Base cation fertilization and liming effects on nutrition and growth of Vermont sugar maple stands

Soil and foliar nutrition, crown condition, and wood growth were measured in three mature sugar maple stands in northern Vermont before and after fertilization with base cations (107 kg ha^-1 K, 53 kg ha^-1 Ca and 11 kg ha^-1 Mg) with or without 3000 kg ha^-1 supplemental lime in order to test the effectiveness of such treatments in ameliorating base cation deficiencies in sugar maple (Acer saccharum Marsh.). Pre-fertilization analyses indicated multiple cation deficiencies in these stands, since foliar K, Ca and Mg were all near or below sufficiency standards suggested for sugar maple. Fertilization with cations in addition to liming elevated soil pH from 3.6 to 4.5 in the first year after treatment, and elevated soil pH was maintained over two additional growing seasons along with significantly improved soil Ca and decreased soil Al. Foliar K, Ca and P concentrations were all significantly improved (P < 0.05) compared with controls for the three growing seasons following the first treatment, while only foliar K concentration showed significant improvement in plots treated with the base cation fertilizer without lime. By the third growing season following treatment, trees in limed plots had significantly less crown dieback than controls or trees in plots treated with the base cation fertilizer alone. Diameter growth showed marginal improvement in the plots treated with cations, annual diameter growth increased 200% compared with controls in the limed plots. Despite these positive results, the long term contribution of increased soil pH and soil calcium to soil nutrient pools and root distribution remains to be determined, as does the sustainability of growth increases. We conclude that in northern Vermont sugar maple stands on relatively infertile podzols with low pH, base cation limitations may be especially important in controlling sugar maple tree health or growth, while fertilization to ameliorate base cation deficiencies may be effective only at relatively high base cation addition rates.