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ESTABLISHING DRYLAND FORAGES IN SEVERELY-SALINE SITES USING IN-SITU WATER

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  022067,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.9326) @2002
Authors:   H. Steppuhn, K.B. Jensen, K.H. Asay,
Keywords:   Salinity, Reclamation, Alfalfa, Wheatgrass hybrid, Solar-powered pump, Plant Emergence

Over time, the evapotranspiration of near-surface, in-situ ground water can salinize root zones. In many saline sites, the near-surface ground water is less saline than the solutions of the rootzone above the water table. In a field study conducted in semiarid Saskatchewan, fall irrigations with in-situ water from a shallow, on-site well fitted with a solar-powered pump preceded spring seedings of Beaver alfalfa (Medicago sativa L.) and an experimental, salt-tolerant strain of the wheatgrass Elymus hoffmannii (Jensen & Asay). Six plots with top-soil averaging 13.85 dS/m (ECe) were irrigated with 4.6 dS/m in-situ water in respective applications amounting to 1010, 1180, 1350, 1860, 2190, and 2530 mm. Six additional plots received no irrigation water.

By spring seeding-time, the fall irrigation treatments lowered the mean soil salinity in the upper 0-900 mm of the soil profile an average -18.2%. The relative gain in profile soil water averaged +10.0%. In the non-irrigated plots, overwinter precipitation (92.1 mm), increased soil water content +10.6% and lowered the profile salinity -5.5% based on the fall values. Differentially, pre-irrigation resulted in a net mean decrease in root-zone salinity of -12.7%. Seedbed salinity decreased -52.5%, from 14.2 to 6.8 dS/m in mean electrical conductivity.

The pre-seeding irrigation increased the mean emergence percentage of the alfalfa four-fold (19.7 to 78.8%), but only from 46 to 65% for the wheatgrass. Pre-irrigation also improved the spacing of the emerged alfalfa plants within the seeded row five-fold, but the wheatgrass spacing was not improved. However, mean plant height at harvest increased significantly for both forages after irrigation, gaining 206 and 119% over the mean heights of the non-irrigated alfalfa and wheatgrass, respectively. Mean establishment-year forage yields of alfalfa and wheatgrass increased 2560 and 958%, respectively.

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