Using Irrigation for Fertigation

Each spring growers start planting not knowing what the growing season will hold; from rainfall to growing degree units. Sometimes, growers even know the challenges ahead of time such as the potential for nitrogen loss can be very high on sandy soils. Growers are always looking for practices to enhance growth potential from mid to late season and capture maximum yield potential. Applying nitrogen in split applications is one of those practices.

One way to replace or add nitrogen after the crop is past the point of over-the-top applications with ground equipment is fertigation, which is the process of applying fertilizer with irrigation water through overhead irrigation systems such as center pivot or lateral move. Irrigated production provides the advantage of fertigation as an option in nitrogen management. Fertigation is often the last step in a three-split nitrogen management plan following starter at planting and sidedress applications. Through fertigation, nitrogen application rates can be increased when the growing season is favoring high yield potential or to replace nitrogen lost in the growing season due to higher-than-average rainfall. Fertigation can also help supply the remaining nitrogen needed for the crop just prior to tassel emergence. This timing is important to help ensure that the nitrogen applied is available for the plant to take up and use during early grain development. Fertigation should be completed by R1 to R2 growth stages. This principle is important for preventing yield penalties, such as kernel abortion, for delaying nitrogen needed for grain development.

The most important part of fertigation is to know the actual amount of fertilizer the equipment can inject into the irrigation system. It is also important to know if the system can apply the water uniformly across the field as this could introduce another level of variability to the field. Furrow irrigation is not recommended for fertigation due to variability. In addition, nitrate moves with water, and if soil is at field capacity, continuing to fertigate increases the risk of nitrogen loss. Irrigation timing can be delayed by rainfall which can delay a critical growth stage nitrogen application.

There are a few things to consider when adding fertigation to a fertility program. One item is to make sure the irrigation equipment is consistently applying the fertilizer evenly by calibrating the nozzles. After determining that irrigation equipment is working properly, it is important to protect the water supply from backflow through chemigation valves. Lastly, it is important to check for mandatory training and certifications for chemigation treatments such as fertigation.

Sources:

Kelley, L. 2018. Irrigation offers producers mid-season options for nitrogen application. Michigan State University. https://www.canr.msu.edu/news/last-chance-nitrogen-application-with-irrigation/.

Ferguson, R. 2009. Using fertigation for efficient nitrogen application. CROPWATCH. University of Nebraska-Lincoln. https://cropwatch.unl.edu/using-fertigation-efficient-nitrogen-application/.

Fernandez, F. and Struffert, A. 2018. Corn fertigation: How much and when? Minnesota Crop News. University of Minnesota Extension. https://blog-crop-news.extension.umn.edu/2018/05/corn-fertigation-how-much-and-when.html

Websites verified 4/16/23. 1221_444551