Perennial Grass and Soil Responses to Four Phosphorus Rates at Point MacKenzie

Abstract

Three perennial grasses were established on Kashwitna silt loam at Pt. MacKenzie in 1985 to test their responses to different rates o f phosphorus (P) fertilization. Laboratory studies with a number o f Alaskan soils have indicated strong P-fixation properties for the Pt. MacKenzie soils (Ping and Michaelson 1986, Michaelson and Ping 1986). Earlier work with cereal forages showed responses for barley up to 90 lbs/acre and for oats up to 60 lbs P205/acre (Michaelson et al. 1984). All three perennial grasses [‘Engmo’ timothy (Phleum pratense), ‘Manchar’ bromegrass (Bromus inermis), and reed canarygrass (Phalaris arundinacea)] responsed to P2O5 up to 120 lbs/acre in their establishment year in 1985 (Mitchell and Mitchell 1986). Reed canarygrass significantly outproduced in 1985, yielding over two tons dry matter/acre at the higher fertilizer levels. Bromegrass was the least productive in the establishment year. This report concerns the results obtained in 1986, which constituted the first full harvest year.