1. In the air temperature near the ground in grassland fire in Zoysia type, Miscanthus type and Sasa type grasslands, the maximum temperature was attained in 15-30, 20-60, and 30-90 seconds, respectively, and the temperature change continued for 2-5, 3-7, and 4-10 minutes, respectively.2. Where the plot consumed greater amount of fuel, the change in temperature at each measuring point was the greater. With the decrease of the rate of spread, the maximum temperature at every measuring point decreased, but the temperature change tended to continue for a longer time. Besides, the change in temperature was smaller in back fire than in head fire, but the temperature change continued for a longer time in the case of the former. 3. In the case of back fire, the time to attain the maximum temperature became earlier with the lowering of the position of the measuring point. Conversely, in the case of head fire, the lower the measuring position was, the later the time of the maximum temperature became. On the other hand, when wind direction and wind velocity changed incessantly in the midst of burning, there existed a number of peak temperatures. 4. The types of the vertical distribution of the maximum temperature could be divided into "Push down type" and "Standing dead type". The push down type showed conspicuous peak near the height of 10cm in the vertical distribution of the maximum temperature. On the other hand, the standing dead type was featured by the nonexistence of big peak in the vertical distribution of the maximum temperature. 5. When the amount of fuel which was burnt was less than about 0.5kg/m^2, the maximum temperature increased with the increasing amount of fuel, and in the case of about 0.5kg/m^2 of the burnt fuel, the maximum temperature recorded from 600 to 800℃. However, when the fuel exceeded about 0.5kg/m^2, the ascending tendency of the maximum temperature showed a crablike course. But, the high temperature was maintained longer with the increasing amount of the burnt fuel.

View full abstract

1. The effect of burning upon soil temperature was governed by three factors, i.e., (1) the amount of the burnt fuel (2) the amount of duff layer left unburnt and (3) the extent of the rate of spread. Especially, the effect caused by the former two great. In Zoysia type, Miscanthus type and Sasa type grasslands, the rise of temperature in soil surface reached 10-80℃, 30-170℃ and 5-48℃, respectively. However, soil temperature rapidly fell down near the soil surface and the temperature at several centimeters below the soil surface did not show almost any change. 2. The burning intensity was recorded as 11-155×10^6 (T^2.5t) in Zoysia type grassland, 45-710×10^6 in Miscanthus type grassland and 200-1280×10^6 in Sasa type grassland. The difference in the burning intensity according to the type of grassland was primarily due to the amount of fuel consumed. Besides the above, the extent of the burning intensity was greatly affected by the rate of spread as well as by the type of disposition of fuel. 3. Generally speaking, even the fire with less burning intensity, burnt the above-ground organ of the dominant plant to death. However, even in the case where burning was carred out very successfully, the direct influence of the fire upon plant organ or noxious insects under the ground could not be observed.

View full abstract

The dry matter production in sward is resulted from the different growth patterns of forage crop, such as growth after germination, vegetative growth, reproductive growth, sprouting growth over the winter, and regrowth after cutting. In order to make clear the character of these growth patterns in orchardgrass sward, this study was carried out using the method for growth analysis of plant community. 1) In the early stage of growth after germination, the growth rate of dry weight of aerial parts per unit area was very low and it required comparatively long period until developed into the effective leaf area index which is sufficiently to use incident energy of radiation. 2) Since the growth in the early stage of regrowth after cutting used the reserve substance in stubble, the growth rate was high compared with the one after germination and the period till developed into the effective leaf area index (LAI) for dry matter production was comparatively short. 3) In the early stage of sprouting growth over the winter, the rate of increase in (LAI) was high and this trend was in general similar to that of regrowth after cutting. 4) In the case of continuing the reproductive growth after the stage reached the condition of an optimum LAI, more photosynthesized substance was distributed to the nonphotosynthetic part than the photosynthetic part. Therefore, the rate of increase in leaf area production was kept down and the effective profile under the condition of an optimum (LAI) was kept for long time. As the result of this, the rate of decrease in net assimilation rate (NAR) was comparatively low and the maximum dry weight of aerial parts throughout this period reached 1550g/m^2. On the other hand, in the case of continuing the vegetative growth afer the stage reached to an optimum LAI, the increase of photosynthetic part was further kept. Therefore, the leaf area profile in the community changed to the direction made to decrease the efficiency of utilization of incident energy of solar radiation. As the result of this, the rate of decrease in NAR was considerably high and the maximum dry weight of aerial parts throughout this period was restricted to 780g/m^2.

