Alfalfa Emergence and Survival Response to Irrigation Water Quality and Soil Series
- J. W. Bauder ,
- J. S. Jacobsen and
- W. T. Lanier
Irrigation with saline-sodic water has increased in the northern Great Plains, due to development of marginal soils and extended drought in the region. A greenhouse study was conducted to determine the effect of irrigation water salinity and sodicity on alfalfa (Medicago sativa L.) seedling emergence and mortality in soils with differing textures. Emerged, live seedlings (designated as percent live seedlings, i.e., percentage of planted seeds that developed into emerged seedlings) were counted at 2-day intervals for 20 d in a randomized block, 3 × 3 × 3 factorial experiment (irrigation water salinity × Na adsorption ratio × soil series). Total dissolved solids (TDS) concentration of irrigation water was maintained at 0.75, 1.15, and 1.65 g L−1 (−4.2 × 10−2, −6.5 × 10−2, and −9.3 × 10−2 MPa osmotic potential); sodium adsorption ratio (SAR) was maintained at 1.1, 5.1, and 9.6. Two supplemental studies of similar design were conducted to determine water quality and soil effects independently on seedling survival. Irrigation water quality treatments caused the percent live seedling counts to be lower than for distilled water. Little seedling mortality occurred. Irrigation with distilled water had a negative effect on germination and emergence in all three soils, but did not increase seedling mortality after germination. Soil series and preplant TDS-SAR of the soil had the greatest effect on survival. Irrigation water TDS significantly affected seedling emergence among soil series. Emergence ranged from 65 to 85%, with the highest emergence occurring in the coarse-textured soil irrigated with the lowest TDS-SAR water. Mortality ranged from 25 to 45%, with the greatest survival occurring in the fine-textured soil and intermediate TDS-SAR combinations. Emergence and mortality were high on well-drained soils irrigated with high TDS and high SAR water. Results of this study indicate that pre-emergence alfalfa seedbed irrigation should be (i) limited to well-drained soils with low indigenous salinity and sodicity, and (ii) confined to periods when salinity and sodicity of irrigation water are lowest.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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