Amelioration strategies for salinity-induced land degradation.

Abstract

Salinization of soils is a major impediment to their optimal utilization in many arid and semi-arid regions throughout the world. In several large irrigation schemes, salinity-induced land degradation has increased steadily over the last few decades with concurrent reductions in agricultural productivity and sustainability. Currently, saline soils occur within at least 100 countries. These soils need explicit approaches in their amelioration since soil salinization cannot be reduced by routine irrigation and crop management practices. The approaches used to ameliorate saline soils can be broadly divided into four major categories: (1) leaching of bare saline soils to move excess soluble salts from upper to lower soil depths or out of soil profile in the presence of a natural or artificial drainage system; (2) leaching of cropped saline soils with certain plant species, which can withstand ambient salinity levels; (3) surface flushing or mechanical removal of salts from soils that contain salt crusts at the surface or where drainage is inadequate and leaching is restricted by the presence of a shallow water table or highly impermeable profile; and (4) reduction of salts from saline soils through biological means - the harvest and removal of high-salt accumulating aerial plant parts - in areas with negligible irrigation water or rainfall for leaching. Research and practice have shown that in the presence of a drainage system, saline soils can be brought back to a highly productive state by leaching the excess soluble salts from the effective rooting depth. Among the amelioration methods, cropping in conjunction with leaching has an advantage; cropping during or between leaching events increases salt removal efficiency because of a decrease in soil-water content under unsaturated water flow conditions with a concurrent decrease in large pore bypass and drainage volume. However, anaerobic conditions in soil may occur during leaching of cropped soils, thereby affecting growth of those plant species that are sensitive to such conditions. Thus, in addition to existing salt-resistant plant species, research is needed to explore or develop genotypes that can withstand the twin stresses of salinity and hypoxia. Although significant efforts have been made to develop models for simulating movement and reactions of salts in saline soils during the amelioration process, these models need evaluation and verification under actual field conditions.

Genetic evaluation and characterization using cluster heat map to assess NaCl tolerance in tomato germplasm at the seedling stage

“…To deal with these stresses, there is a demand to develop the most suitable varieties and a more nutritive tomato with good tonnage. Tomato is quite sensitive to salinity (Lycoskoufis et al, 2005), which affects tomato growing areas of both arid and semi-arid climates (Qadir et al, 2006;Azevedo-Neto et al, 2006). Munns and Tester (2008) reported that salinity stress has affected more than 45 million ha of land and approximately 1.5 million ha will become wasteland each year worldwide because of high salinity.…”

EFFECT OF GYPSUM, SUGAR FACTORY LIME AND MOLAS ON SOME SOIL PROPRIETIES AND PRODUCTIVITY OF SUGAR BEET(Beta vulgaris l.) GROWN ON SALINE-SODIC SOILS OF NILE NORTH DELTA

“…Currently, at least 20 % of the world's irrigated land is salt-affected. Among those affected by salt, about 60 % are sodic, (Qadir et al, 2006). Salt affected soils represent 9.1 % from the total area and 30 % from the total cultivated area in Egypt, (FAO 2005).…”

Agronomic and physiological responses of pearl millet ecotype (Pennisetum<br>glaucum (L.) R. Br.) to saline irrigation

“…However, Tunisia, as in the majority of the arid areas, is classified among the countries threatened by dryness and salinity (Qadir et al, 2006). In fact, water availability is below the threshold of 1000 m 3 /person/year (Paranychianakis and Chartzoulakis, 2005).…”