Influence of Laboratory Methods on Calcareous Saline Soils for EC Measurement and Leaching

Abstract

Electrical conductivity (EC) methods were tested using combinations of surrogate irrigation (SI) waters, soil salinity levels, and soils ground or retaining aggregates. The EC varied in low-salinity soils saturated with SI; the sum of the baseline EC_e and SI EC were not equal to the measured EC. The baseline EC_e and the SI EC sum in the high‐salinity ground soils were not equal to the any measured ECs. Salt‐removal potential from gypsiferous soils was examined using multiple extractions from the same soil sample. Calcium concentrations remained consistent over 14 extractions, whereas Na concentrations decreased. The EC_e decreased from more than 8 dS m⁻¹ in the initial extraction, to approximately 4 dS m⁻¹ by the 9th to 14th extraction. Multiple extraction data suggest that improved leaching will not lower soil ECs to less than approximately 4 dS m⁻¹ because of gypsum and calcite reservoirs in the tested soils.

Keywords:

• Calcite
• electrical conductivity
• gypsum
• lower Arkansas River Basin
• soil chemistry

Acknowledgment

This report was financed in part by the U.S. Department of Agriculture and the Department of Interior, U.S. Geological Survey, Grant 01HQGR0077, through the Colorado Water Resources Research Institute. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. government. Any mention of a product by brand or product name does not imply the endorsement of the U.S. government.