Spatial separation of species at sowing has been proposed as a means of managing interspecific competition in mixed swards. This study examined the effect of row configuration on persistence of lucerne (Medicago sativa L.) in pastures and pasture–cover crop mixtures at three sites in the Central West, and in pasture mixtures at three sites in the Riverina, New South Wales, Australia. Lucerne density, taproot diameter, groundcover, and spatial distribution relative to the original drill row were measured at all sites, and plant-available soil water and light interception during spring were assessed at some sites. Row configuration (alternate or mixed drill rows) did not affect lucerne persistence; however, where lucerne seed was concentrated in every third drill row, intraspecific competition led to increased lucerne mortality. This was estimated to occur at densities >28 plants/m drill row. A lucerne density of ~55 plants/m² in every or alternate drill rows (at row spacings of 250 mm) would likely achieve maximum lucerne production in the semi-arid environments tested, subject to the chance event of favourable conditions in the period after sowing that would maintain that density (e.g. cumulative summer rainfall >100 mm and summer day degrees <2160°C in 2 years at Cowra). The presence of a cover crop in the establishment year reduced lucerne density by 39% compared with pasture only, regardless of row configuration. Changed row configuration did not reduce competition for light under a cover crop, but there was a small increase in available soil water of up to 4.9 mm in the 0–1.15 m depth, mainly during the first summer, where pasture was sown in alternate compared with mixed drill rows with a cover crop. Soil was drier in pasture-only treatments than those with a cover crop, attributable to increased lucerne density and lower levels of litter cover on the soil surface. Pasture species remained largely confined to the original drill row, especially in drier environments, highlighting the importance of narrower row spacings for pasture establishment. In addition, we determined a mathematical relationship between lucerne density and the non-destructive measure of basal frequency; this relationship could be applied in mature lucerne stands with densities ≤80 plants/m².

已经提出了在播种时进行物种的空间分离，作为管理混合草地中种间竞争的一种手段。这项研究检查了行结构对紫花苜蓿（紫花苜蓿的持久性的影响L.）在中西部三个地点的草场和草场中覆盖农作物混合物，在澳大利亚新南威尔士州里维纳纳的三个地点的草场混合物中。在所有地点都测量了相对于原始钻行的卢塞恩密度，主根直径，地被植物和空间分布，并在某些地点评估了春季植物可利用的土壤水和光的截留。行的配置（交替或混合的行）不会影响卢塞恩的持久性；但是，在每三排钻中都集中有卢塞恩种子的地方，种内竞争导致卢塞恩死亡率增加。估计这发生在密度> 28植/米的钻排。卢塞恩密度约为55株/ m ²每排或每排交替的钻头（行距为250 mm）在播种后的半干旱环境中都可能实现最大的卢塞恩产量，但要注意播种后一段时间内有利条件的发生，这将保持该密度（例如，累积的夏季）。考拉（Cowra）在2年内的降雨量大于100毫米，夏季温度小于2160°C。在建立年份中，无论行配置如何，与草场相比，只有盖作作物才能使卢塞恩密度降低39％。行结构的改变并没有减少遮荫作物对光的竞争，但是在0-1.15 m的深度上，土壤水分最多增加了4.9 mm，主要是在第一个夏天，与之相比，牧场交替播种。混合的钻头行与被覆作物。与仅覆盖草场的土壤相比，仅进行牧场处理的土壤更干燥，这归因于苜蓿密度的增加和土壤表层凋落物覆盖率的降低。牧场种类仍主要限于原始钻行，特别是在较干燥的环境中，这突出了缩小行距对于建立牧场的重要性。此外，我们确定了卢塞恩密度与基础频率的无损测量之间的数学关系。这种关系可以应用于密度≤80植株/米的成熟的卢塞恩林分中 强调缩小行距对于牧场建设的重要性。此外，我们确定了卢塞恩密度与基础频率的无损测量之间的数学关系。这种关系可以应用于密度≤80植株/米的成熟的卢塞恩林分中 强调缩小行距对于牧场建设的重要性。此外，我们确定了卢塞恩密度与基础频率的无损测量之间的数学关系。这种关系可以应用于密度≤80植株/米的成熟的卢塞恩林分中²。