José Luiz Gava

Influência da compactação do solo na produtividade da rebrota de eucalipto

In areas of eucalyptus regrowth, field operations such as harvesting, pesticides spraying, fertilization and manuring contribute to soil compaction. In two areas of eucalypt (Eucalyptus grandis Hill ex Maiden) regrowth, with soil of different textures, belonging to Cia. Suzano of Paper and Cellulose, thirty planting rows were selected to evaluate eucalyptus productivity at seven years of age and soil physical characteristics. Undisturbed soil samples were obtained at three depths: 0 - 10; 10 - 20 and 20 - 30 cm; and soil resistance at 60 cm, using a penetrometer SC - 60. Negative correlation between soil density and eucalypt yield was obtained at 10 - 20 cm (r2 = 0,86) depth in sandy soil and, at 20 - 30 cm in clayey soil (r2 = 0,77). At same depths and textures, correlation coefficients between soil penetrometer resistance and eucalyptus productivity were 0,29 and 0,93, respectively. Correlation coefficients between soil bulk density and soil penetrometer resistance were 0,84, in sandy soil and 0,68 in clayey soil. In traffic lanes, eucalyptus productivity was reduced up to 66% compared to non-traffic lanes due to soil compaction. Soil surface layer seems to recover its original soil bulk density values seven years after harvesting, and soil compaction reached its maximum at 10 - 20 cm depth on clayey soil and, 20 - 30 cm on sandy soil. There was negative correlation (r²= 0,86) between soil bulk density (10-20 cm layer), and eucalyptus wood volume on sandy soil. On clayey soil, this negative correlation (r² = 0,77) occurred at 20-30 cm depth.

Planning soil tillage using quality function deployment (QFD)

O setor florestal brasileiro representa aproximadamente 4% do produto interno bruto, valor estimado em US

Soil attributes and wood quality for pulp production in plantations of Eucalyptus grandis clone

21 bilhoes. As florestas denominadas artificiais, ocupam ao redor de 4,8 milhoes de hectares sendo previsto uma necessidade de ampliacao para atender a demanda futura, alem do replantio das areas cohidas. Uma das preocupacoes com essas areas e evitar a compactacao do solo devido as operacoes mecanizadas e uma das tecnicas e o preparo reduzido. O objetivo deste trabalho e definir as prioridades do preparo do solo de acordo com as necessidades da muda de eucaliptus; para tanto utilizou-se da funcao desdobramento da qualidade (QFD) para identifica-las. Os requisitos tecnicos largura e profundidade do sulco e tamanho dos torroes foram os mais importantes para atender as demandas das mudas. O QFD e uma tecnica que tem potencial de aplicacao, tanto na area florestal como agricola, para identificar e traduzir as demandas das culturas em requisitos tecnicos.

Modificações nos atributos físicos de solos submetidos a dois sistemas de preparo em rebrota de Eucalyptus saligna

The soil attributes can affect the wood quality of eucalypt, which may result in considerable effect on cellulose production. This study evaluated the effect of different physical and chemical soil attributes on wood quality of Eucalyptus grandis for cellulose production. Five sites were selected at the Western Plateau of the State of Sao Paulo, planted with one clone of Eucalyptus grandis, with ages ranging between 6.5 and 7.0 years. Four soil types, with texture ranging from sandy to very clayey were found. At each site, three experimental plots were allocated with 100 trees each. Trees representative of each class frequency of diameter at breast height were harvested. Their biomass and wood components were characterized. The wood productivity and quality was affected by physical attributes of soil, mainly clay content, which is directly related to the amount of available water. Basic wood density did not changed at different soil types. Total lignin content decreased and holocellulose content exponentially increased as soil clay content increased (until about 350 to 400 g kg-1 of clay). The wood extractives content was not affected by soil attributes. Screened cellulose yield exponentially increased with soil clay content.

Unidades de colheita: estratégia para evitar a compactação dos solos florestais

Este trabalho teve como objetivos avaliar o efeito do revolvimento do solo das entrelinhas na produtividade de rebrota de Eucalyptus saligna, por meio das modificacoes em alguns atributos fisicos do solo, e estabelecer qual profundidade de revolvimento apresenta maior ganho em produtividade em solos de texturas distintas, no Estado de Sao Paulo. Os sistemas de preparo foram: grade ate 20 cm de profundidade e subsolador ate 30 cm. Foram obtidas amostras indeformadas do solo nas seguintes profundidades: 0 a 10, 10 a 20 e 20 a 30 cm, em nove repeticoes por tratamento; nos mesmos pontos foram coletadas amostras de solo para analise da fertilidade. Os seguintes atributos fisicos do solo foram determinados: densidade do solo, porosidade total e de aeracao, macro e microporosidade e da planta: altura e DAP (Diâmetro a Altura do Peito). No solo de textura media nao houve efeito do preparo do solo no crescimento das plantas, sendo estabelecido correlacao negativa entre a porosidade de aeracao, na profundidade de 10 - 20 cm, e o incremento em DAP (r2= 0,74). Essa mesma correlacao foi positiva no solo de textura argilosa (r2 = 0,78). No solo de textura argilosa, os dois sistemas de preparo de solo apresentaram maiores incrementos em altura e DAP do que a testemunha, diferindo estatisticamente no nivel de 1%, pelo teste de Tukey.

The Brazil Eucalyptus Potential Productivity Project: influence of water, nutrients and stand uniformity on wood production.

Soils with optimum water content for compaction below water field capacity and soils with poor drainage are more susceptible to compaction during forest harvesting operations. Knowing these soil characteristics allows ranking soils by their susceptibility to compaction. These laboratory analyses are time consuming, costly and require specific equipment. Collecting 13 soils with wide texture ranges, from two farms belonging to Cia. Suzano de Papel e Celulose, in the state of Sao Paulo, an index was developed, naming the average soil particle diameter, which allowed estimating the soil liquid limit, optimum water content and water field capacity based on soil particle distribution. Based on that and on daily water consumption by a Eucalyptus plantation, harvesting units were established that accounted for the number of days necessary for the soil water content to be under the optimum value for soil compaction. These harvesting units group soils that will need the same number of days (0 to 10 days) after rain to be harvested, avoiding soil compaction and the need of tilling soil for future planting.