40 Years of Liming to Combat Acidic Soils in the Forest

For 40 years now, forest soils in Saxony have been limed—and even now, helicopters are once again in the air, spreading lime over forests between the Vogtland and Saxon Switzerland. Why is this aerial liming still necessary even after four decades?

Why are forests being limed?

This measure combats acidic soils in the low mountain ranges. These acidic soils are a consequence of decades of air pollution from industrial emissions. “Soil protection liming is still necessary to repair the damage caused in the past to Saxony’s forests,” explained State Forestry President Utz Hempfling. The program began in 1986.

What is the goal of soil protection liming?

Two targets have been set: The soil’s pH level is to be raised to 4.2 at a depth of up to 30 centimeters, and nutrient saturation is to be brought to 15 percent. To achieve this, the areas must be limed multiple times. Affected areas will be treated again no sooner than ten years later.

Where will liming take place this year?

From July through October this year, 6,900 hectares of forest in the forest districts of Adorf, Plauen, Eibenstock, Neudorf, Marienberg, Bärenfels, and in Saxon Switzerland will be surveyed by aerial survey. Most of this is state-owned forest, but 1,680 hectares of privately owned forest, 180 hectares of municipally owned forest, and 100 hectares of church-owned forest will also be limed.

What exactly is being spread as part of this measure?

According to Sachsenforst, a total of just under 21,000 metric tons of magnesium lime will be spread this time. The material comes from a lime plant in the Upper Palatinate. On average, 300 grams of rock dust landed on the forest floor per square meter.

What do forest users need to be aware of?

While the helicopters are in operation, the affected forest areas must not be entered for safety reasons. Information about the restricted access periods is available online, among other places. The spread lime is said to pose no health risk to living organisms. Anyone who finds traces of it on berries, mushrooms, or plants should rinse them off with water before consuming them.

How much does soil protection liming cost?

According to the forestry administration, the cost of the measure runs into the millions each year. Last year, 2.9 million euros in EU funds were allocated for the liming of 5,860 hectares of forest.