The summer manure application window following wheat harvest is typically the 2nd largest application window each year. 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 to emerge. While most fields have reasonable soil moisture today, the very hot weather could result in dry soil conditions by the time wheat is harvested.
Both swine and dairy manure can be used to add moisture to newly planted soybean fields. The soybeans must be properly covered with soil when planted to keep a barrier between the salt and nitrogen in the manure and the germinating soybean seed. It is also important that livestock producers know their soil phosphorus level, and the phosphorus in the manure being applied, so soil phosphorus levels are kept in an acceptable range.
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 just out of the ground, swine finishing manure and dairy manure will both kill the emerged plants. We applied swine finishing manure to early V3 soybeans at the Hoytville OARDC research farm for three years, and while the manure did not kill the soybeans, there was significant leaf burning.
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.
If red clover is frost-seeded in the wheat, young clover is easy to kill with a summer manure application. Livestock producers have told me stories of accidentally killing clover stands when applying manure to wheat stubble just after wheat harvest.
As always, print out the weather forecast when applying manure as part of the Fertilizer regulations in Ohio. Remember the “not greater than 50% chance of more than 0.5 inches of rainfall in the next 24 hours” rule in the Western Lake Erie Basin.