Assessment of fertilizer nitrogen accumulation in Pinus sylvestris trees and retention in soil by ¹⁵N recovery technique

Abstract

Assessment of fertilizer nitrogen accumulation in Pinus sylvestris trees and retention in soil by 15 N recovery technique. Accepted Jan. 9, 1989. Scand. J. For. Res. 4:427-442, 1989.The distribution and quantitative recovery of fertilizer N were determined in three 29-to 43-year-old stands of Scots pine, located in western Uppland, Central Sweden. The experimental technique involved was based on the use of 15 N-labelled fertilizer materials and non-trenched microplots of special design. The standard dose of nitrogen applied was 160 kg N ha -1 . The primary topics examined were (1) fertilizer nitrogen accumulation in trees and in the soil system as influenced by nitrogen source, nitrogen application rate, time of application during the growing season, granule size of the nitrogen material, and method of placement, (2) distribution of labelled N within the tree (different organs of the tree), and (3) redistribution of accumulated N in the tree over an observation period of two to three growing seasons. When quantified at the end of the second growing season, the labelled N accumulation in trees, concerning plots treated with calcium nitrate or ammonium nitrate, averaged 36% (SD=7). The accumulation resulting from split doses did not differ significantly from that resulting from a single-dose application, nor did granule size of the nitrogen materials have any significant effect on accumulation. For urea source of nitrogen, the recovery figure was markedly lower, averaging 28% (SD=6). When expressed as a percentage, the accumulation in trees was not significantly different for 40 and 160 kg nitrogen application rates. In one of the experiments application timing during the growing season proved to be an important factor determining the extent of fertilizer nitrogen accumulation in trees. The figures for total recovery of labelled nitrogen in aboveground parts of trees and in soil, when restricting measurements to the forest floor and the 0-32 cm mineral soil, ranged from 46 to 84%, with an average of 60%. The recovery was lowest for a treatment with calcium nitrate, when applied relatively late in the growing season, and highest for a split application of urea. Treatments with urea source of nitrogen were characterized by a high accumulation of immobilized N in the organic LFH layer of the soils. Recovery figures exceeded 82 % for a 40-kg N dose of nitrogen, regardless of the nitrogen source.

Understorey competition affects tree growth and fate of fertilizer-applied 15N in a Coastal British Columbia plantation forest: 6-year results

“…Vol. 30, 2000 1990; Nômmik and Larsson 1989). Contrasting to the finding in Koopmans et al (1996), who studied sites with high rates of N deposition, the retention of 15 N in the organic layers (primarily humus layer, see the materials and methods section) in this study was quite stable as no obvious decrease of 15 N recovery rate in the soil was found.…”

Current uptake of 15N-labeled ammonium and nitrate in flooded and non-flooded black spruce and tamarack seedlings

“…15 N seedling −1 ) adapted in this study is adequate to study current uptake and retranslocation processes and has been successfully implemented in other studies (Amponsah et al, 2004;Mead and Preston, 1994;Preston and Mead, 1994). Additionally, Nômmik and Larson (1989) found no significant differences in 15 N recovery between split doses vs. a single application. Chelated micronutrients (EDTA 42% and DTPA 13%) were applied at the rate of 0.03 g L −1 to prevent any deficiency (Salifu and Timmer, 2003).…”

Recovery of 15N-urea 10 years after application to a Douglas-fir pole stand in coastal British Columbia

“…Work in an old-growth temperate evergreen mixed-angiosperm forest in southern Chile indicates that the transformation of applied inorganic N was dominated by rapid assimilation and turnover through microbial biomass in the short term (weeks), and transfer from microbial biomass into nitrogen-conserving plant (and to a lesser extent soil organic matter) pools in the long term (years) (Perakis and Hedin, 2001). Such processes (whether the soil or plant biomass is the main sink for the applied-N) result in efficient long-term retention of nitrogen in forest ecosystems, with the bulk of residual fertilizer N generally found in the organic and upper mineral horizons, in both short-and longer-term studies (e.g., Mead and Pritchett, 1975;Nômmik and Larsson, 1989;Preston and Mead, 1994).…”