original vegetation having been subjected to cutting, lopping and over-grazing. This has given rise to formation of active dunes which may pose a serious threat to the adjoining irrigated interdunal valleys.

The Thar is the most extensive sandy region in the country. It comprises the deserts of Cholistan and Thar, a band of about 50 mi wide and extending over a distance of some 500 mi in the south-east, along the Indian border. It covers about 25 000 mi² (64 000 km²). The Thar is actually the western part of the Rajputana sandy desert of India. The origin of the sand is not certain. The oldest part is probably older than the Last Glacial period, in view of the elevation of the sand ridges far above the probable levels of the Indus and Sutlej in the Late Pleistocene. The landscape consists of mainly stabilized hilly sand plain, with longitudinal ridges in the south but alveolar (honey combed) and transverse ridges in the north. The sands are calcareous, rich in weatherable minerals and typically pale brown. They contain less mica, but more quartz than the sands of the Indus river and its tributaries.

The Thar has two distinct climatic zones, i.e. the southern semi-arid zone and the northern arid part. The semi-arid part has well developed soils. The interdunal valleys have loamy soils with a fair amount of organic matter. The subsoils are brighter in colour than the surface soil or the substratum. Towards the southern side the rainfall increases and the temperatures are mild due to the influence of the Arabian sea. These soils are under cultivation for growing sorghum (Andropogon sorghum).

The sandy soils in the semi-arid part occur on the sandy ridges. The soils are sands and loamy sands with bright subsoils. The sandy ridges are 100-200 ft (30-70 m) higher than the interdunal valleys. Very little cultivation is practised on the sandy soils. Natural vegetation provides some grazing for cattle and sheep. Over-grazing and lopping of natural vegetation is the major problem. The crests of the sandy ridges have been transformed into shifting sand dunes.

The arid part of the Thar is far more extensive than the semi-arid part. In this area the interdunal valleys have sandy loam and sandy soils. Due to scanty and uncertain rainfall no cultivation is practised. The sandy ridges have sandy soils and about 10% of their surface is shifting sand. This entire area provides some grazing for cattle and sheep.

The main problem of this great region is the scarcity of water. Only after the rains cattle and sheep herds find their way into the interior of the area and stay there as long as drinking water is available in ponds. These ponds are located on such sites where substratum is tight enough to hold water and can collect considerable run-off from large areas. Areas close to the water points are severely grazed whereas the remote areas are probably under-utilized. After the ponds dry out, the herds move away from the interior towards the margins, partly depending upon the adjoining irrigated floodplains for their supplies of water and fodder. Groundwater in most of the area is highly saline and unfit even for drinking. There are a few narrow belts of land where groundwater is sweet. The exact location and extent of such areas needs investigation. The information would be very useful in the development of this large region.

11.3.3 Western Sandy Desert

The western sandy desert comprises four units separated by hill ranges. These sandy areas together occupy an area approximately equivalent to that of the Thal. The sands of this desert are also of alluvial origin, deposited as sandy piedmont slopes, mostly of Holocene age. The climate is extremely arid and soil development is virtually nil. The vegetation covers less than about two percent of the total area. Almost the entire area is in the form of shifting sand dunes and the reworking by wind is continuing. Groundwater as well as surface water is very scarce and often brackish. So this area has little potential for development.

11.4 CONCLUSION

The extensive sandy soils in West Pakistan have a potential mainly for grazing. The soils occurring in the semi-arid zone of Thal as well as Thar are partly used for grazing and partly for dry-fanning of crops such as gram, mustard, guara (Cyamopsis psoralioides) and sorghum. The soils within the arid zone are exclusively used for grazing. The present use seems to be most suitable under the local conditions.

In Thal where sandy soils occur in close association with irrigated loamy soils, the cropping patterns of the irrigated area should be changed in favour of the crops that have a low water requirement and could also provide feed, fodder and hay for the cattle and sheep during the period when the un-irrigated sandy soils are not able to provide grazing but need rest. The grazing potential of the sandy soils should be developed as a part of the development potential of the irrigated loamy soils, for the production of cattle and sheep.

