In order to apply the theory of minimum stress in plane of soil failure in tillage, author tried to turn out micro soil stress meters which picked up the stress in soil cutting action. Previous to the making of micro soil stress meters, author took consideration on the properties which the stress meters should possess; namely, scale of measurement, disturbance of stress field, accuracy of measuring direction, maximum and minimum measurable pressure, dynamic properties of, pressure plane, linearity of load and indicated value, allowable deflection of pressure plane and effect of temperature change. Then, author thought out testing methods of these properties, and decided the type and dimension of stress meter and how to use it. At first hand, author turned out cylindrical type micro soil stress meters which were of simple structure, but due to large distribution of measured value, as well as deficiency of direction accuracy and durability, it could be used only to measure the rough tendency of stress distribution in cutting fine soil. Then author made diaphragm type micro soil stress meter, which proved to have sufficient properties to be used in tillage of fine soil.
The influences of cooling conditions on the distribution of cylinder temperature of air cooled diesel engine were investigated, and the following results were obtained. 1. Cylinder temperature rises with the increase of load, and is low on the side (0°) of inlet of cooling air, and is high on the opposite side (225°-1.80°). It is necessary to be cautioned that the cylinder temperature approaches the extremely high value of 180°C at the full load of 1100-1500rpm, and reaches the highest limit of 200°C only at the full load of 1500rpm. 2. Both rise and distribution of cylinder temperature by the increase of rpm. are not so much influenced as by the load. 3. Cylinder temperature rises with the blockade of the cooling air screen, and is variable with angular position of cylinder wall. Every one fourth of blockade of the area of cooling air screen, at the angular position (225°-270°) on the upper part of cylinder, rises cylinder temperature by 10°C. 4. Slackness by 10mm of fin cover less influences on the rising of cylinder temperature. Removal of fin cover at the (90°) side or the both side (90° and 270°) are dangerous due to the extreme rising of cylinder temperature. 5. The blockade of the ditch of cooling fin rises temperature of cylinder wall on the blocked side and lowers it on the opposite side. The blockade on the (90°) side influences more on rising of temperature than that of (270°) side. The blockade of the ditch of cooling fin at the inlet of the head-cover rises the temperature of cylinder head, but lowers that of cylinder wall especially at the lower part. With normally equipped fin cover, cylinder temperature rises slightly at the rear side (180°-225°) so far as the blockade is slight.
The behavior of paddled soil under loading plate was examined by model experiment and field survey. In those experiment and survey, circular loading plates, 3 kinds in diameter, with vertical lug along the perimeter, zero to 5cm in height, which cut off the viscous flow of paddled soil, were used. The settlement at 10 minutes after loading was employed, to inspect a conventional allowable bearing ability. Kurdümoff effect was observed even when the soil possessed the flowing consistency, especially this was evident as the height of the lug was sufficient. The higher the height of lug was, and the larger the ratio of the perimeter to the area was, the more the allowable bearing ability for a given settlement became. If the lug should be used in a suitable method, and if the ratio of the perimeter to the area be made should as large as possible, it may be accomplished to make the settlement smaller under the same pressure. The yield point of paddled soil was not observed evidently, however, the allowable bearing abiltity of this kind mightt be determined as 0.005 to 0.02kg/cm2 at the settlement of about 1cm. These figures fit to the observed value of ground pressure of farm machinery which were manufactured by experience and used on the padded field today. When the machinery used on the paddled field are to be designed, it is supposed to be suitable to employ the 0.005-0.01kg/cm2 as the ground pressure considering the factor of safety of paddled soil.
This paper reports results of the investigation which have been carried out in 1960 at TOKOTAN region in KONSFN, HOKKAIDO, to study on the lasting effects of pan-breaking for the first year after the treatment. In these plots, the pan-breaking was practised in last fall, and the results for the first period of the study, concerning to the physical properties of soil before and after the pan-breaking, were reported in Journal of the Society of Agricultural Machinery, Japan, Vol. 22, No. 3, 1960. The results in 1960 are as follows; 1. Pasture land 1) The peak resistance of the soil penetration appears itself at the depth of about 10cm below the soil surface. It may be able to guess that these peaks are caused by both the developed roots of grasses and the plane structure which has been formed by the freezing action of volcanic soil. 2) At both the untreated plots and the unaffected strips in the treated plots where subsoil has not been loosened by the pan-breaker, the peak resistances of the soil penetration are observed in their subsoils. It can be guessed that these peaks in the subsoil in dicate the hard pan which has been formed by the freezing action only. However, at the treated plots where subsoils were loosened, above mentioned hard pan has disappeared and not been regenerated during a year after the pan-breaking. 3) Roots of grasses in the treated plots are able to develop deeply than the untreated plots, and penetrate to the bottom of the loosened soil. 2. Crop field 1) Even in the treated plots, the hard pan which has been formed by the freezing action appears at the upper layer of the subsoil. However, the hard pan has been formed by traffic of tractor at the depth of 10-20cm below the soil surface. 2) The lasting effects upon the subsoil which has been loosened are observed evidently for the first year after the pan-breaking.
The results of soil resistance for penetration in 1960 in Nemuro-kushiro district (East Hokkaido) were reported in previous paper (Report V). This paper reports about the results of the investgation of physical properties of soil and the growth and yields of crops in spring and autumn. The trouble for root development was caused by the soil freezing, the hard pan, and the layer of volcanic ash in the soil. The kind of crops investigated were grass, sugar beet, dent corn, rutabaga and oats. Results are as follows: (1) The thawing of soil continues to early in May at this region, and then soil must be plowed rapidly after thawing. The soil water does not filtrate late in April. In the mechanically treated plots, apparent specific gravity is 0.5 to 0.6. This value is approximately 0.1 less than that in the untreaded plots. Soil porosity is also higher in the treated plots. (2) Permeability at the depth of 30 to 45cm is high in the treated plots. In the low swampy land, however, the difference by treatment is not found clearly. (3) Any crops in the low swampy land did not grow before treatment, but considerable amount of sugar beet was yielded by the treatment. This is due to a drainage effect. The yields of the grass (Timothy) is evidently high at the old farm which has been cultivated for about 30 years.
