Doses of N, P and K in the cultivation of eucalyptus in soil originally under Cerrado vegetation

Residual Influence of Nitrogen, Phosphorus and Potassium Doses on Soil and Eucalyptus Nutrition in Coppice

The management of fertilizer is an important strategy for better nutrition and productivity of eucalyptus. Therefore, the objective of this research was to evaluate the isolated residual effect (carryover) of N, P and K fertilization on macro- and micronutrients in soil, leaf litter, leaf nutritional diagnosis and initial growth attributes of eucalyptus in a coppice system. Three experiments were carried out in a randomized block design with five replications. Experiment 1: four residual doses of N (0, 70, 105 and 140 kg ha−1) were applied as ammonium nitrate. Experiment 2: four residual doses of P2O5 (0, 40, 70 and 100 kg ha−1) were applied to plantations in furrows using triple superphosphate. Experiment 3: four residual K2O doses (0, 90, 135 and 180 kg ha−1) were applied as potassium chloride. The residual N doses did not influence leaf nutrient contents and initial growth of eucalyptus; however, increasing P residual doses increased soil P and Zn content, litter K content, decreased leaf Mg content, and increased initial growth (height and wood volume of eucalyptus). The residual K doses increased leaf litter K content and leaf Mn and Zn content but decreased leaf litter Ca, B and Fe and leaf Mg content. Residual potassium fertilization did not significantly influence the initial growth of eucalyptus in the Brazilian Cerrado.

Management intensification maintains wood production over multiple harvests in tropical Eucalyptus plantations

Plantation forestry, in which trees are grown as a crop, must maintain wood production over repeated harvest cycles (rotations) to meet global wood demands on a limited land area. We analyze 33 yr of Landsat observations across the world's most productive forestry system, Eucalyptus plantations in southeastern Brazil, to assess long-term regional trends in wood production. We apply a simple algorithm to time series of the vegetation index NIRv in thousands of Eucalyptus stands to detect the starts and ends of rotations. We then estimate wood production in each identified stand and rotation, based on a statistical relationship between NIRv trajectories and inventory data from three plantation companies. We also compare Eucalyptus NIRv with that of surrounding native vegetation to assess the relative influence of management and environment on plantation productivity trends. Across more than 3,500 stands with three complete rotations between 1984 and 2016, modeled wood volume decreased significantly between the first and second rotation, but recovered at least partially in the third; mean wood volumes for the three rotations were 262, 228, and 247 m³ /ha. This nonlinear trend reflects intensifying plantation management, as rotation length decreased by an average of 15% (decreasing wood volume per rotation) and NIRv proxies of tree growth rates increased (increasing volume) between the first and third rotation. However, NIRv also increased significantly over time in unmanaged vegetation around the plantations, suggesting that environmental trends affecting all vegetation also contribute to sustaining wood production. Management inputs will likely continue to be important for maintaining wood production in future harvests.

CRESCIMENTO INICIAL DE CLONES DE EUCALYPTUS EM FUNÇÃO DA ADUBAÇÃO DE NPK

A adubação NPK e a escolha do material genético são fundamentais no estabelecimento e na produtividade da cultura. Assim objetivou-se avaliar o efeito de adubação mineral de plantio, no crescimento de clones de eucalipto (Eucalyptus urophylla x Eucalyptus grandis), em solo de Cerrado. O experimento foi conduzido de outubro de 2015 a julho de 2017, na fazenda Campo Verde IV, localizada no município de Selvíria - MS. O delineamento experimental foi o de blocos casualizados com 12 tratamentos e quatro repetições, em esquema fatorial 3x4, sendo três clones (I144, H13 e 1528) e quatro doses: 0, 160, 320 e 640 kg ha-1 da fórmula 08-32-16 + 0,5% B, 0,5% Cu e 0,5% Zn. Cada parcela foi composta por 42 plantas, distribuídas em sete linhas de seis plantas cada, totalizando 378,0 m2 de área, sendo considerada área útil apenas as seis plantas centrais, totalizando 54,0 m2. Foram avaliados aos 17 meses de idade o diâmetro à altura do peito (DAP) e volume de madeira com casca. A adubação propiciou aumento do DAP e da produtividade de madeira para os três clones, sendo o 1528 mais produtivo.