Effect of Urea and Urea-Formaldehyde on the Growth of Lodgepole Pine Seedlings in a Nursery

It is usually difficult to maintain high organic matter and total nitrogen levels in forest nursery soils. Although large amounts of organic matter are often placed in the soil, nitrogen losses resulting from seedling removal and leaching often cause nitrogen deficiencies. Soluble nitrogen fertilizers are usually applied as a preseeding treatment, as topdressings at least once during the growing season, or as both. Wilde (L3) indicated that soluble fertilizers applied to the surface of the soil may result in inferior planting stock which has an unsatisfactory top-root ratio, excessive succulence, and physiological unbalance. Urea-formaldehyde, a slowly available nitrogen fertilizer, has shown promise for crops that require uniform vegetative growth and where flush growth is undesirable (3,_I). May and Posey 6) used a single preseeding application of 248 pounds of 38-percent ureaform nitrogen per acre; loblolly pine seedlings 1 year after planting were as tall as seedlings receiving eight applications of ammonium nitrate totaling 376 pounds of nitrogen per acre. Franzmeier and Arneman (4) compared ammonium nitrate, ammonified peat, and ureaform as sources of nitrogen for red pine seedlings in the nursery. The choice of source had little effect on the concentration of nitrogen in the seedlings.

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Author(s): D. H. Sander

Publication: Tree Planters' Notes - Issue 79 (1966)