Document Type : Research Paper
Authors
Scientific Member , Soil and Water Department, Markazi Agricultural and Resources Research and Training Center, AREEO, Arak, Iran
Abstract
Background and Objectives: Iran, as the third-largest pomegranate producer in the world, possesses one of the richest genetic reservoirs of this crop, with approximately 800 identified genotypes. Saveh is among the most important pomegranate-producing regions in Iran, contributing significantly to the national output and export of the fruit.
However, the arid to semi-arid climate of the area and the declining precipitation have led to salt accumulation in the soil, resulting in salinization and a tendency toward sodicity. Besides reducing growth and yield, salinity negatively affects fruit quality. Assessing the current status of soil salinity and the risk of sodicity is therefore essential for the sustainable management of pomegranate orchards in the region.
Mterials and Methods: This study was conducted in the pomegranate orchards of Saveh. After georeferencing the orchards and preparing a base map, soil samples were taken from the 0–60 cm depth. A total of 23 samples were collected and transferred to the laboratory, where the following chemical properties were determined: pH and electrical conductivity (EC) of the saturation paste, calcium-carbonate equivalent (CCE), soluble Cl⁻, Na⁺, Ca²⁺, Mg²⁺, and SO₄²⁻, and the sodium adsorption ratio (SAR). Descriptive statistics were used for data analysis. For spatial modeling of salinity, log-transformed data were interpolated by ordinary kriging. A spherical variogram (nugget = 1.5, sill = 18, range ≈ 8 km) was selected as the best-fit model, and its performance was validated by cross-validation.
Results: Results showed that 65.2 % of the samples were non-saline, whereas 34.8 % fell into the saline class. Mean ECe was 4.08 dS m⁻¹, mean pH 7.8, and mean CCE 22.02 %. Strong positive correlations were observed between soluble Na⁺ and HCO₃⁻ and the ECe. Average concentrations of Cl⁻, SO₄²⁻, and HCO₃⁻ in the saturation extract were 20.41, 18.25, and 2.16 mmol L⁻¹, respectively. According to the salinity zoning map, 7,000 ha of the studied area are classified as salt-affected, implying a substantial limitation to sustainable pomegranate production.
Conclusion: Although a considerable portion of the orchard soils in Saveh currently suffers from salinity, the risk of sodicity remains low. Continuous monitoring of Na⁺ and HCO₃⁻ concentrations is nevertheless recommended to prevent future structural degradation and fertility decline.
Keywords
Main Subjects