Irrigation and Farm Water Management

Irrigated farming by the numbers

In the United States, USDA’s 2023 Irrigation and Water Management Survey counted 212,714 farms that irrigated 53.1 million acres and applied 81.0 million acre-feet of water, an average of 1.5 acre-feet per acre. Groundwater from on-farm wells supplied 54% of that water, and five states (Arkansas, California, Idaho, Nebraska and Texas) held about half of all irrigated acres. Both irrigated acres and water use were lower than in 2018.

Those numbers explain why farm irrigation gets so much attention. Water is often a farm’s biggest controllable input after fertilizer, pumping costs money, and in the West and on the High Plains the supply itself is shrinking. Small improvements in timing and uniformity add up quickly over a season.

Types of agricultural irrigation systems

Farm irrigation systems fall into three broad groups. Each can work well; the right one depends on the crop, soil, slope and water supply.

Subsurface drip, buried below tillage depth, is a variation used on some row crops. Our articles on center pivot cost and yields and drip irrigation cost and pumps go into each.

Choosing a farm irrigation system

Start with the water, not the hardware. How much can you pump or divert, at what pressure, how reliably through the season, and is it clean enough for small emitters? Then look at the soil: sandy soils take water fast and hold little, so they suit frequent light applications from pivots or drip, while heavy clays take water slowly and run off under high rates. Field size, shape and slope come next, then the crop’s value, which decides how much capital a system can justify.

Check the paperwork for the water as well. In much of the western US, Australia and Europe, taking water for irrigation needs a water right, an allocation or an abstraction license, and the volume and timing it allows can decide which system makes sense. Many arable farms with seasonal or capped supplies add on-farm storage, such as a lined reservoir filled in winter. If you plan to inject fertilizer through the system (fertigation), drip and pivots both handle it, but you’ll need backflow protection on the supply.

Running costs often matter more than the purchase price. Energy for pumping, labor to move pipe or check lines, filter and emitter maintenance, and repairs all recur every year. An irrigation system cost calculator is only as good as these inputs, so get a local installer to quote on your actual water source and fields. Our guide to irrigation system installation costs and setup lists what goes into a quote.

Agricultural irrigation management

A good system badly scheduled still wastes water. Most irrigation management comes down to two questions: how much water has the crop used since the last irrigation, and how much can the root zone hold?

• Crop water use is usually estimated from evapotranspiration. Weather stations give a reference value, and a crop coefficient for the growth stage scales it to your crop, the method set out in FAO’s widely used Irrigation and Drainage Paper 56.
• Soil moisture probes and tensiometers measure what is actually left in the root zone at a few points.
• Uniformity checks catch blocked emitters, worn nozzles and pressure problems, which can leave parts of a field short while others are overwatered.

Our article on water management challenges in agriculture covers scarcity, groundwater and runoff, and the main guide on agricultural water management strategies brings the data together.

Using satellite data to schedule water

A probe measures one spot. Satellites measure every 10 meters of a field, which shows whether a dry patch is local or spreading. Our AI farm advisory combines evapotranspiration, radar soil moisture and weather to give each field a water need in millimeters per day for the next seven days, with the best time to irrigate.

The savings our customers report mostly come from the days when the answer is “don’t water”. On a 124-acre blueberry farm in Florida, the reports said no irrigation was needed on 78 of 175 block-days in one week, and the grower estimates he optimized both irrigation and fertilizer use by 30–50%. A 190-acre farm in Algeria used 51% less water than watering daily. These are the growers’ own estimates from in-app feedback.