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To our knowledge, geographical information system (GIS)-based site-specific nitrogen management (SSNM) techniques have not been used to assess agricultural energy costs and efficiency. This chapter uses SSNM case studies for corn (Zea mays L.) grown in Missouri and cotton (Gossypium hirsutum L.) grown in Texas. In five case studies, the impact of SSNM will be compared with blanket N fertilizer recommendations. The five case studies are investigating (I) the impact N on energy produced in cotton production, (2) the impact of variable-rate N for cotton production based on soil nitrate and crop reflectance, (3) the feasibility of variable-rate N based on corn crop reflectance, (4) the use of corn management zones and crop reflectance for improving N recommendations and energy efficiency, and (5) the ability of using aerial photographs to improve N recommendations in corn.