The present paper deals with the seasonal variations of the population density and biomass of macro soil animals, which exceed 2mm. in body length excluding mites, springtails and enchytraeides, in forage swards, Sapporo. From May of 1965 to April of 1967, twice a month, six replicated soil samples (25 sq.cm.×30cm. deep) were taken, and numbers of larvae or adults were counted and their wet weight was measured. The population density and biomass showed seasonal variations, namely they were large in autumn (September-October), and small in winter (December-March). The macro soil animals collected were classified into 22 groups, covering three phylla and 13 orders. Among them, the groups with the population density of over 2% of the total individual number were: Oligochaetes (74.0%), Formicidae (7.0%), Scarabaeides (3.4%), Elateridae (2.3%), Aranea (2.5%) and Diplopoda (2.2%). Each of these groups showed more or less the peculiar seasonal variation, but in most case the density was large in autumn and small in winter. During winter, Oligochaetes occupied the majority of total individual number and biomass.

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In order to examine the measuring method of photosynthesis in forage plant popultions, this experiment was carried out with chamber method. Forage plants used in this experiment were tall fescue (Festuca arundinacea Schreb.) and red clover (Trifolium pratense L.) which were grown under community condition during the experimental period of 8 days (tall fescue) and of 7 days (red clover). Comparisons between the amount of dry matter calculated from C0_2 balance and one obtained by direct field measurement were made in both forage plant pupulations. The results are as follows ; 1. The results of this experiment showed that calculated values agreed approximately with observed values of dry matter in both forage plant populations. 2. As the reason why calculated and observed values of dry matter production were approximately the same, the following factors may be considered ; a) There were not great differnces in both air and soil temperature between the inside and outside of the assimilation chamber. b) In measurement of photosynthesis in both forage plant populations, the reduction of CO_2 concentration in chamber was maintained within 20% of ordinary atmospheric concentration of CO_2. c) Photosynthetic activity (20-30mg/, dm^2hr) for temperate type forage plants was maintained at higher level by the factors of a) and b) during this experimental period. 3. The results mentioned above indicate that the chamber method will be appropriate for measurement of photosynthesis of forage plant communities, if the condition of temperature and CO_2 concentration in chamber is maintained near the field condition.

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1. In order to examine the fitness of Monsi and Saeki's formula which was proposed for calculation of photosynthesis in plant communities, we calculated the photosynthesis and dry matter production in tall fescue (Festuca arundinacea SCHREB) and red clover Trifolium pratense L.) plant populations and compared these calculated results with the experimental results in the previous paper (1). 2. In the case of calculating the photosynthesis in plant communities from this formula, the light-photosynthesis curve in single leaf must be decided at first. In this experiment the rates of photosynthesis in plant communities were measured under field condition, in which mutual shading degree were relatively low. Correcting these measurement values by the light absorption rate in plant communities, we obtained the equations which approximated the light-photosynthesis curve in single leaf. 3. Based on these equations, the rates of photosynthesis in tall fescue and red clover plant populotions were calculated from Monsi and Saeki's formula at each growth stage. These calculated valued agreed approximately with the observed values. The amount of dry matter production in tall fescue and red clover plant population which were calculated from this formula agreed approximately with the experimental values in the previous paper (1). The latter were the value observed directly and calculated from C0_2 balance measured continuously under field condition. These results indicate that this formula is appropriated for the calculation of photosynthesis in forage plant communities and for the analysis of actual dry matter production under field condition.

