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Tillage machinery systems as related to cropping systems
176
ABSTRACTS - - INTERNATIONAL CONFERENCE ON SOIL DYNAMICS
plasticity theory using Drucker-Prager cap model and checked with experimental tests in soil bin arranged to measure the six components of soil reaction force to the rotary blade and to observe soil surface deformation phenomena. Practicable correspondency is obtained and the pattern of soil failure is studied. The space volume swept by the blade along its path is absorbed at first primarily by the close-up of soil porosity in the compaction field developed in front of the blade along its path, even though some is also absorbed by the free boundaries, and, as the resistance to compaction increases, shear resistance along some throughout slip surface is reached, thus causing relative sliding of two parts of soil as rigid body. Relative sliding furnishes an easier outlet to void increment in this case, let down the compaction resistance and such a cycle is to repeat. A prediction technique is advanced for the estimation of soil reaction for the process with soil lab test data and operation parameters as input.
V O L U M E T H R E E m T I L L A G E M A C H I N E R Y S Y S T E M S AS RELATED TO CROPPING SYSTEMS Abstract No. 28 (Keynote Paper)
TILLAGE MACHINERY SYSTEMS AS RELATED TO CROPPING SYSTEMS H. KUIPERS Professor of Soil Tillage, Soil Tillage Laboratory Agricultural University, Diedenweg 20, 6703 GW Wageningen The Netherlands
Tillage sytstems are largely determined by the cropping system, which dictates the periods for tillage, the results required and the soil conditions when tillage can begin. There are four levels of tillage activities: tillage actions, tillage operations, tillage treatments and tillage systems. The objectives of each level differ. The major objectives of tillage systems are maintenance and improvement of soil fertility, and the technical suitability of the soil for agricultural production. Discussion of general objectives of the four tillage treatments distinguished: seedbed preparation, crop management tillage, post-harvest tillage, and primary tillage, leads to three further objectives which describe the direct effect of tillage activities: mixing, surface shaping and regulation of the soil structure. Mixing and surface shaping led to clear tillage systems with specific tillage machinery. Soil structure regulations leads only to recognizable tillage systems if the aim is to avoid soil compaction. Tillage systems based on more indirect objectives do not lead to recognizable tillage machinery systems. Abstract No. 29
SOIL FAILURE BY INTRODUCING FLUID UNDER PRESSURE KEN ARAYA Professor, Agricultural Engineering Dept., Senshu Univ. Bibai, Hokkaido, Japan
When any fluid was introduced into soil having a low permeability, large horizontal cracks were observed to form by tensile stress caused by fluid static pressure. The fluid energy required for producing such tensile cracks was relatively small. As an application, we designed the subsoiler which injected fluid from the tip of the subsoiler chisel to break down the soil structure in front of the subsoiler, permitting the subsoiler to operate in a looser soil condition. When the soil has a moisture content below the plastic limit, water dissolved air or sewage sludge was effective in reducing draft and may possibly improve the subsoil. When the soil had a moisture content close to the liquid limit, air was effective in making cracks under soil which may improve field drainage. Abstract No. 30
MECHANICAL AND VISCOELASTIC CHARACTERISTICS OF PUDDLED SOIL N. K. AWADHWALand C. P. SINGH Department of Farm Power and Machinery Punjab Agricultural Univrsity Ludhiana 141 004, India
Shear strength characteristic of a wet soil (unpuddled and puddled) were studied with a vane shear apparatus for a wide range of shear velocity (0.45 cm/sec to 133 cm/sec) and their curvilinear relationship were established. The velocity independent components were determined from these relationships. The viscoelastic parameters of the rheological model for puddled soil were estimated experimentally. The effects of puddling and thixotropy (time dependent changes in soil after puddling) on the velocity independent shear strength characteristics, cone index, and viscoelastic parameters of puddled soil were studied. A term, degree of puddle was defined to quantify the physical state of puddled soil.
ABSTRACTS - - INTERNATIONAL CONFERENCE ON SOIL DYNAMICS
plasticity theory using Drucker-Prager cap model and checked with experimental tests in soil bin arranged to measure the six components of soil reaction force to the rotary blade and to observe soil surface deformation phenomena. Practicable correspondency is obtained and the pattern of soil failure is studied. The space volume swept by the blade along its path is absorbed at first primarily by the close-up of soil porosity in the compaction field developed in front of the blade along its path, even though some is also absorbed by the free boundaries, and, as the resistance to compaction increases, shear resistance along some throughout slip surface is reached, thus causing relative sliding of two parts of soil as rigid body. Relative sliding furnishes an easier outlet to void increment in this case, let down the compaction resistance and such a cycle is to repeat. A prediction technique is advanced for the estimation of soil reaction for the process with soil lab test data and operation parameters as input.
V O L U M E T H R E E m T I L L A G E M A C H I N E R Y S Y S T E M S AS RELATED TO CROPPING SYSTEMS Abstract No. 28 (Keynote Paper)
TILLAGE MACHINERY SYSTEMS AS RELATED TO CROPPING SYSTEMS H. KUIPERS Professor of Soil Tillage, Soil Tillage Laboratory Agricultural University, Diedenweg 20, 6703 GW Wageningen The Netherlands
Tillage sytstems are largely determined by the cropping system, which dictates the periods for tillage, the results required and the soil conditions when tillage can begin. There are four levels of tillage activities: tillage actions, tillage operations, tillage treatments and tillage systems. The objectives of each level differ. The major objectives of tillage systems are maintenance and improvement of soil fertility, and the technical suitability of the soil for agricultural production. Discussion of general objectives of the four tillage treatments distinguished: seedbed preparation, crop management tillage, post-harvest tillage, and primary tillage, leads to three further objectives which describe the direct effect of tillage activities: mixing, surface shaping and regulation of the soil structure. Mixing and surface shaping led to clear tillage systems with specific tillage machinery. Soil structure regulations leads only to recognizable tillage systems if the aim is to avoid soil compaction. Tillage systems based on more indirect objectives do not lead to recognizable tillage machinery systems. Abstract No. 29
SOIL FAILURE BY INTRODUCING FLUID UNDER PRESSURE KEN ARAYA Professor, Agricultural Engineering Dept., Senshu Univ. Bibai, Hokkaido, Japan
When any fluid was introduced into soil having a low permeability, large horizontal cracks were observed to form by tensile stress caused by fluid static pressure. The fluid energy required for producing such tensile cracks was relatively small. As an application, we designed the subsoiler which injected fluid from the tip of the subsoiler chisel to break down the soil structure in front of the subsoiler, permitting the subsoiler to operate in a looser soil condition. When the soil has a moisture content below the plastic limit, water dissolved air or sewage sludge was effective in reducing draft and may possibly improve the subsoil. When the soil had a moisture content close to the liquid limit, air was effective in making cracks under soil which may improve field drainage. Abstract No. 30
MECHANICAL AND VISCOELASTIC CHARACTERISTICS OF PUDDLED SOIL N. K. AWADHWALand C. P. SINGH Department of Farm Power and Machinery Punjab Agricultural Univrsity Ludhiana 141 004, India
Shear strength characteristic of a wet soil (unpuddled and puddled) were studied with a vane shear apparatus for a wide range of shear velocity (0.45 cm/sec to 133 cm/sec) and their curvilinear relationship were established. The velocity independent components were determined from these relationships. The viscoelastic parameters of the rheological model for puddled soil were estimated experimentally. The effects of puddling and thixotropy (time dependent changes in soil after puddling) on the velocity independent shear strength characteristics, cone index, and viscoelastic parameters of puddled soil were studied. A term, degree of puddle was defined to quantify the physical state of puddled soil.