Additional Information on Scalping
Scalping is a mechanical process whereby the soil is peeled back in a wide (30-36”) shallow (2-4”) furrow. A site can be scalped with a machine specifically designed for this purpose. More frequently, fire plows are utilized because they are readily available. Since scalping is not breaking up a plow-pan or hardpan, it does not require a large tractor to pull the scalper or fire-plow.
Ripping or sub-soiling, on the other hand, produces a deep (14-20”) narrow (2-4”) trench that is designed to break up a hardpan or plow-pan. It takes significantly more horsepower to rip an agricultural field than it does to scalp an old pasture.
Researchers with the Florida Division of Forestry and the USDA Forest Service examined the effects of scalping in the 1990’s. They conducted studies with both slash pine and longleaf pine on agricultural sites in five counties in Florida. Their studies conclusively demonstrated that both longleaf pine and slash pine survived at greater rates and grew faster on converted agricultural croplands when these sites were scalped prior to planting. Scalping outperformed Benomyl® root dips, herbaceous release, a disking site preparation, and insecticide applications.
Dr. Ed Barnard and others with the Florida Division of Forestry concluded that scalping is extremely beneficial to newly planted pines. They cited the following benefits of scalping: 1) Reduced weed competition, 2) Improved moisture relations, 3) Reduced pressure from certain root pathogens, 4) Reduced insect damage, and 5) Possibly improved planting efficacy.
First and foremost, we believe scalping helps control competition during the first growing season. A scalping site preparation is extremely beneficial for any seedling planted in perennial grasses. Some of the most competitive perennial grasses are Bermuda grass, Bahia grass, fescue, and Johnson grass. Rhizomes and root systems from these species are severely reduced or eliminated in the scalping furrow. This allows seedlings to be planted directly into the mineral soil. Seedlings planted in the scalping furrow also have a greater window of competition-free growth if the grasses were not killed by chemical means prior to planting.
Many people fail to see the benefits of scalping a site that was in row-crop production the year prior to planting. However, we have found that scalping reduces competition even in fields that do not have significant components of perennial grasses. Whether you realize it or not, there is a time bomb lying in these old fields. In this case, the time bomb is the seed-bank of late germinant grasses and broadleaves.
Scalping peels back the upper layer of soil where a large portion of the annual weed seed bank resides. Removing this seed bank greatly reduces the number of weeds that will germinate in the area immediately surrounding the newly planted seedling. By reducing late germinant competition, a single herbaceous release will frequently provide season long weed control. To be successful in these old fields and pastures, new seedlings require one season of good competition control. Scalping combined with the proper herbaceous release will usually yield this result.
As with all forestry practices, there are potential negatives to scalping. If the soils are very wet, or the soils are very heavy (high clay content), scalped rows may hold water and drown the seedling. The major negative associated with scalping is the potential for increased erosion. It is critical that scalping, ripping/sub-soiling, and mechanical tree planting follow the contour of the land. Otherwise, there will be an unacceptable amount of erosion.
On most sites, soil moves away from newly planted tree seedlings. In scalped rows, the soil moves onto the seedling. For this reason, it is recommended that container longleaf seedlings be planted approximately 1” shallower in scalped rows. It is preferable to have the terminal bud at least ½-1” above the soil surface at the time of planting. In some cases, this means the plug will be exposed at the time of planting. In two separate studies conducted by the Longleaf Alliance, container seedlings planted with the plug ½” to 1” above the soil surface in scalped rows survived and grew better than those planted with the plug covered. The results of three separate studies indicate that planting with the plug exposed has no significant effect on either survival or growth of longleaf pine seedlings. The consequences of planting too deep far outweigh the perceived negatives of shallow planting.