- Trial Rationale
- Steps Taken
- Lessons Learnt
- Looking Forward
Previous work has identified potential benefits to farm profitability and natural resources by adding a mixture of Australian perennial shrubs to existing pasture-based livestock systems. This mixed forage system of perennial shrubs and inter-row pasture is referred to as the ‘Enrich system’. (http://pastureimprovementinitiative.com.au/research/enrich/)
Research suggests that the benefits of adopting the Enrich system will include:
- improved whole-farm profit;
- improved groundcover, especially during difficult seasonal conditions;
- improved management of dryland salinity;
- the addition of a predictable feed supply in the autumn ‘feed gap’;
- flexibility to defer the winter grazing of annual-based pastures;
- reduced supplementary feeding costs;
- gut parasite control, and
- possible improvements in soil carbon.
Farm bio-economic modelling has identified that, to maximise profit and to best complement other enterprises in the whole-farm system, there is an optimum farm area that should be grown to perennial shrubs. This optimum area varies depending on precise circumstances, but it is typically in the order of 10-15% of the whole farm.
Even with this wealth of information behind us, adoption is not necessarily straight forward. Critical thinking is required to firstly identify the reasons why the innovation is the ‘best’ option for a given farm and farming system, where on the farm perennial shrubs should be established and in what spatial configurations, what shrub species are most suitable and how can they can be affordably sourced from nurseries, when and how should the shrub-pasture mix be grazed, and can the expected NRM benefits be confirmed at a whole-farm scale?
Approximately 80 hectares was allocated to a mixed shrub-pasture system, classified as:
- mildly saline areas – saline
- rocky hilltops (shallow soils) – ridges
- paddocks unsuitable for cropping but with good quality soil – good
The majority of the 80 hectares was classified as ‘good’, but increasing forage production on these areas was considered beneficial to the whole-farm system because these areas were expected to yield more forage biomass than the saline areas or ridges, and the distribution of the different land types made it logistically easier for sheep to be placed in an Enrich paddocks at any time of the year.
A mix of shrub species was planted 2015, 2016 and 2017 (Table 1), based on recommendations from the Enrich project and also the commercial availability of shrub seedlings. The different species were deliberately planted randomly at each location rather than in species-specific rows. This was for two reasons: to allow sheep to readily access the diversity, and reduce the risks of poor shrub growth in particular areas due to localised incompatibility between the soil conditions and the shrub species.
A diverse pasture mix was also sown days prior to shrub-planting to develop inter-row alleys, comprising of: Prima gland clover, Santorini yellow serradella, Margarita French serradella, Bartolo bladder clover, subclover species, medic species, plantain and chicory. All pasture species were direct seeded using conventional methods.
|Scientific name||Common name||Some highly rated traits|
|Atriplex amnicola||River saltbush*||Edible biomass, regrowth, crude protein, digestibility, mineral content (Ca, Mg, S)|
|Atriplex nummularia||Old man saltbush*||Edible biomass, regrowth, digestibility, mineral content (Ca, Cu, Mg, S, Zn), shelter|
|Atriplex rhagodiodes||River Murray saltbush*||Edible biomass, regrowth, crude protein, mineral content (Ca, Cu, Mg, S, Zn), shelter|
|Chamaecytisus profiler||Tagasaste (exotic)||Palatability, digestibility, calcium, magnesium and zinc content|
|Chenopodium nitrariaceum||Nitre goosefoot||Crude protein, bioactivity (reducing methane, ammonia and gut parasites), calcium, magnesium and sulphur content|
|Enchylaena tomentosa||Ruby saltbush*||Regrowth, calcium, copper, magnesium, sulphur (also good bioactivity)|
|Eremophila glabra||Tar bush||Palatability, reduced methane production, calcium and magnesium content|
|Maireana georgei||Satiny bluebush*||Regrowth, crude protein, calcium and sulphur content|
|Rhagodia candolleana||Sea berry saltbush||Reduced methane production, calcium, magnesium and sulphur content|
|Rhagodia preissii||Mallee saltbush||Regrowth, calcium, copper, magnesium and sulphur content, digestibility, shelter|
|Rhagodia spinescens||Thorny saltbush||Crude protein, calcium, magnesium and sulphur content|
* indicates species planted in saline areas. Note: two cultivars of old man saltbush were used – Eyres Green and Anameeka
Grazing of the Enrich forage areas was managed as part of the normal whole-farm decision-making processes. The first grazing after shrub establishment occurred in one location in January 2016, only 5 months after planting. This was a short duration graze (< two weeks) and virtually all leaves were removed from the small seedlings However, within four weeks, the plants had fully recovered and were well endowed with regrowth foliage, aided by a wet summer (about 70 mm fell during December 2015 and January 2016). Other areas of shrub planting became part of the whole-farm grazing plan within 10-12 months of planting. Most areas have since been grazed twice a year.
