If you are growing loblolly pine in plantations and you are looking for attractive investments in increased wood production, consider forest fertilization. Planning for fertilization requires months of lead time to obtain soils information, to take foliage samples, and to have them analyzed. The only fertilizer elements currently known to produce economically attractive growth increases in loblolly pine are nitrogen and phosphorus. Potassium, and perhaps other elements, limits growth on some sites, but further research is needed before applications can be recommended. Growth responses are not obtainable everywhere.
Foliar analysis is recommended for identifying sites to fertilize.
Even foliar analysis cannot give a perfect prediction of response, but it improves the probability of success. Results of foliar analysis are key indicators of needs for soil nutrients, and special procedures for collecting foliage samples must be followed. If a regeneration cut is planned, foliage samples can be taken from the stand before harvest to determine the need for phosphorus application before a new stand is planted. A needle phosphorus content of less than 0.10 percent indicates a need for soil phosphorus. The growth response to phosphorus fertilization increases as the needle phosphorus content without fertilization decreases from 0.10 to 0.06 percent.