||The impact of roadway lighting on soybean plant growth and development was measured in situ at seven locations in the state of Illinois. The plant data collection included periodic height, reproductive stage, and Normalized Difference Vegetation Index (NDVI), as well as plant moisture content and dried seed weight after harvest. The periodic measurements were made at the same locations over time to determine delays in plant development. The impact of roadway lighting trespass was significant and measurable above thresholds of both horizontal and vertical illuminance as well as a combination of the two. A specification was drafted to minimize the impact of roadway lighting trespass on the soybean, and countermeasures were recommended to control the impact of lighting on the soybean.