Spring planting has been hit and miss for livestock producers in the state. Some producers have corn fields emerging while others have not yet gotten corn planted. Last fall and this past winter were not ideal for manure application. Consequently, most manure storages are close to full, and wet weather has delayed planned spring application.
I have received several calls and texts with questions related to the timing of liquid manure application to corn. The application of manure to corn can make excellent use of the available manure nutrients. Liquid manure has ammonium nitrogen which the corn crop can immediately utilize.
Incorporating manure into growing corn can boost crop yields, reduce nutrient losses, and give livestock producers or commercial manure applicators another window of time to apply manure to farm fields. Not everyone has access to manure incorporation equipment to side-dress corn. Spreading manure on the surface of corn fields can also capture most of the liquid manure nitrogen.
Surface applying liquid manure to corn fields can occur any time after the corn is planted until the corn is in the V4 (four true leaves with collars) stage. The manure will not harm the emerging corn when applied after planting. Most commercial manure applicators simply drive across the field at an angle to the planted rows. The more advanced the corn field, the more damage is likely to occur from the applicator tracks.
To use a drag hose, the field must be firm enough to support the manure hose. Spring tilled fields that were worked deeply are generally too soft to support the hose unless they were compacted by heavy rainfall. No-till and cover crop systems, where the field was not deeply tilled in the spring, generally work well.
Five years of university research has shown that surface applying manure can produce corn yields about 20 bushels per acre less than incorporated 28% Urea Ammonium Nitrate (UAN). When incorporated, the manure produced yields about 15 bushels per acre higher than the UAN. University research has also shown that corn yields are reduced by about 50 bushels per acre when flattened with a drag hose at the V5 stage.
It is important to know the nutrient content of manure if a livestock producer is counting on using the nutrients to replace commercial fertilizer. Various swine integrators use different feeding rations so a recent manure analysis is important.
Numerous livestock producers have adapted manure tankers for side-dressing manure into emerged corn by modifying rims and wheels for traveling down corn rows. Even with the soil compaction concern, corn yields from side-dressing with manure are similar to side-dressing with commercial fertilizer. Using a manure tanker also allows the corn to be taller, providing a wider window for manure application.
A YouTube video created from the 2021 Conservation Tillage and Technology virtual Conference on side-dressing corn with liquid manure can be found here: