Renato Antonio Dedecek

Perdas por erosão e rendimentos de soja e de trigo em diferentes sistemas de preparo de um latossolo roxo de Dourados (MS)

Soil and water losses were evaluated from 1987 to 1995, on a very clayey red dusky latosol, with 0.03 m m-1 slope, of Embrapa-Centro de Pesquisa Agropecuaria do Oeste, at Dourados, Mato Grosso do Sul State, Brazil. Soil tillage systems used for growing wheat and soybean in succession were: chisel plow + tandem disk (ES), offset disk + tandem disk (GP), no tillage (PD) and conventional tillage, with no vegetable cover (DE). All tillage operations and seeding were in the up and down hill. PD was the most efficient tillage system to control soil and water losses and was the most productive. GP was the least efficient. Means of soil and water losses for PD, ES, GP and DE were, respectively: 0.8; 2.8; 5.3 and 7.3 t ha-1 year-1, and 27, 80, 112, and 149 mm year-1. Compared to DE, the PD controlled 89% of soil and 82% of water erosion losses, and yielded 17% more soybean and wheat grain than GP. As for wheat, ES was 12% more productive than GP. Rainfall-runoff erosivity factor (R) was 6.411 MJ mm ha-1 h-1 year-1, and the erodibility fator (K) was 0.0045 t h MJ-1 mm-1, reflecting characteristics of high infiltration and high internal drainage of this soil. During the 1994/95 growing season, the highest soil loss period per time unit was from seedbed preparation to seeding soybean, and the period of highest absolute soil erosion losses was from 30 to 60 days after seeding soybean. This shows the great importance of soil cover, specially during the inicial cropping phase, and support the recommendation of the no tillage system for this region.

Características físicas e químicas de substratos para produção de mudas de Ilex paraguariensis St. Hil.

This work aimed to evaluate the physical and chemical properties of different materials and their compositions, as well as their efficiency in the production of Ilex paraguariensis seedlings in plastic tubes. The work was conducted at the Baldo S.A. Company nursery in Sao Mateus do Sul, PR, Brazil. Six materials were used to formulate 14 treatments: cattle manure, semi-decomposed sawdust, Ilex paraguariensis chopped stems, underground earth, commercial substrate based on pinus bark and earthworm humus. The results indicated that the treatments containing sawdust, Ilex paraguariensis stems and mainly cattle manure, besides being more economical, produced good quality seedlings. The treatments consisting of 40% cattle manure and 60% sawdust stood out because of the good cost-benefit ratio and the easiness of preparation. Substrate chemical characteristics did not affect the physical characteristics, as well the influence of physical characteristics on Ilex paraguariensis seedling production depends on the analyzed variable.

Influência dos atributos do solo sobre a qualidade da madeira de Pinus taeda para produção de celulose Kraft

To meet the increasing demand for forest products, much of the future timber supply will come from trees grown in managed plantations. This work was carried out to analyze the effects of soil attributes on Pinus taeda wood quality to produce Kraft cellulose at Klabin Parana Cellulose Co., in Telemaco Borba, PR, Brazil. The study focused on the influence of soil attributes on the anatomical, physical and chemical wood characteristics, as well as their relation to cellulose production. Eight sites with twelve-year-old trees were selected based on soil type, soil texture and primary vegetation. The soil variables studied were bulk density, total porosity, macroporosity, water availability, fertility and grain size distribution. For tree selection, dendrometric measurements of 50 trees were taken per site, and 5 average size trees selected per site. Total and commercial height and DBH were measured and discs removed. Tree samples were analyzed for basic density, chemical composition, tracheid morphological characteristics, nutritional status and Kraft cellulose production. The soil chemical attributes exerted significant influence on wood quality, but the soil physical attributes showed greater influence on cellulose productivity. Sites with higher growth rate and those with clay texture showed lower values of basic density, higher content of extract and lignin, thus showing lower content of holocellulose and cellulose, shorter and wider tracheids with thinner walls and higher lumen diameters, and lower cellulose yield. Based on these results, it was concluded that cellulose pulp characteristics can be estimated by analyzing wood characteristics combined with the existing site edaphic conditions.

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.

Influência dos atributos do solo sobre a produtividade de Pinus taeda

The present work analyzed the effects of soil attributes on Pinus taeda productivity. This work was conducted at Klabin, in Telemaco Borba-PR. Eight different sites growing twelve-year-old trees were analyzed. These sites were selected based on the soil type, texture and primary vegetation. Soil sampling at 3 depths was carried out to characterize the site . Undisturbed and bulk soil samples were collected. The studied soil variables were: bulk density, total porosity, macroporosity, water availability, fertility and particle size distribution. Five medium trees were selected per site, taking the measures total and commercial height, and DBH. The mainly found results were as follows: clay soils were more productive, regardless of soil class they belonged to. Generally, Pinus taeda productivity is influenced by alterations occurred in physical and chemical soil attributes. These findings contradict several reported studies that soil chemical attributes had effect on productivity only when considered in groups.

