The cost–benefit of irrigating wheat under drought conditions

To make a decision on whether to irrigate, the crop needs to be inspected to ensure it has the potential to meet the minimum yield for profitable investment in irrigation. Irrigators can make realistic yield estimates by multiplying head numbers/m2 by 0.013 or biomass t/ha x 0.42 once the crop is past Growth Stage 35. Along with estimates of commodity prices and variable costs (particularly price of water), a gross margin tool can be used to assess the return required to make a profitable return on investment.

Once the decision is made to irrigate, the need for timely application becomes even more important to ensure the crop is not stressed and potential returns jeopardised. Ensuring nutrients are available to plants before watering further increases the potential returns from irrigating.

Irrigated crops can generate large biomass if they receive adequate water and nutrition. An alternative to taking grain crops through to harvest is hay.

Key Points

• Irrigating wheat can be profitable in drought years, with the top 10 per cent of growers surveyed producing returns of more than $1500 per hectare in 2018
• When deciding on spring irrigation and the water price (temporary as well as any allocation or carryover), grain price and crop potential are the key factors to consider
• Gross margin tools can be used to determine the minimum yield required to give a return on water investment and estimate financial returns to assist in decision making
• Assessment of crop potential is essential to determine if the minimum yield required is achievable. Head numbers per m2 can be multiplied by 0.013 to estimate yield/ha
• Biomass, crop nutrition and timeliness of irrigation are drivers of cost–benefit of irrigating in drought years

Useful Resources

ICC ‘Irrigate or not’ gross margin Excel spreadsheet.
Contact damian.jones@irrigatedcroppingcouncil.com.au

NSW DPI gross margin tool
www.dpi.nsw.gov.au/agriculture/budgets/costs/cost-calculators/correctcrop-sequencing-decision-support-tool

NSW DPI irrigation guides and posters
www.dpi.nsw.gov.au/agriculture/irrigation/irrigation