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This experiment was undertaken to make clear the influence of light extinction coefficient (k) on dry matter production and on optimum frequency of cutting per year in foroge plant populations. As the materials in this experiment, we chose four cultivated forage plants ; perennial rygrass (Lolium perenne L.), tall fescue (Festuca arundinacea Schr.), white clover (Trifolium repens L.), and red clover (Trifolium pratens L.), and native forage plants ; Miscanthus sinensis Anders., Zoysia japonica Stoud. and Artemisia vulgaris L.. These forage plants were sown (cutivated forage plants) and transplanted (native forage plants) on field at early June in 1966 and were grown under same field condition till April in 1968. This experiment was carried out with these materials during the six months from April to October in 1968. As means to obtain the highest dry matter production per year, cutting frequency was treated at four levels in each forage plant population. The results obtained are follows ; 1. Both total net production (Pn) and mean crop growth rate <(CGR)>^^^ during this experimental period varied by each forage plant and cutting frequency. And there was optimum frequency of cutting at which <CGR>^^^ showed maximum value in each forage plant. <CGR>^^^_max (<CGR>^^^ at optimum frequency of cutting) in each forage plant showed much difference ranging from the highest value of about 20g/ml^2. day in Miscanthus g/m^2・day sinensis to the lowest value of about 6g/m^2. day in Trifolium repens (Table 1). 2. There was a highly significant correlation between mean leaf area index (<F>^^^_<opt>) and mean crop growth rate (<CGR>^^^_<max>) at optimum frequency of cutting (Fig.1). This fact may indicate that the forage plant population of which <F>^^^_<opt> shows large value has high productivity in dry matter. 3. k value at optimum frequency of cutting varied among the forage plants examined with the difference ranging 0.34 in Miscanthus sinensis to 1.65 of Trifolium repens. And there were highly significant correlations between k and <F>^^^_<opt>, k and <CGR>^^^_<max> (Fig.3). These results seem to show that the contribution of k value to dry matter production in forage plant population is made through the influence of k value to leaf area index in plant community. 4. On the other hand, mean net assimilation rate <(NAR)>^^^ which was a factor of the components of <CGR>^^^ at optimum frequency of cutting varied also among the forage plants. But there were non-significant correlations between k and <NAR>^^^, <NAR>^^^ and <CGR>^^^_<max> (Fig.5). 5. These results mentioned above suggest that the difference of <CGR>^^^ among the forage plants at optimum frequency of cutting is affected more by <F>^^^ than <NAR>^^^, and that the difference of <F>^^^ among the forage plants depends mainly on extinction coefficient (k). 6. Highly significant correlation was found between k and optimum frequency of cutting (Fig.6). This fact indicates that optimum frequency of cutting to produce the maximum dry matter production per year is influenced by k value, and suggests that k value will be able to become an indicator which show the optimum frequency or interval of cutting in forage plant.

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Influences of extinction coefficient (k) on dry matter production and optimum frequency of cutting in plants were examined in the previous paper (3). In this paper, by using the formula (Monsi and Saeki) which is proposed for calculation of photosynthesis in plant population, we examined theoretically to support the experimental results in the previous paper (3). The results are as following. 1. Under the suitable condition for the growth of forage plant (radiation, 50 klux 8hr/day ; temperature, 20℃), the photosynthesis in plant population showed large amount in the plant population of which light extinction coefficient (k) value was small and LAI was high. In opposition to this fact, in the plant population of which k value was large, the photosynthesis in the population attained saturated state at the level of low LAI. The protosynthesis in forage plant population will be highly efficient, if the forage plant is cut at the level of high LAI in the population of which k value is small and at the level of low LAI in the population of which k value is large. 2. Optimum leaf are index (F_<opt>) and maximum crop growth rate (CGR_<max>) had a tendency to increase and NAR_0 (NAR_0=CGR_<max>/F_<opt>) had a tendency to decrease, as k value decreased. If the cutting is made with longer interval in the forage plant population of which k value is small, LAI and the amount of dry matter production in the population would be increased. In the forage plant population of which k value is large, if the cutting is made with shorter interval, the amount of dry matter production would be increased. When the forage population was cut with the optimum frequency, the amount of dry matter production on the forage plant population of which k value was small was higher than that of which k value was large. The main cause for this is that increasing effect of LAI on CGR is large.

