Salinization of non-irrigated soils and associated streams: a review

Abstract

Saline seepage has reduced agricultural production and increased solute and sediment loads in streams and rivers in Australia and North America. The problem has developed where soils which contain substantial quantities of soluble salts have been developed for cultivation within the last 50-100 years. Salts may accumulate in surface soils by evaporation of saline surface water from poorly drained areas, or by seepage and capillary flow from unconfined or leaky confined aquifers. For some part of the year, water at atmospheric pressure is usually found within a few metres of the surface of a saline seep. In exceptional combinations of soils and weather, salts accumulate in the plant root zone because there is no net movement of water beyond this depth. The key to reclamation of a saline seep is appropriate management of water: either surface or subsurface drainage, or encouraging maximum use of water by plants, particularly in recharge areas. Another strategy is to plant salt-tolerant vegetation on the seep and await the result of natural leaching processes, but these are often very slow. Several reclamation techniques have been investigated, but they have found little application up to the present time.