Effect of Timber Harvest Intensities and Fertilizer Application on Stocks of Soil C, N, P, and S

• Main Authors: Marcella L.C. Menegale, Jose Henrique T. Rocha, Robert Harrison, Jose Leonardo de M. Goncalves, Rodrigo F. Almeida, Marisa de C. Piccolo, Ayeska Hubner, Jose Carlos Arthur Junior, Alexandre de Vicente Ferraz, Jason N. James, Stephani Michelsen-Correa
• Format: Article
• Language: English
• Published: MDPI AG 2016-12-01
• Series: Forests
• Subjects: nutrient cycling; forest residue management; Eucalyptus; nitrogen; carbon; phosphorus; sulfur; minimum tillage
• Online Access: http://www.mdpi.com/1999-4907/7/12/319

The purpose of this study was to determine the stocks of available P and S, total N, and oxidizable C at depth in an Oxisol cultivated with Eucalyptus in Brazil following different timber harvest intensities and fertilizer application over 12 years. The harvest regimes considered were (i) conventional stem-only harvest (all forest residues were maintained on the soil); (ii) whole-tree harvest (only litter was maintained on the soil—all slash, stemwood, and bark were removed); and (iii) whole-tree harvest + litter layer removal. The site was planted in 2004 considering three timber harvest intensities, some with and some without N and P fertilization. In 2012 the experiment was reinstalled, and all the treatments were reapplied in the each plot. From 2004 to 2016, nutrient accumulation and soil N, P, and S stocks were assessed in the 0–20 cm layer. Also in 2016, soil N, P, S, and oxidizable C stocks were measured to 2 m depth. For each treatment, the net balance of N, P, and S were calculated from soil stocks and harvest outputs during two forest rotations. A reduction in all nutrient stocks was observed in the 0–20 cm layer for all treatments. For N, this reduction was 20% smaller in the stem-only harvest treatment and 40% higher when no N fertilizer was applied, when compared to other treatments. Stem-only harvest treatment was observed to reduce the loss of N, P, and S due to harvest by 300, 30, and 25 kg·ha−1, respectively, when compared to the whole-tree harvest + litter layer removal treatment.