Table 3 Demand-driven interventions and scenarios within interventions

Fencing off wetlands and boundary areas to restrict excessive native wildlife grazing (Farm S1)

1. Reduce grazing area by 100 ha (11)

2. Fence, increased feed supply (12)

3. Fence, increase feed supply and weaning (13)

4. Fence, increase feed and stocking rate (14)

To account for variability in land allocation, improvements in pasture growth, improvements in weaning rate or impacts on stocking rates, four scenarios are simulated:

i. Fence off 100 ha of poorer productive land adjacent to the two rivers flowing through the property;

ii. In addition to i., fence off an additional 9 km of boundary fence adjacent to native tree vegetation to increase pasture production in the adjacent paddocks increasing feed supply by approx. 125 ha of feed across the whole farm¹⁰⁰; iii. In addition to i. and ii., increased weaning rate due to increased feed supply; iv. In addition to ii., increased stocking rate due to increased feed supply. See supplementary information for changes in weaning and stocking rates

Change in lambing date (Farm S2)

1. June lambing (15)

2. August lambing (16)

3. June lambing CFA Sept (17)

To account for variation in lambing time, three lambing/ purchased ewe date combinations were examined (in each case with shearing dates altered in a commensurate manner; baseline was lamb in late March and cast for age (CFA) in mid- August)):

i. Lambing begins 1 June and ewes cast for age (CFA) mid-October

ii. Lambing begins 1 August and ewes CFA mid-December

iii. Lambing begins 1 June and ewes CFA mid-September

Ewe purchase and sale age (Farm S2)

1. Purchase 1.5 yr old Cull July (18)

2. Purchase 1.5 yr old Cull Sep (19)

3. Purchase 4.5 yr old Cull Jul (20)

4. Purchase 4.5 yr old Cull Sep (21)

To examine implications associated with ewe culling age and month of year, four scenarios were assessed. The baseline purchases ewes at 5 years of age and sells in mid-August at 7-8 years of age. The intervention involves changing the purchase and sale age and period, where ewes are purchased at 1.5 or 4.5 years of age and sold at 6-7 years of age at either the end of July or early September.

Feeding supplements for earlier weaning and higher weaning rates (WR) (Farm S2)

1. WR 112% + supp feeding (22)

2. WR 120% + supp feeding (23)

3. WR 140% + supp feeding (24)

To examine variability associated with lamb weaning rates, three scenarios were assessed. The baseline farm system does not include any supplementary feed to reach production targets. This was altered with the feeding of lupins to the breeding ewes in the paddock for a week on either side of mating to improve conception. We modelled three conception rates, to stimulate targeted weaning rates of 112% (baseline), 120% and 140%

Single lambing and reduced wool micron (Farm S4)

Single lambs, reduced wool micron (25)

To examine the plan for the farmer to target low micron wool production, lambing rates were reduced to single lambs per ewe (baseline had a proportion of twin-bearing ewes) and decreased wool micron from 14 with the baseline down to 11 in line with farmer targets

Change in confinement feeding and stocking rate (Farm S5)

1. Increased stocking rate (26)

2. Increased confinement feeding (27)

3. Increased stocking and confinement feeding (28)

To examine trade-offs between ground cover conservation and supplementary feed use when animals were in confinement pens, three scenarios were examined: i. stocking rate was increased by 10%, keeping the timeframe of confinement feeding the same as the baseline, ii. commenced confinement feeding one month earlier than baseline while maintaining baseline stocking rate, and iii. The stocking rate increased, combined with the commencement of confinement feeding sooner.

Replacement of inorganic fertiliser with compost (Farm S6)

Compost application (29)

The purpose of this intervention was to substitute synthetic inorganic fertiliser (mono-ammonium phosphate) with organic compost, increasing pasture production¹⁰¹. Costs and GHG emissions are provided in Supplementary Tables S10 and S11.