Despite most attention generally reserved for improved introduced pastures (example; media, agnotes, advertising), the majority of NSW pasture type remains by far native pasture based.
Because most soil types are inherently low in fertility, unimproved native pasture production is generally low and often overgrazed for long periods.
However, the potential to substantially boost their production, as well as preserve a good balance of native species, is high if carefully managed and steps are taken to improve soil fertility.
In our property's case natural soil fertility is typically low, especially in phosphorus, sulphur and nitrogen. Soils are also commonly naturally acid, both in the top and sub soil.
Native pastures unassisted with soil nutrient deficiency correction are very unproductive, no matter what grazing system or non-conventional amendments are added.
It is not possible for us to fatten animals on unfertilised native pastures and the stocking rate is less than 2.5 DSE/ha.
It is a challenge to improve productivity of these native pastures (other than sowing them down to tropical perennials) and at the same time retain a good balance of native perennial species.
Adding acid soil tolerant legumes like serradella, biserrula, Gland clover and even sub clover for moderately acidic parts of paddocks, is a first step. These can be top-dressed in or preferably chiselled in without removing much of the native perennial species.
Ensuring legumes are added appropriately with correct rhizobia bacteria strains is crucial for their success.
Legumes also need soil deficiencies like phosphorus and sulphur corrected for good production and soil nitrogen build-up. In our case superphosphate has been the most economical to correct these deficiencies.
We have been able to combine improved winter legumes with native grass species, and while these pastures are not as totally productive as tropical grasses plus winter legumes, they have an important and profitable role.
For example, native perennial grasses tend to slow their growth in autumn earlier than introduced tropical grasses. This makes them less competitive for autumn early winter soil water, and leaves more water for winter legume establishment.
More autumn water for legumes is important in years with moderate to low autumn early winter rains. In drought years like 2017 and 2018 it made no difference.
In a wet autumn early winter, it also makes little difference, as there is sufficient water even in a tropical grass pasture for good early winter legume growth.
Improved native grass pastures in our environment have a relatively good conservative carrying capacity of around 5 to 6 DSE/ha.
Compare that to 2.5 or less for unimproved and 7.0-9.0/ha for improved tropical grass. Equally important is that improved native or introduced perennial grass pastures suit fattening businesses, whereas unimproved does not.
Improved native grass pastures in our environment have a relatively good conservative carrying capacity.
- Bob Freebairn
Survival of native perennial grasses with winter legumes, and other winter herbage such as annul grasses and broadleaf weeds, can be a challenge.
One challenge is native perennial grasses can be swamped by winter herbage in years with good springs. So much so that the natives can be totally shaded for a few months of their spring growth phase.
Also, as winter herbage in a good spring dries off, soil water may be all used by the winter herbage.
Grazing pressure in good spring years (or hay or silage production) is one way to ensure spring early summer growth of native grasses is not totally shaded out. Around 3.0 t/ha drymatter, generally still a lot of feed, or less generally is not detrimental to native grasses.
Grazing management that ensures native grasses are not constantly grazed into the ground is also important for survival of softer species.
In our case we use flexible rotational grazing to ensure recovery periods and opportunities for periodic reseeding and new recruitment.
We recently assessed our native grasses for diversity and native grass species.
Commonly there were a multitude of species (more than 60 different ones) including lots of softer natives.
Native perennials included red grass, kangaroo grass, barbwire grass, wallaby grasses, several lovegrass species, umbrella grasses (two species), various panics and digit grasses.
Next week: Climate change or climate variability. Farming for both scenarios similar.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.