Canal irrigation cannot be extended to additional areas of Thal due to the unfavourable relief and sandy nature of the soils. In such areas, pockets of usable groundwater exist and efforts have been made to irrigate isolated patches of loamy soils here and there. Due to the extreme aridity, and desiccating winds, the cost of production of sugarcane and wheat is very high in terms of irrigation water. The agriculture in such areas should be entirely complementary to the cattle and sheep production, and only such crops should be grown which would provide feed, fodder and hay for the animals. Similarly, in Thar desert grazing potential could be realized by extending canal irrigation to loamy soils in the desert margins for the production of feed, fodder and hay. This could supplement the forage on the sandy soils.

Irrigation of sandy soils in West Pakistan has remote possibilities, because there is a great disparity between land and water resources in the country, there is far more land than water. Water is insufficient to meet the requirement of even good quality land. The country has to think in terms of maximum returns per unit of water rather than per unit area. Sandy soils have a much lower potential than many other soils presently lying barren for want of irrigation. Their economic utilization is related to their favourable capacity for conserving scanty rainfall in a more efficient manner for the growth of natural vegetation for grazing or dry-farmed crops.

PAKISTAN - SANDY SOILS AND RAINFALL

12. Sudan

by
Abdalla Babiker
and
M. Bakheit Said
Ministry of Agriculture
Food and Natural Resources, Sudan

12.1 INTRODUCTION

Sandy soils in the Sudan are widely extended and cover most of the Northern, Kordofan and Darfur provinces. They are rain-cultivated and there is the problem of the short rainy season which lasts for three to four months only, leaving the rest of the year as a dry hot period. Due to the availability of vast areas which are suitable for agricultural expansion, relatively little attention has been given to the proper development of these sandy soils.

12.2 TYPES AND ORIGIN

Most of the sandy soils are of aeolean origin and are believed to be derived from the northern desert which occupies a large part of Libya and extends southwards into the Sudan. Geomorphologically, these soils are found in the form of slightly undulating sand sheets, transverse dunes or longitudinal sand ridges. They are very deep and have usually uniform texture throughout the profile with the clay content ranging from about 5 to 10%. The ratio of the coarse to fine sand, which are the main components of the mechanical analysis of these soils, seems to narrow from north-west to south-east. Their pH is about neutral. As would be expected from their low clay and organic matter contents, the sandy soils are inherently poor in nutrients especially phosphorus and nitrogen.

The other type of sandy soils has been formed in situ from the Nubian sand-stones or from the Basement Complex rocks. This type is different from the former in that it shows more differentiation in the profile, has high clay content which increases with depth and it is distinctly acidic.

12.3 LAND USE

The rainfall varies considerably over the extensive area of the sandy soils, and it ranges from traces in the north to about 800 mm in the south. For convenience, the area covered by the sandy soils can be divided into the following three zones:-

i. The Northern Zone with rainfall less than 250 nun; this zone is usually used by nomadic pastoralists and the animals kept here are mainly camels, sheep goats and, to a lesser extent, cattle.

ii. The Central Zone with rainfall ranging between 250 and 450 mm; this is a cropping zone and the main crops grown here are sesame (Sesamum orientale), dukhn (Pennisetum typhoideum) and groundnuts. Shifting cultivation with four years continuous cropping followed by twelve years bush fallow is practised. The main component of the bush fallow is the Gum Arabic Hashab Tree (Acacia senegal) which is a leguminous tree and is claimed to fix atmospheric nitrogen. However, with the increase of the population, farmers are now compelled to deviate from this practice and tend to cultivate the same piece of land more frequently. This over-cultivation coupled with the decrease in rainfall in recent years has no doubt resulted in increased wind erosion and encroachment of the desert on arable land.

iii. The Southern Zone with rainfall ranging between 450 and 800 mm; this zone is occupied mainly by the Baggara, the famous cattle nomads. About 70% of the Sudan cattle are raised here. However, with the recent anti-thirst campaign, water points (mainly boreholes) were constructed in this zone, thus making drinking water available for opening more land for cultivation and grazing. Similar wells were also constructed in the other two sandy zones. As a result of this, many Baggara nomads are now settling and giving more attention to crop production.

