Know Your Irrigation Water!

When grain prices were on the rise, irrigation management began to garner more focus in the desire to manage soil moisture levels for optimal yield. This drove greater awareness in soil moisture monitoring and variable rate applications based on the water holding capacity of the soil. As the cost to pump water remains a large expense, there is focus on continually improving water use efficiency through maintenance of the irrigation systems and soil moisture monitoring. The traditional focus of irrigation management has been on technology and the equipment itself. However, the fundamental input of irrigation is still often overlooked; the water itself.
 
Many producers in the Great Lakes region feel that irrigation water testing is not needed since we do not face the salinity and sodium issues that are seen in arid regions of the United States. While it is true that salinity and sodium are rarely a concern for irrigated production systems in the Great Lakes region, we have our own unique challenges that must be managed appropriately.
 
The majority of our irrigation water in the Great Lakes region is “hard”, due to high levels of calcium based minerals. Long term application of untreated irrigation water that is high in calcium carbonate can lead to several challenges. This water tends to have a high pH that can lead to increased pH of surface soils over time causing nutrient availability issues, or could led to herbicide carryover issues. These effects can be exaggerated on sandy or low CEC soils. Irrigation water high in calcium or iron can also lead to calcium deposits on irrigation equipment leading to non-uniform water applications and additional maintenance costs.  An irrigation water suitability test is key in identifying the severity of high pH and high calcium carbonate levels, and can be used to identify, calibrate, and verify cost effective corrective actions.

Irrigation water quality changes during a short period may be slight, but over time can be significant. A water source that started with good quality may change so that it is no longer acceptable for the intended use.

We strongly encourage all users of irrigation water to establish a water quality baseline for each source (well) by testing the water. Follow-up tests should be conducted periodically to determine if the water quality has changed and, if so, the potential effect on the water use.


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