Effect of nitrogen at planting on soft white winter wheat - 1998, Corvallis, Oregon

Methods
In October, 1997, three varieties of soft white winter wheat (Madsen, Rod, Stephens) were planted with and without fertilizer. Soil tests indicated approximately 40 lb NO3-N/acre and 5 lb NH4-N/acre in the surface foot of soil prior to planting. The previous crop was an oats cover crop, incorporated in early summer. The field was fallow during most of the summer. Plots with N at planting received nitrogen at a rate of 20 lb N/a drilled with the seed. Experimental design was a randomized complete block. All plots were topdressed with 150 lb N/a prior to jointing (Jan.30, 1998). The trial was affected by a wide range of diseases including barley yellow dwarf virus and fungal root diseases.

Results
None of the varieties responded to the nitrogen at planting. The high variability in the yield data (CV = 18%) was due to uneven disease pressure in the field. Response to nitrogen at planting is probably dependent on crop rotation, disease pressure, soil conditions, and climate. Therefore, this data cannot be generalized to all sites and all years. However, the data indicates that nitrogen fertilizer at planting is not always beneficial. Growers are encouraged to plant test strips with or without fertilizer at planting to determine needs on their own fields.

report prepared by Ernie Marx