Response of acid forest soils to helicopter liming in the Monongahela National Forest, West Virginia

Typical of soils in humid climates, soils in the Monongahela National Forest (MNF) in West Virginia are acidic because of leaching of base cations, uptake of Ca and Mg by vegetation, and release of organic acids by organic matter (OM) decomposition. Soil acidity has increased because of anthropogenic acid deposition causing declines in forest health. In anticipation of a large‐scale liming project in the MNF, soils at 10 sites were sampled and analyzed in 2009. In 2018, lime was applied by helicopter to a total of 323 ha at a rate of 10 Mg ha−1. One year after liming, soils were resampled and analyzed in 2019 representing five limed and five unlimed areas using the same procedures. The objectives were to determine whether unlimed soils had changed between 2009 and 2019 and to evaluate changes in soils resulting from liming in 2019 for pH, acidity, and Al and Ca concentrations. In O and A horizons, unlimed soils had changed only slightly in the 10‐yr interval. Liming increased soil pH in O horizons from 4.6 to 5.9. Liming reduced acidity values by 73% and Al concentrations by 80% in O horizons. Liming increased Ca concentrations by at least three times in O and A horizons. Based on first‐year results, liming had a significant effect on soil properties of O and A horizons. Future sampling at 3 and 5 yr after liming will help to evaluate further changes in soils as a result of liming and under reduced acid deposition rates. Core Ideas Soils in the Monongahela National Forest, WV, are acidic because of natural acidification processes. Acidification has worsened because of acid deposition, and liming can decrease acid conditions. Soils were sampled before and after a large‐scale, helicopter liming project. After 1 yr, liming increased pH and Ca with corresponding decreases in acidity and Al concentrations in O and A horizons. Future sampling at 3 and 5 yr after liming will evaluate long‐term changes.