Manure Sidedressing

As the warm summer heat pushes the corn taller, it seemed a good time to discuss sidedressing manure. Today, I want to look at three potential reasons people may want to sidedress manure:  storage management, nitrogen management, and equipment availability.

So, what is sidedressing manure?

Sidedressing is the application of fertilizer to an already established and growing crop. In the case of sidedressing manure, it simply refers to the fertilizer source being a manure. This can be done using either tanks or dragline application methods, though equipment must clear the emerged corn and move mostly between rows, giving only a short window.

Storage Management

Sidedressing opens up an additional spring window for manure application and thus potentially a chance to reduce storage pressure by having more room available going into fall. However, there are a few things to consider. Sidedressing with manure has a relatively short window. It probably isn’t a good idea to rely on it as your only land application window, as the weather during this short window can be unpredictable. From a nutrient management perspective, if we miss this window we can still get nitrogen applied using other sources and other equipment to provide it fertility, but that doesn’t provide an opportunity to use the manure.

Nitrogen Management

Sidedressing nitrogen allows it to be placed just before corn uptake is maximized and in so doing the risk of losses from earlier spring rains or long warm falls is reduced. There is some risk the weather during the sidedress window will not be suitable for manure application, but as other forms of nitrogen can be applied at larger growth stages, there is still options available to successfully manage the crop.

In terms of manure, though we often think of it as an organic nutrient source, much of the nitrogen, approximately 70% in the case of liquid swine manures, is available as ammonium. This fraction is immediately available for crop uptake and means this type of liquid manure is a good choice for sidedress fertilizers.

Equipment Considerations

While both tanks and dragline application methods can be used, the equipment needs to be set up so it will fit between the rows. For tanks, this means having tire widths that can move between the rows and injectors. For dragline application, it means making sure application is finished during or prior to the V4 stages so the corn plants are still springy enough they can bend over when the hose crosses over them.

If you’d like to try sidedressing manure with a dragline, consider planting corn at a 45-degree angle to the field, so it follows the natural pattern applicators would use with draglining.

Finally, if you are sidedressing manure, be sure to let us know, we’d be glad to come watch, collect some pictures, and even some crop performance and water quality data if you are willing. Let me know at dsa@iastate.edu or 515-294-4210.

Figure 1. Manure sidedressing using a dragline application method.