Postplant Application of Nitrogen Fertilizer to Pinus sylvestris at Different Stages of Establishment

Abstract Ammonium nitrate and urea formaldehyde at 56, 112, and 224 kg N/ha (50, 100, and 200 lb N/A) were surface-applied to Scotch pine (Pinus sylvestris) planted the same spring and 1 and 2 years previously. Survival and growth were measured and compared with untreated controls during the following two seasons. Survival of plants established the same year as treatment was significantly greater at the lowest fertilizer rate, regardless of material. Second season height growth of trees receiving 56 kg N/ha (50 lb/A) in the year of planting was significantly greater than those receiving 224 kg N/ha (200 lb/A). There were no significant growth responses by trees established for 1 or 2 years prior to treatment. Stem diameter and number of lateral buds at the apex were not affected by any of the treatments.