荒廃草地

An experiment was conducted to investigate the effects of three factors on the establishment of orchardgrass (Dactylis glomerata L.) drilled into tussock-formed orchardgrass sward at Kuju Agricultural Research Center of Kyushu University from August, 1986 to April, 1987. The factors were seeding time (Aug. 1, Sep. 1 and Oct. 1), nitrogenous fertilization (5kgN /10a of fast-release fertilizer, 5kgN /10a and 10kgN /10a of slow-release fertilizers) and postsowing trimming frequency (none, once and twice). The seeds were sown in a groove of about 6 cm depth and 5 cm width in. the orchardgrass sward which had been established in a wooden box (36.8×57.5×22.6cm). The results obtained were as follows: 1) Owing to the significantly higher number of seedlings at two months after seeding and the higher rate of increase in the number of stems in spring (the percentage of the number of stems on Apr. 25 to that on Feb. 25), over-seeding on Oct. 1st showed the significantly higher number of stems in the next spring (April 25) comparing with the other seeding times, although overwintering rate of stems (the percentage of the number of stems on Feb. 25 to that on Nov. 30) was low 2) With the low rate of application (5kgN/10a) of slow-release fertilizer, the increasing effects on the number of seedlings, the overwintering rate of stems and the tillering in spring resulted the highest number of stems in the next spring in October seeding. 3) Post-sowing trimming significantly increased the relative light intensity in the upper layer of seedlings, which increased the tillering in spring and the number of stems in the next spring. These effects were significant in October seeding with twice trimming. The results suggested that seeding in October with the application of slow-release fertilizer of 5kgN/10a followed by twice post-sowing trimming was most effective for the establishment of orchardgrass drilled into tussock-formed orchardgrass sward.