Reclamation of a Saline-Sodic Soil with Organic Amendments and Leaching

Abstract

Excessive amounts of Na+ and soluble salts are characteristics of saline-sodic soils. Loss of soil structure and osmotic stress in plants are negative effects of salinity-sodicity. This study evaluated the effect of cattle manure, biochar and tropical peat at 1 and 2% (w/w) with leaching, on the exchangeable sodium percentage (ESP), electrical conductivity (ECe) and pH of a saline-sodic soil from the High Valley of Cochabamba (Bolivia). The soil was placed in simulated soil columns and two lixiviations were applied. The initial values of soil were as follows: ESP of 66.6%, ECe of 20.5 dS m−1, and pH of 8.55. Results after leaching differed significantly (p = 0.05) among the interactions. Cattle manure at 2% was the most effective in reducing soil ESP to 27.6%, followed by the rest of the treatments. The three amendments at any level were efficient in lowering ECe below 4 dS m−1. Peat at 2% decreased the soil pH to 7.76. The superiority of cattle manure can be explained by the improvement of soil aggregation and leaching efficiency, through its OM and Ca2+ + Mg2+ contribution. Overall, cattle manure was superior in reclaiming the soil salinity-sodicity, and only the ECe threshold value from the US Salinity Lab classification was reached by any amendment, indicating that cattle manure, biochar or tropical peat with leaching, can be used to reclaim some saline-sodic soils.

Keywords

• saline-sodic soil
• soil remediation
• manure
• biochar
• peat