Forage yield and soil characteristics under various crops in Alaska

Forage crops and soil attributes were evaluated for 4 years at three sites in Alaska. Annual herbage yields usually exceeded 5 Mg ha -1 on neutral soils at Fairbanks (64°52' W) and on moderately acidic soils at Point MacKenzie (61°24' N, 150°3' W). Strongly acidic, droughty soils at Delta Junction (63°55' N, 145°20' W) produced low yields for all crops. Soil pH decreased significantly over 4 years under N-fertilized grasses at Delta Junction and under alfalfa and N-fertilized barley at Fairbanks. Soil organic C and N and microbial biomass C showed no differences among treatments at the end of the study. Wet aggregate stability did not vary significantly among crops but was lower for fallow. The results of this study indicated a high potential for use of perennial forage legumes at some locations in Alaska. The lack of large differences in most soil parameters indicates slow responsiveness to management by some commonly used soilquality indicators under subarctic conditions.