View full abstract

Forage intake of cows grazing on the Italian ryegrass pasture was estimated by the chromogens-chromic oxide double indicators method, and the following results were obtained. 1) When dry cows, weighing about 500kg, were grazed on the Italian ryegrass pasture for 3 hours a day, they daily consumed 4.4-6.7kg of TDN and 0.8-1.5kg of DCP. This consumption was fully adequate for maintenance requirement. 2) Milking cows, weighing about 600kg and producing about 13kg of milk, consumed 5.3-10.8kg of TDN and 0.7-2.1kg of DCP from the Itarian ryegrass pasture, when they were additionally receiving 4kg of concentrates per head per day. It was found that the dry matter consumption was highly correlated with the dry matter content of forages (r=+0.84), and also that the dry matter content of forages declined in the rainy day. From this observation, milking cows can consume enough forages to produce about 13kg of milk when the weather is fine and the pasture is good stand. If the rain continues for a long time, however, the grazing cows must be fed additionally some concentrates to produce milk.

View full abstract

This experiment was carried out to determine the forage intake and weight gain of dairy female calves (6-8 months old, 113-225kg body weight) grazed intensively on a orchardgrass-Ladio clover mixed pasture. In addition to this, an effect of supplemented molasses on weight gain of the calves was investigated. The results obtained are as follows: 1) The daily weight gain of the grazing calves was increased by supplementation of molasses (600g/head/day), but no improvement was observed in dry matter consumption, feed efficiency and dry matter digestibility of herbages. 2) The rotationally grazed calves in this experiment daily consumed 3.6-5.0kg of dry matter from the pasture, and feed efficiency was about 0.11. 3) Under the present grazing condition there was no seasonal difference in dry matter, organic matterand crude protein content of pre-grazing herbages. However, crude protein contents of the pre-grazing herbage samples were always higher than those of the post-grazing samples. This fact suggests that grazing calves consumed selectively parts of herbages rich in protein. 4) Dry matter consumption of the calves was estimated to be higher when it was obtained by the herbage sampling method than when it was measured by the double indicator method. Such a difference is considered to be due to the small sample size in the former method, especially at the low intensity of grazing. 5) It was found that the dry matter consumption (Y, kg/100kg body weight/day) was highly correlated with the dry matter digestibility (X, %), being a correlation coefficient r=+0.87, and a regression equation was calculated as Y=0.18X-9.05. It was also found that the dry matter digestibility of herbages changed with grazing time. This finding suggests that calves should be grazed on epasture at at optimal growing stage of herbages.

View full abstract

The present paper deals with the seasonal variation of the age distribution of A. japonica (Lumbricidae), endemic and widely distributed in Japan. From May of 1965 to April of 1967, six soil samples (25sq.cm.×30cm. deep) were taken twice a month in forage swards, and number of worms in each sample was counted. The whole specimens collected were classified into three age categories, namely mature, immature and young. The mature were found in a definite season, namely between spring and autumn season. On the contrary, immatures and youngs were found throughout the whole season. The immatures were abundant during the autumn season, especially in October and their vertical distribution in the soil showed a regular variation ; namely their number was abundant in the first soil layer (0-10cm deep) from summer to autumn season, and in the second soil layer (10-20cm deep) during winter season. The youngs, on the other hand, were abundant in summer and spring season, and most of them were found in the first soil layer throughout the year. Total population was high in autumn and low in winter. The cocoons were found in spring. Most of the youngs collected in spring were small in body size and body weight.

View full abstract

From observations upen field populations of the false melon beetle during past five years at Morioka, Tohoku district, decreasing process of the population density within one generation is summarized as follows: -1. At the first age interval from the egg after hibernation to the mid larval stage, population decreased to about 30 per cent of the initial size. In a year with prolonged drought period before hatching of the egg, population size fell more sharply probably on account of dessication of the egg after termination of diapause. 2. At the second age interval from the mid larval atage to the adult emergence, there was no significant population decrease, unless larval or pupal mortality was caused by fungous disease Isaria farinosa. Diseased specimens were found for the first time at the peak of beetle outbreak in the ladino clover sward. In the next year the parasitism in this sward attained to about 85 per cent of larval population and thereafter decreased gradually. In the mixed sward of ladino clover and orchardgrass, however, no diseased specimens were found throughout the period under observation. 4. At the third age interval after the adult emergence, emigration at the peak of outbreak resulted in highly significant population decrease, but the fall of density was gradual in other years. Among the natural enemies, a tahinid fly was most frequently found, but its total parasitism was negligible every year. Effect of other natural enemies was also negligible at the adult stage as well as at the preceding age intervals.

