Nitrogen is one of the key ingredients in any good crop fertilizer. The chemical enhances crop production for plants that take in the fertilizer, process it and release it back into the air. The trouble is that nitrogen from fertilizers not taken up in the air can end up in groundwater. This not only contributes to climate change, but can also be harmful to fish and other marine life. Too much nitrogen can also injure the crops themselves [sources: Nolte, van Vark].
Enter: GreenSeeker. The hand-held device as well as the boom-mounted version include an optical sensor that measures plant health so that farmers can use fertilizer efficiently. The sensor sends bursts of red and infrared light to the crops and measures the lights that the plants reflect back. The greater the light reading, the healthier the plant and the less need for fertilizer [sources: Trimble, van Vark].