Impact of Gypsum Particle Size on Soil Physical Properties of a Saline-Sodic Soil from North Sinai, Egypt

Abstract

ATER flow through structured soils can substantially affect …….. local water balance, contaminant transport, and plant-available water. Effect of different gypsum radius on hydraulic conductivity (HC) of saline-sodic soils was assessed. Saline-sodic clay soil from Gelbana Village, Sahl El-Tina plain, Sinai, was mixed with three treatment of gypsum (CaSO 4 .H 2 O) different in there particle size: T1"fine" (< 0.5 mm), T2"medium" (0.5-1 mm) and T3"coarse" (1-2 mm), and subjected to continuous leaching increments, and these treatments were compared by the control. Soil samples were packed in columns to make a 30-cm height with a bulk density of 1.36 Mg.m-3. Leaching was conducted by ponding with a constant head of 5 cm water. Leaching water was of EC 1.50 dSm-1 and SAR of 9.1. Six continuous water increments were performed for each column. To assess and simulate the water flow, to quantify improved management strategies, and to derive updated irrigation standards, the soil-water model HYDRUS-1D code was used. Considerable short-lived increase in HC following addition of gypsum occurred to the soil. It quickly decreased in subsequent leaching increments. The increase amounted to 181, 126 and 117% due to the fine-particles, medium-particles and coarse-particles gypsum, respectively. The increase in HC persisted up to the 4 th leachate; and was particularly marked with the fine-particle gypsum, and this increases up to 275% following the 5 th leachate compared with the 1 st leachate. In soils receiving medium-particle or coarse-particle, increased of the HC was less marked, being up to 56% following 5 th leachate increment. The HYDRUS-1D provided reliable simulation results of infiltration rate and cumulative infiltration. Using the model to analyses management options proved an efficient tool for agro-ecosystem assessment.