Electromelioration of a Sodic Horizon from an Illinois Natraqualf
- Efkar Ahmad,
- R. Lewis Jones and
- Thomas D. Hinesly
Sodium-enriched subsoils of Natraqualfs seriously limit crop production by impeding drainage on 150 000 ha in south-central Illinois. We hypothesized that electromelioration of typical Natraqualf subsoils soils is feasible. Columns of natric material (subsoil of Huey silt loam, a fine-silty, mixed, mesic Typic Natraqualf) were fitted with electrodes at either end of the column. Leachate generated by maintaining water at the column's top was collected at the bottom or cathodic end. Treatments were untreated soil or gypsum mixed with the natric material at rates of 38.5 and 77 Mg ha-1. An additional column to which no potential was applied was prepared for each treatment. Fifty-five volts direct current was maintained across the column, and current densities ranged from 0.04 to 0.35 mA cm-2. Sodium leached rapidly from all treatments to which a potential was applied, but leachate was produced only in the treatment without potential and with the equivalent of 77 Mg ha-1 of gypsum. Extractable Na reductions amounted to 96% in the column without added gypsum and 98% in each of the gypsum-treated columns. Water required to leach Na was reduced by gypsum treatment from 138 cm for unamended columns to 84 and 55 cm for the 38.5 and 77 Mg ha-1 treatments, respectively. Substantial changes in soil structure were observed at the end of the experiment. The power calculated to remove 96% of the extractable Na in 58 cm of natric material during 31 d of leaching amounted to 736 560 kW-h ha-1.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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