Ken Araya

Characteristics of Salt-affected Soils by Deep Tillage up to 600 mm -Disaggregation Experiments of Soil Clods-

Abstract A method is proposed for soil improvement of salt-affected soils. We envisaged that a layer of about 600 mm in depth could be tilled by a special plough, producing a coarse layer (soil clods) in the subsoil (B and C horizons) and cutting off the capillarity rise of groundwater. In this paper, indoor testing with soil bins was used to determine the proper size of the soil clods produced in the subsoil which will be used for design of a new plough configuration. The results showed that the porosity of the subsoil reached 0.49 where capillarity restarted, after 2000 mm of precipitation. The size of the soil clods of the B horizon should be about 10 cm to prevent collapse and loss of volume of the topsoil (A horizon). That of the C horizon should be about 14 cm to keep a longer capillarity interception.

Single Droplet Combustion of Sunflower Oil

When sunflower oil (or plant oil, in general) was used as diesel engine fuel, the ignitability at low temperatures was much poorer than for No. 2 diesel oil. In addition, unburned carbon accumulated in the combustion chamber when the engine was idling. The research reported in this paper was conducted to investigate the causes of these problems. A single fuel droplet set at the tip of a combustion thread was inserted into an electric furnace and ignited. The behavior of the combustion was observed and analyzed by a high speed rotary video camera. The fuels studied were sunflower oil, No. 2 diesel oil, sunflower oil methyl ester and fish oil methyl ester. As a result, even if the droplet size of sunflower oil was the same as that of No. 2 diesel oil, its ignition delay was much longer than No. 2 diesel oil. This may be the main cause of poor ignitability of sunflower oil at low temperatures.

Sintering of Salt-affected Soils: Part 1: Sintering of Soil Layers*

Abstract A new method is proposed for soil improvement of salt-affected soils in regions where a sufficient amount of rainfall occurs in summer. The subsoil is made coarse by soil sintering, and the capillarity from groundwater is cut off. In this paper, basic experiments of soil sintering were conducted, based on the thermophysical properties of the salt-affected soils reported in previous papers. The results show that when the soil layer is deep, a long time is required for complete sintering. For instance, the time for the temperature at the 0.04 m in depth to reach maximum (960°C ) was 278 hr. This is fundamental fault of soils whose thermal conductivity (800°C) is small (e.g., 0.1 Wm −1 K −1 ) and thermal diffusivity (800°C) is also small (e.g., 1.19×10 −7 m×s −1 ). The soil should be dry as much as possible when sintering. If the soil water content decreased to 8.7% d.b. (dry) from 26.6% d.b. (wet), the required heating time to reach 960°C at the soil surface was saved to about 200 s from about 500 s.

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils: Part 1: Configuration of Plough for Production of Large Soil Clods in Subsoil*

Abstract A method is proposed for soil improvement of salt-affected soils. Soil clods of desired size are produced in subsoil by deep tillage to cut off capillarity from groundwater and to prevent the rise of salts to the soil surface. In this paper, the plough configuration to produce soil clods with the proper size by brittle fracture was analysed in an indoor soil bin. The results showed that when brittle fracture (tensile failure) took place in the soil, a horizontal crack in the soil was produced at the tip of the plough blade, followed by an another upward crack toward the soil surface with the angle of about 40°. A short blade length (50 and 80 mm) and deep ploughing (150 and 200 mm) of the deep tillage plough generated unwanted huge soil clods of about 25 kg. In order to generate proper soil clods, the ideal rake angle should be 20°, and the ideal blade length was 130 mm.

Haskaop Harvester: — Part 1: Air Drag Coefficient of Haskaop Berry and Leaf —*

Abstract In order to separate haskaop berry and leaf during harvest, a vertical separation column was envisaged. The air drag coefficients of berry and leaf were measured to determine the proper air velocity in the separation column. The results show that the air drag coefficient of a berry set horizontally in the air flow was 0.959-2.21, and that of a berry set vertically was 0.322-0.977. The air drag coefficient of the leaves was 0.622-2.36. The minimum terminal velocity of berries (horizontally, 9.1 ms −1 and vertically, 11.0 ms −1 ) was significantly different from the maximum terminal velocity of the leaves (2.35 ms −1 ). Therefore, it should be possible to separate the berries and leaves using the air velocity from trial experiments in the separation column.

