Note that with potassium nitrate, you get nitrate nitrogen, as well. This should be confirmed by looking at the oldest leaves on the stem. If they are light green, yellow or straw, then nitrogen is low. In the dead of winter, turf will respond best to nitrate fertilizer, rather than just ammonium sources. Therefore, your low-cost options include ammonium nitrate, calcium nitrate, potassium nitrate.
Iron deficiencies occur readily in the winter months.
Chelated compounds last longer, but are more expensive. Use the 'heads up' approach on start times when frosts occur. Under desert conditions, irrigation right at or after dawn may cause ice formation when the air is very cold, still and very dry. Activity on frozen turf is usually catastrophic. Don't roll incessantly to increase greens speeds, on a regular basis.