On measuring the soil displacement, it is necessary to consider about the difference of soil displacement and displacement of measuring pieces. Then the following experiments were performed for the purpose of investigating the displacement of several soil displacement measuring pieces. In these experiments, we put them, on the soil surface, tilled, and then measured the displacement of them. The results of the investigation ate summarized as follows: (1) When the specific gravity of soil displacement measuring pieces are approximately equal to the apparent specific gravity of soil, good results are obtained. (2) When the specific gravity of soil displacement measuring pieces are smaller than that of soil, they are apt to be ref bated on the soil. (3) When the specific gravity of soil displacement measuring pieces are larger than that of soil, they are apt to be subsided into the soil. (4) The state of displacement changes by the size of soil displacement measuring pieces. (5) The chalk pieces of about 1 cm long are suitable for measuring the soil displacement.
The condition of soil displacement changes by the type of tillage machines, the kind of tines, tillage depth and the condition of the field. In the soil displacement, there are horizontal displacement and vertical displacement. The authors investigated the horizontal (direction of travel) displacement of soil using the tillage machines. The results of the investigation are summarized as follows: (1) The distance of soil displacement is determined by the rotation speed of tilling shaft which is equipped with some tines or forks, the ratio of cutting width of soil, and tillage depth. (2) The distances of soil displacement are obtained as follows: crank type: -1.0-77cm rotary type (knife tines): 12-62cm rotary type (fork tines): 6-42cm screw type: 19-34cm (3) The inclination angles of tilled soil are obtained as follows: crank type: 13-41° rotary type (knife tines): 20-47° rotary type (fork tines): 28-56° screw type: 52-63°
The characteristics of soil breaking, soil scattering and soil turning on the up-cut method of rotary cultivation were studied, and these characteristicts including the load characteristics were considered synthetically. It was considered that a soil breaking in the up-cut method arose from a tension mainly, these cracks were apt to grow irregularly but almost horizontally, and they were big and long so that the clods were larger than the case of a down-cut. The influences to a soil breaking of the shape of blade and the rotor speed were almost same tendency as a down-cut method, but they were unsystematic slightly. As a rule, the volume of scattered soil was about twice of the case of a down-cut, and its half volume flew to the front, a 10-20% of its volume flew to the rear and the remainder flew to upward, and these phenomena were influenced by the shape of blade, soil and working conditions. The distribution of soil scattering on the ground was very broad and not concentric, and the characteristics of soil turning had almost some tendency but it was a little better than the down-cut method. On the synthetically, it was considered that the up-cut method is convenient as the tilling method as the resistances of this method were small, and some vertical downward force was usually produced, but the existences of the tractive resistance to the rear and some soil scattering to the front are disagreeable as the tillage. The volume of scattered soil was more than the down cut method and the phenomena of soil scattering to the front or upward are available for the many soil preparing and management works, but the shape of blade and shield, the fitting position of shield, and the working conditions must be carefully chosen. In a word, the up-cut method will be promising as the tilling works or soil preparing and management works if shapes and the conditions are suitably chosen
We studied the effects of the sharpness of blades, the cutting characters of the particular rotary tines, and considered about the arrangement of rotary tines. The principal results obtained from these studies are as follows: 1) When the soil moisture content is much, the difference of the cutting resistance according to the sharpness of the blades is not considerable, but it increases as moisture content decreases. Since the dull blade acts disadvantageously not only to the power required but the strength of the blade, it must be kept sharp. 2) To make the load of each blade as equal as possible, arrangement and hitting order of the tines were considered under various conditions. Assuming that the hitting order of the left ended blade is No. 1, the order of the next blades respectively is No. (1+C), No. (1+2C), ……. But the constant number C does not take any odd numbers and the measures except 2. 3) It is of great advantage to make the width of a blade greater on the power required. But considering the variation of torque and other things, it must be prepared to keep two or three tines at least are in the cutting process. 4) It is advantageous to make length of the edge of the vertical blade as short as possible. But the curved part of the horizontal blade should be more smooth and the length of the blade must be determined according to the total number of blades which is relating to 3). 5) The lower the revolution of the rotary shaft is, the less the power required. While the dropping of the number of revolution of the rotary shaft is limited by the size of the clods, the revolution must be determined by the point of view of keeping the desirable tillage depth rather than size of the clods. 6) The total power required reduces as the cutting width of a blade increases and the number of tines decreases. But the power does not reduce too much over about 100mm with the model blades experimented (1/2 scale of practical blades).
1. A new type of the sprinkler head with many orifices was manufactured for trial to irrigate much water in a short time, reducing evaporation loss of water. 2. Basing on the results of both fundamental experiments and calculation, the orifice diameter, inclination angle of nozzles, and number of orifices in the head was determined to ensure an uniform distribution of water over the sprinkling area. 3. The characteristics of the head observed in the experiments were as follows: (a) The head of this type is effective to distribute water as uniformly as that of the revolving type, if the orifice diameter, inclination angle of nozzles and number of orifices in the head are moderately combined. (b) An excessive increase of the rate of water application from the head, depending on its construction, makes it more desirable to employ it as a movable head than as a stationary one. (c) The lengths of ricer and cylindrical part of the nozzle have no effect on the distribution of water. (d) Water pressure more than 30lbs/in2 will bring a satisfactory result, but the pressure lower than 15lbs/in2 results in a narrow and uneven distribution of water.