In Japan, Japanese pears are usually planted in either pergolas or vase form training. However, in these orchards, there are some difficulties in operating tractors, as the authors have reported in a previous paper. We have proposed a Y form training, suitable for tractor operation. The hedgerow training is also suitable for tractor operation. In order to prove the superiority of the latter two training systems, Japanese pears “Kousui” were planted in vase form, Y form, and hedgerow trainings, and working hours were recorded on each working process.
Here we report the growth and yield of the trees, before reporting the working hours in order to present a better understanding of the trees used to compare the working hours.
The increase of tree girth in the Y form and the hedgerow were about 2/3 of that in the vase form.
The yield per 10a in the Y form was about the same or higher than that in the vase form.
The yield per 10a in the hedgerow was over 3 times the yield in the vase form during the early stage (3-5 years after plantation), but gradually decreased (6-8 years after plantation) to about the same as that in the vase form. However, when the yield in the early stage was controlled to match the vigour of the tree, the yield could be maintained at a higher rate than in the vase form.

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Annual working hours in Japanese pear orchards were compared between two training systems designed for easier tractor operation and one common training system. They were the Y form training, the hedgerow training and the vase form training.
Annual working hours were somewhat less in the Y form training and the hedgerow training than in the vase form training.
However, the difference was not as large as expected. The main cause of this small difference owing to 1) scanty tractor operation in all three training systems and 2) limitations in machine operations in the hedgerow due to the situation of the hedgerow, i. e. the northern side of the northernmost row had to be mowed by hand and spraying for pest control had to be done over a fence from a road outside the orchard.
In the year 1984, total working hours per 10a were, about 243 hours in the vase form, about 224 hours in the Y form, about 250 hours in the hedgerow, with the Y form being somewhat labour saving. All three training systems experimented in our orchard required less working hours compared to statistical data on Japanese pear growing farmlands.
However, total working hours per yield were the same as the statistical data for the vase form, but about 20% higher for the hedgerow and about 110% higher for the Y form.
The reason why working hours per yield were higher in the hedgerow were that 1) it required more fertillizer due to dense plantation, 2) more mowing and pest control than the vase form and Y form due to the situation of the orchard. The reason why working hours per yield was higher in the Y form was that the yield was lower due to the aftermath of the typhoons in 1982, as mentioned in a previous report³⁾.
In the year 1985, total working hours per 10a were, about 216, 172, and 194 hours for vase form, Y form, and hedgerow respectively. That in the latter two were somewhat shorter than in the vase form.
Working hours in all three systems were about 80% of statistical data.
However, total workig hours per yield were, about 108 hours per ton for vase form and Y form, about 80% of the statistical data. Total working hours per yield were about 85 hours/t for the hedgerow, less than 80% of vase form and Y form, about 60% of statistical data, showing that Y form and hedgerow would be largely labour saving if yield of 2 tons per 10a is maintained.
In Y form and hedgerow, trees of proper vigour could produce higher yield than trees of vase form constantly with less working hours.
For the pursuit of higher yield and labour saving training systems, investigation of not only plant physiological and ecological aspects, but detailed research on working hours of work such as soil management, spraying, harvesting, etc. are also required. Detailed investigation on working hours of Japanese pear culture in the three training systems are in progress and will be reported in the near future.

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Yacon (Polymnia sonchifolia POEPP. et ENDL or P. edulis WEDD), an indigenous Andean cultivated food plant, was imported as a new root vegetable from New Zealand in 1985. The cultivaton was already carried on a few advanced farmers. But the character and the planting system of Yacon are almost not known in Japan.
The planting densities, one of the basic problem to Yacon cultivation, were investigated.
Seed tubers were planted spacing of 30cm between the plants and 70cm between the rows (dense planting), spacing of 70cm between the plants and 70cm between the rows (sparse planting), and spacing of 50cm between the plants and 70cm between the rows (control).
Results of the investigation were obtained as follows:
1. Growth of the main stem of Yacon was grown well from July to the middle of October.
2. Growth of the main stem at the dense planting Yacon was slightly succulent grown more than any other growth at the planting density.
3. The fresh and the dry weight of the top at the sparse planting were heavier than any other weight at the planting density.
4. The weight and the number of tubers per a stump at the sparse planting were more than any other yield at the planting density.
5. The computation of the total number of the tubers per 10a of the control was more than any other yield at the planting density, but the number of tubers under 100g at the dense planting were more than any other yield at the planting density. And the number of tubers over 100g at the sparse planting were more than any other yield at the planting density.
6. The computation weight of the total and over 100g tubers per 10a of the sparse planting was heavier than any other weight at the planting density, but the weight under 100g at dense planting was more heavier than any other weight at the planting density.
7. Spacing of 70cm between the plants and 70cm between the rows was determined most useful planting density in this investigation.