Shrub survival exceeded 90% in all areas, and pasture establishment was also successful. Based on visual estimates of edible biomass, feed on offer has been about 3,000-5,000 kg dry matter (DM)/ha in summer/autumn if grazing was deferred during the previous winter, and in excess of 5,000 kg DM/ha if deferred during spring (Figure 4). This level of feed on offer compares to a typical scenario with dry annual pasture or crop stubble providing 1,000-2,000 kg DM/ha in summer/autumn.
In addition to the extra biomass, the perennial shrubs combined with summer active pasture species such as chicory and plantain provided green feed at a time of year where conventional, annual pastures are senesced. Green feed provides more nutrients than senesced pasture, including protein, sulphur and vitamin E, all of which can be limiting sheep production in parts of Western Australia during the drier months. The shrub-pasture mix was highly palatable to sheep, with consumption reducing biomass to 500 kg DM/ha during grazing in summer or autumn.
The provision of extra forage from the Enrich shrub-pasture systems allowed whole-farm stock number to increase by 10%, which represented an extra mob of about 300 sheep. Even with the extra stock numbers, grain feeding over summer and autumn was reduced by 20-25% (from 100-120 tonnes per year to 75-80 tonnes) because animals provided access to the perennial shrub-based paddocks.
The reduction in supplementary feeding and the increase in whole-farm stocking rate are entirely consistent with whole-farm bioeconomic modelling (Monjardino et al., 2010), confirming that predicted benefits can and do occur under commercial farming conditions. In the case of this project, measurable increases in income approached $40,000 p.a. and savings were $6,000.
Additional benefits can also be expected. Although not measured directly in this project, we can expect an increase in wool growth of 8-10% in sheep grazing saltbush-based forage systems (Chadwick et al., 2009) and an increase in wool quality (staple strength) by reducing the risk of tender wool that is often associated with poor quality feed in autumn and rapid changes in feed supply around the break of season (Franklin-McEvoy et al., 2007; Revell 2018). Lamb survival can be expected to be higher if ewes lamb in areas that provide protection (e.g., Robertson et al. 2011); depending on weather conditions at the time of lambing, lambing percentage may increase markedly by reducing lamb deaths due to exposure.
The main expense is the direct cost of seedlings and planting. Indirect costs will vary between different farming enterprises, depending on the requirements for extra fencing, watering points for livestock, and earthworks.
The return on investment ($45,600 returned for an outlay of $111,412) was 40%, with cost recovery expected within 3 years. This excludes any ‘additional’ benefits described above (e.g. increased wool strength and lamb survival, improved risk management).
More details can be found at https://swccnrm.org.au/library/download-info/trial-report-incorporation-of-perennial-australian-shrubs-into-whole-farm-management/ and https://swccnrm.org.au/enriching-pastures-and-profits-with-high-value-forage-shrubs/
Garry thinks that the future for combining shrubs and pasture in one forage system is tremendous.
“As time goes by I can’t see how I could do without them really. In a tough year like 2017, we’ve rotated all the mobs through there and kept their condition up.”
“It’s a no brainer once you experienced it. It keeps a more even health profile with your sheep and a more even production cycle. It levels out the troughs. Any good stockman would just about instantly see the benefit of it.”
The start-up company Wide Open Agriculture was motivated by what it saw in this project to commence a 100-hectare demonstration an Enrich grazing system in Buntine, Western Australia. We believe we are at a tipping point with this kind of forage system, where sufficient data and experiences now exist to replace small trials to large proof-of-concept and commercial-scale projects.