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Show Observations on Alkali Soils in Iran D. w. Pittman! In Iran, most desert countries, one of the chief soil The valley soils are predominantly of the gray desert type and in many places are so rich in salt that after one or two years of irrigation the land becomes worthless. Some rather extensive development projects have failed for this reason. as in problems -is alkali. In the main central valley, known as Draya-i-namek (sea of salt), is a large salt bed resembling that near Salt Lake. On the northern steppe, on the southern low-coastal plain, below Teheran and Ghom, near Ahwaz and Bushire, everywhere in slight de pressions, the salt accumulates. In Dashty Gorgon-a broad short-grass plain to the east of the south end of the Caspian, with a deep brown soil of apparently wonderful fertility-an irrigation project WqS put in, pumping water fsom the Gorgon River to grow cotton. The first year there was a fair_ cotton crop, the second year about half a crop, and the third year no crop at all but a white crust of salt. The engineers were at first inclined to think that the salt came from the river water, but analysis showed no excessive quantitiess of salt in the water but just enough distributed throughout the soil so that when concentrated at the surface it became serious. At Sad Sha'ur, on the southern gulf coastal plain, some ex perimental sugar cane was planted on what seemed to be fine soil, but as soon as irrigation was applied the salt came up and de stroyed most of the crop. At Hamidieh, still closer to the Gulf and at Shabonkareh, farther south by Bushire where another project was started, salt came up sufficient to injure wheat in many cases. Below Isfahan extensive salt flats have developed. In Iran, as in Utah, the most frequent type of alkali is the "solonchak" of the Russian classification, or simple white alkali. The "black alkali" of Hilgard, a basic surface crust, or the "sol onetz" of the Russians, a mildly saline basic hardpan is not so common in Iran. Nearly all the soils of Iran, both saline and non saline, as far as I have investigated, have a reaction of less than pH 8.5 and so would not be considered bad from that standpoint. The excess salt in Iran usually consists predominantly of a mixture of Na2S04 and NaCl in about the proportions of 3 to 1. About 0.4 per cent of such a mixture is usually sufficient to inhibit or seriously retard the growth of ordinary crop plants as shown by tests made at the margins of alkali spots. Occasionally, as at Ka melabad near Karaj, with irrigation some black surface alkali spots may develop for a season, but they are not usually perm. ... lUtah State Agricultural College, Logan, Utah. Volume 21, Proceedings of the Utah Academy of Sciences, Arts and 97 Letters |