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils:—Part 2: Draught and Vertical Force Induced on Plough by Brittle Fracture—

Abstract A method is proposed for soil improvement of salt-affected soils. Large soil clods are produced in subsoil by deep tillage to cut off capillarity from groundwater and to prevent the rise of salts to the soil surface. In this paper, the draught and vertical force induced on this plough body by brittle fracture (not by shear failure) was analysed to get the large soil clods in an indoor soil bin with a soil with cement. The results showed that the normal mean peak draught was about 1 kN, and the downward vertical peak force was about 10 kN at 200 mm in the operating depth. When the blade length was short (50 mm or 80 mm) and huge soil clods were produced, the peak draught and vertical force increased to about 2 kN and 20 kN respectively. When the blade length was long (200 and 250 mm) and the operating depth was deep (150 and 200 mm), the peak draught increased abnormally to 4–5 kN. The peak vertical force also increased abnormally to 30–40 kN. The proper length of the plough blade was determined to be 130 mm because of the smallest draught and downward vertical force.

Improvement of Salt-affected Soils by Deep Ploughing: —Part 2: Plot Field Tests in a Sodic Soil (Solonetz) Region—*

Abstract A method was investigated for improvement of salt-affected soils in regions where a sufficient amount of rainfall to percolate into subsoil occurs in summer. A coarse layer is provided in the subsoil by deep tillage, making soil clods to cut off the capillary rise from groundwater. This paper deals with plot test fields constructed by hand in a local spot of a sodic soil (solonetz) region. The results showed that deep tillage up to the subsoil (C horizon) was beneficial for improvement of the solonetz soil. Application of the gypsum also reclaimed the solonetz soil, and should be mixed into the A horizon. The pH values decreased from about 10 to 9. The EC values decreased from about 8 dSm -1 to 2 dSm -1 .

Sintering of Salt-affected Soils — Part 2: On-board Sintering of Soil —

A new method is proposed for soil improvement of salt-affected soils in regions where a sufficient amount of rainfall occurs in summer. The subsoil is made coarse by soil sintering, and the capillarity from groundwater is cut off. Thus, the rise to the soil surface of salts which are dissolved in the groundwater is prevented. Moreover, the salts that accumulate in the topsoil are washed out by rainfall (leaching) during the summer season. In this paper, based on the previous experiments of soil sintering, a prototypical soil-sintering plough was developed to make soil coarse. A stationary soil-sintering device was used to determine optimal conditions of thickness of spread soil on the conveyor, and conveyor speed. When this soil thickness was 15 mm and the conveyor speed was 5.7 mm s-1, the maximum thermal efficiency (about 30%) was obtained. When these conditions were applied to a prototypical soil-sintering plough attached behind a tractor, the required plough travel speed was 1.9 mm s−1 (6.84s10−3 km h−1) for practical use with 3 burners, 90 mm in the operating depth and 300 mm in the operating width.

A Powered Rotary Subsoiler with Pressurized Sewage Sludge Injection

ABSTRACT THREE factors favor the use of the powered rotary subsoiler concept. They are: (a) Power can be transmitted directly more efficiently than through drawbar pull, (b) Reduction in draft requirements by tillage tools reduces the need for heavy tractive vehicles, thereby reducing the soil compaction, and (c) Reduction in draft requirements allows tillage operations to be performed in more difficult traction conditions. This report deals with the power requirements of a rotary subsoiler which injects the sewage sludge into the soil from the tips of rotor tines. The power requirements for the system was reduced by as much as 50% in the range of a large velocity ratio while injecting liquid sludge under pressure into the soil. With sludge injection, the power required for forward rotation (down cutting) was less than that required for reverse rotation (up cutting)..

Improvement of Salt-affected Soils by Deep Tillage: Part 2: Large-scale Field Tests in a Sodic Soil (Solonetz) Region*

A deep tillage method was tested for soil improvement of salt-affected soils. Capillary rise of groundwater was cut off by the deep tillage, which made a coarse layer in the subsoil. This paper deals with large-scale field tests constructed by a four-stage subsoil plough in a sodic soil (solonetz) region. The results showed that the deep tillage down to the subsoil proved positive for the improvement of the solonetz soil. In the deeply tilled field, the grass height and density of cultivated natural pasture were much greater than those in the conventional (subsoiled) field. In the subsoiled field, the grasses were growing at the areas on the subsoiler channels, but their grass height was much shorter than in the deeply tilled field. At the undisturbed areas between the subsoiler channels, the grasses could not survive at all.