13. Syrian Arab Republic

The total area of the Syrian Arab Republic is 18.5 million ha with widely varying soils; it includes Mediterranean red, dark yellow, reddish brown, yellow desert, gypsiferous and levee soils. Sandy soils are scattered in the different soils mentioned above in small areas that have not yet been surveyed.

Syrian soils vary in their characteristics according to origin and mode of formation of each. Work is now being concentrated on soil surveying in areas which benefit or will benefit from the major irrigation projects. The current work is devoted to some detailed surveying to identify soil groups and basic characteristics of each. Up till now a total area of 280 000 ha has been surveyed in the Euphrates Valley, Ghab and El Sen. Work is in progress on the classification of the present irrigated areas and on those which are planned to be irrigated from the Euphrates dam.

The total area that could be cultivated exceeds 7 million ha of which 600 000 ha is irrigated. The rest is under rainfed agriculture using a crop rotation with fallow. Of course the area under irrigation will be doubled after completion of the Euphrates dam.

The Syrian Government pays considerable attention to water resources since a sound knowledge of the water balance is essential for the planning of agricultural development when the water resources are rather limited in comparison to the water requirements of the crops. About 60% of Syria has a rainfall of less than 250 mm where the evaporation reaches 2 500 mm per year. Therefore it is necessary to adopt wise measures and techniques for management and utilization of irrigation water.

Experimental farms have been established to find out the best irrigation methods, crop rotations and determination of crop water requirements.

In the past, because of the misuse of irrigation water coupled with the introduction of cotton, the salinity problem became apparent especially in the Euphrates and Khabour valleys and some parts of El Ghab. The problem is being aggravated year after year. This has led to the need for planning land reclamation on a large scale in the country. Such work is in hand at present and we have reached conclusions of value in the successful and economic utilization of these lands. A final plan is now being drawn up for an integrated irrigation and drainage system for all the Euphrates valley, having an area of 640 000 ha.

Horizontal expansion in the agricultural development of Syria, based on an increasing total area of irrigation, goes hand in hand with vertical expansion by applying modern techniques to crop management and using fertilizers according to scientific patterns; concerning the latter, a new policy has been established for fertilizing cotton, sugarbeet and wheat and there are also plans for improving soil properties.

14. Tunisia

DEVELOPMENT AND MANAGEMENT OF SANDY SOILS

Sandy soils in Tunisia cover a large area, particularly in the centre and the south. In the north, they are in the form of dunes limited to the litoral.

14.1 CLASSIFICATION OF SANDY SOILS

In Tunisia, the sandy soils are part of the following classes:

- undeveloped soils; regosol type of aeolian origin

- weakly developed soils: in this class the sandy soils are of aeolian origin, or alluvial and included in these sub groups:

- saline
- calcareous
- gypsiferous
- hydromorphic

- isohumic soils: in this class the sandy soils appear in the groups:

- modal
- sierozems

- halomorphic soils: in particular in the saline group.

This is one of the preoccupations of the Tunisian Government at present which is making considerable efforts with a view to improving the productivity of these soils and meeting the needs of a constantly increasing population.

This development includes the following actions.

14.2.1 Dry farming

- Improvement of the olive grove productivity by fertilizing the soil with mineral fertilizers.

- Extension and creation of different types of tree plantations.

- Limiting the growing of cereals in regions with poor annual rainfall and those exposed to erosion, particularly by wind.

Operations carried out in the irrigated areas are:

- Orchards, mainly citrus, in the north-east and date palms in the south.
- Market gardening and fodder crops.

