Irrigation Cost per Acre-Inch Calculator

About the Irrigation Cost per Acre-Inch Calculator

The cost to apply one acre-inch of irrigation water is a key metric for farm budgeting and irrigation investment decisions. It includes energy costs (electricity, diesel, or natural gas) to run the pump, maintenance and repair of equipment, labor for system operation, and any water purchase or delivery charges.

Knowing your cost per acre-inch lets you calculate the total irrigation expense for the season, compare the economics of different crops and irrigation methods, and determine when deficit irrigation or dryland farming becomes more profitable.

This calculator sums the main cost components and divides by seasonal application volume to give you a per-acre-inch cost you can plug into crop budgets.

When This Page Helps

Irrigation is often one of the largest variable costs in crop production. Knowing your cost per acre-inch helps you compare crops, irrigation levels, and equipment changes on the same basis.

How to Use the Inputs

1. Enter the annual energy cost for pumping in dollars.
2. Enter annual maintenance and repair costs.
3. Enter annual labor cost for irrigation operations.
4. Enter annual water purchase or delivery charges.
5. Enter the total acre-inches applied during the season.
6. Read the cost per acre-inch.

Example Calculation

Tips & Best Practices

• Energy is typically 50–70% of total irrigation cost.
• Track actual energy use with a dedicated meter on the pump.
• Maintenance budgets should include pivot tire replacement and lubrication.
• Diesel pumps cost more per kWh-equivalent than electric in most areas.
• Water charges from irrigation districts are often per acre-foot delivered.
• Compare cost per acre-inch against the value of yield per inch to gauge profitability.

Energy Cost Breakdown

Energy costs depend on three factors: total dynamic head (TDH), pump and motor efficiency, and the energy rate. Increasing pump efficiency by just 5% (e.g., from 65% to 70%) reduces energy cost by about 7%. Annual pump tests identify efficiency degradation.

Comparing Fuel Sources

Electricity, natural gas, diesel, and propane are the main pump fuels. Electricity is often cheapest per kWh-equivalent, followed by natural gas, then diesel or propane, but local tariffs and demand charges matter more than generic averages. Variable-rate electric plans with off-peak irrigation discounts can offer additional savings.

Using Cost per Acre-Inch in Crop Budgets

Multiply cost per ac-in by total seasonal application to get irrigation cost per acre. Compare this with yield response curves: the last few inches of irrigation may cost more than the additional revenue they generate, especially for crops with diminishing returns to water.

Frequently Asked Questions

• What is a typical cost per acre-inch?

  Costs vary widely: $2–$4/ac-in for efficient electric wells, $5–$8/ac-in for diesel or deep wells, and $8–$15/ac-in for high-lift or distant water sources. Your actual cost depends heavily on energy prices, pumping depth, and system efficiency. Tracking your cost over several seasons helps identify trends and opportunities for savings.

• How do I calculate energy cost separately?

  Energy cost = kWh per ac-in × electricity rate. For typical center-pivot conditions, 20–50 kWh per ac-in at $0.08–$0.12/kWh gives $1.60–$6.00/ac-in for energy alone.

• Should I include fixed costs?

  This calculator focuses on variable (operating) costs. Fixed costs like depreciation and insurance are important for investment analysis but are usually separate from per-acre-inch operating costs.

• How does depth to water affect cost?

  Deeper wells require more energy per gallon pumped. Total dynamic head (TDH) is the key variable: energy cost is proportional to TDH. A well pumping from 200 ft costs roughly twice as much per ac-in as one from 100 ft.

• What about water district charges?

  Districts charge per acre-foot, per acre, or both. Include only the variable portion (per ac-ft charge) in your per-acre-inch calculation.

• How can I reduce irrigation cost?

  Improve system efficiency (less gross water per net inch), switch to off-peak electricity rates, maintain pumps for peak efficiency, and use soil moisture sensors to avoid unnecessary irrigations. Scheduling irrigations based on crop water demand rather than a fixed calendar can reduce water use by 10–20%. Regular pump testing ensures your equipment is operating at optimal efficiency and not wasting energy.