Eucalypt plantations in Brazil have the highest mean productivity when compared to other producing countries, and fertilizer application is one of the main factors responsible for these productivities. Our aim was to identify appropriate rates of N, P and K in eucalypt plantations and their interactions with edaphoclimatic factors. Four trials with four rates and three nutrients (N, P and K) were set up. Each nutrient was studied separately, and the trees received sufficient rates of all of the other nutrients through fertilization, to avoid limitations not related to the desired nutrient. We assessed solid wood volume (SV), productivity gains (PG), leaf nutrient content and leaf area index (LAI) to determine the responses to fertilization. PG, regarding N, rates ranged from 104% to 127% at 60 months after planting. P fertilizer application led to gains in productivity in soils with levels of P-resin up to 5 mg¨kg´1mg¨kgmg¨kg´1 , but decreased with stand age. K fertilizer application responses increased within age in three sites. In Paulistania, responses to K application were close to zero. N and K responses were climate related. Leaf nutrient content and LAI were not able to predict the highest yields obtained.
Fertilization increases productivity in Eucalyptus plantations, but losses in productivity associated with soil fertility continue at operational scales. In this study, we evaluated the fertilization response (FR), light use efficiency (LUE) and growth efficiency (GE), i.e., the amount of wood biomass accumulated per unit of light absorbed (LUE) and per unit of leaf area index of Eucalyptus plantations. We used a "twin plot" approach, with 161 blocks representing 52,700 ha of planted forests that spanned a broad range of edaphoclimatic conditions in southeastern Brazil. The normal plots (NP) were part of a permanent inventory network, whereas the twin plots (TP) received extra high levels of fertilization and extra weed control after fertilization. The intensive management (twin plots) led to a large increase of 5.3 Mg¨ha´1¨year´1 of wood increment. The region without dry periods and with soils with high clay content was most responsive to fertilization, with a 15% increment in the LUE and 10% increase in the GE of the TPs compared with those of the NPs. Our results suggested that water availability was the primary element affecting productivity and potential response to fertilization. With this information, decisions can be made on which regions should receive priority fertilization investments. However, more research is required to determine the most limiting nutrient in each type of environment.
Ethanol is an alternative source of renewable fuel, but increasing production of vinasse as a by-product requires proper management. Combining concentrated vinasse (CV) and nitrogen (N) fertilizer into a single operation is increasing in Brazil. However, the chemical stability and potential for volatilization losses remain unknown. Our objectives were to characterize the chemical stability of CV and N fertilizer mixtures and to evaluate volatilization losses following application to sugarcane trash. In an initial study, we monitored variations in pH, total N and inorganic N content after a 22-day incubation of mixtures of CV and N fertilizer. In a second study, we evaluated N-NH 3 volatilization losses following surface application to sugarcane trash. We used a medium-textured soil covered with trash (8 Mg ha -1 ), and measurements of N-NH 3 losses were taken using acid traps in semi-static chambers during 40 days after mixture application. The addition of urea to the CV did not increase the pH and resulted in the maintenance of N in amidic form, demonstrating the chemical stability of the mixture. However, after application to sugarcane trash, N losses from urea added to the CV ranged from 29 to 35 % of the applied N. The addition of phosphoric acid and boron has the potential to reduce the N loss of 26 % of the applied N. The use of UAN mixed with CV had the lowest loss through volatilization (21 % of applied N) and is the suggested to use for application to sugarcane trash.
Aos meus pais,Hélio e Maria Carolina, grandes exemplos de minha vida, que sempre me incentivaram e me proporcionaram todas as condições necessárias para formação pessoal e profissional. Por todo amor, carinho e sábios conselhos que me deram durante estes anos ...
À minha irmã,Maria Izabel, mulher de grande personalidade e que sempre esteve ao meu lado, amiga para todos os momentos...
DEDICOÀ sociedade, OFEREÇO 4 6 Aos colegas de pós-graduação e amigos José Henrique Rocha, Eduardo Sereguim e Eduardo Mattos por estarem juntos nesta jornada e pelas intensas discussões sobre o trabalho e as atividades, sempre regadas de entusiasmo e boas ambições; Aos alunos do PTSM Caio Polizel, Felipe Saldanha, Maurício Prieto, Estela Foltran e Ana Zucon pela dedicação com que realizaram as atividades e pela paciência e compreensão durante todo o período; Ao Grupo Florestal Monte Olimpo, base de minha formação prática e motivador da paixão pela Ciência Florestal, pela acolhida em Piracicaba e apoio na execução das atividades,
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