We had investigated an actual growth of volunteer wheats in barley field, and have conducted a field experiment on the control of volunteer wheat by different tillage methods.
The results obtained were as follows.
1) Ninety six hills of volunteer wheat per 10 a were observed in the barley field.
Eighty five percent of volunteer wheat grains harvested were grain size of >2.5mm, which could not separate from the barley grains by use of grader.
2) Emergence depth of volunteer wheats grown in the barly field were distributed in the soil surface layer less than 5cm depth.
3) Emergence times of volunteer wheats showed the varietal differences, as low rate in summer and high rate in fall for the varieties which need long term after-ripening.
4) Volunteer wheats did not grow in either plot where plow-till in summer followed by rotary-till in autumn, and where plow-till in summer and no till in autunm.

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It is not obvious which flower buds on each bearing shoots should be kept to obtain fruits of good quality. We studied the influence of position of flower buds on fruit shape, using weak shoots which growth has stopped and moderate growing shoots, both bearing five flower buds.
Results as follows:
1. Flower buds in the center and those near the center were heavier, and larger diameter.
2. The proportion of blooming was highest on the fourth day of blooming on moderate shoots. Blooming was earlier for flower buds in the center and near the center.
3. Longitudinal diameter of all fruits 3 to 5 weeks after full bloom reached 70 to 80% of their final longitudinal diameter. Particularly, the basal fruits showed higher daily increase in diameter in the early period.
4. Basal fruits on weak shoots and fruits in the center and neighbouring fruits on moderate shoots grew larger, while apical fruits grew less. Basal fruits tended to be flatter, and apical fruits tended to be more cylindrical. Fruits in the center borne on moderate shoots tended to have higher green value compared to basal fruits. No difference was found in Brix and hardness of the fruits according to the fruiting position.
5. From these results, it can be assumed that in order to produce fruits of good quality, flower buds on either end should be removed regardless to the growth of fruit bearing shoots in the early period. Early disbudding and/or deblossoming would reduce working hours and increase working efficiency.

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In this study we practiced a joint experiment on tillage methods (PT, RT and NT) and soil types (volcanic L, volcanic SiC and sandy LS) simultaneously throughout the three places (Tokyo, Niiga taand shimane) from April in 1988 to June in 1991. In this paper we report the experimental results on six croppings for three years (crops=dent corn in summer and barley in winter) at volcanic L soil.
1) Significant differences of the grain yield of dent corn were not observed in plots at the third and fifth croppings though they didn't reach to an ordinary yield level because of damages by tornado and hail. The grain yield of barley of NT was the maximum in plots at the second cropping, but it decreased at fourth cropping. It decreased more sharply at the sixth cropping. There were no differences in harvest index of the plots.
2) The quantity of weed of NT at the fourth and sixth croppings were more than those of PT and RT. The dominant species of weed were commonly observed in the plots.
3) Significant differences of soil hardness (penetrating resistance) were observed in depth and plots. Soil hardness of NT were higher than other plots because of passed an half year from the final tillage. In the results of soil hardness changes during one cropping, the hardness of PT and RT increased after one month from the final tillage.
4) Significant differences of soil pH were not observed in depth and plots.
5) From the viewpoint of crop yield, no-tillage farming is profitable to the early cropping, so a renewing tillage to NT become to be important in practical.

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An experimental planting-mechanism to be applied for the planting of taro-seeds was developed, with examinations of delivery performances and planting-accuracy of the device.
The results obtained are as follows.
1. The delivery-rate of the single seed and the delivery-rate of the zero seed (Variety: Daikichi; 90-92%, 6-7% Ishikawawasemaru; 85-89%, 8-9%, respectively) were obtained under the circumferential bucket-conveyor-speed of 10.6-12.7cm/s.
2. The proper planting-rate of the individual seed (Variety: Daikichi; 96-97% Ishikawawasemaru; 90%, respectively) was obtained under the circumferential planting-roll-speed of 14.4-17.3cm/s.
3. In order to develop a taro planter of high performance, the effect of the field test and the durability of the planting-mechanism must be investigated in the near future.

