Fourth year response of aspen seedlings to lime, nitrogen and phosphorus applied at planting and 1 year after planting

The 12.5 g P (as 64 g triple superphosphate) per tree applied at planting increased height growth 15-18% according to site and increased stem volume growth 42-58% after 4 years. Survival was increased at Drayton Valley (5%) and Manning (12%), with no effect at Linaria. Responses to the same fertilizers applied in May of the second year, to previously unfertilized trees, were small, except that N fertilizers caused mortality of as much as 33% at Drayton Valley. Except at Manning, N treatment increased leaf N concentrations without affecting growth, apparently, because N concentrations were already adequate. At Manning, N increased stem volume in year 1. When increased survival was also considered, the P treatments at Drayton Valley and Manning increased volume on a land area basis 69.6 and 62.6%, but at Linaria, where survival was unaffected, the increase was 49.1%. Dolomitic limestone had a small effect on growth at Manning, which was increased in P treatments also receiving lime. Survival was strongly affected by lime at this site and showed an overall linear increase with lime level, up to 9.4%, with increases of 13-18% in the presence of P. Fertilization at planting was very effective in promoting growth and establishment and the alternative of fertilizing in May of the second year was a failure. Inadequate spring precipitation and competing vegetation might explain this failure.