Manure Applications for Grain Production
Manure can be a great source of nutrients in crop production. When applied properly, the benefits can significantly outweigh any costs of the manure itself, or the application.
Let’s take a look at how manure could be a beneficial addition to your cropping plan.
What You Get With Manure Applications
There are many different types of manure, so it’s understandable that the nutrient analyses can vary. But as a general rule, manure contains significant amounts of not only N, phosphorus (P) and potassium (K), but also organic matter and other nutrients that are required for crop growth. The nitrogen captured in manure can be deducted from total nitrogen (N) needs of your future crop, and the soil attributes from the application can last several years.
For example, an average beef feedlot composted manure analysis reveals 16 pounds of nitrogen, 20 pounds of phosphorus, and 25 pounds of potassium per ton. When a broadcast application of 20 tons per acre is completed on the soil surface, the nutrient totals are 320 pounds of nitrogen, 400 pounds of phosphorus, and 500 pounds of potassium per acre.
Available Nitrogen: How Quickly Can You Work It
The amount of available nitrogen is dependent on environmental temperatures and the amount of moisture received following application. But another key factor for successfully utilizing manure is how quickly you can get it worked in.
Let’s look at a nitrogen availability study, using the same example from above, 20 tons per acre of beef feedlot composted manure:
With this info in mind, you can see that delayed or no incorporation can result in a possible nitrogen loss of 175 pounds per acre from a 20 ton per acre application.
Remember that nutrient numbers vary from year to year, and region to region.
Timing Matters When It Comes to Manure
Timing of a manure treatment becomes important for a couple of reasons:
Application after fall harvest is best because it often allows for immediate incorporation to capture the nitrogen benefit contained within the manure.
Application of manure to frozen ground is the least desirable timing, even on no-till farms.
A few more considerations for manure applications:
Manure should not be applied to wet soils as the heavy equipment for application will cause soil compaction.
When applying manure to no-till farms, leave as much crop residue on the soil surface as possible to capture the manure. The crop residue will reduce any movement of the manure from weather events to off target areas.
Don’t Let Manure Make You a Stinky Neighbor
If not managed properly, manure can be a bad neighbor.
Manure is subject to movement from rainfall, snowmelt or wind, which can lead to contamination of surrounding surface and subsoil waters with nitrogen and phosphorus. Rainfall runoff and freeze thaw cycles can also relocate manure to lower areas, causing unwanted and nonuniform deposits of the manure across field.
One of the most difficult characteristics of manure application is odor.
The smell itself is caused by odorous gases and volatile organic compounds (VOC) comprised of organic acids formed by microorganisms. These VOCs are then broken down to methane gases by bacteria. When the bacteria present are unable to keep up with the VOC produced, the pungent aroma emerges.
Cold and freezing temperatures slow microbial activity, reducing the amount of unpleasant odor; however, the freeze/thaw action during the winter months can supply a plentiful quantity of noxious gases to be dealt with.
The best way to reduce the odor is to immediately incorporate the manure.
The bottom line is: If you can smell the manure you are most likely losing nitrogen.
Being respectful of your neighbors when selecting where and when to apply manure is a solid way to be both a good neighbor and a good steward of the land.