Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia.

Approximately 3.1 Mha (22%) of the agricultural area of south-eastern Australia can be classified as native pasture. There is the assumption that, owing to the widespread occurrence of low-fertility soils in Australia, native grass species do not respond to increased phosphorus (P) fertility. Currently, there are no industry recommendations of target soil-test P values for native-grass-based pastures. This paper reviews the responses of perennial native pasture species endemic to south-eastern Australia to P application in controlled environments, surveys, replicated experiments and paired-paddock trials. Eighty-seven site-years of trial data where different levels of P were applied, conducted over the last two decades, on native-based pastures in south-eastern Australia are reviewed. Data indicate that application of P fertilisers to native grass pastures can increase dry matter (DM) production and maintain pasture stability. However, minimum targets for herbage mass (800 kg DM/ha) and groundcover (80%) are required to ensure persistence of perennial native grasses. Stocking rates also need to match carrying capacity of the pasture. Based on previous research, we recommend target soil-test (Olsen; 0–10 cm) P levels for fertility-tolerant native grass pastures, based on Microlaena stipoides , Rytidosperma caespitosum , R. fulvum , R. richardsonii , R. duttonianum and R. racemosum , of 10–13 mg/kg, whereas for pastures based on fertility-intolerant species such as Themeda triandra , lower levels of <6 mg/kg are required to ensure botanical stability. Within south-eastern Australia, native pastures exist in parts of the landscape where it is either not feasible or not economic to introduce perennial species. This paper reviews management guidelines relating to phosphorus (P) application on native pasture. Target soil-test (Olsen) P values of 10–13 mg/kg are recommended for fertility-tolerant perennial native pastures. [ABSTRACT FROM AUTHOR]