With the combination of high corn yields, above average precipitation this year, we might see more response to fall nitrogen on our small grain crops. Fall is a good time to meet the phosphorus and potassium needs of the small grains and often some nitrogen is added in the process if using MAP or DAP as part of the program. A recent Maryland study found that economic responses to fall nitrogen are most likely when soil nitrate-N levels are below 10ppm following corn. They found no response to nitrogen following full-season soybeans.
When soil nitrate levels are less than 10ppm, emerging seedlings can sometimes exhibit nitrogen deficiency that can limit fall tiller development.
Our recommendations have been to apply up to 20 pounds of nitrogen and all of the phosphorus and potassium broadcast prior to planting, or to apply a portion with the drill and the remainder broadcast. To minimize fertilizer burn, do not apply more than 15 pounds (nitrogen) or 30 pounds (nitrogen + potash) per acre in the row with the seed.
It’s not that common to apply fertility with the seed here, but farmers and researchers in Ontario report responses of an average of 7.5 bushels per acre, using 50 to 100 pounds of MAP in the row with the seed. This idea may have a benefit on no-till wheat, which often lags a bit in development in high residue seedbeds. It may be especially beneficial in those late-plated fields with low to medium phosphorus levels. Last year we saw some responses to the old starter rows in no-till wheat and barley, and we suspect these crops would've responded well to some phosphorus with the seed.