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How to make most of irrigation

Salute Soil Health: Building soil organic matter can help avoid water loss.

May 21, 2024

2 Min Read
An irrigation system in an open field
KEEP IT PARKED: Learning and incorporating ways to help your soil hold on to water better could mean more time between irrigation water applications. Allison Lund

by Amanda Kautz

According to the 2022 Census of Agriculture, which was released earlier this year, about 5.6% of Indiana cropland is irrigated. Where does the water go when you irrigate? Hopefully it infiltrates 100% and is available for crops to use, but a percentage will be lost to evaporation and runoff.

Improving your soil’s infiltration capacity will allow water to move into the soil more efficiently. A key part of boosting infiltration is building soil structure and organic matter. For water to move into the soil, soil pores must be present to let the water in. If the soil is disturbed through tillage or compaction, soil structure is broken up and those pores are destroyed.

Organic matter acts like sponge

In addition to creating soil pores, organic matter helps soil hold water. It acts a bit like a sponge. As water enters the soil, the organic matter soaks it up and holds on to it. Every 1% of organic matter can hold tens of thousands of gallons of water per acre.

To build both soil structure and organic matter, follow the soil health principles:

  • minimize disturbance

  • maximize soil cover

  • maximize living roots

  • maximize diversity

Practices like reducing tillage and planting cover crops are great places to start.

Once your soil is infiltrating as much water as possible, it’s important to think about if you’re getting the most out of your irrigation system. While you may think you know how much water you’re applying, it’s always a good idea to do a uniformity test to confirm.

The uniformity test consists of setting catch cans at even distances under the whole irrigation system and running the system for a specified time. By analyzing how much water is in each can, you can identify areas of the system that are over- or underapplying due to pressure issues, broken nozzles, holes in the waterline and other system malfunctions.

You can also install moisture sensors in fields that can help schedule irrigation applications based on real-time data. The sensors are installed at a specified depth, and the data is instantly accessible via smartphone or computer.

Cut back on evaporation

The last piece to think about is reducing evaporation. It’s easy to see that during hot weather, some water may evaporate before it reaches the soil surface or even from the soil surface. A wide variety of drop nozzles and high-efficiency nozzles can be used to reduce evaporation losses.

Keeping the soil covered by using high-residue cropping systems that incorporate cover crops and less tillage will protect the soil from evapotranspiration, improving infiltration and leaving more water for the crop to use. 

Weather patterns the last couple of years have included long dry spells during the summer months. If your soil holds on to a little more rainfall or irrigation water, it could mean more time between costly water applications.

Kautz is the state soil health specialist with the Natural Resources Conservation Service in Indiana. She writes on behalf of the Indiana Conservation Partnership.

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Irrigation
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