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Nutrient cycling and growth in Eucalyptus grandis plantation under different forest residues management and fertilization

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Author(s):
Ayeska Hubner Braga Nunes Souza
Total Authors: 1
Document type: Doctoral Thesis
Press: Piracicaba.
Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
Defense date:
Examining board members:
José Leonardo de Moraes Gonçalves; Carolina Braga Brandani; Marcos Vinicius Winckler Caldeira; Alexandre de Vicente Ferraz; Edgar Fernando de Luca
Advisor: José Leonardo de Moraes Gonçalves
Abstract

The minimal tillage system is characterized by practices of reduced soil management which retains most part of forest residues in the production site, aiming to supply the forest demand and the sustainability of the production system. The aims of this study are: i) Access the effect on soil fertility and site production of total and partial removal of harvest residues and mineral fertilization. ii) Quantify the biomass and nutrient rates in trees along one eucalypt rotation, under different residues management and mineral fertilization. iii) Quantify the effects of residues management and mineral fertilization on deposition, accumulation, decomposition and nutritional qualities of litter. iv) Quantify the nutrient exportation due to the harvest, considering steam and other parts. v) Access productivity potential according to the nutritional balance under different forest management cases. For this study an experimental site with different residues management and mineral fertilization was established. The treatments were separated in two groups. The first one included the treatments with total or partial removal of forest residues: canopy (leaves and stems), bark and litter. The second group of treatment included the omission of nutrients in mineral fertilizer: N, P, K or lime. During eight years rotation were monitored soil fertility, biogeochemical cycling of nutrients, growth and tree nutritional status. The different residues management and mineral fertilizations has showed minor effects on soil fertility once the nutrient rates on soil were suitable due to the mineral fertilization applied for site preparation. However, when the fertilization was carried out without K, reduction of 50% in growth was observed. The omission of P in fertilization did not affect the wood productivity during the forest rotation, but P was the most limiting nutrient for the potential number of future rotations. The biochemical nutrient cycling was not affected by total or partial removal of forestry residues. Annual deposition of K was 60% reduced when the nutrient was not applied by fertilization, which affected the nutrient cycling. The results of this study demonstrated that despite the benefits of forest residues retention on chemical proprieties of soils, the inadequate fertilization reduces expressively the productive potential of the site. (AU)

FAPESP's process: 11/20600-7 - Harvest residue management and mineral nutrition in stands of Eucalyptus grandis.
Grantee:Ayeska Hubner Braga Nunes Souza
Support type: Scholarships in Brazil - Doctorate