A field experiment was conducted to study the mechanism of competition by seed mixtures which were made of timothy and red clover under combinations of various seed ratios and fertilizer treatments. Following seed ratios (total number of germinable seed being 8,000) of timothy vs. red clover were adopted in this study, viz. 10:0, 7:3, 5:5, 3:7 and 0:10. Further six fertilizer treatments were taken: 2 NPK, NPK, NP, NK, PK and none. Both factors were combined in all possible ways. Results obtained over 3 harvest years were summarized as follows: 1. Each fertilizer treatment and seed ratio gave a respective effect on rise and fall of plant vigor of both species in the mixture over 3 years. 2. Total cured hay yields over 3 years were higher in the mixture than in single sowing and 5:5 seed ratio showed the highest yields at respective fertilizer treatment except PK treatment which gave the highest yields at 3:7 seed ratio. The order of high yields by fertilizer treatments was 2 NPK>NPK>NP, NK and PK>none by means of Duncan's test. 3. Red clover, regardless to plant vigor in the mixture, gave somewhat beneficial effects on the yields of timothy and as the ratio of red clover to timothy increased, the yields of timothy became higher. Red clover conversely suppressed by timothy in the 2nd and 3rd crop year in the plots where the seed ratios of red clover were higher. In the plots where PK treatment was given, such a phenomenon was not observed. 4. The botanical composition in the plots of 7:3 seed ratio was more stable than the other ones shown by the value of coefficient of variation of timothy content in the hay through each cutting of 3 years. 5. Generally speaking, customary 2:1 seeding ratio (in weight) of timothy-red clover mixture taken in Hokkaido area seemed to be a little too high in timothy against red clover. By reducing timothy seed percentage, both plant may grow more favorably.

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Percent cover, relative frequency and percentage contribution to vegetation were estimated by the two methods, the vertical and inclined point quadrats, in Trifolium subterraneum and Lolium rigidum pasture swards. A comparison of results by appropriate statistical tests was made. The two methods gave similar estimates of percent cover and relative frequency for Trifolium subterraneum, and percentage contribution for Trifolium subterraneum and Lolium rigidum. On the other hand the vertical point puadrat gave underestimates of percent cover and relative frequency for Lolium rigidum than did the inclined point quadrat. Though no record were kept of times taken, the vertical point quadrat as obviously more rapid than the inclined point quadrat. The results are discussed in relation to previously published work and with regard to their application to pasture analysis studies.

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Amount of herbicide, plowing method, direction of inclinationation and seeding time were examined for pasture establishment. 1.Shady slope was more favorable than sunny one in establishing pasture. 2. September seeding was easier for pasture establishment than June seeding. 3. Pasture could be established by noneplowing method with weeding by applying sixty kg of sodium chlorate per ha. 4. After pasture was once established, the yields of noneplowed plots were not inferior to those of plowed plots.

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1. For the purpose of improving grass stand at slope land in warmer districts of Japan, several kinds of root tubercle trees (Robinia Pseudoacacia L. var. Bessoniana Nichols, Robinia Pseudoacacia L. var. umbraculifera D. C., Amorpha fruticosa Linnaeus, Lespedeza bicolor Turcz, var. Japonica Nakai, Alnus tinctoria Sargent var. Obtusiloba Callier) were planted and their adaptation to those area, enevironmental factors affecting growth of them and their effect on grasses were determined. 2. It was observed that Alnus tinctoria Sargent grew more rapidly than any other tree and its adaptation to slope land was very high. But when it had grown up, it was necessary to control its shade because Alnus was apt to suppress the growth of grasses underneath. 3. Growth and yield of grasses under tree were mainly influenced by weather but not much by tree species. But existence of root tubercle tree gave favorable effect on grasses underneath because yields of open plots were always lower those of tree-covered plots of any of the tree species and this tendency was observed as early as the second year of the experiments. 4. Temperatures both in the soil and in the air under tree of tree-covered plots were lower than those of open plots and soil moisture percentage was a little higher in the former. Density of light irrdiation of the former was one half of the latter. 5. The soils in the experimental plots nourished by tree were remarkably improved comparing with those of native land which remained untouched but no definite differences of physical and chemical properties of top soil were shown by difference of the tree species planted.

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