It will depend on soil and weather conditions, but particularly on coarse soils, it is a good idea to split apply your ammonium sulfate as follows:

• A first application in the fall to promote tillering before the wheat goes dormant – typically in a blend with phosphorus and potassium sources
• If fall tillering is poor for any reason, an early spring application of ammonium sulfate at green-up time may be in order
• The bulk of the nitrogen is often applied right before stem extension, typically as an ammonium sulfate and stabilized urea blend