Carbon Dynamics in Salt-Affected Soils

Abstract

Salt-affected soils are soils with high concentrations of dissolved mineral salts in their profiles to the extent that such dissolved salts adversely affect crop production. Globally 75 countries have been recognized as having vast areas of salt-affected lands. Australia, United States, Turkey, India, Iran, Iraq, Mexico, Syria, Pakistan, and China are countries with serious salinity problems. In a recent estimate, nearly 831 million hectares of land are salt-affect worldwide. Salt-affected soils mostly exist in arid and semiarid regions of the world and many salt-affected wastelands have been productive lands in the past. Worldwide about 95 million hectares of soils are under primary salinization (i.e salinity occurs naturally in soils and water) whereas 77 million hectares suffer from secondary salinization (as a result of human activities and ever rising groundwater table). Also, 23% of arable lands of the world are affected by salinity while further 10% are saline sodic soils. In Australia sodicity affects about 17 million hectares of land. The key objectives of this study were to 1) study the effects of chemical (Gypsum) and organic (plant material) amendments on carbon dynamic in soil aggregate. 2) evaluate the effects of an organic amendment (Alkaline biochar) on chemical, biological and C stocks of “saline soils” with different salinity levels. 3) study the effects of two types of biochar (Acidic and Alkaline) as an organic amendment on physical, chemical, biological and C stocks of a “saline-sodic” soil. 4) and finally, study the effect of vegetation cover on carbon dynamics in different depths of saline-sodic soils (phytoremediation).