Low phosphorus (P) constrains productivity of many of the permanent pastures of south-eastern Australia where wool and meat production are important. Whereas the need for fertilisation with P is indisputable for many soils, the benefits of liming to ameliorate soil acidification are not always clear in terms of forage production or quality. This experiment, by measuring botanical composition and groundcover over 10 years, aimed to address the issue of forage composition and groundcover. Merino wethers were continuously grazed on a permanent pasture under two stocking rates (low and high) following treatments with three rates of surface-applied lime and two rates of P. The lime rates were: nil, and sufficient to raise the pH_CaCl2 of the 0–10 cm soil layer to 5.0 and to 5.5. Phosphorus was added as two rates of single superphosphate: 125 kg ha^–1 every 2–3 years, and 250 kg ha^–1 every year. Two hypotheses were proposed: (i) as lime application rate increased, it would lead to the pasture swards having a higher percentage of species favourable for grazing animal production, and a higher level of sward groundcover would be maintained; and (ii) legume presence would be favoured by a higher level of applied P over the long term. The Millennium Drought (1997–2008), which coincided with this experiment (1998–2008), tended to mask or reduce lime effects; nevertheless, the higher legume content in the sward, as well as the superior groundcover found in the high lime–high P treatments at various times throughout the experiment and at its completion compared with the nil-lime control, indicated positive forage effects of lime application. Moreover, by the termination of the experiment in 2008, groundcover generally tended to be lower under nil lime than in treatments that had received lime. The higher proportion of legume in the sward was closely linked to greater applied P, although this did not occur at the low stocking rate in the absence of lime. By contrast, similar high P–low stocking rate treatments but with applied lime had the highest clover contents. It is proposed that the poor persistence of the treatment without lime may be due to a combination of poor legume seedset, because of excessive competition from accompanying grasses, and aluminium toxicity adversely affecting legume growth.

低磷（P）限制了澳大利亚东南部许多永久性牧场的生产力，在这些地区，羊毛和肉类的生产很重要。尽管在许多土壤上对P施肥的需求是无可争辩的，但从石灰的角度来看，改善土壤酸化的益处并不总是从草料产量或质量上看清楚。该实验通过测量10年的植物成分和地被植物，旨在解决饲草成分和地被植物问题。在使用三种表面施石灰速率和两种P速率进行处理之后，以两种放养率（低放和高放）在一个永久性牧场上连续放牧美利奴羊水草。石灰量为：无，足以提高pH _CaCl20-10厘米土壤层的厚度分别为5.0和5.5。磷以两种过磷酸钙的比率添加：每2–3年125 kg ha ^–1和每年250 kg ha ^–1。提出了两个假设：（i）随着石灰施用量的增加，牧草中的草种比例更高，有利于放牧动物生产，并且草皮地被植物的水平将保持较高水平；和（ii）从长远来看，较高水平的施用磷有利于豆类的存在。与该实验（1998-2008）相吻合的千年干旱（1997-2008）趋向于掩盖或减少石灰的影响。然而，与无石灰对照相比，在整个实验的不同时间，草皮中较高的豆科植物含量以及在高石灰-高磷处理中不同时间发现的优良地被植物，显示了积极的草料效果。此外，在2008年实验终止之前，在没有石灰的情况下，地被植物的覆盖率通常比在接受石灰的处理中要低。豆科植物中较高的豆科植物比例与较高的施用磷紧密相关，尽管在没有石灰的情况下，低放养率下不会发生这种情况。相比之下，类似的高磷低放养率处理，但施用石灰的三叶草含量最高。有人提出，不加石灰处理的持久性很差，可能是由于豆类种子集差，与陪伴草的过度竞争以及铝毒性对豆类生长的不利影响所致。