Why renew, A sheep farm example
Renewing under-performing or weedy paddocks with high quality cultivars can give significant financial gains. In this example an investment of $1585can give a net return of $8130 - one few other investments can match!
In this example after a crop, herbicide is sprayed to kill weeds prior to cultivation. Full costs are presented, but these should be partly attributed to the cost of the crop.
Typical costs of renewal
1. Average price for North and South Island-based contractors, July 2026.
2. Estimated retail prices, July 2026.
Cost benefit example
This financial returns from renewal in this example come in two ways. First, the new pasture increases growth by 4 t DM/ ha, which is often achievable, but depends on the situation. The extra yield increases carrying capacity by 2.8 ewes/ha in year one, while the new pasture is still establishing, and by 4.5 ewes/ha once the pasture is established.
Second, new pastures typically have higher feed value, as you replace weeds with quality forage. This means lambs grow faster (e.g. 200 g/day) than on old pasture (e.g. 120 g/day). This sets up the opportunity to trade and finish an extra 15 lambs/ ha. This would vary year to year depending on rainfall and availability of store lambs.
Gross margin from extra productivity
1. Loss of growth of 1500 kg DM/ha with renewal. This is subtracted from 4000 kg DM/ha benefit first year, to give a net gain of 2500 kg DM/ha. A ewe intake requirement of 660 kg DM/year allows an extra 2.8 ewes/ha, each returning a gross margin of $370. (This is based on income: 1.2 lambs @ $200/lamb, plus cull ewe income @ $145, plus 5 kg wool @ $3/kg. Less expenses: freight $2.50, animal health $7, shearing expenses $6, ram purchase 20% of rams (1:50 service) @ $1000 (=$5), interest 5% on capital (=$10).
2. 4000 kg DM/ha/year increased pasture with 75% utilisation. A ewe intake requirement of 660 kg DM/year allows an extra 4.5 ewes/ha.
3. Assuming average lamb LWG on old pasture 120 g/day (i.e. 100 days to gain 12 kg), on new pasture 200 g/day (i.e. 60 days to gain 12 kg). Allowing for an extra 15 lambs/ha from 40 days extra grazing at a gross margin of $35/lamb. (This is based on lambs growing at 200 g/day, for 40 days, gain 8 kg LW; at 46% yield gives an extra 3.7 kg CCWT @ $11/kg CCWT ($40) plus 1 kg wool @ 3/kg ($3). Less expenses: freight ($2), animal health ($2) shearing ($3), interest ($1) gives a gross margin of $35/lamb).
