Winter wheat in southern Indiana and Illinois is beginning to break dormancy and enter the spring regrowth phase and, as growth rates increase, so do nutrient demands of the developing crop. While a limited number of top-dress applications have taken place in southern parts of the Great Lakes region, recent rains and wet soils are limiting the opportunities for planned field operations. This has many wheat growers considering the best time for making a top-dress application to maximize benefit to the crop.
Information published by Charles Mansfield and Stephen Hawkins with Purdue University Extension suggests that nitrogen top-dress applications should be targeted for the early green up period as wheat comes out of dormancy when making a single application. On sandy soils, a split application may be beneficial to wheat development, with the second application planned near boot stage. When conditions prevent timely operations, nitrogen can be applied as late as heading, but yield will likely be limited due to nitrogen deficiency during vegetative growth stages.
Table 1. These recommendations are for mineral soils with adequate drainage and 1 to 5% organic matter, with wheat planted within 7 days after fly-free date last fall.
Wheat nutrient uptake demands in early spring are increasing at a time when temperatures are normally low, microbial activity is suppressed, and the soil has a limited capability for supplying nitrogen, sulfur and other key nutrients. Timely plant tissue analysis can be used to monitor the status of the crop and fine tune management decisions to maximize yields.