Iron Fertilization in Bareroot Nursery Seedbeds

With adequate fertilization, bareroot conifers grow well at pH 4.5 to 5.5. Because some guidelines suggest that seedlings grow best at pH 5.5 to 6.5, lime is sometimes applied when soil drops below pH 5.5. Liming, however, can result in “lime-induced” chlorosis which may be attributed to an iron (Fe) deficiency. Fe deficiency is often associated with “summer chlorosis” or “nitrate-induced” chlorosis. With no treatment, however, seedlings may return to a green color when temperatures cool. At many bareroot nurseries, Fe deficiency has declined because: (1) soil acidity of seedbeds has been lowered to below pH 5.6; (2) nitrate application has decreased by more than 55 percent; and (3) irrigation is used to cool seedbeds in July. Now, about one-third of bareroot nurseries in the southern United States do not fertilize with Fe. This article gives an overview of publications and observations regarding the use of Fe in bareroot nurseries and associated products, challenges, and misconceptions.

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Author(s): David B. South

Publication: Tree Planters' Notes - Volume 64, Number 2 (2021)

Volume: 64

Number: 2