Leaching requirement of super-cyclone affected coastal soils of Orissa

Leaching behaviour of three super-cyclone affected coastal soils of Orissa was studied. The soils belonged to Aeric Fluvaquent, Typic Haplaquept and Aeric Tropaquept. The study was conducted in PVC columns of 0.50 m length and 0.108 m internal diameter. Air-dried soils, ground and passed through a 2-mm sieve, were packed to a bulk density of 1.5 ± 0.2 Mg m⁻³ in the PVC columns, and different amounts of water were applied on them for leaching purpose. Leaching with 2.50 pore volumes of water removed 96% of total salts and brought down EC_e below 4 dS m⁻¹ in 0–40 cm soil layer of Typic Haplaquept and Aeric Tropaquept, while the same amount of water removed 88% of total salts from Aeric Fluvaquent. Exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR) in all the studied soils decreased progressively with various levels of water application tried. Decrease in ESP with leaching indicated no prospects of sodification in these soils under the extent of leaching tested. The relationships between EC/EC_o (EC_o and EC are electrical conductivities of saturation extracts of the soils before and after leaching, respectively) and D_W/D_S (D_W and D_S are the depths of water and soil, respectively) established for the soils were EC/EC_o = 0.876–0.570 (D_W/D_S), R² = 0.98 for Aeric Fluvaquent; EC/EC_o=0.382–0.197 (D_W/D_S), R² = 0.92 for Typic Haplaquept; and EC/EC_o = 0.902–0.657 (D_W/D_S), R²=0.97 for Aeric Tropaquept for 0–0.40 m soil layer. These relationships suggested that to accomplish 80% reduction in salinity, each cm of Aeric Fluvaquent, Typic Haplaquept and Aeric Tropaquept should be leached with 1.19, 0.92 and 1.07 cm water, respectively.