Field experiments were undertaken on two infertile and acidic soils in the semi-arid Mackenzie Basin, South Island, New Zealand, to determine the influence of fertiliser placement and rate of N application (0, 15, or row, respectively) but not when N was drilled 20 mm below the seed. Seedling numbers declined in all treatments over summer, and 32 weeks after sowing, numbers were only significantly lower when 30 kg ha -1 N was drilled with the seed (11.1 and 7.9 m -1 , respectively). Early seedling growth of legumes, apart from lupin, responded to N, the largest increases occurring where N was drilled with the seed. Although individual plant weight increases where N was drilled with the seed were still evident 32 weeks after sowing, legume DM yields were not significantly affected because of the lower establishment. Plant growth 32 weeks after sowing was affected by competition from existing vegetation, and increases in individual plant weight and legume DM yield from N occurred only where herbicide was applied. Basal superphosphate was more effective when it was drilled with rather than below the seed. The role of N fertiliser in the establishment of legumes overdrilled into low fertility situations is discussed.
The establishment of lotus (Lotus corniculatus), alsike clover (Trifolium hybridum), cocksfoot (Dactylis glomerata), and mountain brome (Bromus marginatus) were compared following overdrilling by an experimental strip seeder and a conventional triple disc drill in the presence and absence of paraquat herbicide. Drilling was carried out in late August or in late January at two sites on dry, undeveloped soils in the Mackenzie Basin, New Zealand. With August sowing, the number of lotus, cocksfoot, and brome, but not alsike seedlings at the end of the first growing season, were higher with the strip seeder drill than with the triple disc drill. With January sowing, lotus, alsike, and cocksfoot seedling numbers were higher with the strip seeder drill.
A97005 Received 22 January 1997; accepted 27 May 1997Numbers declined over the following four years but the advantage of the strip seeder drill remained. Improved seedling nodulation, root development, root length, and shoot length were recorded with the strip seeder drill. Drill effects on legume herbage accumulation in Years 2-4 were not consistent. There were no significant herbicide effects on seedling establishment in the first growing season but herbicide increased legume herbage accumulation in Years 2-4, particularly with the triple disc drill. The higher seedling establishment and enhanced early seedling growth indicate the potential of the strip seeder drill technology particularly for establishing species with low seedling vigour.
A prototype strip seeder was developed to establish grasses and legumes in the semi-arid and montane environments of the Mackenzie Basin and Central Otago. Specifications of the strip-seeder required for cost-effective performance were identified on the basis of previous direct drilling investigations in this environment, and included: (a) removal of a strip of existing vegetation to reduce competition; (b) creation of seed bed tilth; (c) controlled and separate placement of seed and fertiliser; and (d) compaction of the drilled seed bed to enhance contact between seed and soil. The prototype strip seeder was built around a modified Duncan 730 multi-seeder chassis, and was used to install spring and autumn trials at Eamscleugh in Central Otago and at Ohau Downs in the Mackenzie Basin. Mechanical improvements were made as the trials progressed. The experience gained, and results from the trials, confirm the suitability of the prototype strip seeder concept for successfully introducing grasses and legumes into this terrain. Keywords direct drilling, strip seeder, seed placement, seed depth, sowing depth
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