A model roller was traveled repeatedly along a soil bin with low traveling slip under 3 different coverage conditions; uncovered, and covered by a 1-mm or 3-mm thick rubber sheet. Soil displacement during each traveling was recorded by taking series of pictures through the transparent acrylic soil bin wall and application of image processing. Soil surface coverage affects the size and shape of the soil displacement trajectory for each travel. The soil particles at the deeper layers under coverage by the 3-mm sheet were displaced the furthermost downward among the 3 sets of conditions after only one travel. Coverage by a thick sheet significantly decreased the horizontal displacement of the soil during travel repetition, while that by the thin sheet had the opposite result. The results showed that consideration of soil surface coverage would help in the control of soil compaction.

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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.

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When haskaop berries were harvested by vacuum suction, trash such as leaves was collected together. In order to separate haskaop berries from other materials during harvest, a vertical separation column (mean air velocity was 4 ms^-1) was designed and built, as described earlier. In this paper, a portable and prototypical haskaop harvester was designed and built with this separation column. The results showed that the average harvest speed by handpicking was 0.45 berries/s (1 kg/h) and that by the harvester was 2.5 berries/s (6 kg/h). A soft plastic sheet (2 mm thick) was the most feasible as a material for rake fingers. The best shape for the harvester collection scoop employed a pitch of fingers at 12 mm and height 5 mm. The percentage of damaged berries by handpicking was nearly 0%, but that by the harvester was generally acceptable at 4%. Berries never found their way into the exhaust (dust) hopper.

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A method of ploughing was investigated for improvement of salt-affected soils. A coarse layer provided in the subsoil by deep tillage created soil clods to cut off the capillary rise from groundwater. This paper deals with large-scale test fields constructed by using a four-stage subsoil plough in a saline soil (solonchak) region. The results showed that the deep tillage to the subsoil was beneficial for the improvement of the solonchak soil. In the deeply tilled field, rapes and potatoes were taller and healthier than in the conventional field where the topsoil alone was tilled. Weeds were almost completely eliminated in the deeply tilled field. The yield (dry mass) of the rape in the deeply tilled field increased 1.27 times, and potato yields more than doubled. A reduction of pH and EC values was obtained in the deeply tilled field.

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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.

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In order to understand the driving performance of a vehicle, accurate measurements of its position and posture are required. In this study, a method was proposed for measuring the position of a turning vehicle using a camera at an arbitrary position, along with 6 markers on the vehicle. The trajectory of a 4-wheel drive and 4-wheel-steering vehicle during steady-state circular turning was then measured using the proposed method. Although it was confirmed that there was an error in the depth direction from the camera, the turning trajectory of the vehicle could be measured with high precision. However, a variation in the measurement of the vehicle posture was recognized.

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