Marcelo Ivan Mentges

Relação entre solo e haste sulcadora de semeadora em Latossolo escarificado em diferentes épocas

The objective of this study was to evaluate the chiseling effect duration in an Oxisol, based on the study of soil and planter shank relation. The treatments were: no-till for 13 years; four years since chiseling (2001); two years since chiseling (2002); and six months since chiseling (2005), where all treatments were submitted or not to traffic with agricultural machinery. Data about vertical force and moment associated to: shank, soil mobilized area, specific operational resistance, macroporosity, microporosity, total porosity and soil density, were collected, and draught on shank was calculated. Increasing of time since chiseling required increasing of the forces, and six months since chiseling showed the smallest demand. Four years since chiseling had similar behavior to the no-till treatment, resulting in the smallest soil mobilized area and the greatest operational resistance. Physical property differences occurred only in layer 0-0.10 m, and recent chiseling showed the greatest soil macroporosity, and the smallest soil microporosity and bulk density. After four years, chiseling effect was not found on soil-planter shank relations.

Compressibilidade de um Argissolo Vermelho-Amarelo trafegado e escarificado

Farm machinery wheeling is considered a major source of soil compaction. The use of chisel plow can minimize such effects, but the chisel can cause subsurface compaction. The aim of this study was to evaluate the effect of traffic and is present below the compaction layer thought compressive parameters of soil. The treatments investigated were: no-tillage, no-tillage with additional traffic (traffic intensity of 24.67Mg km ha-1), no-tillage chiseling recent implanted, no-tillage with additional traffic and chiseling recent implanted. For the density, void ratio, preconsolidation pressure and coefficient of compressibility determination in the layers 0.0-0.10m, 0.10-0.20m, 0.20-0.30m and 0.30 to 0.40m samples were collected. The treatment no-tillage showed the lowest load support capacity and greater susceptibility to compaction. The traffic intensity of 24.67Mg km ha-1 increased bulk density and decreased void ratio until 0.30m depth. The chisel plow did not affect the preconsolidation pressure and coefficient of compressibility of soil layer below the line of action of the chisel tip.

Cultivo mínimo: efeito da compactação e deformação abaixo da atuação da ponteira do subsolador

A B ST R A C T Soil compaction at the depth of mobilization by tillage implements may occur under some soil conditions. The objective of this study was to verify the existence of compaction under the working depth and evaluate the effect of chisel plow in soil under determined levels of compaction. The treatments in study were 13 years of no-tillage and no-tillage with additional compaction. Horizontal force (F H ), Draught (F T ), vertical forces (F V ), and moment (Mo) associated the chisel tool, operation specific resistance, mobilized area, elevation area, swelling, soil penetration resistance, and physical properties of soil were determined. The additional compaction showed an increment of 18.9% in the horizontal force and draught. The greatest contribution of additional compaction was in vertical force, which provided an increment of 78.2%, showing that the load action is mainly in the vertical direction. No-tillage demonstrated smaller draught demand per mobilized soil area compared to additional compaction treatment. Instead of occurring compaction under the chisel action depth, there was soil mobilization, resulting in smaller soil mechanical penetration resistance in this layer.

Propriedades físico-hídricas do solo e demanda energética de haste escarificadora em Argissolo compactado

The objective of this work was to evaluate the soil compaction effect on its physicohydric properties and on chisel energy demand, as well as to quantify the behavior of these properties below the chisel working depth. The experiment was carried out in a sandy loam Alfisol, with the following treatments: no-tillage for 13 years; no-tillage for 13 years and chiseling; no-tillage with additional compaction; and no-tillage with additional compaction and chiseling. Compaction along the chiseling depth was verified through data of traction effort associated to the chisel, obtained with the aid of an octagonal ring linked to a data acquisition module. Soil bulk density, total porosity, macroporosity, microporosity, hydraulic conductivity and soil resistance to mechanical penetration were also determined. Soil compaction increased both soil bulk density and resistance to mechanical penetration, reducing the total porosity and the macroporosity, without causing significant effects in microporosity. The compaction increased chisel energy demand in 21.64%, increasing the mean value of traction effort from 5.33 kN to 6.35 kN. Soil chiseling did not increase soil compaction status below the chisel working depth in the sandy loam Alfisol.

