Sensor based nitrogen fertilization using NDVI (normalized difference vegetative index) has been shown to accurately predict nitrogen needs and allow for proper amounts of nitrogen fertilizer to be applied.  However, commercially available sensors are expensive and thus their use is limited, especially in developing countries where 70% of all nitrogen is applied.  An inexpensive ($200 USD) NDVI sensor prototype was evaluated at the International Maize and Wheat Improvement Center (CIMMYT) in Ciudad Obregon, Mexico during the 2010-2011 crop cycle.  Various versions of the sensor were evaluated in wheat and maize to see if the prototype sensor could be used with the same results as more expensive sensors.  In wheat and corn, the prototype sensors were highly correlated (r²=0.95) with NDVI readings taken with a GreenSeeker Sensor.  Based on this research, the prototype sensors could be used in developing and developed countries to make better fertilizer recommendations to improve farmer income and protect the environment.