- Determination of water resources at deep levels in southern Tunisia under the regional project REG 100 UNDP/Unesco.

- Elaboration of a master plan for the exploitation of water in the centre and south of the country.

- Further improvement of the hydraulic works in the irrigated areas.

- Realization of new irrigated areas.

- Study of irrigation with saline water (1.5 g/l to 6.5 g/l) and determination of water requirements for different crops. This study was undertaken with the help of UNDP and Unesco and was the subject of a report published in 1970.

- The creation of an agricultural research organization in the south of the country to study the problems brought to light by the development of sandy regions.

These actions concern:

- The stabilization and fixation of the litoral dunes.
- Protection of the oases and the campaign against invasion by sand in the south of Tunisia.

These are situated in the north of the country and their development began in 1904. The technique used comprises the following operations:

a. establishing a coastal protective cordon with the help of brushwood and branches.
b. establishing complete squares of earth with the help of "saccharum".
c. fixing them with the help of a cover of branches.
d. reafforestation with appropriate species: acacia, eucalyptus, pines.

The problem of defense of the oases and the fight against sand invasion was traditionally carried out with date palms which assured also protection of the nearby crops. But the oases are more and more menaced in their entirety by the sand. Their protection is therefore a paramount necessity.

The technique of fixation used is relatively different to the first in that the immediate aim sought is the protection of the oasis, buildings and substructures by placing them in the shelter of artificial dunes or tabia (earth levees) of 0.80 m high supporting a fence of palm fronds or slabs of fibro-cement raised at regular intervals. The distance arranged between these dunes placed perpendicular to the wind direction and the zone to be protected is about 200 m. This band is reforested with certain local species (tamarix, calligonum, acacia and atriplexis).

The forestry activities have led to the following results:

- from the soil improvement point of view; the forestry plantations have contributed to the enrichment of the soil with organic matter and have improved its structure. These improved dune soils could be suitable in certain oases for more profitable tree growing operations.

- from the sylviculture production point of view; the reforestation carried out on the coastal dunes has an actual annual production of between 3 and 5 m³/ha of resinous trees and 6 to 8 m³/ha for the foliaged ones. This production has by far surpassed that of natural forests in the same climate (600 mm/a).

- from the protection point of view; the results achieved are very encouraging. They can be seen as a noticeable improvement in the production from the oases and irrigated areas. This is why a particular effort was made regarding the same problem in the centre and south of Tunisia in the framework of the four-year plan 1973-76, because the fight against the invasion by sand fills a vital need in putting a brake on the process of desertification which is set in motion as a consequence of thoughtless exploitation of the natural vegetation, the intensity of grazing and cultivation.

15. People's Democratic Republic of Yemen

by
Anwar Girgirah
Abdulla Al-Dukail
Martin Smith

15.1 INTRODUCTION

The People's Democratic Republic of Yemen (P.D.R.Y.) is situated on the southwestern side of the Arabian Peninsula and stretches over 750 miles along the Indian Ocean covering a total area of about 112 000 mi² with a population of about one and a half million. The country lies within the arid region and the climate is tropical, characterized by hot and humid conditions in the coastal region with a very low rainfall of about 25-65 mm per annum, whereas the mountainous and semi-mountainous areas encounter a somewhat cooler and less humid climate with annual rainfall that might reach 350 mm.

Only about one percent (600 000 ac) of the total area of the Republic can be considered as cultivable land and is situated in the numerous wadis intersecting the country from north to south. Due to the total lack of rainfall, especially in the coastal region, agriculture is completely dependent on irrigation. Most of the research up to now was concentrated in the Wadi Tuban and Wadi Abyan deltas, both classified within the coastal region; therefore this paper will be restricted to these two areas.

