By Glen Arnold, CCA, Ohio State University Extension
Several livestock producers have inquired about applying liquid dairy or swine manure to newly planted wheat fields using a drag hose. The thought process is that the fields are firm (dry), there is very little rain in the nearby forecast, and the moisture in the manure could help with wheat germination and emergence.
The manure nutrients could easily replace the commercial fertilizer normally applied in advance of planting wheat. The application of fall-applied livestock manure to newly planted or growing crop can reduce nutrient losses compared to fall-applied manure without a growing crop.
Both swine and dairy manure can be used to add moisture to newly planted wheat. It’s important that the wheat seeds were properly covered with soil when planted to keep a barrier between the salt and nitrogen in the manure and the germinating wheat 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.
If the wheat is planted at its typical one-inch depth and swine or dairy manure is surface applied there should be no problem applying 5,000 gallons per acre of swine manure or 8,000 gallons per acre of dairy manure. If the wheat is emerging when manure is being applied, there is the possibility of some burn to the wheat from swine manure, but this has not happened in fields I have looked at in past years. If the wheat is fully emerged, there is little concern for burning.
If incorporating manure ahead of planting wheat, try to place the manure deep enough (at least three inches) so the manure does not impact the germination and emergence of the wheat crop. Another option is to incorporate the manure and wait a few days before planting the wheat. If incorporated, the opportunity to carry some of the manure nitrogen through the winter could allow for a reduction in the amount of topdress nitrogen needed for the wheat crop next spring.
The application of 5,000 gallons of swine finishing manure could contain 200 pounds of nitrogen, 100 pounds of P2O5 and 150 pounds of K2O. The application of 8,000 gallons of dairy manure could contain 175 pounds of nitrogen, 60 pounds of P2O5 and 150 pounds of K2O. Manure nutrient content can vary tremendously from one manure storage facility to another but stay reasonably consistent from the same facility year after year.
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 watershed. Also be certain to observe the proper setbacks from ditches and streams.