Forage Yield and Quality of Indigenous and Introduced Grasses at Palmer, Alaska
- W. W. Mitchell
‘Manchar’ bromegrass (Bromus inermis Leyss.) and ‘Engmo’ timothy (Phleum pratense L.) are the major forage grasses in Alaska. Other grasses have been insufficiently evaluated to determine their agronomic value at northern latitudes, and current developments portend agricultural growth into areas that may be relatively unfavorable to bromegrass and timothy.
Thirty-six accessions in 15 species, many indigenous, were compared with Manchar and Engmo to obtain yield characteristics, to make forage quality determinations relative to feeding requirements, and to assess variability within certain species. The grasses were grown on silt loam soil (Typic Cryorthent), pH ca. 6.2, and harvested twice annually for 3 years. Concentrations of N, P, K, Ca, and Mg were determined for all entries and in vitro digestibility for selected entries from certain harvests.
Indigenous Bering hairgrass (Deschampsia beringensis Hulten) IAS 19 yielded the most herbage, averaging 9.8 metric tonsha over the 3 years, not differing significantly from the 9.2 metric tons/ha for Manchar. The hairgrass produced an exceptional 14.3 metric tons/ ha in the 1st year, but harvest-pressure injury reduced subsequent yields. The native accessions of polargrass [Arctagrostis latifolia (R. Br.) Griseb], bluejoint reedgrass Calamagrostis canadensis (Michx.) Beauv.], red fescue (Festuca rubra L.), and Bering and tufted hairgrasses [Deschampsia caespitosa (L.) Beauv.], which are adapted to cool, acid locations, often produced more forage than Engmo timothy, generally used in more moist, acid situations in Alaska. Various introduced grasses yielded more than most native grasses on this mildly acid test site.
Engmo timothy herbage was notably high in digestibility, otherwise the forage cultivars demonstrated no advantage in quality over many indigenous entries. Crude protein generally exceeded 13% up to 20.3%. Magnesium and sometimes P tended to be limiting for animal performance, while other minerals were adequate. The first-harvest herbage of polargrass contained consistently high amounts of the assayed elements.
The quality and yield characteristics within species varied enough to indicate their possible improvement through collection and selection programs. Hairgrass, polargrass, bluejoint reedgrass, and red fescue are currently being evaluated in more comprehensive studies.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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