Traditionally the main source of irrigation water is that of the spate floods (which flow from April to September in most of the wadis of the second and third governorates). These floods occur in two seasons; the main one being from July to October when the south-west monsoon brings heavy thunderstorms in the northern mountainous catchment areas, three-quarters of which lies in the sister country of the Arab Yemen Republic. A second season of minor importance caused by northeastern winds occurs in April to May. This system of spate irrigation usually affords one single irrigation just enough to raise one crop of cotton or sorghum per year. Due to these conditions the actual cultivated area is dependent upon the amount and frequency of the spate floods. Consequently only about 30% of the total cultivable area is utilized for agriculture production. A vast area is under long fallow or is abandoned agricultural land owing to the deficiency of the irrigation systems and scarcity of irrigation water.

Since independence in 1967, the Government of P.D.R.Y. is giving increasing importance to agriculture, which employs 80% of the working population, but contributes only 20% to the national gross product of the country. Hence the essential problem remaining to be solved in the immediate future is an overall agriculture development, improvement of irrigation water sources and soil reclamation. This problem was taken into consideration in the 3 year plan and will be the ultimate goal to be achieved in the forthcoming 5 year plan (1974-79).

15.2 SOILS OF WADI TUBAN AND WADI ABYAN DELTAS

Most of the agricultural areas in the coastal plain and wadi beds consist of alluvial deposits formed from the annual sedimentation of the suspended load carried by the floods. Basically the texture of the alluvium mainly consists of silt and sand with a few clays. Due to the lack of rainfall, the soil profile shows no feature of any pedogenesis; hence the soils are immature and show no genetic horizons.

The only real soil forming process is that imposed by human activities. Each year the spate water spreads a thin layer of mainly fine particles on the irrigated fields, thus forming the so-called, anthropic soils with a clay to silty loam texture. A third soil forming factor is that of the aeolian activity. Strong winds form sand dunes of uniform fine sandy texture and carry or erode alluvial and anthropic soils. In the upper reaches of the wadi there are anthropic soils with a silt loam to loam texture. The lower part of the wadi has natural alluvial soils with loamy sand to sandy loam textures.

As mentioned above, scarcity of water is the limiting factor which hinders agricultural development, so the main task of the Ministry of Agriculture and Agrarian Reform is therefore to investigate the possibilities of extending the agricultural area by exploitation of the groundwater resources by drilling wells in the lower parts of the deltas in the coastal region (Wadi Tuban and Abyan) and Wadi Hadramawt in order to assure a more permanent and reliable source of irrigation water to reclaim the sandy soils and render them productive. In this respect we have to overcome the following problems:

i. the low fertility of these virgin and sandy soils;

ii. the low irrigation efficiency due to high infiltration rate and the frequent irrigation due to low water holding capacity of the soil and high evaporation;

iii. the wind erosion and wind deposits which are seriously affecting the cultivated land.

a. During the first 2 years selected crops suitable for cultivating virgin soil will be planted, such as sorghum and millet, in order to minimize the poor yield expected and characteristic of soils under such conditions. Also other crops will be tried for reclamation.

b. To increase the fertility of virgin and sandy soils, the following trials will be laid out:

(a) green manure of local and imported species
(b) animal and chicken manure
(c) compound fertilizers especially with nitrogen and phosphorus

c. To reduce the salinity of the soils, extra amounts of irrigation water will have to be applied to reduce the salinity hazard. At the present time up to 800 mm of irrigation water is applied for leaching salts. Trials have been laid out to establish the right amount for leaching requirements.

d. In order to prevent unnecessary loss of precious irrigation water and to improve the current low irrigation efficiencies, new irrigation methods and practices are to be tried out. The introduction of furrow irrigation and the improvement of levelling techniques for basin irrigation seems to be promising. Also water requirement experiments are carried out to find the exact amount of water needed for irrigation.

e. At an early stage of reclamation, windbreaks and shelterbelts are going to be established so as to prevent serious damage by wind erosion and sand deposition. Hence rows of tamarix, parkinsonia, conocarpus and casuarina species are going to be planted around and inside the pilot farms at Jawala and Fiyush.

