Juvenile Southern Pine Response to Fertilization Is Influenced by Soil Drainage and Texture
AbstractWe examined three hypotheses in a nutrient dose and application frequency study installed in juvenile (aged 2–6 years old) Pinus stands at 22 sites in the southeastern United States. At each site, eight or nine treatments were installed where nitrogen was applied at different rates (0, 67, 134, 268 kg ha−1) and frequencies (0, 1, 2, 4 and 6 years) in two or four replications. Phosphorus was applied at 0.1 times the nitrogen rate and other elements were added as needed based on foliar nutrient analysis to insure that nutrient imbalances were not induced with treatment. Eight years after treatment initiation, the site responses were grouped based on texture and drainage characteristics: soil group 1 consisted of poorly drained soils with a clayey subsoil, group 2 consisted of poorly to excessively drained spodic soils or soils without a clay subsoil, and group 3 consisted of well-drained soils with a clayey subsoil. We accepted the first hypothesis that site would be a significant factor explaining growth responses. Soil group was also a significant factor explaining growth response. We accepted our second hypothesis that the volume growth-cumulative dose response function was not linear. Volume growth reached an asymptote in soil groups 1 and 3 between cumulative nitrogen doses of 300–400 kg ha−1. Volume growth responses continued to increase up to 800 kg ha−1 of cumulatively applied nitrogen for soil group 2. We accepted our third hypothesis that application rate and frequency did not influence the growth response when the cumulative nitrogen dose was equivalent. There was no difference in the growth response for comparisons where a cumulative nitrogen dose of 568 kg ha−1 was applied as 134 kg ha−1 every two years or as 269 kg ha−1 every four years, or where 269 kg ha−1 of nitrogen was applied as four applications of 67 kg ha−1 every two years or as two applications of 134 kg ha−1 every four years. Clearly, the sites examined here were limited by nitrogen and phosphorus, and applications of these elements to young stands effectively ameliorated these limitations. However, there were differences in the response magnitude that were related to soil texture and drainage. Juvenile fertilizer applications resulted in high stocking levels early in the rotation; this condition should be considered when undertaking juvenile fertilization programs. View Full-Text
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Albaugh, T.J.; Fox, T.R.; Allen, H.L.; Rubilar, R.A. Juvenile Southern Pine Response to Fertilization Is Influenced by Soil Drainage and Texture. Forests 2015, 6, 2799-2819.
Albaugh TJ, Fox TR, Allen HL, Rubilar RA. Juvenile Southern Pine Response to Fertilization Is Influenced by Soil Drainage and Texture. Forests. 2015; 6(8):2799-2819.Chicago/Turabian Style
Albaugh, Timothy J.; Fox, Thomas R.; Allen, H. L.; Rubilar, Rafael A. 2015. "Juvenile Southern Pine Response to Fertilization Is Influenced by Soil Drainage and Texture." Forests 6, no. 8: 2799-2819.