Irrigation benefits a sandy soil, draining a marshy soil.
The method of this irrigation is peculiar.
Except on the scattered oases, where irrigation from springs and mountain streams has reclaimed small patches, the desert is barren and forbidding in the extreme.
In the neighbourhood of the Vaal, confluence, where the river passes through alluvial land, and at some other places, the waters of the Orange are used, and are capable of being much more largely used, for irrigation purposes.
Owing to the high barrier which shuts off almost all Syria from the sea, and precipitates vapours mainly on the western slope, little of the land is highly productive without irrigation, except the narrow littoral strip which was the ancient Phoenicia, and the small deltas, such as that of Latakia (Laodicea).
Milan undertook the irrigation works which enriched the soil of Lombardy for ever.
The fact also that many of the most ancient of these ruins, like Ur, Lagash (Sirpurla), Larsa, Erech, Nippur, Sippara and Babylon, were situated on the banks of the great canals would indicate that the control of the waters of the rivers by a system of canalization and irrigation was one of the first achievements of civilization.
The other cereals may be seen occasionally, where artificial irrigation is practised, in all stages of progress at all seasons of the year, though the operations of agriculture are, as a general rule, limited to the rainy months, when alone is the requisite supply of water commonly forthcoming.
Attica was famous for its olives and figs, but general agriculture excelled in Peloponnesus, where, by means of irrigation and drainage, all the available land was utilized.
For the rest, Syria needs irrigation; and since neither of its larger rivers, Orontes or Jordan, flowing as these do in deep beds, is of much use for this purpose, all Mid-Syria, except the lacustrine oases, is a region mainly occupied by pastures, and yielding only thin cereal crops.
Irrigation is almost entirely confined to rice farms. In the prairie region there is abundant water at depths of too to 400 ft.
Beneath the surface, but this was little used for irrigation for the first few years of the development of this field, when water was pumped from the streams and canals.
To add to the uncertainties of navigation, the inhabitants along the eastern bank of the stream frequently dig new canals for irrigation purposes, which both reduces the water of the river and tends to make it shift its channel.
The state came under British management, and the administration was improved, the revenue increased, a system of irrigation developed, new tanks and wells constructed and an excellent system of roads and public buildings organized.
The survey for the Truckee-Carson system was begun in 1902, with the object of utilizing the waters flowing to waste in western Nevada for the irrigation and reclamation of the adjacent arid regions in Churchill, Lyon and Storey counties.
It also conducts campaigns against locusts and other pests and helps irrigation settlements.
The object is to allow sufficient water to drain off to the westward for the due irrigation of the land, while the Hillah bed still retains the main volume of the stream, and is navigable to the sea.
The work on agriculture' of Ibn-al-Awam, who lived in the 12th century A.D., treats of the varieties of soils, manuring, irrigation, ploughing, sowing, harvesting, stock, horticulture, arboriculture and plant diseases, and is a lasting record of their skill and industry.
The great canal was not begun; irrigation works were started but were soon given up. The letters of Kleber and Menou (the successors of Bonaparte) show that the expenditure on public works had been so reckless that the colony was virtually bankrupt at the time of Bonaparte's departure; and William Hamilton, who travelled through Egypt in 1802, found few traces, other than military, of the French occupation.
This supersedes artificial irrigation, and the plains so watered yield abundantly in rice, jute and mustard.
The Mugan steppe is, however, in spite of its dryness, a more fertile region in virtue of the irrigation practised; but the Kura has excavated its bed too deeply to admit of that being done along its course.
It has published a topographical map of the Nile valley (1:50,000), an irrigation map (I:10o,000), a general map (1: 2 50,000), numerous cadastral plans, &c. Work on similar lines is carried on in the Anglo-Egyptian Sudan.
The Truckee river flows with more vigour, having its source in Lake Tahoe, in California, at an altitude of 6225 ft., and entering the Carson river through an irrigation canal :completed in 1905; before this date it flowed into Pyramid Lake and Lake Winnemucca in the depression at the foot of the Sierra Nevada.
In this tract the rainfall is nowhere sufficient for the purposes of agriculture, which is only possible by help of irrigation; and the fixed population (which contains a non-Turkish element) is comparatively small, and restricted to the towns and the districts near the rivers.
It is a region of lakes and morasses, of arid plains and high temperatures, but experiments with irrigation toward the end of the 19th century were highly successful and considerable tracts have since been brought under cultivation.
The vegetation of each region has its distinctive character, modified here and there by elevation, irrigation from mountain streams, and by the saline character of the soil.
Many bayous are convertible by improvement into excellent drainage and irrigation canals.
- Climatic conditions in Egypt differ radically from those in the United States, the rainfall being so small as to be quite insufficient for the needs of the plant, very little rain indeed falling in the Nile Delta during the whole growing season of the crop: yet Egypt is in order the third cottonproducing country of the world, elaborate irrigation works supplying the crop with the requisite water.
The irrigated rice area increased 92.9% from 1899 to 1902, and the construction cost of irrigation works ($4747,359 in 1902; $12.25 per irrigated acre) 87.7% in the same years.