1. Sandy soils	22%
2. Loamy sand soils	33%
3. Sandy loam soils	27%
4. Silty sand loam soils	2%
5. Silty clay loam soils	16%
	100%

The soils of Abyan delta were classified as uniform to slightly stratified with no distinct genetic horizons due to the uniformity of the sediments brought by the annual floods. The characteristics of the analysed samples were as follows:

Saturation percentage:	23-45% by weight
Soil colour:	Light brown to yellow
Permeability:	5-15 cm/hr
Gypsum:	0.5-1.7%
Calcium carbonate:	10-20%
EC of saturated extract:	1-60 mmhos/cm
pH:	7.2 to 8.8
Organic matter:	0.35 - 1.0%
Total Nitrogen:	60-550 ppm
Total P2O5	1.4 - 8.7 ppm
Total K2O	1 000-4 000 ppm

The Government has one major research station at El-Kod in the Abyan delta in the third province. This was formerly the Cotton Growing Research Station but after independence the station was reactivated and has been developed by FAO/UNDP Agriculture Research and Training Project into an Agriculture Research Centre for the whole Republic. The current studies of the Soil and Forestry sections of this centre are devoted to:

I. Experiments on infiltration rate, water holding capacity, salinity and salt balance due to the addition of various amounts of irrigation water of different quality.

II. Sand Dune Fixation and Afforestation

In 1971, Dr. E. Costin, Forestry Expert and Project Manager of FAO/UNDP Agriculture Research and Training project, started research on sand dune fixation and afforestation. Experimental plots were set up on maritime and continental sand dunes, whereby a network of pre-planted mechanical devices was established in order to protect the seedlings from burial or uncovering by the blowing sands. The distance between the strips as well as the size of the checkerboard differs according to wind speed, the steepness of the slopes and form of dunes. The fences were built of dead materials locally available such as reeds (Phragmitis communis). During this time movement of sands inside the fences was recorded monthly by special sticks. From the research that has been done up to now it can be concluded that checkerboard fences acted not only as a mechanical device for stopping the sand movement, but also improved ecological conditions by reducing the evaporation from the soil and providing better conditions for the survival and growth of the seedlings.

Afforestation of sand dunes was related to ecological studies, especially the moisture content of the soil. From the studies that were performed in this field the following can be concluded:

- moisture content increases with depth with the top layer being very dry;
- the sands have a low water holding capacity but preserve the moisture for a long time;
- dew is one of the very important water resources for plants growing in sands and deserts.

From the experiments carried out both on maritime and continental sand dunes, deep planting up to 1.50 m gave the best results, especially for long cuttings of tamarix. The planting should be done according to site conditions -shallow on depressions and deeper on high sites.

Regarding the tree species, the following are the most suitable for desert conditions:

- On top of high dunes:

Tamarix aphylla, Acacia tertilis, Calligouum somosym

- On slope of dunes:

Tamarix aphylla, Prosopis juliflora, Acacia cyanophylla, Parkinsonia aculeata

- On depressions between dunes:

Parkinsonia aculeata, Tamarix, Azadirachta indica, Acacia arabica, Salvadora persica

- On sandy soils from depressions:

Casuarina equisetifolia, Azadirachta indica, Eucalyptus camaldulensis

Our country needs to undertake more research in agriculture and irrigation as a whole on various crops and on different agricultural and irrigation practices at different areas. We would like to mention that not less than 60% of the cultivated land of P.D.R.Y. consists of sandy soils. Indeed the reclamation of such soils will be one of the major problems we have to overcome in order to obtain an expansion in the cultivated area hand in hand with the vertical expansion to be gained from research to increase the yield/acre and the irrigation efficiency. Therefore, there is no doubt that this Seminar, with the fruitful discussions of a panel of experts, will enrich our knowledge and will be of great benefit to P.D.R.Y. in this field.