Local acidification of soil as a means to alleviate iron chlorosis in quince orchards

Abstract

Iron chlorosis is widespread and severe on fruit trees growing In calcareous soils In Iran. Local acidification of soil under the trees and Its effect on iron chlorosis of quince trees (Cydonia oblonga) was investigated in quince orchards in the Esfahan region of Iran. Elemental S, H₂SO₄ or H₂SO₄ + FeSO₄ was added to the soil in two holes (35 cm in diameter x 80 cm deep) dug opposite of each other at a distance of 120 cm away from the tree trunk. Results showed that elemental S decreased the soil pH, and increased the gypsum content, electrical conductivity, and concentrations of SO₄ ^2‐, Ca²⁺ and Mg²⁺ in soil extracts. However, the soils were not acidified and iron chlorosis was not prevented. Local acidification of the soil with H₂SO₄ or H₂SO₄ + FeSO₄ resulted in similar changes in soil properties, however, CaCO₃ content and HCO₃ ^‐ concentration decreased and Iron chlorosis was corrected. The chlorophyll and Fe²⁺ content of leaf samples determined one month after treatment application showed a significant Increase over the control. The results indicated that local acidification of soil was an effective means of alleviating Iron chlorosis In quince orchards.

Key words:

• Soil acidification
• Elemental Sulfur
• Sulfuric acid‐banding
• Iron deficiency