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Soil Management

Efficiency of Sulfuric Acid, Mined Gypsum, and Two Gypsum By-Products in Soil Crusting Prevention and Sodic Soil Reclamation

^a Agricultural Resources Evaluation Center, Dep. of Agriculture, Gobierno de Navarra, Ctra Sadar s/n, Edificio "El Sario", 3^a planta, 31006 Pamplona, Navarra, Spain
^b Dep. of Soils and Irrigation, Research and Agronomic Technology Center, Diputación General de Aragón, Apdo. 727, 50080 Zaragoza, Spain

^* Corresponding author (espe{at}amezketa.net; esperanza.amezketa.lizarraga{at}cfnavarra.es)

Received for publication September 6, 2004. Sulfuric acid and gypsum-like by-products are potentially effective amendments in preventing soil crusting and reclaiming calcareous sodic soils. However, their relative efficiencies at chemically equivalent rates are not well documented. We evaluated the efficiency of four amendments (sulfuric acid, mined-gypsum, and the by-products coal-gypsum and lacto-gypsum) in crusting prevention of two calcareous nonsodic and sodic soils and in sodic soil reclamation. Treatments for crust prevention consisted of surface-applied amendments at equivalent rates of 5 Mg pure-gypsum ha^–1. Treatments for sodic soil reclamation consisted of surface-applied acid and soil-incorporated gypsums at rates of 1 pure-gypsum requirement. The efficiency of these amendments was evaluated by comparing the final infiltration rates (FIR) of the amended vs. the nonamended soils measured in disturbed-soil columns pounded with low-salinity irrigation water. Electrical conductivity (EC) and Na in the leachates of the sodic soil were measured. In the crusting prevention experiment, FIRs (mm h^–1) of the nonsodic soil were 21 (nonamended), 33 to 35 (gypsum materials), and 53 (sulfuric acid), whereas those for the sodic soil were 0 (nonamended), 9 (lacto-gypsum), 15 to 17 (coal- and mined-gypsum), and 21 (sulfuric acid). In the sodic-soil reclamation experiment, FIRs were 0 (nonamended), 8 to 9 (gypsum-materials), and 17 (sulfuric acid) mm h^–1. All amendments were effective in crusting prevention and soil reclamation, but sulfuric acid was the most efficient due to the fastest EC and Na reductions in the leachates. The three gypsum-materials were equally effective in the reclamation process and in the nonsodic soil crusting-prevention, whereas lacto-gypsum was less efficient in the sodic-soil crusting-prevention.

Abbreviations: A, cross sectional area of the soil columns • ANOVA, analysis of variance • C, total electrolyte concentration • CEC, cation exchange capacity • CG, coal-gypsum • CV, coefficient of variation • CW, canal water • EC, electrical conductivity • ESP, exchangeable sodium percentage • FIR, final infiltration rate • FV, flocculation value • HC, hydraulic conductivity • IR, infiltration rate • LG, lacto-gypsum • MG, mined-gypsum • OM, organic matter • PGR, pure gypsum requirement • PV, pore volume • Q, volume of water collected in the leaching of soil columns • RFIR, relative final infiltration rate • SA, Sádaba (the soils' local name) • SAR, sodium adsorption ratio