Fig. 3. Soil nitrate in fall after the third cut at three soil depths for low, moderate, and high fertilizer treatments. All sites shown were cut three times. Fertilizer amounts shown in the legend represent lb N per acre applied: at spring green-up – after first cut – after second cut.

Image from Forage and Grazinglands article:
Assessing Nitrogen Fertilization Needs for Irrigated Orchardgrass in the Intermountain Region of California