ALTERAÇÕES ESTRUTURAIS E MECÂNICAS DE SOLO DE VÁRZEA CULTIVADO COM ARROZ IRRIGADO POR INUNDAÇÃO

A conversao de area natural para area de uso agricola pode degradar a estrutura do solo, favorecendo a ocorrencia de compactacao. Este trabalho teve por objetivo avaliar as alteracoes nas propriedades fisico-hidricas e mecânicas de um Gleissolo Haplico provocadas pela conversao de um campo natural antropizado para area de cultivo de arroz irrigado. Propriedades fisico-hidricas (densidade, porosidade total, macro e microporosidade, indice de vazios e retencao de agua) e mecânicas (pressao de preconsolidacao, indice de compressao, coeficiente de descompressao e indice de recuperacao) foram avaliadas nos horizontes A1 (0,0-0,25 m), A2 (0,25-0,51 m), Cg1 (0,51-0,92 m) e Cg2 (0,92-1,20+ m) em solo sob campo antropizado sem uso agricola e nos horizontes Ap (0,0-0,17 m), A (0,17-0,40 m), Cg1 (0,40-0,70 m) e Cg2 (0,70-1,00+ m), em solo cultivado com arroz irrigado. Oito anos de cultivo de arroz sob preparo convencional e irrigacao por inundacao nao alteraram significativamente as propriedades fisico-hidricas e mecânicas, de acordo com a analise de agrupamentos. Porem, o cultivo de arroz aumentou a densidade do solo e reduziu o indice de vazios, a porosidade total e a macroporosidade. A relacao da elasticidade com a densidade do solo, a porosidade total e o indice de vazios foi influenciada pelo tipo de estrutura, pois maiores compressoes e descompressoes ocorreram nos horizontes de estrutura prismatica, em comparacao aos horizontes de estrutura macica.

Métodos de obtenção da capacidade de suporte de carga de um argissolo cultivado

The control of soil load support capacity can reduce the damaging effects of compaction. The main objective of this study was to evaluate the use of prediction models of consolidation stress under different conditions for a Hapludalf. The treatments consisted of: (a) soil under no-tillage (control) (b) soil under no-tillage with traffic intensity of 24.79 Mg km ha-1 and (c) 49.59 Mg km ha-1; (d) soil after five months of minimum tillage; and (e) soil under minimum tillage compacted by traffic (soil stress of 260 kPa and 24.67 Mg km ha-1). The soil support capacity was predicted by the following methods: (1) intersection of virgin compression line (VCL) with x-axis at zero deformation; (2) intercept of the VCL and regression with the first two points of the curve; (3) intercept of the VCL and regression with the first three points of the curve; (4) soil resistance at 2.5 % deformation; (5) method of Casagrande with sigmoidal fit of the van Genuchten equation (reference); and (6) method of Pacheco & Silva with sigmoidal fit of the van Genuchten equation. The values by the methods with 2.5 % deformation and intersection of VCL with the x-axis tended to be underestimated, compared to the reference in all layers. The regression method on the other hand varied according to the slope of the VCL; at high slopes, the values tended to be over- and at low slopes underestimated.

Demanda de tração e propriedades físicas de um Argissolo em diferentes manejos e intensidades de tráfego

The objective of this work was to evaluate the effect of traffic intensity and soil management on the draught demand of a fertilizer furrow-opener, and on the physical properties of a Hapludalf. Treatments were: no-tillage with natural traffic, no-tillage with traffic intensity of 24.79 Mg km-1no-tillage with traffic intensity of 49.59 Mg km-1, minimum tillage and minimum tillage in compacted soil with 24.67 Mg km ha-1. Data were collected for: total porosity; bulk density; penetration resistance; and for horizontal, vertical and draught forces demanded from the fertilizer planters. The subsoiling of minimum tillage used as an isolated technique did not reduce the compaction effects by a traffic intensity of 24,67 Mg km ha-1The traffic changes the soil structure but not the draught requirement. The changes in its intensity from 24.79 to 49.59 Mg km ha-1 does not further affect in the evaluated properties.