Abstract
During the 20th century, managers at sandy nurseries utilized sulphur (S) to lower soil pH and mitigate the risk of iron deficiency. During that time, however, applying S as a fertilizer was a rare event. At many nurseries, S in rain and irrigation water was sufficient to avoid visual deficiency symptoms. The S status of soil and foliage was typically unknown, and many researchers did not test for S due to the additional cost. Consequently, S became the most neglected macronutrient. While a few nursery trials demonstrated that elemental S reduced damping-off and increased height growth, a majority showed no benefit after applying S at rates lower than 100 kg ha-1. Even so, by 1980, S-deficiencies occurred at bareroot nurseries in Alabama, Oklahoma, Virginia, Wisconsin, the United Kingdom, and likely in North Dakota and New York. The risk of a deficiency increases when N-only fertilizers are applied to seedbeds. Due to research, experience and the precautionary principle, several managers transitioned to using ammonium sulfate instead of, less expensive, N-only nitrogen fertilizers. After soil tests became affordable, managers began to ask questions about the need to apply S to seedbeds.
Only a few hydroponic trials with small pine seedlings have been used to estimate “threshold” or “critical values” for foliar S. Since an initial 1,500 μg g-1 S value is “unreliable” for pine seedlings, some authors lowered the value to 1,100 μg g-1 and even as low as 500 μg g-1 S. Others ignore all estimates based on total S concentrations and, instead, monitor only foliar SO4 levels.
Reference202 articles.
1. Albaugh JM, Blevins L, Allen HL, Albaugh TJ, Fox TR, Stape JL, Rubilar RA (2010) Characterization of foliar macro-and micronutrient concentrations and ratios in loblolly pine plantations in the southeastern United States. South J Appl For 34(2): 53-64. https://doi.org/10.1093/sjaf/34.2.53
2. Aldhous JR, Mason WL (1994) Forest Nursery Practice. London, UK: Her Majesty’s Stationery Office.
3. Forestry Commission Bulletin 111, 268 p.
4. Allen HL (1987) Forest fertilizers J Forest 85(2): 37-46. https://doi.org/10.1093/jof/85.2.37
5. Allen JW, Shachar-Hill Y (2009) Sulfur transfer through an arbuscular mycorrhiza. Plant Physiology 149(1): 549-560. https://doi.org/10.1104/pp.108.129866