View full abstract

In order to elucidate factors regulating the population density fluctuation of the false melon beetle, observations have been carried out in a single-sown ladino clover sward and in a mixed sward of the ladino clover and the orchardgrass at Morioka, Tohoku district. The results are as follows: -1. In the initial two years after establishment of the swards, beetle population increased more rapidly in the mixed sward than in the ladino clover sward, but at peak of outbreak the larval population in the former was about half the size of that in the latter. Thereafter, populations in both swards stayed at rather low level with a narrower range of yearly fluctution. 2. In the ladino clover sward, mortality due to fungous disease Isaria farinosa suddenly rose after the beetle outbreak. This shows that the disease reacts to host number in a 'delayed-density-dependent' manner, but the parasitism was kept at high level during several years after the end of the outbreak. In the mixed sward no disease occurred even after the host outbreak. In either case no correlation was detected between the parasitism and the multiplication rate of the beetle from year to year. From this fact it was concluded that the disease is not main factor in population regulation of the false melon beetle in the swards. 3. Field census showed that many adults immigrated into the swards in the growing period of beetle population for the first three years. Moreover, a close parallel relation was found between the immigration rate and the multiplication rate from one generation to the next. This suggests that immigration is the important factor causing the outbreak and that there are two decisive conditions influencing the population density fluctuation of the false melon beetle ; existence of the sources of adult immigrants in the vicinity and the growing state of grasses, the latter of which is highly influential upon the colonization and oviposition of adults.

View full abstract

As a part of studies on mechanical method in grassland establishment, an investigation was carried out on the transfer of surface soil due to the mechanical operation. The field investigated was volcanic ash soil in Kamikita region, Aomori Prefecture. The results are summarized as follows ; 1. Grubbing work-In this work, most surface soil was employed to fill up the hole after grubbing. For example, when a stubble is 70cm in diameter, the neighboring surface soil was moved extending over 700cm in width. It should be noted that transfer of surface soil was inevitable by the conventional mechanical operation. 2. Clearing work-In this work, the stumping roots were temporarily collected to one place, and then were pushed to the clearing lines. As a factor of soil-removing, topographic condition was more important than quantity of cleared roots. Mostly, surface soil was removed 20-30cm in depth. But in case of the steep sloped lands, soil was removed over 100cm in depth. As seen from above examples, clearing work at the steep sloped lands involves some risk on the soil-removing. 3. Brush breaker plow-This work was operated over all area. Therefore, after this work, the land surface was almost exposed subsoil. 4.When comparing the soil analysis before and after this work, it was shown that subsoil was greatly improved with applying lime and phosphatic fertilizers. Therefore, it seems that this work has not not so much effect on growing grasses.

View full abstract

In this experiment, the influence of cutting intervals and different fertilizer applications on the death of slender plant in orchardgrass sward was examined in 1969. Cutting intervals were varied from 30 days to 80 days, at intervals of 10 days, after the first cutting. Each was treated with two levels of fertilizer application. Results are summarized as follows ; 1. At 30, 50 and 70 days after first clipping, plant height in a population in 50×100cm area were measured, The variance of plant height, standard deviation and coefficient of variance were increased in the prolonged cutting interval. 2. In the plots of heavy fertilizer application, the variance of plant height was markedly increased comparing with light fertilized plots. Many dead plants were exhibited, and density and basal coverage were fallen. 3. The regrowth was examined at 6 days after cutting. The variance of plant height and the percentage of poorly regrowth plants were markedly increased in the plots of large variance of plant height before cutting (Table 1). 4. Number of tillers per plant had much influence to the regrowth of orchardgrass ; 23% of poorly regrowth plants had only one or awo tillers per plant, on the contrary, one half of plants with 4 and 5 tillers and about 100% of plants with 6 or more tillers exhibited favorable regrowth (Fig.4). 5. From these results, it is considered that for the survival of orchardgrass plant during regrowth, it is necessary to have many number of tillers per plant, as well as high plant height with light-receiving efficiency.

View full abstract

The quantitative and qualitative variation of available carbohydrate in the root and leaf sheath of orchard grass at the successive stages of growth after cutting was investigated in fall season. 1. The fructosan content in the non regrowth-leaf sheath at the 9th day after cutting decreased to about half as much as that before cutting, but it was recovered with the growth of new shoots. 2. The fructosan content in the root decreased a little after cutting, but little in the regrowth-leaf sheath. 3. In the non regrowth-leaf sheath, the variation of concentration of fructosan was accompanied with that of non reducing sugar, but little variation of reducing sugar. 4. At the first step, the degrees of polimerization of fructosan became high in proportion to fructosan concentration in plant, and at the second step, it was increased higher by descending of atomospheric temperature. 5. The fructosans in the root were consisted of longer chain than those of other tissues. 6. The variation of content and chain length of fructosan was mainly found at the fraction of long chain fructosans. The short chain fructosans were not so variable both quantitatively and qualitatively. 7. The degrees of polimerization of fructosan extracted between 85 and 50% ethanol were about 31, and those extracted between 50% ethanol and water were about 83. It seemed that the chain length of fructosan varied between D.P.31 and D.P.83.

View full abstract