Fertilization/Herbicide Treatments

Approximately 90% of southern plantations utilize fertilization and/or herbicide treatments. These treatments are site specific and are determined by the managing forester. Fertilization and herbicide treatments can have similar effects on the growth and yield of wood volume. 

Fertilizer increases wood production by adding available nutrients for tree crown growth. Larger, healthier crowns result in gains in diameter growth. Tree diameters are directly proportional to the value of the trees. The effects of fertilization typically last for 5-10 years depending on site characteristics and can greatly increase the tons per acre wood growth. Many sites throughout the South are phosphorus deficient as a result of early cotton farming.

The optimal time for fertilization in order to capture the best growth response is mid rotation. However, the optimal time for fertilization to maximize return on investment is about 5 years prior to a thinning or harvest in order to only carry the cost of fertilization for as short a time as possible. 

Herbicide treatments reduce herbaceous competition thereby making existing nutrients more available for tree growth. Herbicide treatments can provide similar results but generally cost about half as much as fertilizer. However, herbicide treatments cannot improve the site as they only reduce interspecies competition.