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 bare ground 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 post-sowing trimming frequency (none, once and twice). The seeds were sown in a groove of about 6 cm depth in a wooden box (36.8×57.5×22.6 cm) filled with volcanic soils. The results obtained were as follows: 1) Seeding in August showed the highest number of stems in the next spring (Apr. 25) per area due to the highest overwintering rate of stems (the number of stems on Feb. 25 as a percentage of that on Nov. 25), and the highest rate of increase in the number of stems in spring (the number of stems on Apr. 25 as a percentage of that on Feb. 25). Because of the serious damage to the seedlings by low temperature, the number of stems in spring with October seeding was significantly low compared to the other seeding times, though its number of seedlings at two months after seeding showed the highest value. 2) The dressing of 5kgN /10a of slow-release fertilizer was effective for establishing more seedlings at two months after seeding and more stems in spring. All of the seedlings in October seeding under the treatments of fast-release fertilizer and 10kgN slow-release fertilizer applications died off in winter. 3) Post-sowing trimming had little effect on the number of stems in the next spring. The results suggested that August seeding with 5kgN /10a of slow-release fertilizer was most effective in the next spring for producing the highest number of stems of orchardgrass drilled into bare ground.