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Tips for spring manure application

Melissa Wilson, Extension Specialist, University of Minnesota

Spring is here! While we all hope it sticks around, it probably has some people thinking about getting manure applied before planting. While you may already have a plan for where and how you want to apply the manure, here are some other tips to consider before getting started.

Prepare your equipment and monitor it through the application season

Whether you are pumping liquid manure or loading solid manure, going through your equipment now is important for avoiding spills or downtime when it is “go time”. For liquid systems, how did your hoses hold up over the winter? Are the pumps ready to go? For solid spreaders, are the beaters worn down? Is there slack in the apron chain that should be adjusted? For any system that needs to travel on the road, are your signals and break lights working? During heavy use, keep monitoring these things to watch for wear and tear that can be fixed before it becomes a problem.

Collect a manure sample and send it for a nutrient analysis

Manure is a valuable nutrient source for crops. Knowing the nutrient content can help you maximize its use and get the best bang for your buck. Collecting a manure sample when the manure is well mixed is ideal. This could be after liquid manure has been agitated or during loading of solid manure. Either way, collecting several smaller samples during the loading process and mixing them well before sending to a lab is the preferred method. Choose a clean, plastic bottle with a wide opening and tight lid to ship the manure to the lab; do not use glass! It turns out the post office isn’t happy when manure sample bottles break in transit.

What tests should you choose? At a minimum we suggest total nitrogen, phosphorus, and potassium, though ammonium content can also help you understand the first-year nitrogen fertilizer value of the manure. If you are interested in getting secondary and micronutrients tested in the manure, too, many laboratories offer these services. Look for laboratories that participate in the Manure Analysis Proficiency (MAP) Program or the Certified Manure Testing Program. Both programs are coordinated by the Minnesota Department of Agriculture and help laboratories refine their manure analysis techniques to provide more reliable results.

Consider options for reducing soil compaction

Soil compaction during spring manure application is a concern. The first and main thing you can do to reduce this issue is stay off wet fields if at all possible! 

The second thing to consider is tire size on your equipment. For example, say you have a 6,000-gallon tanker that weighs 55,000 pounds when full. Tires that are 20 x 20 on 2 axles on this tanker will likely have to be inflated to 32 PSI, while 28.1 x 26 tires on 2 axles will be able to be inflated at 16.5 PSI. To minimize compaction, you want ideally to be around 10 PSI when in the field. Speaking of tires, making sure they are properly inflated is another key tip! Road inflation is usually at a much higher PSI than is needed in a field and is sometimes overlooked when entering a field. 

Another consideration is controlling traffic patterns in the field as much as possible. The first pass of a heavy implement usually causes 80% of the compaction, so limiting equipment to the same areas can minimize the overall compaction in the field. 

And finally, a healthy soil with good structure can resist compaction! Consider using cover crops and minimizing tillage to build up soil structure. Check out the Minnesota Office of Soil Health for tips on getting started:

A version of this article was originally published in the Dairy Star U of M Dairy Connection section on April 10, 2021 (page 29) and has been republished here with permission.


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