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A series of room tests (8 in total) were conducted on equilibrium moisture content, dry matter losses and molding of hay at various of relative humidity. Levels of relative humidity were controlled in bottles, petri-dishes, desiccators, etc., with supersaturated solution of salt or sulfuric acid solution of different specific gravity. The results are summarized as follows. 1) At relative humidity (abbreviation R.H.) under 70%, no difference of equilibrium moisture content (abbreviation E.M.C.) was detected between levels of humidity. The value of E.M.C. was 13.0±2.1%) At 70〜80% R.H., E.M.C. tended to go up as the increase of R.H. (E.M.C. value was 18.2±2.2%). At R.H. of more than 80%, there was a sudden rise of E.M.C. value. Finally at 100% R.H., it reached 53.3±12.0%. In this case, variation of E.M.C. at the same level of humidity was also large. 2) In comparison of materials, E.M.C. at the same level of humidity was higher in legume hays than in grassy hays. High values of E.M.C. were also obtained in hays cut early stage growth, those with high proportion of leaves, those stored in low moisture content and those less fermented at the process of haymaking. 3) 16% was the minimum ceiling value of moisture for molds incursion. Occasionally, molds were not formed even at 39% moisture content. Generally speaking, molds were scarcely found at the moisture content lower than the order of 20〜23%. 4) As for relative humidity, hays stored at R.H. below 75〜80% were nearly free from molds. Although water content at which molds had appeared, fluctuated according to humidity and the duration before appearance of molds also differed, at 95% R.H. molds began to appear at approximately 35% water conten, while at 85% R.H., at approximately 25% water content. 5) Losses of dry matter were the order of 9〜25% at 95% R.H., 0〜5 at 85% R.H.. They scarcely occured at R.H. under 85%. Hays of high water content which were kept at the constant humidity caused great losses of dry matter, though E.M.C. was not high. Those not fermented enough caused great losses, too. 6) Absorption of moisture diminished according to the degree of compaction of forage and there was certain difference of water content between inner and surface layers of bailed hay. It was surface layers only that hay pressed as tightly ordinary bailed was strongly influenced by surronnding humidity. In hay with 13% water content, molds were found only at the surface (0〜2cm) even at 95% R.H.. In hay with 25% water content, on the contrary, materials remained moisty and molds grew at the depth of more than 15〜19cm from the surface at each of 75 and 53% R.H..

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A survey of intensive grasslands was made for determine sward type at Tohoku University farm which was located in northern Japan. Sward types were classified by dominant species in the sward. Relationship between sward types and their carrying capacity was also studied. 1. Nine sward types were distinguished from about 20 pastures and meadows, namely ladino clover type (La), ladino clover/orchardgrass type (La/Or), orchardgrass/ladino clover type (Or/La), orchardgrass type (Or), orchardgrass/redtop type (Or/Top), redtop/orchardgrass type (Top/Or), redtop type (Top), orchardgrass/sweet vernal grass type (Or/Sw) and sweet vernal grass type (Sw). It was found that Or/La, Or and Or/Top types were the most common for the hay land and that Top/Or and La types were common for the grazing land. 2. It was difficult to find out the relationship between the sward types and their carrying capacity, but it was suggested that Top type sward had lower capacity than the others. Pastures were invaded by three groups of weeds in correspond with deterioration. Digitaria adscendens Henr. and Setaria viridis P. Beauv. etc. was group of weeds in cultivated field, and Rumex obtusifolius L. and Pennisetum alopecuroides Spreng. etc. was a group in roadside, and Artemisia princeps Pampan, Anthoxanthum odoratum L. and Miscanthus sinensis etc. was a group in seminatural grassland. It was concluded that invation of the last group species indicated most severe deterioration. 3. Sward type was influenced by topography, for instance Top/Or type was established in the higher position of the slope and La/Or type in the lower position. Not only sward type but also species number of weeds and basal area were thought to be useful indicators for condition classification. 4. Succession of sward type is considered schematically as follows ; 1. Ladino clover, orchardgrass or these both species dominate in the first stage; 2. Under rough management redtop (Agrostis alba) takes the place of orchardgrass and becomes dominant species in the second stage ; 3. Sweet vernal grass, Altemisia princeps Pampan and Miscanthus sinensis etc: invade and the sown species disappear in the last stage. The first stage is stable under intensive management, but if the pasture is abandoned, it seems to develop to the second and the last stage rather quickly.

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This trial was carried out to clarify the influence of the growing stage on the dry matter digestibility estimated by in vitro method and also the chemical composition in stem and sheath, leaf, and head into which sorgo was divided, as well as to discuss the feeding value of the above three parts. 1. There was an increase in dry matter, lignin and silica contents of leaf with advancing of growth stage in the first cut and second one. But there was little change in other chemical contents. 2. There was a marked increase in dry matter, lignin and crude fiber content of stem and sheath with advancing of growth stage in the first cut and second one, but a decline in crude protein, crude fat and crude ash. The dry matter of stem and sheath was about two-thirds of the total dry matter of the plant after the boot stage. 3. The estimated dry matter digestibility of leaf show little variation with growth stage, but that of stem and sheath decreased sharply. There were significant correlations between the estimated dry matter digestibility of stem and sheath and lignin content, and between that of stem and sheath and crude fiber content. 4. It can be said that stem and sneath should be considered as a poor roughage in view of the dry matter digestibility estimated and the chemical composition after the boot stage, but leaf still as a good rouhage.

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