Crop Species, Amendment, and Water Quality Effects on Selected Soil Physical Properties
- J. W. Bauder and
- T. A. Brock
Saline and sodic soils have developed in some irrigated areas of Montana. Cropping systems that promote maximum efficacy of surface-applied amendments for reclamation need to be identified. Effects of crop species, amendment, and water quality on alteration of selected physical properties of a Haverson silty clay (fine-loamy, mixed [calcareous], mesic Ustic Torrifluvent) were compared. Crops grown in lysimeters and compared with a noncropped control were alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), and sorghum-sundangrass [Sorghum bicolor (L.) Moench- S. × drummondii (Steudel) Millsp. & Chase], commonly referred to as sordan. Soil amendments included a check, gypsum (CaSO4·2H2O), phosphogypsum (CaSO4·2H2O with <1% [w/w] P), and MgCl2. Lysimeters were irrigated with water having either a total dissolved solids (TDS) concentration of 0.75 g L−1 and a sodium adsorption ratio (SAR) of 1.15 or TDS of 1.65 g L−1 and SAR of 7.01 until three barely crops were successively grown. The presence of a crop caused a significant increase in bulk density in all lysimeters and a significant decrease in total porosity, compared with the uncropped control treatments. Barley caused the greatest decrease in total porosity, followed by alfalfa, then sordan. Total porosity decreased nearly 0.1 m3 m−3. The result was a significant increase in number of micropores (<0.149 × 10−2 mm radius) and a disproportionately greater decrease in number of macropores (>1.49 × 10−2 mm radius). Soil water release characteristics differed among the different crop treatments. Neither amendment treatment nor irrigation water quality had a significant effect on either porosity, pore-size distribution, or bulk density. Results of this study indicate that crop selection and rotation may affect the significance of surface-applied amendments used for reclamation and leaching of Na- and salt-affected soils.
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