Manejo dos resíduos da colheita de acácia-negra ( Acacia mearnsii De Wild) e a sustentabilidade do sítio.

Black wattles can grow on several environmental conditions being a fast growing and short life pioneer specie. This work was established on Acacia mearnsii De Wild commercial plantations, belonging to TANAGRO Co., in Piratini, Rio Grande do Sul, Brazil, growing on different soil types, with plants from the same origin. In each of the five-soil type, a treatment to evaluate black wattle growth in DBH and height, and above ground biomass was considered. Soils had their surface horizons characterized morphological, chemical and physically, and nutritional status were measured in every plant compartment, tannin yield in plant bark, amount of lignin and total extractives were determined in commercial stem wood. Neossolo Litolico eutrofico (Entisol) showed the greatest commercial stem volumes and Neossolo Litolico alico (Entisol) was the least productive, especially due to soil fertility differences, mainly P level, base saturation and aluminum saturation. The amount of macronutrients returned, keeping harvesting residues (branches and crown) on soil surface, was greater than the amount exported in commercial stem and bark, attesting its efficiency on soil reclaiming, if the residues are not burned. In most productive soils in volume of commercial stems, the amount of calcium and magnesium exported was greater than the amount returned to soil. The amount of tannin in black wattle bark was greater in plants growing in adverse soil conditions (shallow and stony soils).

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

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.

Produtividade de trigo e soja em Latossolo Vermelho distrófico sob erosão simulada e causada pela chuva

O objetivo deste trabalho foi avaliar o efeito da erosao hidrica, simulada pela retirada de camadas superficiais de solo e causada pela chuva, na produtividade do trigo e da soja. As espessuras das camadas de solo retiradas foram de 0 cm, 3 cm, 6 cm e 14 cm, representando a perda de todo o horizonte Ap. Foram avaliados atributos quimicos e fisicos do solo ate a profundidade de 30 cm. A produtividade do trigo nao permitiu estabelecer qualquer correlacao com a remocao artificial de camadas de solo, enquanto a da soja foi reduzida em 148 kg ha-1 por cm de solo removido na espessura de solo de 0-6 cm e de 105 kg ha-1 por cm de solo removido na espessura de 0-14 cm. O teor de Ca+Mg e a capacidade de troca de cations, em diferentes profundidades, foram os atributos do solo que mais influenciaram na produtividade da soja. O teor de C orgânico foi o unico atributo do solo que se correlacionou com as producoes de trigo e soja, tanto nas condicoes de erosao causada pela chuva como nas de simulacao de erosao. A simulacao do efeito da erosao pela retirada artificial de camadas do solo pode ser utilizada para predizer o efeito da erosao hidrica na produtividade da soja em Latossolo Vermelho, uma vez que a diferenca do efeito da remocao artificial no rendimento desta cultura em relacao as condicoes sob chuva foi menor do que 6%.

Influência da posição na encosta na manifestação do caráter coeso em solos da formação Macacu, no estado do Rio de Janeiro

The cohesive nature of horizons of certain soils interferes directly with plant growth, by reducing the effective soil depth, plant root volume and seedling emergence, due to the decreased availability of water and air in the soil. This paper aimed to use soil physical characteristics to describe the cohesive character and the influence of the soil landscape position on two slopesof soils developed from sediments of the Macacu Formation in Itaborai, RJ, Brazil. The soils of both slopes were classified as Argissolo Amarelo distrocoeso tipico (Ultisol) in the upper position and as Latossolo Amarelo distrocoeso tipico (Oxisol) at the foot slope. The soil bulk density of the cohesive subsurface horizons reached 1.78 Mg m-3. Another evidence of the trendto show cohesive character was the great difference between soil physical propertiesofthe A horizon and the subsurface layers (BA and BW). In the soils at the foot slope position the moisture content, hydraulic conductivity, and available water content were higher. The expression of the cohesive character was stronger at the upper position of the landscape. The physical properties that best distinguished the soil samples in terms of landscape positions were bulk density and macroporosity for soils at the summits, and available water and total porosity for the foot slope. The soils at the bottom of the slope had higher water contents, which must have minimized the expression of the cohesive character. This study indicates the importance of developing more studies on different aspects of the degree of cohesion existing along a landscape, controlled primarily by water flows down the slope.

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

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.