Native Grasses for Biomass Production at High Elevations - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 114

It can tolerate up to 1 % soluble soil salts. Tall wheatgrass increases production
yields in soils with salinity levels of 6,000-18,000 ppm and persists in soils with
electrical conductivity (EC) up to 26 mmhos/cm [ 100 ].
Tall wheatgrass is adapted to semiarid range sites receiving a minimum 35-
40 cm of precipitation annually, or on irrigated or subirrigated soils at elevations
from 1,300 to 1,850 m. In North America, it is widely used throughout the
Mountain West and the northern Great Plains in salty areas in association with
greasewood and salt grass. In the Columbia River drainage and the Great Basin, it
competes well with native species such as basin wildrye on saline soils [ 101 ]. Tall
wheatgrass has large seed that is easy to harvest and plant. It has good seedling
vigor, and established plants have an exceptionally deep root system, which
contributes to its resistance to drought [ 98 , 102 ]. Under favorable conditions, it
establishes as a dominant and may form a monoculture,

thereby reducing

diversity [ 101 ].
Tall wheatgrass remains green 3-6 weeks later than most other range grasses and
is often valued as a source of forage during late summer, fall, and early winter
[ 66 ]. It also has been used successfully as a silage crop. Because of its late maturity,
it is usually recommended that tall wheatgrass be seeded alone. Leaving 20-cm
stubble is recommended at year's end to prevent animals from grazing too close the
following year. Grazing should not be initiated until at least 25 cm of new growth
has accumulated above last year's stubble [ 21 ]. To ensure a successful seeding, it is
recommended that one growing season be required for establishing tall wheatgrass
on irrigated land and two growing seasons under dryland conditions. The major
limitation in establishing tall wheatgrass stands are that young seedlings are slow to
establish. Due to its late maturity, competitive ability, and tendency to become
coarse during the growing season, it is recommended that tall wheatgrass be seeded
alone rather than in a mixture with other grasses [ 66 ]. Although it tends to become
coarse at advanced stages of maturity, when managed properly, tall wheatgrass has
relatively good palatability and nutritional value. It is usually recommended for
cattle; however, it has proven to be a good source of grazing for sheep [ 98 ].
Based on Vogel and Moore [ 103 ], sufficient variation exists in NPGS collec-
tions, particularly, PIs 98526, 264770, 283163, and 401006 to improve biomass
production through selection in tall wheatgrass. On saline soils that ranged from 1.7
to 21.7 mmhos under dryland conditions, tall wheatgrass (cv. Alkar) averaged
4,331 kg ha 1 over a three-year period compared to 4,405 kg ha 1 for intermediate
wheatgrass (cv. Greenar) and 4,107 kg ha 1 for the RS hybrid (cv. NewHy) in
NRCS plant materials salinity trials in Roosevelt, UT [ 104 ]. In an irrigated trial near
Elmo, UT, on saline soils that ranged in EC values from 5.7 to 20, tall wheatgrass
(cv. Alkar) averaged 3,319 kg ha 1 over a four-year period compared to
4,624 kg ha 1 for tall fescue (cv. Festorina) and 2,376 kg ha 1 for the RS hybrid
(cv. NewHy) [ 104 ]. On an upland site near Hays, Kansas, tall wheatgrass cultivars
Alkar and “Jose” averaged 5,600 and 4,26 kg ha 1 over 3 years, respectively,
compared to 3,696 and 2,800 kg ha 1 in intermediate wheatgrass cultivars Oahe
and Slate, respectively [ 105 ]. Alkar tall wheatgrass ranked among the four highest