Long-term effects on soil-water nitrogen and pH of clearcutting and simulated disc trenching of previously N-fertilised pine plots

Forest fertilisation with nitrogen (N) typically increases N leaching for 1–2 years. Some studies have reported effects also after clearcutting. This study presents an analysis of soil-water chemistry data from the 3rd to the 15th year after clearcutting of fertilised experimental plots on a low-fertility site in Sweden. Before clearcutting in 1987, study plots had been fertilised with NH4NO3 in 1967, 1974, and 1981, resulting in total applications ranging from 0 to 1800 kg N·ha−1. In 1989, disc trenching was simulated by manual digging on small subplots within the fertilised main plots. Soil-water samples were collected at a depth of 50 cm. Previous N fertilisation and site preparation, respectively, affected (p < 0.05) the total N and NO3–-N concentrations and pH of soil water, but no statistical interaction between fertilisation and site preparation was found. The NO3–-N concentration was elevated for total N applications above 720 kg·ha−1 (mean NO3–-N concentration of 0.93 mg·L−1 for 1080 kg N·ha−1, 1...