Abstract
In North America, most tree nursery nutrition publications during the past two decades involved either container-grown stock or stock grown in greenhouses. In contrast, most bareroot nursery fertility trials in North America were published during the last century. As a result, some bareroot fertilization recommendations have remained the same since 1980 and some practices continue to be based on myths and assumptions. The bareroot nursery industry in the USA might benefit if the next generation of graduate students will consider testing old and new theories about nursery fertilization. Hopefully, they will discover new facts so that future fertilization regimes will be based on science. This paper provides various fertilizer trials that should be established in bareroot nurseries.
Highlights
South and has been on a decline ever since
Myths can be relatively easy to stop by graduate students who follow the scientific method
The objective of this paper is to provide a list of hypotheses for those graduate students who choose to test fertilizers in bareroot nurseries in North America
Summary
Urea is the second most popular N source for farmers in the United States and is sometimes used as the primary N source for growing tree seedlings (Jacobs et al 2005; Knight 1978; McNabb and Heser 1997; Sing et al 2017). H0: When liquid urea (23-0-0) is applied to six-week old pine seedlings (< 11 cm tall), seedling tolerance is not affected by either the amount of irrigation after application (zero, 1 cm) or the rate of application (0, 10, 20, 40, 80, 160 kg ha-1). H0: Increasing foliar N concentrations in the fall with either nitric acid or urea (0, 33, 66, 99 kg N ha-1) does not affect freeze tolerance of ponderosa pine (Pinus ponderosa) seedlings. H0: There is no difference in growth of bareroot loblolly pine seedlings when initiating a fertilization program (e.g. 23-0-0 @ 10 kg ha-1 per application) at three different times after sowing (5-, 7-, 9-weeks). H0: Phytotoxicity to 6-week old whitebark pine (Pinus albicaulus) seedlings is not increased when applying a liquid urea (23-0-0) solution to oxyfluorfen
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