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The Chinese Yam which is one of specialized product in sand dune field forms the axillary buds called bulblets or propagules grown along the aerial leaf axil, and falls a large number of them on the field surface at the harvesting season. The fallen bulblets are partly harvested by manual mode, but mostly are left in the field as it is because of labor shortage. The object of this paper is to obtain the practical designing information being suitable for the development of the bulblet harvester. Several findings concerning the physical properties of bulblets and sieve analysis of dune sand can be drawn as follows.
1) The amount of bulblets fallen in the field is approximately 780kg and more than 1.3 million pieces per 10a. This scattering distribution seems to be affected considerably by the yearly sites conditions.
2) An average diameter of single bulblet shows 10.3mm and the average mass takes 0.1 to 3.3g, while the average diameter ranges 5 to 20mm.
3) Morphologically, more than 40% of all the samples are dominated by the ones of round shape, and they tend to be more round slightly with the decrease of the bulblet size.
4) The static coefficient of friction of the bulb lets fall within less than 0.6 on the inclined board covered by vinyl chloride.
5) When serving dune sand at less than 1.5% d.b. soil moisture content on the sieve, the dune sand tends to flow downwards immediately after supply without any retention on to the sieve even under no oscillating condition. Furthermore, with the increase of moisture content at exceeding 2% d.b., the amount of dune sand passed through sieve begings to decrease suddenly and little flow could take place at more than 3%.
6) To attain 100% in terms or the percentage of dune sand passed through sieve, the working depth of the harvester should be maintained as shallow as possible in dry dune sand, which is moisture content about 0.3%, generally formed under the fine climate condition.

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In this study, we practiced a renovation trial by plowing to the continuous no-tillage field passed 11 years. The field seemed to be deteriorated for cultivation judging from the changes of soil condition and crop yield. The renovation trial based on the two-factors experiment with three levels of tillage and three levels of materials for soil improvement was started at April in 1991.
1) Water content of soil in NC (renovation of notillage plot) was equal to that in CC (continuous plowing plot), but soil hardness (penetration resistance) in NC was higher than that in CC.
2) Field efficiency of plowing in NC was higher than that in CC. Depth of tillage in NC was equal to that in CC, but the average value of width of tillage estimated from total width of plowed area and number of furrow in NC was wider than that in CC.
3) Fuel consumption per unit area in NC was 5% higher, and the consumption per unit time in NC was 14% higher than those in CC.
4) Specific resistance of soil estimated from the measured values, such as fuel consumption and traveling speed, in NC was higher by 8% than that in CC.
5) From the result of analysis of variance for dry matter yield of corn, there was the significant difference with 1% level for tillage factor only. When we adopted the value of 100 to crop yield in CC as a standard, the crop yield in NC was 97, that was 67 in NN (continuous no-tillage plot), respectively.
6) From the result of analysis of variance for the quantity of weed, there was the significant difference with 5% level for the tillage factor only. The quantity of weed in NN was much than any other plots.
7) In NN, notable pH drop was observed at the soil layer of 5-10cm in depth. The pH profile in NN at the layer of 0-20cm approached to that in CC which showed an uniform distribution of pH.
8) In spite of the deteriorated field by continuous no-tillage farming for 11 years, the crop yield almost recovered to the yield level in CC by only once tillage as a renovation.

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All of farm fatal-injured accidents in 4 years during 1983 to 1990 occurred in Hokkaido were surveyed by interview. The results of the servey is divided two report, named part-2 and 3. In this part-2 report, the general aspects for all accident data and the detail of accident on the road were described. And following guidance principle against farm safety policy was pointed out.
1) The statistical analysis for the fatal-injured accidents showed that the number of injured by tractor over-turn or tumble down from road or farm field were largest case in every year, and number of injured by catch-in to machines, run-over by vehicle or pinch-in to machines are 2nd largest case.
2) The fatal-injured accident of road traffics were classified under the occurred location, month or operator's age. And guidance principle against safety was clarified.
3) The fatal-injured accident classified under the local area showed that the greater the rate of safety flame (ROPS) attached tractors, the smaller the rate of injured-accident and fatalinjured became.
4) The fatal-injured accidents of tractor tumble down from road were classified and analyzed. And main and 2nd reasons of accidents were clarified.
5) For the farm safety, the significant structural difference of farm tractor from an automobile must be known to farm tractor operators.

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