Impact of Salinity and Sodicity on Crop Growth and Physicochemical Properties of Some Aridisol and Vertisol Soils in Sudan: A Review

Abstract

Comprehensive field and laboratory studies were undertaken to
investigate the performance of some crops on salt-affected soils in Sudan.
To separate salinity and sodicity indicators some laboratory studies were
conducted on soils equilibrated with mixed NaCl-CaCl 2 solutions. The
relative hydraulic conductivity (RHC) or diffusivity increased with
increase in total salt concentration (C) and decrease in exchangeable
sodium percentage (ESP). A dispersion index (DI), a swelling index (SI),
shrinkage volume and modulus of rupture increased with increase in ESP
and decrease in C. The data showed a highly significant linear decrease in
RHC with increase in DI or SI. The threshold salt concentrations (THC),
which gave 75% of the highest RHC, and ESP relationships, were
obtained for samples from an Aridisol and a Vertisol soils.. The salinity
profile obtained after intermittent leaching with water suggested the
presence of a desalinized zone followed by a salinized one with the
highest salt concentration below the wetting front. The depth of the
desalinized zone increased significantly with increase of the amount of
water stored (r2 = 0.968) and the length of the wetting front (r2 = 0.974).
Soil amendments promoted salt leaching in the following order: Sand>
chicken manure> water hyacinth> gypsum> dry sewage> farm yard
manure> control. Cumulative evaporation (E) for the various amendments