Wheat harvest is underway in parts of the state, and some farmers are planting double-crop soybeans. 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.
Both swine and dairy manure can be used to add moisture to newly planted soybean fields. 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 is also important that livestock producers know their soil phosphorus levels, 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 allow for incorporation.
If soybeans are just out of the ground, swine finishing manure will kill the emerging plants. For three years we applied swine finishing manure to early V3 soybeans at the Hoytville OARDC research farm and while the manure did not kill the soybeans or reduce yields, there was significant leaf burning. If you dragline manure on emerged soybeans, allow the plants to have three or four trifoliate to help with regrowth from the leaf burn. Drag hose research on soybeans showed no yield reduction at the V3 and V5 stages of growth. At the V7 stage, about 30% of the soybean plants were snapped at the soil level.
If manure is incorporated before planting double-crop soybeans be sure the manure salt and nitrogen are not placed in the planting zone. Placing the manure in contact with germinating seeds can result in severe emergence problems.
If red clover was frost seeded in the wheat, then 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 surface applying manure. Remember the “not greater than 50% chance of 0.5 inches of rainfall in the next 24 hours” rule in the Western Lake Erie Basin.