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In this paper, we investigated the effect of weeding at pre-seeding and soil pH on growth and yield of wheat which corresponded to the 16th cropping sequence in a serial experiment on no-tillage farming for eight years.
1) Soil water content of no-tillage plot (NT) measured at harvest time of wheat was higher than that of conventional tillage plot (CT) in 0-5cm layer, but the value of NT was lower than that of CT in 5-25cm layer. NT almost included the quantity of soil water as much as CT in a whole layer of 0-25cm, but a gradient of water content in the layer of NT differed from that of CT.
2) Soil bulk density of NT was lower than that of CT in 0-2cm layer, but the value of NT was higher than that of CT in 2-10cm layer. There was no difference in bulk density between CT and NT below 10cm.
3) pH (H₂O) was not agreed with pH (KCl), but coefficient of correlation of 0.952 was obtained between NT and CT. We could not find the dense correlation among water content, bulk density, pH (H₂O) and pH (KCl).
4) pH (H₂O) of NT was lower than that of CT in 0-10cm layer, but the value of NT was higher than that of CT below 10cm.
5) Supplied lime had notably effect on wheat yield of NT, but the effect was not observed in CT. Lime was required about three years to take an effect after supplying on soil surface in NT.
6) Both treatments of herbicide and mechanical weeding at pre-seeding could not control vigorous weed growth and wheat yield in NT.
7) It seems that pH is one of the most effective factors on wheat yield in our long-term experiment.

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The tractor mounted straw mulching rotary seeder and the no-till seeder equipped in front of a riding-type rice transplanter for soybeans were developed in order to improve the emergence on the converted paddy fields under various weather and field conditions.
1. By using shallow cultivating rotary tiller which forms uncultivated ridge under tilled surface soil, the risk of seed submergence were evaded even in the heavy rainfall. The emergence percentage was improved by means of mulching chopped straw. In addition, the mulch suppressed weed markedly and avoided the drought stress or crust making of the surface soil.
2. The no-till seeder which was developed to perform seeding under wet field conditions during suitable sowing period. The emergence percentage decreased with increasing soil moisture content but the value attained about 70% around maximum water holding capacity. This no-till seeding method was adaptable to the wet field conditions.

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Accidents occuring from the use of farm machinery have been increasing year by year, with the resulting damage and injuries becoming more and more serious. This has been found to be the result of the increased ownership of more complicated machinery by farm households, especially that of the riding-type, leading to one of the social problems in the rural area.
This survey, taken of 219 farm households in 39 counties from 7 provinces in the Republic of Korea, is to provide basic information on accidents requiring medical treatment longer than 3 days.
The results are summarized as follows:
1. The annual frequency of accidents per hundred machines requiring medical treatment longer than 3 days was 8.75 incidents for combines, the highest frequency, 6.45 incidents for farm tractors, 5.77 for power tillers, 1.23 for rice-transplanters and 1.16 incidents for binders. Riding-type machinery record a higher frequency of accidents than the walking-type machinery.
2. Forty-six percent of the farm households owning farm machinery faced accidents more than one time, including the number of farm households having more than 5 accidents (6.1%), and the number of households suffering only single accident (25.1%). The annual average frequency of repeated accidents was 1.02 times per year.
3. The major causes of accidents were carelessness and unskilled operation of machinery, accounting for 78% of the total. Only 6% of the accidents were caused by machinery malfunction. Most accidents, 53%, occured during transport and running operation. Twenty-nine percent of the total accidents occured while connecting and disconnecting implements, which illustrates the necessity of strengthening training of the operators and improving machinery. Forty-nine percent of accidents occured on paddy and upland fields, with 46% occuring on vehicle and farm road.
4. Seventy-two percent of the total injured were the machinery operators, and twenty-four percent the co-workers. Most injuries, 62.4%, were to the hands and arms while the most common kinds of injury were bruises, representing 53.1% of the total.
5. The period of medical treatment of 29.6% of the injured was over one week, including 8.8% of that number which was longer than 4 weeks. The average amount of damage from accidents per farm household was 150 thousand won (190). Seventy percent of all farm households recorded amounts less than 100 thousand won (125), and 1.5% suffered damage of more than one million won ($1, 250).
6. Concerning the issue of executing a national insurance system for protection against accidents, 64.9% of the respondents replied in favor of its necessity while 23.6% replied negatively. Also, 54.6% responded against the necessity of issuing operator's licence for farm tractors.

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