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Systems and methods of determining nitrogen levels from a digital image and in-season nitrogen measurement and fertilization of non-leguminous crops from digital image analysis are disclosed. In particular, a method of determining leaf nitrogen concentration and yield from a digital photograph of a fully developed leaf (collared leaf) of a crop of non-legumes, such as corn, wheat, rice, cotton, potatoes sugarcane, turfgrass or forage grass species. The digital image is processed to determine a dark green color index ("DGCI"), which is closely related to leaf nitrogen concentration and yield. Standardized color disks having known DGCI values are included in the digital photograph and serve as an comparative standard. The comparative standard allows correction of DGCI of samples when using different cameras and/or when lighting conditions change. The DGCI values can then be used to determine the amount of nitrogen fertilizer that should be applied to recover crop yield potential.


Horticulture; Crop, Soil & Environmental Sciences

Patent Number


Application Number

US20130044919 A1

Application Published


Application Filed



Board of Trustees of the University of Arkansas (Little Rock, AR)


Larry C. Purcell, Department of Crop, Soil and Environmental Sciences

Upton G. Siddons, Department of Crop, Soil and Environmental Sciences

Douglas E. Karcher, Department of Horticulture

Robert L. Rorie, Department of Crop, Soil and Environmental Sciences