Friday, 14 July 2006 - 11:45 AM

Reclamation of Salt Affected Soils by Growing Salt Tolerant Plants and Using Nuclear Techniques Management.

Seyed Jalal Rastegari and Mojgan Farhangisabet. Nuclear Reaserch Center for Agriculture and Medicine, Mahmood Abad street, Moazen Street, Karaj, 31485/498, Iran

Salt-affected soils are wide spread in arid and semi arid regions of the world. Iran is located between 25 and 40 degrees north latitude and is predominantely an arid and semi-arid country. It covers 165 Mha, out of this area 25 Mha is highly affected by saline soils. According to data published by UNESCO, IRAN ranks 3rd in Asia only after Russia and China and ranks 5th in the world in total salt affected land areas. Reclamation of salt affected land is being practiced using different combinations of leaching and drainage. Besides the high costs, this solution has some other difficulties such as removal of drained water. One more effective way of using saline land and saline water is to use plants. Plants have vast genetic variability and during their evolution they have adapted to many kinds of habitats. A Large number of crop plants, vital to human life as food, feed and fiber sources, trace their origins to the part of the old world known as the Middle East, and a good number have their center of origin and center of diversity in or around Iran. Although some of these crops are of major importance to the economy of the country, their adaptation to salinity, drought, and heat is not well documented. To demonstrate the feasibility of utilizing wastelands using saline water to grow salt tolerant plants, and screen for salt tolerant species, ten- hectare plots of salt affected wasteland were selected in Yazd, in centeral Iran. Yazd's climate is harsh dry and desert-like. Annual rainfall is low (60-80mm) and the evaporation is very high (4000mm) due to rather low humidity and hot weather with great day and night temperature fluctuations. Thereby the province has the worst peculiarities of the world's deserts. The annual temperature ranges from -16 to 45 degrees. About 90% of the land surface are heavily affected by salinity. Data on initial soil and ground water characteristics of the site have been collected. Initial soil EC of the site was 148 ds/m and EC of water was 8 ds/m. The total of 20 salt-tolerant species plus 6 varieties of wheat, 3 varieties of barley and 6 varieties of rye were selected to test in the site of Yazd for their salt tolerance. Neutron moisture probe were used to manage irrigation water with the EC 8dS/m. Ground water was collected at regular intervals from the site and from several locations with a radius of 1-2 km around the site, chemical and isotopic (deuterium, oxygen-18, tritium) analyses have been performed to monitor its dynamics. The soil miosture was also monitored regularly. Out of six Salt tolerant wheat cultivars planted, wheat mutant cultivar T-58-8 showed the best performance, followed by mutant T-67-60 and Lu 29 from Pakistan. The barley variety Afzal had the best performance. Out of all tree and shrub species planted six Atriplex spp, two tamrix, and pistachio had more than 80 percent survival rate in the field. Elaegnus angustifolia L., Pomegrante and Eucalptus had more the 50% survial rate. The result also indicated that although it is not always possible or practical to eliminate all salts from the soil, but managing the soil to minimize salt damage is a necessary part of using saline soils. In sodic soils some of the exchangeable sodium must be removed; with slightly saline soils, the control of water, the proper techniques of planting, and the choice of tolerant crops are essential for successful crop production. Soil salinity was measured twice before planting and 5 years after planting. Results of soil EC changes showed dramatic a drop in EC from 148 dS/m at initial stage to 10 to 15 dS/m after 5 years of plantation.

Keywords: Biosaline Agriculture, halophytes, nuclear techniques, saline soils, saline water

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