Wheat fields will be harvested in Ohio over the next 10 days and many farmers will plant double-crop soybeans. In recent years there has been more interest from livestock producers in applying manure to newly planted soybeans to provide moisture to help get the crop emerged.
Both swine and dairy manure can be used to add moisture to newly planted soybeans. It’s important that the soybeans were properly covered with soil when planted to keep a barrier between the salt and nitrogen in the manure and the germinating soybean seed. It’s also important that livestock producers know their soil phosphorus levels, and the phosphorus in the manure being applied, so we don’t grow soil phosphorus levels beyond what is acceptable.
An acre-inch of water is 27,154 gallons. The application of 10,000 gallons per acre of dairy manure would be about 0.37 inches of moisture. The application of 7,000 gallons of swine manure would be about 0.26 inches of moisture. While we strongly encourage the incorporation of livestock manure whenever possible, the use of manure to help with double-crop soybean emergence does not really allow for incorporation.
If soybeans are emerged, swine finishing manure is likely to kill the emerged plants. Swine nursery manure and sow manure are unlikely to kill emerged soybeans.
If manure is incorporated prior to planting double-crop soybeans be sure the manure salt and nitrogen is not placed in the planting zone. Placing the manure in contact with germinating seeds can result in severe emergence problems.
As always, print out the weather forecast when surface applying manure. Remember the “not greater than 50% chance of 0.5 inches of rainfall in the next 24 hours” rule.